(Feature Image: The NTU research team behind the solar-powered method to convert sewage sludge into green hydrogen and animal feed. Source: Science Tech Daily)
On the occasion of World Water Day 2025, SANDRP compiles ten studies and research papers revealing the various cost effective and efficient methods to treat sewage and recover nutrients from sewage sludge. The first part of the series highlights water efficient practices being adopted by farming communities in India and the second part covers the water sources conservation efforts being made by the rural communities in the country. The third part has focused on sewage treatment and rainwater harvesting efforts being made in various cities in the country.
1. Constructed wetland for wastewater treatment A comprehensive investigation, published in the Journal of Environmental Management discussed constructed wetland as an engineered ecosystem designed to replicate natural wetlands, utilising aquatic plants and microorganisms to filter contaminants from wastewater. By incorporating a microbial fuel cell into this system, the technology enhanced wastewater treatment while simultaneously generating clean energy.
The procedure is described as wastewater flowing into the wetland, where plants and microorganisms collaborate to decompose organic contaminants. Below the surface, special bacteria in the microbial fuel cells consume the organic matter, initiating a biochemical reaction that produces electrons. These electrons are captured and transferred through an electrode system, generating a small but usable amount of electricity. This innovative approach ensures dual benefits — efficient water purification and renewable energy production, making constructed wetland coupled with microbial fuel cells a sustainable, cost-effective solution for wastewater treatment in urban, rural, and industrial applications. https://www.downtoearth.org.in/water/how-this-nature-based-solution-can-generate-clean-energy-while-purifying-wastewater (12 Mar 2025)
2. Scientists convert sewage sludge into green hydrogen & nutritious protein Scientists at Nanyang Technological University, Singapore (NTU Singapore), have developed a groundbreaking solar-powered process to convert sewage sludge—a by-product of wastewater treatment—into green hydrogen for clean energy and single-cell protein for animal feed. Published in Nature Water, this innovative sludge-to-food-and-fuel method addresses two critical global challenges: waste management and sustainable resource generation. It also aligns with NTU’s commitment to tackling climate change and environmental sustainability.
Lab tests showed the new method recovers 91.4 percent of the organic carbon in sewage sludge and converts 63 percent of the organic carbon into single-cell protein without producing harmful by-products. In comparison, traditional anaerobic digestion typically recovers and converts around 50 percent of organic materials in sewage sludge. The solar-powered process achieves an energy efficiency of 10 percent, generating up to 13 liters of hydrogen per hour using sunlight, which is around 10 percent more energy efficient than the conventional hydrogen generation methods. https://scitechdaily.com/scientists-convert-sewage-sludge-into-green-hydrogen-and-nutritious-protein/ (15 March 2025)
3. IIT-G researchers devise eco-friendly wastewater solution A team of researchers at IIT-Guwahati, under the leadership of Prof Kannan Pakshirajan, has introduced an innovative technique for eliminating ammonium from wastewater through the combined action of microalgae and bacteria. This eco-friendly solution substantially reduces power consumption compared to conventional wastewater processing methods. https://timesofindia.indiatimes.com/city/guwahati/innovative-eco-friendly-wastewater-treatment-solution-developed-by-iit-guwahati-researchers/articleshow/115218551.cms (12 Nov 2024)
4. Algae based solution for wastewater treatment Indian researchers have proposed a theory for a sustainable wastewater treatment method using a microalgae-bacterial consortium to remove toxic ammonium. The method, proposed in a recently published study, leverages algae’s photosynthesis mechanism to produce oxygen, cutting energy costs by up to 90% compared to traditional aeration methods.
According to a 2022 Niti Aayog report, the India generates approximately 39,604 MLD of wastewater in rural regions, while in the urban centres, the wastewater generation has been estimated as 72,368 MLD in 2020-21. https://india.mongabay.com/2024/12/researchers-propose-algae-based-solution-for-wastewater-treatment/ (03 Dec. 2024)
5. DTU scientists develop nanoparticles for water pollution treatment Scientists at Delhi Technological University (DTU) have made significant progress in creating nanoparticles from natural plant extracts with antibacterial properties. These particles show potential for various applications, particularly in treating water pollution caused by untreated sewage, dyeing industry effluents, and other contaminants. Dr Mohan Singh Mehata, associate professor in engineering physics at DTU, has led groundbreaking research in developing nanomaterials using eco-friendly sources, including tulsi, neem, and paddy straw. Laboratory assessments have demonstrated positive results, with the liquid nanomaterials showing effective purification capabilities. The scientific team suggests this innovation could help solve pollution issues in rivers. https://timesofindia.indiatimes.com/city/delhi/dtu-scientists-develop-eco-friendly-nanoparticles-for-water-pollution-treatment/articleshow/117361137.cms (18 Jan. 2025)
6. IIT Bombay scientists develop water-pollutant detecting device ‘AroTrack’ Scientists at the Indian Institute of Technology Bombay (IIT Bombay) have introduced AroTrack, an economical & portable device to accurately detect harmful pollutants such as phenol or benzene in water. Scientists say that the device can be a game-changer given the increasing water pollution due to industrialisation, urbanisation & unregulated effluent discharge.
The key component of the device is a biosensing module called MopR – a sensitive sensor for detecting phenol. MopR is both selective and stable, meaning it can detect pollutants even in complex environments with a high degree of precision. Researchers have further diversified the MopR biosensor to detect other pollutants from the benzene and xylenol groups by engineering mutations in the bacterial protein. Once interfaced with an in-house, multi-channel monitoring apparatus, the MopR-based sensor forms the core of the new device—AroTrack.
The overall cost of the device is a minimum of $ 50 [less than ₹5,000]. AroTrack can detect several aromatic contaminants, including phenol, benzene, and 2, 3 dimethylphenol, even when these pollutants are present in low concentrations – usually in the 10-200 parts per billion range. Tests in simulated wastewater and actual environmental samples have found that the AroTrack is highly reliable, offering a degree of accuracy and efficiency on par with modern spectrophotometers, which are currently used for detection. The device also reliably worked in water temperatures up to 50 degrees Celsius and completed the tests in under 30 minutes, the scientists said. https://www.thehindu.com/sci-tech/science/iit-bombay-scientists-develop-water-pollutant-detecting-device-arotrack/article68883355.ece (19 Nov. 2024)
7. AquaWISE – A decision support tool for greywater treatment solutions ATREE’s women-led team of scientists and young researchers working on water science and social science aspects of wastewater treatment identified that government schools in semi-arid southern India are particularly vulnerable to wastewater related health risks while also experiencing irregular freshwater supplies. These schools also have access to fewer resources as compared to their private counterparts. Treating greywater (generated from kitchens, bathrooms, house cleaning) from schools has the potential to reduce human and environmental health risk while also reducing dependency on freshwater sources.
AquaWISE was developed as an evidence-based decision support tool for optimal deployment of Nature-based Solutions (NbS) for greywater treatment in schools. The tool can minimise or eradicate the need for costly and time-consuming baseline data collection while also generating school-specific wastewater treating NbS. AquaWISE allows users to select from a menu of treatment options based on their desired end use of treated water. https://www.indiawaterportal.org/articles/aquawise-decision-support-tool-greywater-treatment-solutions (02 Sept. 2024)
8. ‘Aquapreneurs’ are turning the tide on water pollution Through a five-year collaboration, UpLink and HCL Group’s Aquapreneur Innovation Initiative, with support from the World Economic Forum’s Centre for Nature and Climate’s water initiatives, is unlocking the potential of early-stage innovation by creating an ecosystem to empower ‘Aquapreneurs’ to scale breakthrough technologies that can transform water management. By enabling partnerships, driving investment, enabling regulations and supporting these solutions, stakeholders can not only mitigate risks but also capitalize on water’s value as a motor of climate resilience, sustainable development, and economic progress.
As part of this initiative, UpLink ran the Tackling Water Pollution Challenge to raise awareness of the early-stage water innovation ecosystem and elevate the most scalable solutions across the sector. The challenge received 273 submissions globally and identified 10 high-potential start-ups, termed Top Innovators, or Aquapreneurs, selected to join the UpLink Innovation Ecosystem. The winners of the challenge have developed various solutions to tackle water pollution. The UpLink challenge page provides information about all 10 challenge winners. https://theprint.in/environment/aquapreneurs-are-turning-the-tide-on-water-pollution/2485392/ (8 Feb. 2025)
9. Efficient techniques & practices for wastewater treatment: an update Abstract: -Several water treatment methods, including adsorption, nanotechnology, and membrane technology, have been developed to mitigate health and environmental impacts. However, many of these methods are too expensive, especially for people living in low-income countries. Additionally, some of the technologies are not very effective at removing pollutants, which exacerbates the problem. The physical, chemical, and biological approaches for treating water are categorized in this review, along with the benefits and drawbacks of each approach. Given that the adsorption method is thought to be one of the more economical and environmentally friendly techniques to treat water, this review recommends that in order to increase the efficacy of the adsorbents, a comprehensive investigation into the exact operation of the adsorbents at the cellular and molecular levels be conducted. https://link.springer.com/article/10.1007/s43832-024-00131-8 (12 Sept. 2024)
10. Potential of I&D based wastewater managementInterception and diversion (I&D) of drains offer a scalable solution to reduce river and lake pollution in India by preventing untreated wastewater discharge. This approach enhances water quality and supports sustainable water management. However, when drains carry industrial waste and contaminated runoff, treatment becomes complex, often leaving residues that limit safe reuse. Overloaded plants may struggle to remove all pollutants, compromising water quality. Effective I&D requires stricter pollution control and advanced treatment to ensure safe and sustainable water reuse. https://www.downtoearth.org.in/water/interception-and-diversion-based-wastewater-management-can-conserve-indian-rivers-and-lakes?34534532 (17 March 2025)
Compiled by Bhim Singh Rawat (bhim.sandrp@gmail.com)
SANDRP 