Community level vulnerability of groundwater fluoride contamination and exposure by the application of multi-criteria model
Das K., Puppala H., Pandey G., Mondal M., Pathak P., Dey U., Chell S., Dutta S., Kumar P.
Article, Journal of Hazardous Materials Advances, 2025, DOI Link
View abstract ⏷
Elevated fluoride (F⁻) levels in groundwater, primarily due to geogenic processes, pose significant health risks, including dental and skeletal fluorosis and neurological disorders. This study aimed to quantify source-dependent F⁻ exposure at the community level in selected tropical dry regions of Andhra Pradesh, India. These locations include Chintal Cheruvu, Rompicharala, Shantamangalur, Thimmapur, and Nadendla. Community surveys and drinking water sample analyses were conducted in these regions. Dental Fluorosis Index (DFI) was used to estimate exposure levels across age and sex groups. Findings of surveys indicate that groundwater consumption with high F⁻ (4.3 mg/L) results in the highest exposure dose (0.62 mg/kg/day), with Chintal Cheruvu identified as the most affected. A strong positive correlation was observed between exposure dose, water F⁻ content, and the Community Fluorosis Index (CFI), with R² values of 0.98 and 0.97, respectively. Dental fluorosis prevalence exceeded 80% across all age groups, and household surveys revealed 100% unawareness of F⁻ exposure risks. Though there exist many ways to determine the impact of fluoride, the hierarchy of regions may change with the type of parameter chosen. To address this, we developed the Fluoride Impact Index (FII), a multi-criteria index computed considering various parameters indicating the impact of fluoride in a region. The magnitude of FII for Chintal Cheruvu is 0.563 which is highest among the considered regions indicating that it is most impacted region that needs remedial measures first in the hierarchy. Rompicharala with FII as 0.252, Nadendla (0.223), Shantamangalur (0.214), and Thimmapur (0.188) follows the hierarchy. These findings highlight the urgent need to raise awareness about F⁻ exposure risks and to identify sustainable alternative water sources. Immediate interventions, including human health risk assessments using the USEPA approach and the provision of safe drinking water, are critical to achieving SDG-6 of safe drinking water for all by 2030.
Assessing Different Tools Employed in Auto-segregation of Plastic Waste
Pankaj Kumar, Hephzi Jones, Pankaj Pathak, Surya Nikhil Mallampalli, Pavan Rahul Konathala, Pooja Vishali Vasireddy, Manasa Mugdha, Priyanka Singh
Book, Plastic Footprint: Global Issues, Impacts and Solutions, 2025, DOI Link
View abstract ⏷
Segregation and recycling of waste have been recognized to be vital for both economic and ecological reasons, with industries demanding high efficiency. However, current studies on automatic waste detection lack benchmarks and widely accepted standards, making comparisons difficult. This chapter addresses the issue by employing deep learning for waste classification into two categories: recyclable and non-recyclable materials. The dataset explained in this chapter has been compiled from various sources, ensuring a diverse representation of waste types. The garbage classification model is trained on the MobileNetV2 deep neural network architecture, enabling rapid and accurate classification of domestic waste. The model achieved an impressive 94% absolute accuracy, in 15 epochs, showcasing its efficiency and effectiveness. The applications of this research aim to provide better waste categorization and encourage more widespread recycling practices. By leveraging deep learning techniques, the proposed model streamlines the waste-sorting process, potentially saving substantial labor, material, and time costs associated with manual sorting. The development of efficient and accurate waste classification systems can significantly contribute to environmental sustainability efforts and promote a circular economy. The proposed waste classification model automates plastic segregation by making the process more efficient and faster.
Sustainable mitigation and management of segregated organic wastes: a socio-economic-environmental analysis for metropolitan cities
Dalia Carbonel, Gopa Nandikes, Nidhi Pandey, Yordin Garriazo, Mayhua Mary, Sara Orozco, Pankaj Pathak
Journal, Toxicological and Environmental Chemistry, 2025, DOI Link
View abstract ⏷
Organic waste upsurges with rapid urbanization and incessant population growth. To restrain this trend and lessen environmental impacts, sustainable management of food waste imposes an ambitious target of resource recovery and mitigating greenhouse gas emissions. This study quantifies environmental impacts and socio-economic benefits of municipal solid waste (MSW) management as a proof-of-concept case study for the Lima, Peru. Economic feasibility and life cycle assessment studies were used to compare the efficiency of segregated organic waste for scenarios such as landfilling and composting. Resource recovery, GHG emissions, and revenues are assessed to decide the environmental contour and downstream strategies. It was found that composting has less environmental impact in 11 out of 12 life cycle impact categories (ReCiPe method) during collection, processing, and distribution of 1 ton of waste as functional unit. Composting resulted in 40% less climate impact with global warming potential (GWP) of 476.20 kg CO2eq whereas landfilling showed 785.81 kg CO2eq GWP. Additionally, organic waste to compost conversion rate of 13%, can bring positive upshots to economy and society. This study is instrumental in MSW management, decision-making, and mitigate climate change in line with United Nations Sustainable Development Goals (UN-SDGs) for sustainable society.
Plastic Footprint: Global Issues, Impacts and Solutions
Pankaj Pathak, Sadia Ilyas, Rajiv R. Srivastava
Book, Plastic Footprint: Global Issues, Impacts and Solutions, 2025, DOI Link
View abstract ⏷
This book gives a broader framework of plastic pollution, which is a significant issue worldwide. The book emphasizes the primary (plastic waste discharged from the direct source) and secondary pollutants (plastic trash which is disposed of on land and converted to micro and nano plastics in ocean). In addition to this, the volume also addresses the issues of plastic pollution by managing plastic waste in a circular closed loop. The book is divided into three parts: (1) generation and assessment of plastic waste, (2) impact assessment of plastics due to improper management and disposal, (3) sustainable management of plastic waste and converting them into resource.
Preface
Pankaj Pathak, Sadia Ilyas, Rajiv R. Srivastava
Book, Plastic Footprint: Global Issues, Impacts and Solutions, 2025,
Plastic Utilization in the Modern Era: The Twenty-First Century
Hephzi Jones, Pankaj Pathak
Book, Plastic Footprint: Global Issues, Impacts and Solutions, 2025, DOI Link
View abstract ⏷
Plastics are among the greatest industrial innovations in the world, but their extensive use and improper disposal methods are making them more and more harmful to the environment and human health. Marine pollution, chemical contamination, biodiversity loss, and climate change are some of these repercussions. This calls for immediate action to address these pressing issues. Due to the enormous demand and frequent use, several nations are now affected by plastic waste that requires rapid attention and effective management strategies. Polymer pollution on terrestrial and aquatic is on the rise worldwide, highlighting the far-reaching consequences of plastic solid waste on both living and non-living elements of the ecosystem. Accordingly, in this chapter, we focus on the various applications of plastics, their disposal rates, and their impacts on the human environment. Furthermore, this chapter critically evaluates and suggests circular economy solutions to mitigate these impacts and contribute to achieving the sustainable development goals.
Selective Extraction of Cobalt and Lithium Phosphates from Spent LiCoO2 Cathode Cells: A TRL-4 Study on Process, Kinetics, and Techno-Economics
Sadia Ilyas, Rajiv Ranjan Srivastava, Pankaj Pathak
Journal, Industrial and Engineering Chemistry Research, 2025, DOI Link
View abstract ⏷
Lithium cobalt oxide (LiCoO2) cathodes, comprising 70% of global cobalt and over 1/4th of lithium production, are crucial for recycling to support a sustainable circular economy for critical metals. This study presents an industry-oriented recycling process at technology readiness level-4, involving phosphoric acid leaching of LiCoO2 cathodes. The process was optimized by using response surface methodology with a central composite design, examining five factors at three levels. The parameters, temperature, and concentrations of H3PO4 and H2O2 were identified as key factors influencing the selective leaching of lithium and precipitating >99% cobalt as Co3(PO4)2. The activation energy for lithium dissolution suggests that the leaching process follows an intermediate-controlled mechanism. Lithium was subsequently recovered as Li3PO4 by adding a 10% stoichiometric excess of Na3PO4 and adjusting the filtrate pH to above 12. The profitability of the recycling process is demonstrated by a 39.6% return on investment and a 9.7% internal rate of return.
Optimizing the photodegradation process of low-density polyethylene using Taguchi’s robust statistical design
Tejaswini, Pankaj Pathak
Journal, Next Materials, 2025, DOI Link
View abstract ⏷
The present study employs the Taguchi statistical design for optimizing the photodegradation process of low-density polyethylene (LDPE) films by varying five significant parameters i.e., catalyst loading (%), exposure time (in days), pH, size of the films (cm x cm), and temperature (℃), simultaneously to determine the maximum photodegradation on LDPE. The physiochemical, morphological, and molecular structural changes were observed in all-nanocomposite (LDPE and catalyst samples) before and after degradation. One way-ANOVA (Analysis of Variance) results demonstrated that catalyst loading, and exposure time were the most influential factors and contributed 65 % and 25 %, respectively to determine the degradation rate. Further, a kinetic study was performed to determine the photo-degradation rate, and it follows first-order photo-kinetics model. The maximum photodegradation was observed for that LDPE sample that was loaded with 12 % catalyst with a pH of 6 at 45°C that was exposed to the UV light for 10 days in a photoreactor, it degraded most efficiently with a weight loss of 16.25 %. Additionally, recyclability studies confirmed that stability and reusability of TiO2 as a photocatalyst for carrying out degradation experiments upto three consecutive cycles. Moreover, there is a high co-relation between predicted and experimental data with R2> 0.96, which demonstrates the effectiveness of the prediction with the maximum degradation of LDPE film.
Upcycling of Li-Ion Battery Recycling Residues to Graphene Oxide: Life Cycle Hotspots and Production Scale Impacts
Gopa Nandikes, Lalit Goswami, Seungdae Oh, Pankaj Pathak
Journal, ACS Sustainable Chemistry and Engineering, 2025, DOI Link
View abstract ⏷
The increasing production of Li-ion batteries (LIBs) for the green transition is underscored by the absence of feasible recycling methods for graphite, regardless of its criticality as a raw material. This study addresses the gap by using residual waste from spent LIBs recycling to synthesize graphite, which is then used as a precursor for graphene oxide (GO) synthesis. This circular approach offers environmental advantages over traditional methods that rely on natural (mined) or fossil-fuel-derived synthetic graphite. Despite the increasing industrial interest in GO, there remains a limited understanding of its production-related environmental impacts. Therefore, a life cycle assessment (LCA) is conducted using primary data sourced from laboratory experiments. Further, a prospective upscale LCA model is performed for a pilot (10 kg/batch) and hypothetical industrial scale (100 kg/batch) based on theoretical calculations and material balance. The results show a significant reduction in environmental impacts with increasing production scale. Sensitivity analysis further revealed that electricity use is the dominant factor influencing the environmental impact in laboratory-scale production, while chemical reagents become more significant contributors at larger scales. These findings highlight the importance of process optimization and the adoption of clean energy sources in GO manufacturing to minimize environmental impacts.
Material feasibility and environmental impacts of critical metals in NMC cathodes under a sustainable framework for electric vehicles
Nidhi Pandey, Gopa Nandikes, Pankaj Pathak, Sadia Ilyas, Rajiv Ranjan Srivastava
Journal, Sustainable Energy and Fuels, 2025, DOI Link
View abstract ⏷
The rapid growth of electric vehicles (EVs) emphasizes the urgent need for sustainable battery manufacturing practices, particularly in sourcing critical elements like lithium, nickel, manganese, and cobalt. This study employs a life cycle assessment approach to evaluate the environmental and energy impacts of recycling nickel-manganese-cobalt oxide (NMC) cathodes from spent lithium-ion batteries compared with those of the primary extraction of these metals from nickel lateritic ores. Lithium recycling is similarly assessed against conventional processing from spodumene ore. The results clearly indicate that recycling is the more sustainable option, offering higher yields with significantly lower energy demands and reduced environmental burdens. Specifically, the global warming potential associated with recycling 1 kg of NMC cells is 5.97 kg CO2-eq, compared with 109.9 kg CO2-eq for primary extraction to acquire a similar yield of metals. Additionally, the cumulative energy demand for primary extraction is 20-fold higher, requiring 1415.2 MJ compared to 70.5 MJ required for recycling for spent batteries. Moreover, sensitivity analysis reveals that the electricity mix plays a crucial role in shaping the environmental profile of recycling processes. Transitioning to cleaner, renewable energy sources could further reduce impacts across all evaluated categories. Overall, this study highlights the essential role of recycling in decreasing reliance on virgin raw materials, conserving finite mineral resources, and accelerating the shift toward a circular and sustainable battery economy.
Hydrometallurgical Recovery of Zinc from Municipal Solid Waste Incineration Fly Ash
Rajiv Ranjan Srivastava, Sadia Ilyas, Hyunjung Kim, Dilip Kumar Rajak, Pankaj Pathak, Yuti Desai, Vinay Kumar Singh
Book Series, Minerals, Metals and Materials Series, 2024, DOI Link
View abstract ⏷
The recoveryRecovery of heavy metals from municipal solid wasteMunicipal solid wasteincinerated fly ashIncinerated fly ash (MSW-IFA) before its final disposal is highly desirable for sustainableSustainable waste management and resource recoveryRecovery. RecyclingRecycling of zinc via leaching-solvent extractionSolvent extraction techniques has been studied, therefore yielding > 90% efficiency of zinc dissolution at a H2SO4 concentration of 1.5 mol/L, a temperature of 90 °C, a S/L ratio of 150 g/L, a time of 2 h, and a stirring speed of 300 rpm. Further, zinc was efficiently extracted using 0.6 mol/L D2EHPAD2EHPA at an equilibrium pH of 2.0 and an organic-to-aqueous phase ratio of 1. Finally, the highly pure zinc solution could be quantitatively stripped in a solution containing 1.5 mol/L H2SO4. This could lead to a circular economy of zinc with MSW-IFA as a possible secondary source.
Recycling Technologies and Resource Recovery from Plastic Waste
K. Hephzi Jones, Pankaj Pathak
Book, Valorization of Resources from Urban Mined Materials: World Scientific Series on Advances in Environmental Pollution Management - Volume 3, 2024, DOI Link
View abstract ⏷
Plastics have become one of the most integral parts of our day-to-day lives; however, after use, plastic waste accumulates on land and in water bodies, which wreaks havoc in the environment by releasing toxic gases. As the usage of plastic increases, it will result in the depletion of natural resources and greater difficulties in managing plastic waste. Accordingly, in this chapter, we focus on various types of resources, such as fuel, gas, energy, and electricity, which are recovered from plastic waste through different waste management technologies such as primary, secondary, tertiary, and quaternary recycling. This chapter is set forth by critically evaluating different types of plastic waste technologies, the products, and their byproducts formed during tertiary treatment. Material and resource recovery of different types of waste plastics through gasification and pyrolysis offers significant environmental benefits by promoting resource extraction and reducing the associated environmental impacts linked to the extraction process.
Valorization of Resources From Urban Mined Materials: World Scientific Series on Advances in Environmental Pollution Management – Volume 3
Dharmendra K. Gupta, Pankaj Pathak, Dheeraj Mittal
Book, Valorization of Resources from Urban Mined Materials: World Scientific Series on Advances in Environmental Pollution Management - Volume 3, 2024, DOI Link
View abstract ⏷
The manufacturing of recyclable products and an efficient recovery of resources such as chemicals, materials, and energy from waste streams are the key enablers of the circular economy. This book highlights the efficient management of waste into resources through the introduction of advanced technology able to convert waste into a secondary resource. It describes different technologies and urban mining tools used to recover materials from different types of waste. It also emphasizes that natural materials are limited though demand for the materials continues to increase, and how that demand can be sustainably fulfilled by secondary resources materials that come from urban mining.
Mesoporous LaFeO3 perovskite as an efficient and cost-effective oxygen reduction reaction catalyst in an air cathode microbial fuel cell
Gopa Nandikes, Pankaj Pathak, Karthikeyan, Abdulaziz A.M. Abahussain, Lakhveer Singh
Journal, International Journal of Hydrogen Energy, 2024, DOI Link
View abstract ⏷
Microbial fuel cells (MFCs) produce renewable energy from organic matter in presence of electrochemically active anaerobes at the anode and cathode oxygen reduction reaction (ORR). The ORR catalyst is pivotal for power generation and the overall cost of constructing an MFC. This study uses a synthesized novel LaFeO3 perovskite electrocatalyst as an alternative to the conventional Pt/C cathode catalyst which enhances ORR activity in a pH-neutral electrolyte. LaFeO3-based air cathode MFC produced 726.43 mWm−2 of maximum power density and is comparable to the commercial Pt/C catalyst i.e., 775 mWm−2. Furthermore, it has achieved 2.3 mAm−2 of the maximum current density and 556 mV of voltage. The improved catalytic activity of the synthesized LaFeO3 is associated with a large number of active sites, oxygen vacancies, and its mesoporous nature. Therefore, LaFeO3perovskite was able to catalyze ORR with an electron transfer of 3.8 in a neutral medium which is close to superior indirect four-electron pathways. It is highlighted that LaFeO3 perovskite iscost-effectiveand has comparable electrochemical properties with Pt/C which is evident in its scale-up potential of MFCs for green energy synthesis.
Techno-environmental analysis to valorize the secondary energy resources from refuse-derived fuel-based waste to energy plant
Harshit Patel, Tejaswini MSSR, Gopa Nandikes, Nidhi Pandey, Debleena Bhattacharya, Pankaj Pathak
Journal, Environmental Science and Pollution Research, 2024, DOI Link
View abstract ⏷
The present study quantifies the environmental and sustainability impacts associated with municipal solid waste management (MSWM) in India which plays a vital environmental issue in recent times. The upsurge in population has resulted in massive waste generation, leading to a concerning rise in the level of greenhouse gas (GHG) emissions. Therefore, the sustainable management of MSW has been discussed and highlights the conversion of MSW into refuse-derived fuel (RDF) to identify its potential for generating electricity in waste-to-energy (WtE) plants. The life cycle assessment (LCA) study has been done to identify and compare the environmental impacts associated with different scenarios (SC) as SC1: landfilling without energy recovery, SC2: open burning and SC3: processing of RDF in WtE plant by considering the nine impact categories from the inventory data obtained over a period of 12 consecutive months (Jan 2021–Jan 2022). The results exhibited that the global warming potential caused by emissions of GHG are in the order of SC1 (1188 kg CO2 eq) > SC2 (752 kg CO2 eq) > SC3 (332 kg CO2 eq), respectively from 1 t of MSW. It is concluded that the WtE plant can help in the reduction of environmental issues, strengthening the capacity of electricity generation and improving the aesthetic view of the city which is socially acceptable as well. Thus, WtE technology can help in achieving sustainable development goal 12 to regenerate the sustainable secondary resources for the twenty-first century and minimize global climate change. Graphical Abstract: (Figure presented.)
Sustainable Synthesis Strategies: A Comparative Life Cycle Perspective on LaFeO3 Nanoparticles
Gopa Nandikes, Nidhi Pandey, Pankaj Pathak, Lakhveer Singh
Journal, ACS Sustainable Chemistry and Engineering, 2024, DOI Link
View abstract ⏷
Perovskite oxides, particularly LaFeO3 (LFO), have gained significant attention due to their diverse applications in catalysis, energy storage, solar cells, and environmental remediation. However, the environmental impacts associated with their production remain largely unexplored. The present study demonstrates a comprehensive life cycle assessment (LCA) of experimentally synthesized LFO nanoparticles (NPs) by a hydrothermal method against 7 mainstream synthesis routes, focusing on their environmental and resource implications. The mass and specific surface area were kept as functional units in the cradle-to-gate LCA study that utilizes TRACI midpoint and ReCiPe end point methods to quantify the environmental impacts associated with LFO NPs synthesis routes and precursors. Key environmental indicators such as greenhouse gas (GHG) emissions, cumulative energy demand (CED), and health impacts are assessed using LCA methodologies. Furthermore, sensitivity analysis is conducted to identify critical factors influencing LCA and to prioritize areas for improvement in synthesis chemistry. It is revealed that green synthesis produced the highest environmental impact, with a global warming (GW) potential of 33.52 kg of CO2eq and ecotoxicity (ET) of 30.32 CTUe for 1 kg of LFO NPs. However, microwave, sonication and hydrothermal synthesis produced 38-52% less environmental impact compared to green synthesis. The experimental lab-scale inventory data and LCA analysis fill in the existing data gaps and aid future studies on the sustainable synthesis of LFO NPs and other ABO3 type perovskites for industrial settings.
Towards a low-emission resource circulation of valuable metals from municipal solid waste incineration fly ash
Rajiv Ranjan Srivastava, Gopa Nandikes, Sadia Ilyas, Pankaj Pathak, Dilip Kumar Rajak
Journal, Science of the Total Environment, 2024, DOI Link
View abstract ⏷
The incineration fly ash (IFA) resulting from municipal solid waste combustion is laden with heavy metals, necessitating proper treatment not only for environmental management but also to reclaim the metal values. The surge in non-traditional metals like cobalt as emerging contaminant within IFA samples further attracts to address this issue. In response, the hydrometallurgical recycling of a cobalt-bearing IFA has been studied. Thereby, approximately 98 % zinc and 96 % cobalt were leached using a 1.0 mol/L H2SO4 solution at 90 °C and 1 h of leaching time. In-depth analysis of the leaching process unveiled metals' dissolution primarily via the ion-exclusion mechanism, as evidenced by lower diffusion coefficients (between 10−9 and 10−11 m2/s) and activation energies (9.6–14.9 kJ/mol). Above 99 % separation of zinc from the cobalt-bearing leach liquor was achieved by extraction with 1.0 mol/L D2EHPA at an equilibrium pH below 3.0, followed by stripping with a 2.0 mol/L H2SO4 solution. Cobalt, remained in the raffinate was efficiently precipitated by adding a 20 % excess dosage of oxalic acid to the stoichiometric ratio of C2O42−:Co2+, resulting in only 5 mg/L cobalt left in the solution when precipitation occurred at a pH of 2.8. Additionally, the conversion of CoC2O4 to high-purity Co3O4 was conducted through heat-treatment at 600 °C. The resulting Co3O4 was mixed with Li2CO3 at a Li/Co molar ratio of 1.1, yielding a LiCoO2 precursor that exhibited good electrochemical properties with a capacity of 128 mAh/g, thus affirming the high quality of the recycled cobalt. A comprehensive life-cycle assessment of the recycling process revealed that cobalt precipitation alone contributes approximately 50 % of the total global warming potential (GWP = 4.2624 kg CO2-eq). Notably, this value is remarkably lower than the GWP reported for primary cobalt production, highlighting the environmentally-friendly approach of this recycling endeavor.
Unveiling microbial degradation of triclosan: Degradation mechanism, pathways, and catalyzing clean energy
Gopa Nandikes, Pankaj Pathak, Lakhveer Singh
Journal, Chemosphere, 2024, DOI Link
View abstract ⏷
Emerging organic contaminants present in the environment can be biodegraded in anodic biofilms of microbial fuel cells (MFCs). However, there is a notable gap existing in deducing the degradation mechanism, intermediate products, and the microbial communities involved in degradation of broad-spectrum antibiotic such as triclosan (TCS). Herein, the possible degradation of TCS is explored using TCS acclimatized biofilms in MFCs. 95% of 5 mgL−1 TCS are been biodegraded within 84 h with a chemical oxygen demand (COD) reduction of 62% in an acclimatized-MFC (A-MFC). The degradation of TCS resulted in 8 intermediate products including 2,4 -dichlorophenol which gets further mineralized within the system. Concurrently, the 16S rRNA V3–V4 sequencing revealed that there is a large shift in microbial communities after TCS acclimatization and MFC operation. Moreover, 30 dominant bacterial species (relative intensity >1%) are identified in the biofilm in which Sulfuricurvum kujiense, Halomonas phosphatis, Proteiniphilum acetatigens, and Azoarcus indigens significantly contribute to dihydroxylation, ring cleavage and dechlorination of TCS. Additionally, the MFC was able to produce 818 ± 20 mV voltage output with a maximum power density of 766.44 mWm−2. The antibacterial activity tests revealed that the biotoxicity of TCS drastically reduced in the MFC effluent, signifying the non-toxic nature of the degraded products. Hence, this work provides a proof−of−concept strategy for sustainable mitigation of TCS in wastewaters with enhanced bioelectricity generation.
Separation, Identification, and Quantification of Microplastics in Environmental Samples
Gopa Nandikes, Om Banerjee, Manaswini Mirthipati, Anitha Bhargavi, Hephzi Jones, Pankaj Pathak
Book Series, ACS Symposium Series, 2024, DOI Link
View abstract ⏷
Microplastics (MPs) are identified ubiquitously in various environmental compartments ranging from marine, freshwaters, sediments and terrestrial ecosystems including biotic components. Due to its smaller size (<5 mm), poor capture rate, and challenges in environmental removal, MPs contamination is a serious problem for the entire world. In the past decade, numerous techniques have been developed and put to use in order to track and measure MPs, identify the type of polymer, and characterise the particle’s shape, size and colour. The chapter provides an overview on the separation, identification and quantification procedures in MP analysis, with emphasis on potential ways ahead and remaining challenges. The analytical protocol largely varies with nature of MPs, its abundance and the type of environment sample. Additionally, advanced quantification techniques such as Pyrolysis coupled with Gas Chromatography-Mass Spectrometry (Py-GC-MS) and AI supported automated image analysis have been discussed. Therefore, standardization of MPs analytical techniques on the basis of the research aim will aid in obtaining a more comprehensive picture.
Exploring B-site Doping in LaFeO3 Perovskites for Superior ORR Performance in Acidic and Alkaline Conditions
Gopa Nandikes, Pankaj Pathak, Lakhveer Singh
Journal, ChemCatChem, 2024, DOI Link
View abstract ⏷
In recent times, perovskite oxides have recognized to be an ideal alternative to platinum-based oxygen reduction reaction (ORR) electrocatalysts due to their excellent stability, cost-effectiveness, and tailorable properties. Herein, an ABO3 type LaFeO3 perovskite was doped at its B-site to form electrochemically active LaFeB′O6 (B′=Cr, Zn, Co) by one-pot hydrothermal synthesis process. Due to the synergistic effects of increased surface area and electrochemically active sites, Cr-doped LaFeO3 largely improves the mass transfer kinetics for ORR in both conditions, alkaline (0.1 M KOH) and acidic (0.5 M H2SO4) with a positive onset Eon of 0.80 and 0.81 V (vs Ag/AgCl). Similarly, a half-wave (E1/2) potential of 0.68 and 0.63 V (vs Ag/AgCl), which was comparable to the commercial 20 % Pt/C. Moreover, the La-based perovskites were able to catalyze ORR with an electron transfer number (n)>3.6 signifying the superior 4-electron pathway. Doped and undoped LaFeO3 exhibited remarkable stability in the chronoamperometry studies with a relative current of 92–95 % sustained over 8 h. Additionally, the La-based electrocatalysts was unaffected by the crossover effect of methanol in both acidic and basic conditions, contrary to the commercial 20 % Pt/C. The present work serves as a useful strategy to maximize the efficiency and reliability in perovskites for energy-related electrocatalytic applications and for alternative fuel generation.
Challenges, Regulations, and Case Studies on Sustainable Management of Industrial Waste
Rajiv Ranjan Srivastava, Dilip Kumar Rajak, Sadia Ilyas, Hyunjung Kim, Pankaj Pathak
Journal, Minerals, 2023, DOI Link
View abstract ⏷
Incessant generation and mismanagement of industrial waste, resource scarcity, and environmental degradation have created non-sustainability in human life. Though industrial wastes are hazardous or non-hazardous in nature based on their source, open dumping disposal is commonly done for both types of waste. The adversity associated with waste enhances the environmental and health impacts. However, this waste has the potential to recycle and minimize resource scarcity. The circular economy works on the concept of reuse, recycling, and recovery to convert waste into a resource. Thus, industrial waste can benefit the environment and economic growth to build industrial ecology. However, the opportunities and challenges associated with industrial ecology for the reuse and recycling of waste have to be identified and preserved. Therefore, this study has identified challenges associated with waste, analyzed their impact, and industrial regulations, prioritized their criticality, and developed solution strategies to alleviate them. Two case studies on industrial byproducts, i.e., fly ash and red mud, based on different income groups are discussed in this study. It highlights the circular economy has minimized waste generation and enhanced the recovery of secondary resource materials. In addition, this study supports achieving the sustainable development goals (SDGs) 11 and 12 to build a sustainable industrial ecosystem.
A novel circular approach to analyze the challenges associated with micro-nano plastics and their sustainable remediation techniques
Tejaswini Mssr, Pankaj Pathak, Lakhveer Singh, Deep Raj, Gupta
Journal, Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering, 2023, DOI Link
View abstract ⏷
The mismanagement of consumer-discarded plastic waste (CDPW) has raised global environmental concerns about climate change. The COVID-19 outbreak has generated ∼1.6 million tons of plastic waste per day in the form of personal protective equipment (masks, gloves, face shields, and sanitizer bottles). These plastic wastes are either combustible or openly dumped in aquatic and terrestrial environments. Open dumping upsurges emerging contaminants like micro-nano plastics (MNPs) that directly enter the ecosystem and cause severe impacts on flora and fauna. Therefore, it has become an utmost priority to determine sustainable technologies that can degrade or treat MNPs from the environment. The present review assesses the sources and impacts of MNPs, various challenges, and issues associated with their remediation techniques. Accordingly, a novel sustainable circular model is recommended to increase the degradation efficiency of MNPs using biochemical and biological methods. It is also concluded that the proposed model does not only overcome environmental issues but also provides a sustainable secondary resource to meet the sustainable development goals (SDGs).
Anthropogenic Environmental Hazards: Compensation and Mitigation
Pankaj Pathak, Rajiv Ranjan Srivastava, Sadia Ilyas
Book, Anthropogenic Environmental Hazards: Compensation and Mitigation, 2023, DOI Link
View abstract ⏷
This book delves into the anthropogenic activities responsible for environmental hazards, their compensation, and potential mitigation strategies. It sheds light on the major contributors to the climate change issues aggravated by non-sustainable practices for the overexploitation of natural resources. Critical topics such as high emissions in primary mining, the recovery of energy-critical metals by urban mining, solid waste management, and forest conservation are explored, offering insights into the urgent challenges we face. Amidst the rapid demand for resources and the expansion of human habitats, the book emphasizes the need for new approaches to natural resource management and introspection of our actions. Experts in the field discuss existing anthropogenic environmental hazards in detail, alongside environmental compensation, and effective mitigation approaches. The book begins with a chapter dedicated to risk assessment in primary mining activities for precious metals, proposing potential routes for mitigation. Chapter 2 focuses on assessing and mitigating the environmental footprints of energy-critical metals used in permanent magnets. In Chapter 3, a case study examines sustainable resource utilization through end-of-life room air conditioner recycling. Additional chapters provide critical insights into: The environmental impacts of e-waste and government policies for responsible management Hazards associated with industrial effluents and corresponding mitigation strategies The role of roadside plants in phytoremediation of heavy metal pollution Sustainable utilization of anthropogenic coal fly ash through mechanical and chemical activation Environmental damages resulting from the mismanagement of municipal solid waste Environmental problems and remediation strategies for anthropogenic biomass waste Challenges in sustainable municipal solid waste management and suggestionsfor environmental risk mitigation The book concludes with a chapter discussing collaborative governance and non-monetary compensation mechanisms for sustainable forest management. Given its breadth, this book serves as an indispensable resource for researchers, policymakers, and environmental professionals seeking sustainable approaches to tackle pressing environmental challenges.
Risk Assessment from Primary Mining of Precious Metal (Gold) and Possible Mitigation Route
Sadia Ilyas, Hyunjung Kim, Pankaj Pathak, Rajiv Ranjan Srivastava
Book, Anthropogenic Environmental Hazards: Compensation and Mitigation, 2023, DOI Link
View abstract ⏷
Mining is an important activity at the present time that causes severe environmental stress. The heavy metals (metalloids) easily released into the environment, surface water and groundwater contamination, and soil and air pollution are also potential risks to human health. Due to the stringent environmental rules and global thirst for achieving Sustainable Development Goals, human negligence cannot be affordable in the long run. It is time to recognize the need for people connected with safe and sustainable mining activities of lucrative precious metals like gold. Therefore, in this chapter, we assess the risks caused by the primary mining of gold and discuss mitigation routes involving various factors.
Preface
Pankaj Pathak, Rajiv Ranjan Srivastava, Sadia Ilyas
Book, Anthropogenic Environmental Hazards: Compensation and Mitigation, 2023,
Environmental Impacts and Government Policies for Responsible Management of E-Waste
Nidhi Pandey, Pankaj Pathak
Book, Anthropogenic Environmental Hazards: Compensation and Mitigation, 2023, DOI Link
View abstract ⏷
The exponential advancement of technology, along with our demanding consumption habits, has ended up in an alarming growth in electronic waste (e-waste) creation, posing a severe environmental risk. This chapter highlights the environmental implications of e-waste as well as government attempts to promote responsible waste management, sustainable consumption, and separation of raw materials from these wastes. Dangerous chemicals, including Hg, Pb, and Cd, along with brominated flame retardants (BFRs) are released into the atmosphere during illegal disposal or informal recycling of e-waste, eventually building up in our ecosystem and disrupting the normal ecological cycle. It results in heavy metal contamination in the soil and water, emissions in the air, as well as negative impacts on human lives such as reproductive abnormalities and respiratory disease. The government policy like extended producer responsibility (EPR) implementation frameworks emphasize the collection and recycling systems and promote the sus-tainable waste management practices. EPR requires producers to take responsibility for their goods complete life cycle, including proper disposal and recycling. Collab-oration among governments, manufacturers, consumers, and recycling sectors is required to manage e-waste effectively. Thus, environmental risks can be reduced by adopting ecosystem-friendly practices in sustainable e-waste management and nurturing a circular economy.
Techno-Economic Evaluation of Waste To Energy (WtE) Plant
Harshit T. Patel, Debleena Bhattacharya, Pankaj Pathak
Conference Proceeding, IEEE Region 10 Humanitarian Technology Conference, R10-HTC, 2023, DOI Link
View abstract ⏷
Human activities inevitably results in waste. Generated Municipal solid waste (MSW) simply collected and dumped which causes environmental problems and health hazards. Refuse Derived Fuel (RDF) - A bio-fuel obtained from dry residue of waste. Conversion of MSW to RDF substitutes fossil fuels, reduces burden of land filling, reduction in emission, volume reduction of MSW, hygiene etc. Waste to Energy (WtE) plant evaluated by plant visit, data collection, sample collection and literature review. Detailed analysis has been carried out of MSW, RDF, Fly Ash, Bottom Ash and stack emission sample. MSW processed by mechanical processes as manual segregation, splitting, shredding, magnetic separation and air density separation to prepare RDF which shows upgradation in properties for utilization as fuel. 1 MT of MSW processed to yield RDF 0.6-0.65 MT. Characteristics of RDF shows calorific value-2684 kcal/kg, moisture content-26 % and ash content-24 %. WtE plant designed to process 400 TPD MSW to generate power at 9 MWH rating. The company has signed a power purchase agreement at INR 7.07/kw. Cost benefit analysis carried out considering capital investment, term loan, interest rate, manpower cost, raw material cost, fixed cost, processing cost etc. Comparison of strengths and opportunities with weakness and threats in (SWOT) analysis makes project interesting in waste management and energy sector. The economic evaluation shows Cost Benefit ratio (CBR)- 1.83, Internal Rate of Return (IRR)- 13.09 % and Net Present Value (NPV)- 9.41 crore which means project is viable and positive. Results from this study will support policy makers and local authorities to decide, design and develop approaches for resource and energy recovery from MSW.
Hydrometallurgical recycling of critical metals from spent Ni-Cd batteries with emphasis on the separation of Cd2+ over Ni2+ using D2EHPA
Pankaj Pathak, Nidhi Pandey
Journal, Geosystem Engineering, 2023, DOI Link
View abstract ⏷
The present study is comprised of a hydrometallurgical process investigated for the recovery of critical metals viz. nickel (Ni) and cadmium (Cd) from spent Ni-Cd batteries with a focus on solvent extraction of Cd-ions. The leaching performed at 5 (w/v)% pulp density using 2.0 M H2SO4 with 7 (v/v)% H2O2 for 6 h duration at 90°C yielded the maximum leaching efficiency of >91% Ni and >99% Cd along with a significant quantity of Fe (>87%). Iron was subjected to hydrolytic precipitation to its complete removal (below 10 ppm in the solution) from the leach liquor at a pH of ~3.5. After that, the Ni-Cd-containing solution was contacted with di-(2-ethylhexyl) phosphoric acid (D2EHPA) to study the extraction behavior as a function of extractant concentration, equilibrium pH, and organic-to-aqueous (O:A) phase ratio. At an equilibrium pH of 3.3, a significant quantity of Ni (>18%) was co-extracted with ~73% Cd by contacting 20 (v/v)% D2EHPA, which was completely scrubbed by contacting 15 g/L CdSO4 solution at an O:A ratio of 2. The scrubbed organic containing 14.4 g/L Cd was then recovered by stripping with 1.5 M H2SO4 solution at an O:A ratio of 1, yielding >99% Cd into the aqueous phase. Further, Ni was recovered from the raffinate by adding soda ash at Na2CO3:Ni2+ ratio = 2.5, temperature = 50°C, and time = 1 h, which was analyzed to be NiCO3.2Ni(OH)2 with purity >99.9%. The experimental results showed the potential of hydrometallurgical tools for the recovery of critical metals from spent Ni-Cd batteries.
Cathodic Catalysts for Microbial Electrolysis Cell to Produce Biohydrogen
Gopa Nandikes, Pankaj Pathak, Lakhveer Singh
Book Series, ACS Symposium Series, 2023, DOI Link
View abstract ⏷
Renewable Energy Solutions for Fueling the Future. Green hydrogen, which is produced by using renewably generated electricity that splits water molecules into hydrogen and oxygen, holds significant promise to meet global energy demand while contributing to climate action goals. Currently, the production of green hydrogen is not yet economical or efficient enough. The key to solving this problem is through the development of innovative electrocatalysts. This book reviews recent research and perspectives on these essential areas of focus and provides must-have information for moving new research in green energy forward.
Preface
Pankaj Pathak, Lakhveer Singh
Book Series, ACS Symposium Series, 2023, DOI Link
Co-combustion of multilayered plastic waste blend with biomass: Thermokinetics and synergistic effect
Tejaswini, Pankaj Pathak
Journal, Fuel, 2023, DOI Link
View abstract ⏷
Improper management of inert plastic waste causes severe threats to the environment and leads to global climate change. The thermochemical combustion process adequately converts the plastic waste into a potential energy resource as refuse-derived fuel (RDF), however, to get maximum energy yield, it is required to optimize the combustion process. Therefore, the physio-chemical and thermal characteristics of multilayer plastics (MLPs) and their blends with different biomass are determined under non-isothermal conditions. Five representative samples S1 to S5 which includes MLPs and their blend with biomass were selected for this study. Thermogravimetric analysis was used to perform the combustion process with temperatures ranging from 30 °C to 1000 °C. It is noted that sample S1 has 77.87 % volatile matter, 8.30 % ash content, and 0.01 % sulfur and shows a higher energy potential of 27.10 MJ/kg with minimum environmental emissions, demonstrating good agreement with the RDF I category. Thermo-kinetic parameters using the Coates-Redfern integral method demonstrated that the co-combustion follows a diffusion–reaction mechanism. The sequence of activation energy (Ea) and Gibbs energy (ΔG) follows in the order of S4 > S5 > S1 > S2 > S3. Moreover, the maximum Ea and ΔG required for the decomposition of these samples are in the range of 101–142 kJ/mol and 115–120 kJ/mol, respectively. It is concluded that the optimized S1 sample shows similar characteristics to conventional fuels and can be directly co-processed in cement industries or waste-to-energy plants. The obtained results can help in modeling and designing the thermochemical reactor for bench-scale operations.
Circular transformation in plastic management lessens the carbon footprint of the plastic industry
Pathak, Sharma, Ramakrishna
Journal, Materials Today Sustainability, 2023, DOI Link
View abstract ⏷
Improper management of plastics showed a significant impact on climate change and biodiversity loss. Around 400 million tonnes of plastic waste (PW) have been generated so far and are projected to be doubled by 2040. Despite having plastic management rules worldwide, only 12% of PW is recycled and reused and the remaining waste directly enters the terrestrial and aquatic environment, leading to plastic pollution. It is noted that ∼1.7 GT of greenhouse gases releases into the environment during the production and incineration stages of plastics, demonstrating a higher carbon footprint and leading to climate change. To overcome these issues, it is mandatory to curtail single-use plastics from everyday use and enhance the recycling option from the production to disposal stages, bringing circularity to the plastic industry. This paper recommends limiting the use of virgin plastics from fossil carbon and endorsing recycling and reusing PW as a secondary resource that can minimize the ∼3.0 kg CO2 emission per kg of plastics. Further, to promote a low-carbon economy in the plastic manufacturing process, the CO2 feedstock from fossil carbon can also be replaced by direct carbon capture and storage processes such as the power to x technology. This paper advocates setting up stepping milestones for a circular transformation in plastic industries that can reduce the carbon footprint by 25% and fulfill the target of the United Nations Sustainable Development Goals.
Comprehensive technological assessment for different treatment methods of leather tannery wastewater
Mohit Nigam, Puranjan Mishra, Pradeep Kumar, Sunil Rajoriya, Pankaj Pathak, Shraddha Rani Singh, Smita Kumar, Lakhveer Singh
Journal, Environmental Science and Pollution Research, 2023, DOI Link
View abstract ⏷
Abstract: The leather-making process necessitates large amounts of water and consequently generates tons of liquid waste as leather tannery wastewater (TWW) is disposed of directly in the open environment. Open disposal of untreated TWW into the natural environment causes an accumulation of various polluting compounds, including heavy metals, dyes, suspended solids inorganic matter, biocides, oils, tannins, and other toxic chemicals. It thus poses potential hazards to the environment and human health. This study primarily focuses on providing in-depth insight into the characteristics, treatment strategies, and regulatory frameworks for managing TWW in leather processing industries. Different technologies of conventional physico-chemical (equalization, coagulation, and adsorption), advanced approaches (Fenton oxidation, ozonation, cavitation), thermo-catalytic and biological treatments available to treat TWW, and their integrative approaches were also highlighted. This review also sheds light on the most frequently applied technologies to reduce contaminant load from TWW though there are several limitations associated with it such as being ineffective for large quantities of TWW, waste generation during treatment, and high operational and maintenance (O&M) costs. It is concluded that the sustainable alternatives applied in the current TWW technologies can minimize O&M costs and recirculate the treated water in the environment. The exhaustive observations and recommendations presented in this article are helpful in the industry to manage TWW and recirculate the water in a sustainable manner. Graphical abstract: [Figure not available: see fulltext.]
Quantification of environmental impacts associated with municipal solid waste management in Rajkot city, India using Life Cycle Assessment
Yash Pujara, Janki Govani, Harshit T. Patel, Pankaj Pathak, Deepak Mashru, P. Sankar Ganesh
Journal, Environmental Advances, 2023, DOI Link
View abstract ⏷
This study quantifies the environmental impacts associated with municipal solid waste management (MSWM) in Rajkot city, India using the life cycle assessment (LCA). Presently, around 0.2 million tonnes of municipal solid waste (MSW) is generated annually in Rajkot city and non-segregated MSW is preferably sent to open dumping. However, 70‒80% of the total cost of MSWM is employed in the collection and transportation which is sent to a centralized material recovery facility (MRF). Accordingly, the research hypothesis is built-up focusing on the current practice of MSWM to develop an environmentally sound and economical practice. Henceforth, four integrated scenarios (SC) comprise (i) SC1– open dumping of MSWM; (ii) SC2– a combination of anaerobic digestion (AD), composting, incineration, landfilling without energy recovery, and MRF; (iii) SC3– a combination of AD, composting, incineration, landfilling with energy recovery, and MRF, and (iv) SC4– a combination of AD, composting, landfilling with energy recovery, and MRF is examined using the LCA. The results exhibit the environmental impacts due to the potential emissions of greenhouse gases of tested scenarios following the subsequent order; SC1 (17600 kg CO2eq) > SC2 (1500 kg CO2eq) >> SC3 (511 kg CO2eq) >>> SC4 (285 kg CO2eq). Based on the results analysis, mandatory source segregation along with decentralized MRF is highly recommended where waste is converted as secondary resource materials. This study highlights the suitability for sustainable management of MSW for middle-income Indian cities and helps to achieve the targets of sustainable development goals.
In-situ photocatalytic degradation of low-density polyethylene: A pathway towards eco-sustainability and circular economy
Tejaswini, Pankaj Pathak
Journal, Sustainable Chemistry and Pharmacy, 2023, DOI Link
View abstract ⏷
The present study demonstrates the accelerated rate of photo-degradation in low-density polyethylene (LDPE) films using nanomaterials like titanium dioxide (TiO2) in a photochemical reactor, an efficient, environmentally benign, and sustainable chemical. The effect of various parameters such as source of light, catalyst loading, pH, and temperature was investigated to achieve maximum degradation on a laboratory scale. The surface morphology with molecular and chemical structure changes in the nanocomposite films was monitored before and after degradation using various analytical techniques. It is found that the degradation reaction rate is greatly affected by pH and temperature and follows the first-order photo-thermal kinetics reactions. The calculated activation energies for the different properties range from 77.6 kJ/mol for carbonyl group formation to 55 kJ/mol for vinyl group formation at an optimum pH of 4 and temperature of 30 °C, respectively. The optimized sample's storage modulus (Esm) increased from 17.76 to 210 MPa, demonstrating the loss of tensile strength after irradiation and increased elasticity. Thus, it clearly demonstrated that the LDPE sample loaded with 12% catalyst and exposed to 288 h at pH 4 and 30 °C temperature degraded most efficiently with 6.25% weight loss. In addition, there is a high correlation between the area of degradation and carbonyl index with R2 > 0.96, which helps in validating the fact that during the degradation process, there is volatilization of degradation products that leads to the formation of 0.523 mm (in length) of holes (microscopic analysis). This study brings new insights into reducing plastic pollution by minimizing waste prevention and generation at the source by promoting the usage of intermediates (formed during degradation) as a secondary material for producing new plastic products.
Application of Taguchi method in activated carbon adsorption process of phenol removal from ceramic gasifier wastewater
Jagniyant Lunagariya, Karan Chabhadiya, Pankaj Pathak, Deepak Mashru
Journal, Environmental Challenges, 2022, DOI Link
View abstract ⏷
Ceramic gasifier wastewater (CGWW) contains organic toxic substances such as phenolic compounds and direct disposal of CGWW into the ground and surface water causes severe environmental impacts. Therefore, phenol removal from CGWW is utmost important to safeguard the natural water resources. Adsorption technique using activated carbon is employed to lessen the impacts of phenol. However, the pollution load on CGWW is very high and necessitates pretreatment using coagulation-flocculation process. Further, the sanctity of each parameter on phenol removal has to study by varying all-dominating parameters simultaneously and determined its significance. Therefore, Taguchi's L9 orthogonal array (OA) design is used in this study to optimize the carbon adsorption process on CGWW. The most governing parameters are time (30−60 min), temperature (30−60 °C) and liquid to solid, L/S (5−15) ratio and it is prioritized in the following order L/S>Temperature>Time. The optimized experimental conditions, i.e., time 30 min., temperature 45 °C at L/S 5 was predicted and that demonstrated 96% phenol removal from CGWW. The predicted results of Taguchi's OA is compared with an experimental analysis showed a good agreement (R2 > 0.97) with each other and vital significance. Accordingly, it is concluded that the Taguchi method is a promising, efficient, and cost-effective technique for the industry to minimize the experiments and maximize the phenol removing efficiency.
Microbial Polyhydroxyalkanoates (PHAs): A Brief Overview of Their Features, Synthesis, and Agro-Industrial Applications
Lavanya Addagada, Pankaj Pathak, Muhammad Kashif Shahid, Prangya Ranjan Rout
Book, Advances in Agricultural and Industrial Microbiology: Volume 1: Microbial Diversity and Application in Agroindustry, 2022, DOI Link
View abstract ⏷
Polyhydroxyalkanoates (PHAs) are biopolymeric intracellular inclusions that serve as carbon and energy storage compounds for diversified microorganisms. PHAs are synthesized by a variety of bacterial strains such as Alcaligenes latus, Azotobacter vinelandii, Pseudomonas sp., and Escherichia coli under limited oxygen but sufficient availability of carbon source. Rubber-like nature along with biocompatibility, biodegradability, eco-friendly, renewable, and biological production features make the PHAs as promising alternatives to synthetic plastics which can mitigate plastic-waste disposal mediated environmental pollutions. However, carbon source requirement driven high production cost and low yield limit the large-scale production of bioplastics and so as to its wider applications. For minimization of production cost, many researchers focused on utilization of waste/by-product based carbon sources for PHA biosynthesis. On the other hand, several other researchers emphasized on the exploitation of genetically engineered microbes and plants to address the low yield issues. Consequently, these attempts of improvements will be helpful in making the bioplastics more competitive than the conventional ones in long run. In addition to their common use as bioplastic, PHAs are widely used in various fields, including medical, pharmaceutical, agro-industries, textiles, households, etc. This chapter provides an overview of classification, structural components and properties of microbial PHAs, progresses in PHA biosynthesis, highlighting different biosynthetic pathways, role of various substrates, microorganisms, and experimental parameters on PHA biosynthesis. Recent advancements in enhancing the physico-chemical properties of PHAs and trends in agro-industrial applications of PHAs have also been discussed. Futuristic approaches to overcome the challenges associated with the yield and improved mechanical properties of PHA are also recommended in this chapter.
Recycling of Rechargeable Batteries: A Sustainable Tool for Urban Mining
Pankaj Pathak, Karan Chabhadiya
Book, Handbook of Solid Waste Management: Sustainability through Circular Economy, 2022, DOI Link
View abstract ⏷
Renewable energy, by means of energy capture, storage, and transmission, is able to fulfil the catastrophic energy demand worldwide but requires suitable storage devises. Rechargeable batteries are prominent to do so. However, based on the capability of energy storage, Ni-Cd, Pb-acid, and Li-ion batteries are the most important and remained in wider use among others. Therefore, a large number of batteries is being spent after completion of their life span, and this needed to be handled in proper manner. The landfill disposal may cause severe environmental problems like soil, ground, and water pollution with the hazardous and toxic contents therein (like Cd, Ni, Co, KCl). Additionally, such kind of disposal is a huge loss of resources as to the criticality and strategic importance of these metals due to their crustal abundance and geopolitical scenario. Efficient recycling of spent batteries can lead toward the sustainable solution of this problem via conservation of primary ores by recovery of metals, waste minimization, and recycling. Recycling of spent battery is in trend and has been a global topic for environmentalists and metallurgists. Several research works have been done that clearly indicate the economic and environmental interests in this area. Therefore, we attempt, in this chapter, to investigate and discuss the recycling processes for the extraction, separation, and recovery of metals from not only a technological perspective but also the related environmental issues.
Electronic waste: An emerging contaminant in the geo-environment
Pankaj Pathak, Kumar Sushil
Book, Emerging Contaminants in the Environment: Challenges and Sustainable Practices, 2022, DOI Link
View abstract ⏷
Electrical and electronic equipment (EEEs) has made our life easy and comfortable, but after its end of life, it becomes electronic waste (e-waste). The e-waste comprises metals and organic and inorganic materials, wherein some of the material present in the EEEs are toxic and hazardous and turn out to be an emerging contaminant in the geo-environment. However, some materials have economic value, and if it is recycled and recovered appropriately (scientifically), it could be used as a secondary resource in the sustainable world. Several studies have been conducted for the safe management and handling of e-waste and have demonstrated that e-waste could act as a boon or a curse, depending on how it has been handled. Therefore, this chapter introduces the global perspective of e-waste and its different types, the environmental and health effects of e-waste, and its management.
A comprehensive review on integrative approach for sustainable management of plastic waste and its associated externalities
Tejaswini, Pankaj Pathak, Seeram Ramkrishna, P. Sankar Ganesh
Journal, Science of the Total Environment, 2022, DOI Link
View abstract ⏷
The management of post-consumer discarded plastic wastes (PCPW) creates new challenges in developing countries due to the lack of amenities, technological interventions, and associated negative environmental externalities. The fate of untreated recyclable and non-recyclable plastic wastes lies in open dumping along with other solid waste, and improper management leads to environmental externalities such as pollution, global climate change, and health issues. Additionally, open dumping upsurges the emerging microplastics and nano plastics (MNPs) contaminants. The externalities depend on the waste generating sources (household, industries, commercial), waste composition, and its characteristics. However, urban mining can minimize environmental externalities where waste plastics can convert into potential anthropogenic resources and also helps in achieving the target of sustainable development goals (SDGs 11 & 12). Moreover, various treatment technologies that help in the sustainable utilization of plastic wastes are extensively reviewed in this study and evaluate the costs benefits arising during various stages of treating plastic waste through recycling (R), incineration (I), and landfilling (L). The recycling of plastic waste has demonstrated the lowest impact on global warming potential (GWP) and total energy use (TEU), followed by landfilling and incineration (R < L < I). Nevertheless, when energy is recovered from inert (non-recyclable) plastic waste in the form of fuel or by its utilization in construction purposes, the environmental impacts are more negligible (Incineration < Landfilling). Therefore, this study determines the significance of circular economy with legislative approach and standards on plastic waste management, which help in reducing environmental externalities besides yielding a secondary resource as energy and materials through urban mining. A sustainable plastic waste management (SPWM) model is proposed for developing countries to convert plastic waste into resources and use it as a sustainable tool in urban mining.
Occurrence, environmental risks and biological remediation mechanisms of Triclosan in wastewaters: Challenges and perspectives
Gopa Nandikes, Pankaj Pathak, Abdul SyukorAbd Razak, Vigneswaran Narayanamurthy, Lakhveer Singh
Journal, Journal of Water Process Engineering, 2022, DOI Link
View abstract ⏷
Triclosan (TCS) is an antimicrobial agent used widely in pharmaceutical and personal care products (PPCPs). The extensive use of TCS in PPCPs has increased over the past few decades and its sizeable production and consumption are causing adverse effects on the environment and humans. TCS has been made into the list of emerging micropollutants (EMPs) due to its omnipresence in water resources, and even in biological samples such as urine and breast milk. Therefore, it is imperative not only to understand the current status of TCS pollution, but their occurrence, exposure routes, and environmental risks to identify remediation technologies for mitigating TCS. Present review targets to provide the cumulative data on the abundance of emerging TCS in water resources and its associated health burdens, simultaneously. It is identified that TCS remediation can be achieved through advanced physical and chemical methods such as enzyme oxidation and ozonation. However, there are drawbacks such as high energy consumption and the formation of toxic by-products. Therefore, the article endeavors to provide an in-depth understanding of the biological remediation of TCS by microbial degraders as well as its superiority over other remediation techniques. Insights into the various microbial communities such as bacteria, algae, and fungi and their unique bioremediation mechanisms are comprehensively summarised. Moreover, challenges associated with existing bioremediation methods and future perspectives are also discussed in the present work.
Sustainable approach for valorization of solid wastes as a secondary resource through urban mining
Tejaswini, Pankaj Pathak, Gupta
Journal, Journal of Environmental Management, 2022, DOI Link
View abstract ⏷
The incessant population has increased the production and consumption of plastics, paper, metals, and organic materials, which are discarded as solid waste after their end of life. The accumulation of these wastes has created growing concerns all over the world. However, conventional methods of solid waste management i.e., direct combustion and landfilling have caused several negative impacts on the environment (releasing toxic chemicals and greenhouse gases, huge land use) besides affecting human health. Therefore, it is requisite to determine sustainable alternative technologies that not only help in mitigating environmental issues but also increase the economic value of the discarded solid wastes. This process is known as urban mining where waste is converted into secondary resources and thereby conserves the natural primary resources. Thus, this review highlights the technological advancements in the valorization process of discarded wastes and their sustainable utilization. We also discussed several limitations of the existing urban mining processes and further the feasibility of valorization techniques was critically analyzed from a techno-economical perspective. This paper recommends a novel sustainable model based on the circular economy concept, where waste is urban mined and recovered as a secondary resource to support the united nations sustainable development goals (SDGs). The implementation of this model will ultimately help the developing countries to achieve the target of SDGs 11, 12, and 14.
Dual role of grass clippings as buffering agent and biomass during anaerobic co-digestion with food waste
Debkumar Chakraborty, Sankar Ganesh Palani, Ghangrekar, Anand, Pankaj Pathak
Journal, Clean Technologies and Environmental Policy, 2022, DOI Link
View abstract ⏷
There is a dire need to replace the chemical buffers that regulate the redox environment in single-stage anaerobic digestion of food waste. Hence, the applicability of grass clippings as an eco-friendly buffering agent and biomass during the anaerobic co-digestion of food waste was explored. A focus was primarily given on the effects of grass clippings on the redox environment and acidogenesis. Concomitantly the production of volatile fatty acids, hydrogen and methane in mesophilic conditions was monitored. Organic load and substrate-to-inoculum ratio were kept constant in all the experiments, and no chemical buffer was used. The results revealed that the redox environment was regulated with 10% grass clippings by inhibiting rapid pH drop in the digester. The addition of 2, 4, and 6% grass clippings promoted acidogenesis with increased production of acetic and butyric acids, whereas 8 and 10% grass clippings promoted solventogenesis with ethyl alcohol production. Hydrogen generation from the experiments with grass clippings was in the range of 27–30% of the total biogas, which was marginally higher than the control (25%). Methane concentration was negligible in the biogas generated from all experiments. The acidification rate, VFA production/consumption rate, specific hydrogen yield, hydrogen conversion efficiency, and volatile solids removal were maximum and minimum in the reactors with 6 and 10% grass clippings, respectively. From the above results, it can be concluded that adding grass clippings to food waste would regulate the sudden pH changes and enhance the production of value-added biochemicals, making the process cost-effective. Graphic abstract: [Figure not available: see fulltext.].
Design of mass burial sites for safe and dignified disposal of pandemic fatalities
Eng-Choon Leong, Hossam Abuel-Naga, Venkata Siva Naga Sai Goli, Bhagwanjee Jha, Pankaj Pathak, Devendra Narain Singh
Journal, Environmental Geotechnics, 2021, DOI Link
View abstract ⏷
The huge number of fatalities due to the coronavirus disease 2019 pandemic has imposed an unprecedented pressure on existing burial facilities. Thus, mass burial is being used in different parts of the world to cope with this unusual situation. As a dead body might be contagious for at least hours, if not days, there is a need to manage/design/construct the mass burial considering the safe handling of coffins and other environmental, social, economical and ethical/dignity aspects. However, the guidelines of the World Health Organization do not thoroughly address the potential risk associated with groundwater pollution due to mass burial construction. Hence, the present study discusses the potential risk of groundwater pollution in mass burial sites and sheds light on the factors that control the survival/retention of bacteria and viruses in porous media. Furthermore, using the available knowledge on designing/monitoring of municipal/industrial waste disposal sites, a cost-effective and simple construction method of mass burial is proposed to mitigate its potential environmental impact.
Water reclamation, recycle, and reuse
Muhammad K. Shahid, Ayesha Kashif, Pankaj Pathak, Younggyun Choi, Prangya Ranjan Rout
Book, Clean Energy and Resource Recovery: Wastewater Treatment Plants as Biorefineries, Volume 2, 2021, DOI Link
View abstract ⏷
Water reclamation includes the processing of water obtained from different sources to generate a new water appropriate for other purposes like groundwater replenishment, agriculture and land irrigation, potable water supplies, industrial facilities, and environmental restoration. Recycled water can be applied for diverse perspectives to share the burden of freshwater sources. In many areas of the world, the entire potential of using reclaimed water is not yet explored. Moreover, different national and international bodies defined different guidelines for reclaimed water specific to the particular use. This chapter details the sources, treatment technologies, reusability, regulations/guidelines of different global authorities, and the possible issues connected with economic, environment, and the public health.
Waste-to-energy: Suitable approaches for developing countries
Yash Pujara, Janki Govani, Karan Chabhadiya, Harshit Patel, Khevna Vaishnav, Pankaj Pathak
Book Series, Handbook of Environmental Chemistry, 2021, DOI Link
View abstract ⏷
A global estimate for the generation of solid waste is projected to be ~1.3 billion tonnes/year. This volume is supposed to further increase up to 2.2 billion tonnes/year by the mid of 2030. In this context, the effective treatment and disposal of solid waste around the globe is becoming of utmost importance. Moreover, sustainable management of solid waste is not only necessary to solve the disposal issues but also beneficial in terms of energy production. Developed countries have already adopted technologies for utilization of their solid waste in energy production, heat generation, conversion to biofuel, compost preparation and as the metal reservoir. In contrast, developing countries are still struggling to manage their solid waste as an alternative resource. Amongst all other ways of solid waste management, the waste-to-energy (WtoE) technology is better suitable for developing countries in terms of building up their energy resources. In this chapter, the status of solid waste in the developing nations along with their WtoE options is being discussed. Moreover, the cost estimation has marked as significant tool to identify suitable WtoE option for developing countries.
Cellulose and extracellular polymer recovery from sludge
Anee Mohanty, Sumer Singh Meena, Pankaj Pathak, Prangya Ranjan Rout
Book, Clean Energy and Resource Recovery: Wastewater Treatment Plants as Biorefineries, Volume 2, 2021, DOI Link
View abstract ⏷
Population explosion-mediated demand has led to an unprecedented increase in the consumption of natural resources across the globe. Most of the nonrenewable natural resources have failed to meet the ever-increasing demand, resulting in a gradual widening of the supply and demand gap. Therefore, in the recent decades, the mainstream research focus has aimed at developing technological solutions to recover secondary resources from anthropogenic wastes or waste streams. This chapter discusses about the technical possibilities and the bottlenecks associated with the recovery of cellulose, polyhydroxyalkanoate (PHA), and extracellular polymeric substances (EPS) from sewage sludge. Basic resource recovery techniques involve biochemical, physicochemical, and some of the previously unexploited biological processes. The important applications of sludge-derived cellulose fibers for the production of cellulose nanocrystals and cellulose nanofibers, recovered PHA for biopolymer synthesis, and extracted EPS application as a bioflocculant, along with other diversified application prospective have also been deliberated in this chapter. The sources and extraction methods of various resources to be recovered are highlighted in this chapter that can be helpful in choosing the suitable extraction methods depending on the sources from which the secondary resources are to be recovered and the intended use of the recovered resources. The recovery of secondary resources from waste sources is a very essential practice from the global sustainability view point.
Growth projections against set-target of renewable energy and resultant impact on emissions reduction in India
Karan Chabhadiya, Rajiv Ranjan Srivastava, Pankaj Pathak
Journal, Environmental Engineering Research, 2021, DOI Link
View abstract ⏷
In accordance with the Paris Climate Agreement (COP21) and Sustainable Development Goals (SDGs), India is greatly focused on deployment of renewable energy (RE) for supplementing the energy requirements of the country. The present article assesses the validity of the promises offered by RE technologies in India and its necessary action to understand the gap between setting goals and the ground situation, which can also show a pathway to other developing countries. Therefore, the long-term projection perspectives on RE growth have been made using the India Energy Security Scenario-2047. In order to achieve the set target for emissions reduction of greenhouse gases (GHGs) i.e., 1209 MT CO2e in support of SDGs to the 2005 level by 2030, three renewable growth scenarios have been tested for transitioning the Indian energy system. Accordingly, the regression analysis reveals that the most desirable growth scenario will require a steady rise of RE contribution in the overall energy mix of India by 2030 from the current ~21% to 68% of the installed capacity. In this view, the present study highlights the exploration of new alternatives in long-term energy planning, and less on one-sided scenario to achieve the emissions’ reduction target.
Valorisation of waste tires into fuel and energy
Pankaj Pathak, Sweta Sinha
Book, Advanced Technology for the Conversion of Waste into Fuels and Chemicals: Volume 2: Chemical Processes, 2021, DOI Link
View abstract ⏷
Automobiles production is increasing at a faster rate due to rapid globalization and industrialization. However, after the end of life of automobiles, huge amounts of waste is generated. One of the wastes is used tires. Worldwide, ~1 billion tonnes of used tires are generated as a waste every year. However, the processing of the waste tires is extremely challenging due to their complex structure and varied composition. Therefore, either it has been directly thrown or burned on landfill. Thus, inadequate management of used (waste) tires causes adverse impact to the environment and social life. Hence, formal processing of waste tires needs extensive research in front of the scientific community. In this regard, gasification and pyrolysis techniques are being used to vaporize the waste tires into fuel and energy. This chapter describes the environmental impacts associated with waste tires if it is not processed properly and energetic valorization of waste tires into fuel and energy.
Renewable energy as a sustainable alternative: A way forward
Pankaj Pathak
Book Series, Handbook of Environmental Chemistry, 2021, DOI Link
View abstract ⏷
Coal, oil, and natural gas are major conventional energy sources in the world but limited in amount. However, these sources create several environmental and health impacts during energy extraction processes. Coal mining and exploration, transportation, energy/electricity generation processes cause negative environmental externalities. Notably, electricity generation from coal alone emits approximately 60% of the global CO2, which has been projected as 36.4 GtCO2 in 2016. This scenario would be more challenging for developing nations to balance the increasing economic and industrial growth along with climate change issue. Therefore, alternative energy resources are recommended for the sustainable modern society to fulfill global energy demand with minimum environmental impacts.
Preface
Pankaj Pathak, Rajiv Ranjan Srivastava
Book Series, Handbook of Environmental Chemistry, 2021,
Sequential Leaching of Strategic Metals from Exhausted LNCM-Cathode Batteries Using Oxalic and Sulfuric Acid Lixiviants
Pankaj Pathak, Vinay K. Singh, Karan Chabhadiya
Journal, JOM, 2021, DOI Link
View abstract ⏷
Hydrometallurgical extraction of strategic metals from exhausted Li-ion batteries has been explored using sequential application of biodegradable oxalic acid and sulfuric acid solutions. Following L25 orthogonal design of experiment (DoE), optimized extraction of > 99% Li and Cu with organic acid was achieved using a H2C2O4 concentration of 0.25 mol L−1, solid–liquid ratio of 10%, H2O2 at 0.5%, temperature of 80°C, and duration of 90 min. Subsequently, leaching of the residual mass in mineral acid yielded 99% efficiency of Ni, Co, and Mn at the optimal condition of H2SO4 concentration of 3.0 mol L−1, solid–liquid ratio of 6%, H2O2 at 2%, temperature of 60°C, and duration of 120 min. Fitting of the kinetic data using a logarithmic rate law revealed that, except for Cu that followed an intermediate-controlled mechanism with Ea = 27.6 kJ mol–1, all the other metals exhibited a diffusion-controlled mechanism with Ea < 12 kJ mol–1. Not only does this study demonstrate selectivity that will be beneficial to downstream processing, but the use of DoE also makes it applicable industrially.
Two-step leaching process and kinetics for an eco-friendly recycling of critical metals from spent Li-ion batteries
Karan Chabhadiya, Rajiv Ranjan Srivastava, Pankaj Pathak
Journal, Journal of Environmental Chemical Engineering, 2021, DOI Link
View abstract ⏷
With growing awareness to protect the urban environment and fulfill the soaring demand for critical metals, recycling of postconsumer Li-ion batteries has become imperative to deal in a sustainable manner. In this context, a two-step leaching of the exhausted LiNixCoyMnzO2 cathode material was studied by sequential application of both organic and mineral acids. To optimize the experimental parameters of both steps, leaching was conducted using the L25 orthogonal array design. In the first-step leaching, lithium and copper was selectively leached into oxalic acid at the optimal condition of C2H2O4 (OA), 0.25 M; pulp density (PD1), 10%; H2O2 dosage (HPD1), 0.5%; temperature (T1), 80 °C; and time (t1), 90 min. The parametric influences for achieving more than 99% efficiency of lithium and copper followed the order: t1 > HPD1 > OA > PD1 > T1 and t1 > T1 > OA > HPD1 > PD1, respectively. Residual metal-oxalates of cobalt, nickel, and manganese were subsequently dissolved into sulfuric acid solutions. Approximately 99% of all remaining metals could be leached at the optimal condition of H2SO4 (SA), 3.0 M; pulp density (PD2 -), 6%; H2O2 dosage (HPD2), 2%; temperature (T2), 60 °C; and time (t2), 120 min. The parametric influences on sulfuric acid leaching of metals followed the order as: SA > HPD2 > t2 > PD2 > T2. Leaching followed logarithmic rate law and exhibition of the diffusion-controlled mechanism was revealed through the values of apparent activation energy determined to be Ea(Li), 9.7 kJ/mol; Ea(Cu), 22.3 kJ/mol; Ea(Co), 9.5 kJ/mol; Ea(Ni), 11.2 kJ/mol; and Ea(Mn), 6.2 kJ/mol. This study successfully demonstrated the applicability of OA in the selective leaching of LiNixCoyMnz-type cathode materials, eliminating the need for copper and lithium separation from leach liquor of SA-medium. The present process offers two-fold advantages that securing the secondary supply for critical metals, and providing an environmentally sustainable route for waste valorization in a circular economy.
Assessment of the alkaline earth metals (Ca, Sr, Ba) and their associated health impacts
Pankaj Pathak, Rajiv Ranjan Srivastava, Gonul Keceli, Soma Mishra
Book Series, Handbook of Environmental Chemistry, 2020, DOI Link
View abstract ⏷
This chapter provides an outline of alkaline earth metals’ contamination caused by the industrial and nuclear pollution. The assessment has been done for quantifying sources (viz. natural and anthropogenic) of the alkaline earth metals along with describing the physicochemical characteristics of calcium, strontium, and barium. The isotopes of strontium, calcium, and barium are found to have significant impact not only onto the human health but also the geoenvironment. In this view, estimation of risk assessment caused by these metals is mandatory and also described in this chapter. Notably, calcium is one of the most significant elements in human body in the form of bone skeleton. In contrast, strontium and barium are non-essential elements for human beings; however, due to their similar characteristics with calcium, they get managed to enter within the human body via accumulation onto the tissues and bones. Therefore, the quantification of strontium and barium is imperative that can be done by measuring ratios with respect to calcium (as, Ba:Ca and Sr:Ca).
Removal of strontium by physicochemical adsorptions and ion exchange methods
Nevin Koshy, Pankaj Pathak
Book Series, Handbook of Environmental Chemistry, 2020, DOI Link
View abstract ⏷
Strontium, a relatively abundant alkaline element in the earth’s crust, occurs in four stable isotopes, 84Sr, 86Sr, 87Sr and 88Sr. The separation of soluble Sr2+ ion from water, mainly seawater, can be achieved through one or a combination of methods such as adsorption, chemical precipitation, ion exchange, membrane technology and solvent extraction, amongst which adsorption and membrane processes are popular solutions. The regeneration of spent adsorbents along with Sr recovery is the inherent advantage of the adsorption process. Natural adsorbents such as alginate microspheres, attapulgite, bentonite, dolomite, goethite, hematite and natural zeolites and inorganic ion-exchange materials, viz. activated carbon, antimony oxide, artificial zeolites, carbon and titanate nanotubes, gel and macroporous resins, titanium oxide and synthetic birnessite, have been used for immobilization of Sr. Industrial wastes (coal fly ash and industrial sludges) and agricultural byproducts (almond green hull, eggplant hull, moss and waste rice straw) are also potential Sr adsorbents. The adsorption process is greatly influenced by pH, initial concentration of contaminant, temperature and textural characteristics of the adsorbents. Membranes from polymeric and ceramic materials have also been used for Sr attenuation, and hybrid membrane technologies using multiple membranes have been found to be effective.
Preface
Pankaj Pathak, Dharmendra K. Gupta
Book Series, Handbook of Environmental Chemistry, 2020,
Phytoextraction of heavy metals by weeds: Physiological and molecular intervention
Pankaj Pathak, Debleena Bhattacharya
Book, Handbook of Bioremediation: Physiological, Molecular and Biotechnological Interventions, 2020, DOI Link
View abstract ⏷
Phytoextraction is the most promising technique and commonly used to remove heavy metals from the geo-environment. It is nonintrusive, cost-effective, and fast emerging technology. Different types of weeds such as Ipomoea carnea, Jatropha curcas, Trianthema portulacastrum, Cynodon dactylon, Typha angustifolia, Phyllanthus reticulatus, Echinochloa colonum, Vetiveria nemoralis, Amaranthus viridis, and Eleusine indica are being utilized to remediate the soil from heavy metals such as cadmium, chromium, lead, and mercury. The extraction of the heavy metals is basically done by root and shoot of weeds. These weeds have interlinked physiological and molecular interaction with the heavy metals (HMs). However, uptake capacities of HMs from the weeds are getting reduced due to interaction between plants genotype and its environment. Therefore it necessitates understanding the HM tolerance mechanism in the plants. In this context, this chapter gives overview of different types of weeds used for heavy metal extraction, physiological and molecular mechanism involve in phytoextraction process, and improvising weeds for increasing phytoextraction processes.
Personal Exposure to Air Pollutants from Winter Season Bonfires in Rural Areas of Gujarat, India
Sneha Gautam, Adityaraj Talatiya, Mirang Patel, Karan Chabhadiya, Pankaj Pathak
Journal, Exposure and Health, 2020, DOI Link
View abstract ⏷
The present study quantifies the personal exposure to air pollutants (i.e., PM2.5, PM10, CO2, and CO) and its bound chemical constituents during bonfire activities occurring in rural area of Gujarat, India. The study was performed during the late 2017 and early 2018 winter season, when bonfires are a very common practice. Three major sites, viz., University Reception Area (URA), Workshop Area (WSA), and Hostel Wing-A (HWA) were delineated to reveal discrete patches of personal exposure. Particulate matters, gaseous pollutants, and associated ionic constitutes were analyzed by an air quality monitor and ion chromatography. The concentration profile of PM2.5, PM10, and CO were found in the range between 81–206, 188–282, and 2.8–5.8 µgm−3, respectively, at the study area which are more than the permissible limit. The major ions such as Na+, K+, Ca2+ Mg2+, NH4+, Cl−, Br−, NO2−, NO3−, PO42−, and SO42− were obtained on particulate matter. Based on this observation it is concluded that if personal exposure to these pollutants increases, then metabolic activities may change and lead to severe diseases, viz., asthma, rhinitis, tuberculosis. It is a grave concern for the WHO to improve the human health and eradicate the communal diseases under sustainable development goals. Henceforth, it is mandatory to understand the variations of air pollutants at workplace and the associated exposure to individuals.
Environmental management of e-waste
Pankaj Pathak, Rajiv Ranjan Srivastava, Ojasvi
Book, Electronic Waste Management and Treatment Technology, 2019, DOI Link
View abstract ⏷
The waste derived from electrical and electronic equipment (i.e., E-waste) causes severe issues for the geo-environment. The heterogeneity and complexity of E-waste, containing lethal and toxic substances, are difficult to decompose and are classified as hazardous materials. High exposure of hazardous materials is harmful to human life. The improper management of E-waste with processing by the informal sector in nonscientific manner is making this scenario catastrophic. Additionally, illegal shifting by mislabelling E-waste from developed countries and exporting to developing countries makes it difficult to calculate the inventory and handling of the E-waste. Therefore, a sustainable environmental management of E-waste by policies and governing regulations from its collection to recycling are necessary. These measures of E-waste management should increase the advance recycling practices by the formal sector and decrease the amount of waste contamination to the environment that is endangering human health and whole ecosystem.
Review on Indian Municipal Solid Waste Management practices for reduction of environmental impacts to achieve sustainable development goals
Yash Pujara, Pankaj Pathak, Archana Sharma, Janki Govani
Journal, Journal of Environmental Management, 2019, DOI Link
View abstract ⏷
Open dumping is a common practice for MSW disposal in most of the Indian cities, apart from the metro-cities. This practice poses significant environmental and health risks due to toxic and greenhouse gases (GHGs) emission through direct combustion and/or decay of wastes. Therefore, integrated solid waste management (ISWM) using different methods viz., incineration, composting, anaerobic digestions, refuse derived fuel, material recovery facility and sanitary landfilling, is much needed. Accordingly, three waste management case scenarios were studied for year 2001–2051 by keeping weightage of sustainable development goals 2030 of India. Case I depicts Indian present scenario of waste management where 164–735 tonnes/year of wastes would be generated for year 2001–2051. Further, 60% of waste can be treated in case II that help in reducing the land requirement up to 40% from estimated conditions of 2031 i.e., 83.8 × 107 m3. The case III is most ideal waste management condition for year 2031 to reduce 80% waste hence landfill requirement would minimize up to 16.76 × 107 m3 where population is at controlled conditions. This article concludes the formal handling and treatment of ISWM would minimize the landfilling, where LCA can be an antidote to achieve sustainable development goals.
Policy issues for efficient management of E-waste in developing countries
Rajiv Ranjan Srivastava, Pankaj Pathak
Book, Handbook of Electronic Waste Management: International Best Practices and Case Studies, 2019, DOI Link
View abstract ⏷
An efficient management of E-waste is rendered indispensable and regarded as a major challenge for today’s society. Greater contributory developed countries have established their policies on it and control their interests via either way of binding the legislation, paying to poor countries, and transferring used items in the name of bridging the techno-gap to underdeveloped countries. Such practices combined with in-house generation volume of E-waste in developing countries possess serious challenges to them. The major challenges they are facing either due to lack of or inadequate to handle the E-waste management practices. Most of the developing countries are still struggling for specific policy direction on E-waste, while one of the fastest growing economy and a large producer of E-waste countries, China and India could have finalized their legislation in very recent times; the implementation results are yet to have come. In this chapter, the policy constraints of developing countries for the effective management of E-waste have been analyzed with some particular examples. For this, the current practices, policy comparison between the developed and developing countries, and recommendations for a circular economy to the sustainable E-waste management in developing countries have been included.
Sorption Isotherms, Kinetics, and Thermodynamics of Contaminants in Indian Soils
Pankaj Pathak, Susmita Sharma
Journal, Journal of Environmental Engineering (United States), 2018, DOI Link
View abstract ⏷
The sorption isotherms, kinetics, and thermodynamics of contaminants, e.g., strontium, lead, and uranium, for four different Indian soils (named S1, S2, S3, and S4) were investigated. Batch testing was performed to determine sorption properties of the soils. It was found that among the four soils, S1 has the maximum sorption at each contaminant metal. The uptake capacity for strontium, lead, and uranium was found to be 55.78, 103.6, and 2.07 g·kg-1, respectively, after 24 h interaction at 45°C. The Langmuir and Freundlich isotherms have shown good fits (R2≥0.9) in comparison with other isotherms, revealing the sorption characteristics of the soil-contaminant system (SCS). The experimental data of the SCS followed pseudo-second-order kinetics; however, Soils S1 and S2 exhibited a pseudo-first-order reaction on sorption of uranium. The effect of temperatures from 27°C to 45°C on sorption has revealed higher uptake of contaminant metals onto soils, and sorption of SCS is established to be spontaneous and endothermic. Moreover, the results revealed the physisorption regime in the SCS, and the soils exhibit good binding with the contaminants.
Assessment of legislation and practices for the sustainable management of waste electrical and electronic equipment in India
Pankaj Pathak, Rajiv Ranjan Srivastava, Ojasvi
Journal, Renewable and Sustainable Energy Reviews, 2017, DOI Link
View abstract ⏷
The waste electrical and electronic equipment (WEEE or e-waste) are the globally recognized hazardous material, though containing a full spectrum of valuable and critical metals. India, being the fifth largest generator of WEEE, is facing a great challenge in the sustainable management of such waste. Therefore since the past few years, Government of India has been trying to establish a proper institutional and legislative framework to implement the sustainable management of WEEE in the country. Accordingly, the global issues related to WEEE and how it is being tackled by other countries/regions with implemented regulations has been reviewed in this paper. Furthermore, the status-quo of WEEE generation, management policies and recycling practices in India has been systematically assessed while emphasizing the key issues of future initiatives, environmental and health hazards. The mathematical model of WEEE generation in India along with identifying the influences of recycling in sustainable management of WEEE has also been established.
An assessment of strontium sorption onto bentonite buffer material in waste repository
Pankaj Pathak
Journal, Environmental Science and Pollution Research, 2017, DOI Link
View abstract ⏷
In the present study, changes occurring in sorption characteristics of a representative bentonite (WIn-BT) exposed to SrCl2 (0.001–0.1 M) under the pH range of 1–13 were investigated. Such interaction revealed a significant variation in surface charge density and binding energy of ions with respect to bentonite, and alteration in their physicochemical properties viz., specific surface area, cation exchange capacity, thermal and mechanical behaviour were observed. The distribution coefficients (kd) calculated for sorption onto virgin (UCBT) and contaminated bentonite (CBT) indicated a greater influence of mineralogical changes occurred with variance of pH and strontium concentration. Notably, the sorption mechanism clearly elucidates the effect of structural negative charge and existence of anionic metal species onto CBT, and depicted the reason behind significant kd values at highly acidic and alkaline pH. The maximum kd of UCBT and CBT(0.001M SrCl2) were 8.99 and 2.92 L/kg, respectively, at the soil pH 8.5; whereas it was 2.37 and 1.23 L/kg at pH 1 for the CBT(0.1M SrCl2) and CBT(0.01M SrCl2), respectively. The findings of this study can be useful to identify the physicochemical parameters of candidate buffer material and sorption reversibility in waste repository.
Guidelines for quantification of geomaterial-contaminant interaction
Pankaj Pathak, Singh, Pandit, Rakesh
Journal, Journal of Hazardous, Toxic, and Radioactive Waste, 2016, DOI Link
View abstract ⏷
In nature, when contaminants come in contact with geomaterials (i.e., soil, minerals and rock mass), geomaterial-contaminant interaction occurs, which can be quantified, mathematically, by employing distribution or partitioning coefficient, kd. This interaction is strongly influenced by the geomaterial and contaminant specific parameters. Among these parameters, the concentration and nature of the contaminant (in solution form) is one of the most important parameters that control this interaction critically. However, it is the authors' hypothesis that another parameter, electrical conductivity of the geomaterial-contaminant system (GCS), which is dependent on type of the geomaterial (i.e., its chemical and mineralogical properties) and contaminant(s) could be used for a precise understanding of geomaterial-contaminant interaction. Hence, in order to investigate the effect of the concentration and electrical conductivity of the GCS on this interaction, geomaterials and contaminants of different types were used in this study for performing a series of batch tests and electrical conductivity measurements under controlled environmental conditions. Based on these investigations, guidelines for selecting appropriate concentration of the contaminant(s), Mcrt, to quantify geomaterial-contaminant interaction have been developed and recommended for the precise determination of kd.
Statistical analysis for prediction of distribution coefficient of soil-contaminant system
Pankaj Pathak, Singh, Apte, Pandit
Journal, Journal of Environmental Engineering (United States), 2016, DOI Link
View abstract ⏷
The soil-contaminant interaction is significantly influenced by various attributes of soil and contaminant, and it can be quantified by employing a term known as distribution coefficient (kd). However, because of the involvement of many parameters related to soil and contaminant, determination of kd becomes a tedious and time-consuming exercise that requires extensive experimental investigations. In this context, application of the Taguchi method for minimizing the number of experiments and establishing the most critical parameters which influence kd (obtained from the linear isotherm) has been shown to be quite useful by the researchers in the recent past. Keeping this point in view, application of L25 orthogonal array (OA) used in the Taguchi method has been employed to design experiments which would facilitate establishment of the influence of various parameters concomitantly on kd and its prediction as well. The kd has been predicted by employing two methods viz, the Taguchi method and the statistical regression model (SRM). With this in view, four parameters (viz, cation exchange capacity of the soil, ionic species, temperature, and interaction time of the soil-contaminant system) were selected for developing the L25OA, and it has been clearly demonstrated that these methodologies help in easily (1) identifying the most significant parameter on which kd is dependent and (2) predicting the precise kd by inputting the four parameters. Moreover, based on this study, the sorption mechanism that yields a maximum kd for a given soil-contaminant system (SCS) by employing the most optimized parameters has also been proposed.
Determination of distribution coefficient: A critical Review
Pankaj Pathak, Singh, Pandit, Rakesh
Journal, International Journal of Environment and Waste Management, 2014, DOI Link
View abstract ⏷
Geomaterials (soils and rocks) exhibit peculiar physical, chemical, mineralogical and biological properties, which influence their interaction with the contaminant(s) to a great extent. This interaction can be quantified by employing a parameter 'Distribution coefficient', kd, which plays an important role for determining sorption and desorption characteristics of the contaminant when it interacts with geomaterial(s). Apart from the soil specific properties, kd depends upon the pH of the pore solution, ambient temperature, type and concentration of competitive ions, the presence of microorganisms, etc. Usually, batch, column and lysimetric tests are employed for determining kd. However, it has been observed that kd varies in a wide range and the methodologies adopted for its determination have their limitations and shortcomings. As such, these methodologies are being critically evaluated by researchers so that they may be modified or replaced by new ones, which are easy to adopt and yield reliable results quickly. With this in view, efforts have been made in this paper to highlight the importance and role of parameters that influence determination of kd. Further, details of the studies related to determination of kd as reported by earlier researchers and a commentary on the guidelines for determining it are also presented in this paper. Copyright.© 2014 Inderscience Enterprises Ltd.
Establishing sensitivity of distribution coefficient on various attributes of a soil-contaminant system
Pankaj Pathak, Singh, Pandit, Apte
Journal, Journal of Hazardous, Toxic, and Radioactive Waste, 2014, DOI Link
View abstract ⏷
The distribution coefficient, kd, of a soil plays a vital role in controlling its interaction with contaminant(s). Studies conducted by earlier researchers, demonstrate that kd is quite sensitive to various attributes of the soil-contaminant system viz, ratio of the contaminant in the liquid form to the solid (soil) form, pH, the cation-exchange capacity; mineralogy and redox potential of the soil, temperature, types of ionic species, and concentration of the contaminant. Hence, it becomes difficult, if not impossible, to identify the parameters that have most significant influence on the kd. Such an exercise would be helpful in minimizing the number of batch tests to be conducted for determining the kd of a soil-contaminant system, which otherwise is a very cumbersome task. To achieve this objective, application of the Taguchi method, which primarily helps in designing experiments, appears to be a panacea. With this in view and to demonstrate the potential of this methodology for identification of the dominating factor(s) to which kd is highly sensitive, the Taguchi method was employed (both static and dynamic analyses) for designing batch tests. Subsequently, five parameters-cation-exchange capacity of the soil, contaminant type (ionic species of contaminant), pH of soil-contaminant system, liquid to solid ratio and concentration of the contaminant-were selected and temperature was maintained as a noise parameter. In this paper, kd is demonstrated to be highly sensitive to the concentration of the contaminant, cation-exchange capacity of the soil, and ionic species of the contaminant, in a decreasing order. © 2014 American Society of Civil Engineers.
Novel techniques for simulating and monitoring impact of contaminants on geoenvironment
Iyer, Pathak, Singh
Book, Coupled Phenomena in Environmental Geotechnics: From theoretical and experimental research to practical applications, 2013, DOI Link
View abstract ⏷
This paper presents details of the techniques, which are indigenous, need based, economical and developed by researchers at IIT Bombay, for investigating the impact of hazardous and toxic wastes on geoenvironment. Suchwastes, which inherently contain heavy metals, are being disposed of by various industries, thermal/atomic power stations and research facilities. The heavy metals leach out of the waste matrix, in due course of time due to their interaction with the geoenvironment, and contaminate it. Under these circumstances, the techniques presented in this paper have been found to be quite helpful in simulating and monitoring the spread and fate of contaminants in the geoenvironment. This paper also emphasizes the need of adopting these techniques for geomaterial characterization when it comes in contact with contaminants.
Novel techniques for simulating and monitoring impact of contaminants on geoenvironment
Iyer, Pathak, Singh
Conference Proceeding, Coupled Phenomena in Environmental Geotechnics: From Theoretical and Experimental Research to Practical Applications - Proceedings of the International Symposium, ISSMGE TC 215, 2013, DOI Link
View abstract ⏷
This paper presents details of the techniques, which are indigenous, need based, economical and developed by researchers at IIT Bombay, for investigating the impact of hazardous and toxic wastes on geoenvironment. Such wastes, which inherently contain heavy metals, are being disposed of by various industries, thermal/atomic power stations and research facilities. The heavy metals leach out of the waste matrix, in due course of time due to their interaction with the geoenvironment, and contaminate it. Under these circumstances, the techniques presented in this paper have been found to be quite helpful in simulating and monitoring the spread and fate of contaminants in the geoenvironment. This paper also emphasizes the need of adopting these techniques for geomaterial characterization when it comes in contact with contaminants. © 2013 Taylor & Francis Group.
Solvent mediated interactions for the selective recovery of Cadmium from Ni-Cd battery waste
Archana Agrawal, Pankaj Pathak, Mishra, Sahu
Journal, Journal of Molecular Liquids, 2012, DOI Link
View abstract ⏷
This work deals with the development of a solvent extraction process for the selective separation of cadmium, from cobalt and nickel, using DEHPA as an extractant. After mechanical separation, dissolution of the electrode material in H 2SO 4 and iron removal the leach liquor obtained was subjected to solvent extraction for the extraction and separation of all the three metal ions. The conditions were optimized for the selective recovery of Cd using 20% D2EHPA with 60% saponification. Saturated loading capacity for 20% (60% saponified D2EHPA) was found to be 10.89 g L -1 Cd, 1.404 g L -1 Ni, and 0.032 g L -1 Co at O/A ratio of 1:1. McCabe-Thiele plot at varying O/A ratio indicated the requirement of 4 stages for 100% extraction of Cd at O/A ratio of 1:1.5. The dependence of extraction on pH indicated that the extraction of Cd(II) proceeds according to a cation-exchange reaction at lower acidity and to a solvating reaction at higher acidities. The co-extracted Ni and Co were effectively scrubbed with 50 g L -1 CdSO 4 at pH 0.5. 99.6% Cd was stripped from the loaded D2EHPA with 75 g L -1 of H 2SO 4. Based on the slope analysis of the plots of log D Cd versus log [(HR) 2] and pH vs log D Cd, Cd was found to be extracted as CdR 2.(HR) 2. The process seems to be promising for the production of pure metal streams which can further be used to produce valuable commercial products vis-a-vis the environmental protection. © 2012 Elsevier B.V. All rights reserved.
Characterization of aeolian sands from Indian desert
Padmakumar, Srinivas, Uday, Iyer, Pankaj Pathak, Keshava, Singh
Journal, Engineering Geology, 2012, DOI Link
View abstract ⏷
Aeolian sands, from Sam, Jaisalmer, Rajasthan, India, belong to the Great Indian Thar desert and, primarily, attract tourists from India and all over the world. Though, certain studies were conducted on the geological origin of these sand and deserts, results related to their physical, chemical, morphological, mineralogical, thermal, electrical and geotechnical characteristics are scanty. However, with an increase in demand of the land for infrastructure development (for residential, commercial and strategic facilities), for which their stabilization may be essential, and a need to utilize these (aeolian) sands as a construction material, particularly due to acute scarcity of sand, their complete characterization becomes essential. With this in view, a detailed study was conducted to characterize these sands and details are presented in this paper. In general, these sands are found to exhibit properties similar to aeolian sands from the Arabian Peninsula, Australia and China. Further, with an intention to utilize these sands in construction industry, especially as fine aggregate in concrete and mortar and designing thermal beds for buried conduits and electrical cables, the results have been compared with those for the Indian standard sands. Based on the chemical composition and chemical properties, and crushing strength of aeolian sands, their utilization in concrete and other construction materials (viz., bricks, building blocks, paver blocks etc.) appears to be quite promising. Also, the collapse potential of these sands has been found to be quite low while its angle of internal friction is quite high. These parameters suggest that aeolian sands from the Great Indian Thar desert can also be used for various engineering applications. © 2012 Elsevier B.V.
