Department of Environmental Science and Engineering

The potential of live microalgae Scenedesmus obliquus was tested for removing Brilliant green dye (BGD). BGD is a cationic dye that has been widely used as a colouring agent in various sectors, but this dye has been reported in wastewater due to its high solubility in water. Scenedesmus obliquus is one of the most widely employed microalgae species with good bioremediation potential and biochemical composition. This study reports growth inhibition of Scenedesmus obliquus in test runs 5 mg/L (17 %), 10 mg/L (31 %), 25 mg/L (42 %), and 50 mg/L (57 %), and the EC50 value was predicted to be 33.7 mg/L using probit statistical analysis. The removal efficiency decreased from 99 % to 87 % as the BGD concentration increased, and the removal mechanism was reported in the order of biodegradation > bioaccumulation > bioadsorption. The biodegradation potential decreased from 97 % to 84 % at the BGD concentration of 50 mg/L, and the Monod kinetic study revealed that the half-saturation constant increased when the BGD concentration crossed the EC50 value. Protein (498 mg/L) and lipid (728 mg/L) accumulation was highest at 5 mg/L of BDG, implying growth-stimulating effects on microalgae as the growth inhibition is less. These findings highlight Scenedesmus obliquus potential for effective BGD removal below EC50 concentrations with identification of 6 biotransformed products and simultaneous production of value-added biomass.

Preserving stone-built cultural heritage from environmental degradation poses significant challenges, as moisture ingress and extreme weather accelerate weathering, leading to structural damage and escalating maintenance costs worldwide. While hydrophobic coatings show promise for protection, achieving long-term durability under harsh conditions remains elusive. The present research demonstrates a robust hydrophobic nanocomposite coating based on silica nanoparticles (SiNPs) functionalized with 1 H,1 H,2 H,2H-perfluorodecyltriethoxysilane (PFDTS), synthesized via alkaline hydrolysis of tetraethylorthosilicate (TEOS) and applied by spray coating to diverse heritage stones including sandstone, granite, and marble. The coatings achieve water contact angles of 130°–137° and sliding angles of 9°–10°, conferring exceptional self-cleaning properties that endure after saline exposure, wet-dry cycles, and marine simulations. Additionally, various water absorption tests, including the Karsten tube, ASTM D6489 surface uptake, ASTM C642 immersion tests, and droplet impact tests, showed a significant decrease in water absorption compared to uncoated stones. The overall results suggest that the water penetration at the coated surface was reduced by a factor of about 80–100 for the stone samples. This research study offers a scalable, cost-effective approach to enhance the longevity of cultural monuments, minimising preservation expenses and safeguarding irreplaceable historical assets for future generations.

Coal-fired thermal power plant operations significantly impact aquatic environments by releasing fly ash leachate, untreated effluents, and airborne pollutants, thereby deteriorating surface water quality. This study assesses the spatial distribution, pollution load, and ecological risk of potentially toxic elements (PTEs) in surface water collected from the surroundings of coal-based thermal power plant (TPP) in Andhra Pradesh, India. Jupudi Reservoir (JR) showed relatively lower pH levels, indicating mildly acidic conditions possibly resulting from ash pond leachate influence, while the other water bodies maintained a more alkaline nature. The mean concentrations of Chromium (406 µg/L) and Arsenic (214 µg/L) were highest at JR and comparatively elevated relative to other water bodies. Furthermore, the total metal load was significantly higher in JR, TPP, and RC across water, sediment, and plant samples, reflecting the significant influence of coal-based thermal power plant activities on these aquatic ecosystems. Geospatial distribution using ArcGIS-IDW interpolation revealed contamination hotspots near coal ash discharge zones, especially at JR and TPP canal sites. Pollution indices highlighted severe pollution and ecological threats at JR and TPP, with ERI values indicating high ecological risk (> 400). Health risk assessments showed that children are particularly at risk, with elevated non-carcinogenic hazard index (HI > 1) and incremental lifetime cancer risk (ILCR > 1 × 10⁻4) through both ingestion and dermal pathways. Among the studied sites, JR and TPP canal exhibited the highest PTE concentrations, whereas RC served as the least contaminated reference site. statistical analyses, including Pearson correlation and Positive Matrix Factorization (PMF), identified coal combustion by-products, atmospheric deposition, and ash leachate as the dominant sources of contamination, with minor contributions from domestic and agricultural runoff. The findings underscore the urgent need for pollution control, regular monitoring, and site-specific remediation strategies to protect both ecological and human health in coal-affected aquatic systems.

Student diversity plays a crucial role in fostering inclusive education, which enhances innovation, creativity, and problem-solving. In India, while the student mobility is increasing, disparities across regions and institutions continue to influence students’ decision in choosing an institution. Understanding student’s decision making will enhance equal opportunity for quality education. This study aims to identify the factors affecting interstate student diversity in Indian higher education. Secondary data from a national ranking body were analysed using statistical techniques and supervised machine learning algorithms using tool OriginPro 2024 and MATLAB’s R2024a respectively. Statistical analyses, including Pearson correlation, Spearman correlation, and Kruskal–Wallis tests, were employed to analyse relationships among factors, while machine learning models such as Gaussian Process Regression, Ensemble methods, Support Vector Machines, and Kernel-based approaches were used to assess feature importance. The findings show that the factors of student diversity vary across institution types. In Central Government Funded Institutions (CGFIs), location (23%) and course offerings (9%), while in State Government Funded Institutions (SGFIs), international student proportion (17%), were significant factors. For Self-Financed Institutions (SFIs), institutional rank (13%) and placement opportunities (10%) were key factors. These insights can guide policies and strategies to enhance student diversity and promote inclusive education in alignment with National Education Policy (NEP) 2020 and quality education Sustainable Development Goals (SDG) 4.

Hydrogen, a carbon-free fuel, has the potential to aid global nations in achieving eight of the 17 Sustainable Development Goals (SDG). The shortcomings associated with H2 transportation and storage can be mitigated by using NH3 as hydrogen carrier because of its better safety, physical, and environmental properties. However, to achieve the global climate target, green ammonia production must be incremented by four times (688 MT) from the current level. Hence, understanding of advanced green NH3 production and storage technologies, along with the factors that influence them becomes necessary. It also aids in identifying the factors hindering green H2 and NH3 production, which can be resolved by promoting research. At the same time, drafting policies that encourage green H2 and NH3 production can abet in overcoming the bottleneck faced by the industry. Presently, green ammonia production can be made feasible only when the renewable electricity cost is less than $20/MWh and carbon price of $150/t of CO2 emissions is levied. Approximately 80 % of the energy consumed during NH3 is spent on H2 generation; therefore, it is necessary to enact policies that promote green H2 production globally. Producing green H2 can aid in mitigating ∼90 % of the greenhouse gases emitted during NH3 manufacturing thereby facilitating to reduce the carbon footprint of H2 carrier and decarbonize NH3 industry.

The use of micro-algae for wastewater treatment is a promising technique that contributes to CO2 capture and nutrient recovery. However, the lack of effective forecasting models limits the scalability of this technique. This study aims to develop a time-series-based forecasting model to predict the growth curve of microalgal biomass under environmental conditions similar to those found in wastewater. Data collected on microalgal growth was used to train six time-series models: Long Short-Term Memory (LSTM), Extreme Gradient Boosting (XGBoost), Auto-Regressive Integrated Moving Average (ARIMA), Random vector functional link (RVFL), Physics-informed neural networks (PINN) and Prophet. The model performance metrics were compared, and the best model was identified. The results demonstrated that the RVFL was the most accurate model, with minimal prediction errors ( < 0.01). Residual analysis confirmed a normal distribution of errors without outliers, supporting the model's reliability. These findings suggest that the proposed RVFL model can effectively forecast microalgal growth, potentially reducing the need for costly and labour-intensive laboratory trials and advancing microalgae-based wastewater treatment.

Microalgae cultivation is gaining interest as a sustainable alternative to the conventional wastewater (WW) treatment and nutrient recovery. Current study presents a comprehensive life cycle assessment (LCA) of microalgae cultivation in distinct wastewaters. Two different microalgae species in three different wastewaters were compared for sustainability performance in six scenarios. LCA was conducted using SimaPro (v9.3.0.3) and ReCiPe 2016 Midpoint method. The findings of the study reveal that global warming potential ranged between −678 and − 1357 g CO2eq./m3. Chlorella sp. cultivated in dairy WW shown higher environmental performance across the scenarios with GWP of −1357 g CO2eq./m3. The average global warming potential (GWP) of single-pot microalgae-based wastewater treatment got reduced by 240 %. The key inference of this study is that cultivation of the microalgae as single-pot treatment system not only helps in environmental sustainability but also holds significant promise for combating climate change as negative emission technology (NET).

Microalgae-based wastewater treatment has resulted in a paradigm shift toward nutrient removal and simultaneous resource recovery. However, traditionally used microalgal biomass quantification methods are time-consuming and costly, limiting their large-scale use. The aim of this study is to develop a simple and cost-effective image-based method for microalgae quantification, replacing cumbersome traditional techniques. In this study, preprocessed microalgae images and associated optical density data were utilized as inputs. Three feature extraction methods were compared alongside eight machine learning (ML) models, including linear regression (LR), random forest (RF), AdaBoost, gradient boosting (GB), and various neural networks. Among these algorithms, LR with principal component analysis achieved an R2 value of 0.97 with the lowest error of 0.039. Combining image analysis and ML removes the need for expensive equipment in microalgae quantification. Sensitivity analysis was performed by varying the train-test splitting ratio. Training time was included in the evaluation, and accounting for energy consumption in the study leads to the achievement of high model performance and energy-efficient ML model utilization.

Wastes are unceasingly generated in the world, and most of them can be recycled, reused, or recovered to promote a circular economy. Among waste treatment approaches, the anaerobic digestion (AD) process has been considered as an ideal process due to its ecological benefits (reduction of unpleasant odor, pathogens accumulation, or greenhouse gas emission), social and economic advantages, and energy saving. In addition to biogas production, this process can be used to produce various bioproducts, such as biopolymers, bioplastics, biomass, biofertilizers, and biolipids. Interestingly, the AD process residue or digestate is a nutrient-rich by-product that can be used as a biofertilizer for agronomical purposes to balance N-P cycle in the soils. Despite of numerous benefits of AD, less than 1 % of waste is treated by this process. This process has the potential to be integrated with other waste treatment approaches to increase waste treatment efficiency. Therefore, it is essential to focus on each advantage and clarify ambiguity in order to satisfy more countries for employing AD for waste treatment. In this review, various benefits of AD are evaluated; and its potential impacts on particularly agriculture are examined in detail. Additionally, potential biomass and wastes that can be used for anaerobic digestion worldwide are deliberated. Besides, a critical perspective has been developed on the economic, environmental, and social evaluation of the benefits of AD and, as a final point, focused on an integrated circular cascading approach.

The fish transport sector plays a crucial role in both domestic and export markets in India, with insulated vehicles accounting for approximately 60% of fish transit immediately after landing. These insulated vehicles, although essential for maintaining fish quality and minimizing spoilage, contribute significantly to environmental concerns, including increased greenhouse gas emissions, energy consumption, and material use, particularly given their reliance on fossil fuels. This study assessed the environmental impact of using insulated vehicles to transport 1 tonne of fish over a distance of 200 km. Using SimaPro (V9.3) for a life cycle assessment, a landing-to-consumer approach was adopted, incorporating questionnaire-based and secondary data collection. The results revealed significant impacts on human health, with vehicle operations posing high risks (1.13E-05 disability-adjusted life years) due to diesel engine emissions. The long-term global warming potential from vehicle operations was higher than that from depreciated vehicle construction, with emissions measured at 4.44 kg CO2 equivalent per tonne per trip over 100 years. The findings indicated that emissions from insulated vehicles during fish supply contributed approximately 0.4% of global emissions, underscoring the need for environmentally sustainable transportation practices in the fish transport system. Adopting electric vehicles, hybrids, biofuels, and emission controls can enhance sustainability in fish transport. Policies like the National Green Hydrogen Mission, carbon-neutral practices, and green exports support this transition in the fish transport system.

Background: Aquaculture relies significantly on effective aeration systems to ensure optimal conditions for aquatic organisms. This 96-day study investigates the dynamic relationship between Oxygen Transfer Rates (OTR) and seasonal variations, with a specific focus on the impact of seasonal dynamics and the placement of paddle wheel aerators. The study recognizes the pivotal role of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) as key water quality parameters influencing aeration efficiency. Methodology: A series of water circulation experiments were conducted at regular intervals to assess mixing rates, revealing a nuanced trajectory ranging from 27.05 to 14.22 m³/kWh. The study scrutinized the influence of TDS and TSS on these rates. Additionally, water velocity variations, ranging from 0.45 to 1.67 m/s, were examined, highlighting density-dependent changes, particularly evident post four weeks of operation. Oxygen stratification analysis provided insights into deviations in Dissolved Oxygen (DO) concentrations, with particular attention to climatic aberrations. Rigorous statistical analyses, including chi-squared, Pearson correlation, Gaussian distribution checks, and student's t-tests, validated the methodological robustness and data reliability. Significant findings: Employing a Seasonal Auto Regressive Integrated Moving Average (SARIMA) model, the study achieved a remarkable 97 % accuracy in forecasting DO levels for the subsequent 96 days. Real-time validation, complemented by a Chi-square goodness of fit test, reaffirmed the model's reliability, establishing congruence between observed and forecasted values. This research underscores the critical roles of strategic aerator placement and seasonal considerations in optimizing pond aeration efficiency, providing substantive insights for the sustainable management of aquaculture ecosystems.

Halogenated polycyclic aromatic hydrocarbons (HPAHs) including chlorinated (ClPAHs) and brominated (BrPAHs) variants, are emerging contaminants that are considered the next-generation candidates of persistent organic pollutants. Since there was a significant gap exists in understanding of partitioning dynamics of HPAHs between the particulate phase (PP) and dissolved phase (DP) considering many congeners, this study analyzed 75 congeners of parent PAHs and HPAHs (p/HPAHs) in the samples collected from 27 sites from 20 water bodies in Sri Lanka. The results revealed that the mean of the total concentrations of PAHs, ClPAHs, and BrPAHs in the aqueous phase (PP + DP) were 55.79, 1.89, and 0.49 ng/L, respectively. Partition coefficients of HPAHs increased with molecular weight, and pyrene and its halogenated derivatives dominated both phases. A predominance of HPAHs in the DP suggested that their distribution was more influenced by source characteristics than by phase partitioning processes. Most p/HPAHs originated from mixed petroleum and combustion sources, with additional input from decaying contaminated biota. The risk quotients determined via the acute and chronic ecological risk assessment indicated many waterbodies had medium to high risks to fish and daphnids, whereas the consumption of well water for drinking purposes did not pose a risk to humans. This study provides the first comprehensive phase-specific evaluation of HPAHs in a tropical aquatic environment and calls for targeted monitoring strategies, effective management plans, and public awareness to mitigate future contamination.

Microplastics, a complex category of pollutants containing microorganisms and toxins, pose a significant threat to ecosystems, affecting both biotic and abiotic elements. The plastisphere's bacterial community differs significantly from nearby habitats, suggesting they may significantly contribute to the degradation of plastic waste in the ocean. This study evaluated the diversity of culturable bacterial populations attached to the microplastics in the coastal zones of the A&N Islands and their potential for plastic degradation. Three A&N Islands beaches were surveyed for microplastics. Low-density polyethylene (LDPE) was the most abundant polymer found, followed by Acryl fibre, polyisoprene etc. A total of 24 bacterial isolates were chosen based on their morphological traits and underwent the initial screening processes. With the highest degrading activity (10.79 %), NIOT-MP-52 produced noteworthy results. NIOT-MP-25 (5.07 %), NIOT-MP-43 (3.78 %), NIOT-MP-61 (3.51 %), and NIOT-MP-82 (3.36 %) were the next most active strains. Strain NIOT-MP-52, selected for its superior degradation efficiency, underwent further screening and analysis using FT-IR, SEM, AFM, and DSC. Variations in infrared spectra indicated the breakdown of LDPE while SEM and AFM analyses showed bacterial attachment, roughness, grooves, holes, and pits on the LDPE surface. DSC provided thermal analysis based on the biodegradation potential of the bacterial strain targeting LDPE sheets. These findings highlight the ability of marine bacteria to efficiently degrade microplastics and utilize plastics as an energy source, emphasizing their importance in future plastic waste management.

Microplastics (MPs) in aquatic ecosystems readily promote biofilm formation, creating the plastisphere, a dynamic interface that interacts with environmental pollutants and acts as a reservoir for microorganisms. Recent studies emphasize the plastisphere's contribution to the spread of pathogens, antibiotic-resistant genes (ARGs), and antimicrobial resistance (AMR) within aquatic organisms and across diverse environments, a phenomenon collectively called the ‘Plastiome’. Although the prevalence and effects of the plastisphere have been studied extensively, a systematic synthesis of updated insights into the behavior of the plastiome is urgently needed. This review explores the development and behavior of plastics, focusing on its interactions with ARGs and pathogens within aquatic ecosystems. Microplastics selectively enrich ARGs and pathogenic microorganisms, fostering unique microbial communities distinct from those in surrounding waters. The plastiome facilitates horizontal ARG propagation, increasing the quantity of antibiotic-resistant pathogens and presenting substantial risks to the hydrosphere and public health. Additionally, key research opportunities are identified and strategies are recommended to advance our understanding of plastiome-driven antibiotic resistance in aquatic environments.

Conversion of metal–organic frameworks (MOFs) into metal-nitrogen-doped carbon (M–N–C) catalysts requires a high-temperature process and longer processing time under a protective atmosphere. This study utilizes a low-energy nanosecond laser processing (LP) technique to convert aqueous synthesized 2D leaf-like Co-MOF (L-Co-MOF) into nanoscale cobalt metal encapsulated within a nitrogen-doped graphitic carbon matrix (Co@N-gC, Co-LP) in a shorter period under air atmosphere. The laser-induced process results in the formation of Co@N-gC with smaller Co particle size, uniform distribution, and better interaction with the carbon support compared to the conventional pyrolysis process (CP). LP catalysts result in enhanced multifunctional electrocatalytic activity over CP (Co-CP) catalysts owing to the tunable metal–support interaction, higher charge transfer, and presence of multiactive sites. Under optimized conditions (laser fluence: 5.76 mJ cm−2 and scan speed: 10 mm s−1), the Co-LP-5 catalyst exhibits better ORR performance, with onset and half-wave potentials of 0.92 and 0.76 V, respectively. Additionally, Co-LP-5 delivers excellent water-splitting performance, with OER and HER overpotentials of 380 and 280 mV, respectively, achieving an overall energy efficiency of 77.85%. Furthermore, Co-LP-5 demonstrates exceptional durability over 48 h of real-time testing, outperforming the Co-CP, and the proposed low-energy LP is viable for fabricating multifunctional catalysts.

Two-dimensional (2D) PdCu bimetallene (PdCu) exhibits unique structural and electronic properties, enhancing surface reactivity for crucial electrochemical reactions in energy conversion and storage. The one-pot synthesis, followed by dealloying (DA) to form DA PdCu, further enhances surface reactivity by altering the electronic structure. This process induces geometrical effects, significantly impacting surface strain and influencing selectivity and performance for (oxygen reduction reaction) ORR and (methanol oxidation reaction) MOR in an alkaline medium. The heterogeneous surface of DA PdCu with crystalline and amorphous regions and abundant surface defects, enhances active sites for improved ORR and MOR kinetics. During ORR, the DA PdCu exhibits superior mass activity (MA) of 0.62 mA μg−1 and extended stability with a positive shift (10 mV) in half-wave potential after 20,000 cycles. Additionally, it exhibits excellent MOR-MA (3335.9 mA mg−1) with 62.3% retention after 10,000 cycles, effectively competing with reported catalysts. Theoretical studies clarify the electronic strain transformation and its influence on adsorption energies of reaction intermediates on PdCu and DA PdCu during ORR and MOR, crucially correlating with experimental findings. The alloying-dealloying process in 2D-layered PdCu is a promising strategy to enhance the structure-activity relationship for improved multi-functional electrocatalysis with greater endurance.

Microplastics (MPs) are impacting coastal and ocean ecosystem and also have been linked with ‘blue economy’, which accounts major portion to the total economy of a nation. The ocean serves as a sink for MPs, receiving them from rivers, runoff, industrial effluents, and direct waste discharge. Consequently, marine organisms are impacted, leading to indirect economic losses, and causing irreparable damage to the blue economy. In addition, the presence of chemicals and microorganisms on MPs is causing detrimental effects on marine organisms, leading to economic repercussions. Coastal tourism, a key aspect of the blue economy, relies on a sustainable and visually appealing environment, which is being threatened by rising marine debris, primarily plastic waste generated by tourists. The clean-up cost is very high, whereas the existing removal technologies do not have higher efficiency and are not that much cost effective. Thus, this study reviews the country wise economic effect of plastic pollution, along with existing policies, regulations and the management strategies to control MPs in marine system considering its potential impacts on sectors associated with marine resources vis-à-vis blue economy.

The rapid population, industrialization, and urbanization increase have led to a multi-fold increase in automobiles, thereby increasing the demand for lubricating oil. Among the available lubricants, automotive lubricating oil (motor oil) accounts for 57% of global lubricant demand, which is used to lubricate vehicular engine’s metal parts, reducing wear and increasing engine efficiency. However, with usage, it degrades due to (i) oxidation, (ii) thermal breakdown, (iii) micro-dieseling, (iv) additive depletion, and demands alteration with fresh motor oil. This chapter aims to discuss the characteristics of fresh and waste motor oil. Besides, it extensively explains the impact of waste motor oil (WMO) on water bodies, marine life, soil, and human health due to illegal disposal to overcome high waste management costs. Furthermore, it also focuses on the WMO hierarchy and suggests different treatment methods based on the hierarchy. However, among the available treatment methods, pyrolysis has drawn notice due to its adaptability and product diversification.

The present research examines the combined pyrolysis of rice stubble and waste motor oil, utilizing a laboratory-scale pyrolysis setup to generate alternative energy fuels. This approach leverages the hydrogen-rich nature of waste oil to improve the quality of the resulting fuel. The goal of the study is to enhance the yield of co-pyrolytic oil by optimizing process parameters such as reactor temperature (TR, °C), blending ratio (M, %), and residence time (t, min). The work also evaluates improvements in pyro-oil quality when using rice stubble alone. A maximum oil yield of 89% was achieved under optimized conditions of 500°C, 95ppele% blending ratio, and 20 min of reaction time. Besides, the absence of undesirable components like the thiols and acids or esters was found in the co-pyrolytic oil favoring its usage toward alternative fuel. Further, the alignment of the BET and FESEM results suggests that the co-pyrolytic char possesses better absorbent properties due to improved pore volume and surface area than the pyrolysis of individual feedstocks.

Reverse osmosis concentrate (ROC), a hyper-saline byproduct of domestic RO systems, contains elevated ionic and heavy metal content, posing environmental risks. This study developed a decentralized treatment system using a fluidized-bed column packed with chitosan-impregnated zinc-oxide nanocomposite (CS@ZnO) and acid-treated resin (ATR) beads. ROC samples were collected from residential RO units in groundwater (GW) and surface water (SW) dependent regions in Gujarat, India. Physicochemical analysis revealed elevated total dissolved solids (TDS: ≥3241 mg L−1), electrical conductivity (EC: ≥5440 μS cm−1), anions, cations and heavy metals exceeding regulatory limits. A negative correlation between pH and EC/TDS revealed acidification linked to ion accumulation, informing sorbent optimization. The hybrid column, operated in upward flow (570 mL min−1), demonstrated effective stabilization of pH and removal of TDS (25.9 %) and EC (39.5 %) up to 60 L. Significant contaminant removal efficiencies included: Ca2+ (73.2 %), Mg2+ (62.4 %), Na+ (31.3 %), F− (76.6 %), Cl− (46.2 %), SO₄2− (99.7 %), NO₃− (92.1 %), Mn (100 %), Zn (65.3 %), Ni (42.5 %), Co (16.7 %), and Cd (54.5 %). The adsorption mechanism combined CS's chelation, ATR's ion-exchange, and ZnO's surface reactivity. Although Pb and Cr exceeded safe limits post-treatment, the effluent complied with standards for non-potable reuse. This column offers a scalable, low-cost method for ROC valorization, promoting sustainable water reuse and environmental protection in water-stressed areas.