Removal of Emerging Contaminants Using Low-Cost and Advanced Treatment Technologies: Evidence from Six Indian Cities

Abstract

Emerging contaminants (ECs)—including pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), and microplastics—pose significant risks to aquatic ecosystems and public health due to their persistence, bioactivity at trace levels, and resistance to conventional wastewater treatment processes. This study investigates the occurrence, seasonal dynamics, and treatment efficiency of selected ECs across six major Indian urban-river systems: Varanasi (Ganga), Delhi (Yamuna), Indore (Kahn), Kolkata (Hooghly), Nashik (Godavari), and Thiruvananthapuram (Killi River). Water samples were collected during pre-monsoon, monsoon, and post-monsoon seasons from four strategic points in each city, including upstream reference sites and downstream effluent receptors. Quantitative analysis was performed using LC-MS/MS for pharmaceuticals and PFAS, and FTIR spectroscopy for microplastic polymers. Results revealed widespread presence of ciprofloxacin (1.6–3.2?µg/L), diclofenac (0.8–1.6?µg/L), PFOS (92–145?ng/L), and microplastics (145–240 particles/L), with higher loads in densely urbanized areas. Seasonal trends indicated dilution during monsoon and contaminant mobilization post-monsoon. Bench-scale treatment trials using coagulation, UV/H?O?, activated carbon adsorption, and nanofiltration showed variable removal efficiencies, with nanofiltration achieving the highest (>90%) across all EC classes. Principal Component Analysis (PCA) distinguished high-risk zones based on EC clustering and hydrological influence. The findings underscore the urgent need for EC-inclusive regulatory frameworks, decentralized treatment upgrades, and seasonally adaptive monitoring protocols in India. This study provides a foundational dataset and a scalable methodology for future EC management and policy development.

Introduction

India’s water bodies are increasingly contaminated by emerging contaminants (ECs)—a group of persistent, biologically active pollutants including pharmaceuticals, endocrine-disrupting compounds (EDCs), PFAS, personal care chemicals, pesticides, and microplastics. These substances pose environmental and health risks even at trace concentrations, and conventional wastewater treatment plants (WWTPs) are largely ineffective at removing them.

The issue is exacerbated by rapid urbanization, poor infrastructure, improper pharmaceutical disposal, and seasonal variability. Only 37% of sewage from major Indian cities is treated, leaving rivers like the Ganga, Yamuna, and Godavari heavily polluted with untreated EC-laden wastewater. Seasonal monsoon patterns further complicate monitoring, causing fluctuations in contaminant concentrations.

While advanced treatment technologies like ozonation, nanofiltration, and activated carbon are effective globally, their use in India is limited by cost, energy demand, and lack of context-specific evaluation. This study addresses these gaps through:

• A multi-city, multi-seasonal assessment of ECs (pharmaceuticals, PFAS, microplastics) in six Indian urban rivers.

• Evaluation of four treatment technologies: coagulation–flocculation, UV/H?O? advanced oxidation, activated carbon adsorption, and nanofiltration.

• Statistical modeling to analyze spatial and temporal trends and support evidence-based policy recommendations.

Key Literature Insights:

• ECs were first noted in water systems by Daughton & Ternes (1999), and are now widely studied globally.

• In India, studies show poor EC removal from WWTPs and significant regional variability.

• Modern techniques like LC-MS/MS, GC-MS, and FTIR are used for EC detection, though limited access to such tools hinders Indian labs.

• Seasonal studies show monsoon dilution and post-monsoon concentration spikes in EC levels.

• Indian rivers like the Ganga, Yamuna, and Godavari show heavy EC loads, but comprehensive, comparative datasets are rare.

Research Gaps Identified:

• Lack of nationwide, multi-season EC data.

• Limited testing of cost-effective treatment technologies suited for Indian contexts.

• Absence of a regulatory framework for EC monitoring and discharge standards.

Methodology Highlights:

• Sampling was conducted in six urban river systems (e.g., Ganga–Varanasi, Yamuna–Delhi).

• Samples were collected pre-monsoon, monsoon, and post-monsoon at four points: upstream, WWTP influent, WWTP effluent, and downstream.

• Water quality and ECs were analyzed using advanced methods (UHPLC-MS/MS for chemicals, FTIR for microplastics), with strict preservation and testing protocols.

Conclusion

1) The study confirmed the widespread presence of emerging contaminants (ECs)—notably Ciprofloxacin, Diclofenac, PFOS, and microplastics—in six major Indian rivers, with the highest concentrations found in highly urbanized regions like Delhi and Kolkata. 2) Seasonal patterns were significant: EC concentrations were diluted during the monsoon but increased again post-monsoon due to surface runoff and contaminant mobilization. 3) Among the tested treatment technologies, nanofiltration and Advanced Oxidation Processes (AOPs) achieved the highest removal efficiencies for the target contaminants. 4) Principal Component Analysis (PCA) successfully identified pollution clusters and high-burden sites, indicating zones that should be prioritized for intervention. 5) The findings advocate for the integration of EC-targeted technologies into existing wastewater treatment plants, particularly in urban and semi-urban regions. 6) The study was limited by the number of sampling sites, lab-scale validation of technologies, and the exclusion of other classes of ECs such as hormones, pesticides, and surfactants. 7) Future work should: o Expand monitoring to include a broader spectrum of ECs, particularly endocrine-disrupting compounds. o Use machine learning tools to predict EC behavior under varying environmental conditions. o Pilot-test hybrid EC removal systems (e.g., AOPs + activated carbon) at municipal scale. o Investigate cost-effective solutions like biochar or algal-based treatments. o Evaluate long-term human and ecological health impacts through socio-economic studies.

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Copyright

Copyright © 2025 Manish Bhupatsinh Sisodiya, Mr. Abhishek Upadhyay, Mr. Azharuddin . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.