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Identifying best available technologies for decentralized wastewater treatment and resource recovery for India

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Delivering decentralised waste water treatment systems to India

Many people across India lack access to safe drinking water. Researchers for the Saraswati 2.0 project tested a range of decentralised waste water treatment technologies to give local communities cleaner, more plentiful water.

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India suffers from a low level of waste water treatment, with over 90 million people lacking adequate access to safe water. The nation is also increasingly urbanised, with roughly a third of the population living in cities, making the treatment of urban waste water fundamental to public health. However, large, centralised water treatment plants can prove unwieldy and inefficient in urban settings. The Saraswati 2.0 project, co-funded by the EU and India’s Department of Science and Technology, investigated the potential of decentralised systems to offer a more flexible alternative that can address water scarcity issues by offering treated water for reuse. “In countries such as India, the fragmented urban planning and large scale of cities makes centralised solutions generally unfeasible,” explains Markus Starkl, Saraswati 2.0 project coordinator and senior scientist at the University of Natural Resources and Life Sciences in Austria. “Decentralised systems provide the opportunity for treated waste water reuse, which is not possible in centralised systems due to the high cost involved in laying a pipe network,” adds Makarand Ghangrekar, professor of Civil Engineering at the Indian Institute of Technology Kharagpur (IITKGP), and coordinator of the Indian Saraswati 2.0 team. The project takes its name from the Hindu goddess of knowledge, music, arts and nature, as well as a lost holy river that once flowed through India. It is a continuation of a previous project that completed in 2017. In the project, the European and Indian researchers are testing a series of waste water treatment and reuse technologies to identify candidates for best available technologies (BAT) status – technologies approved by regulators for meeting standards required for a given purpose.

Testing pilot technologies

Saraswati 2.0 is running 10 pilots in locations selected based on recommendations from Indian partners. At the Indian Institute of Technology Bhubaneswar, one pilot is testing an integrated waste water treatment system centred on an upflow anaerobic sludge blanket (UASB) reactor. This technology forms a granular sludge within a reactor, where the waste water is treated by anaerobic microorganisms. “This has been proven to be a feasible and cost-effective technology for the regions with warmer climate conditions,” says Ghangrekar. Another technology known as C-TECH is being tested in Haridwar along the Ganga River. This is a sequencing batch reactor system, in which all treatment steps are integrated into one basin before the treated water is discharged. This technology is currently used in India at large system sizes, and the Saraswati 2.0 project is testing a smaller-scale version for its potential use in decentralised treatment. In a third pilot, a photoheterotrophic bioreactor is being employed for post-treatment of anaerobic digester effluent. This technology is proposed by TU Delft and is being piloted at the IITKGP. Other pilots include technologies for household waste water treatment, effluent treatment using an electrically conductive biofilter, sludge treatment to enhance methane content, and an ion-exchange membrane bioreactor technology for nitrogen removal.

Monitoring and evaluation

All pilots have been implemented across India and are now in operation. “Currently the ‘monitoring and evaluation’ phase of the project is taking place,” notes Starkl, adding that this will continue until the end of 2023. While all pilots have been set up in institutional settings, the project ran three stakeholder workshops with local communities in Kolkata, Mumbai and Chennai. “The performance evaluation of most of the pilots is in advanced stages, and we have reliable performance results for some of the pilot technologies,” remarks Ghangrekar. The collaboration between EU and Indian researchers has run smoothly. “Our project is still running for a year and will finish in July 2024,” says Starkl. “Most of the pilots are expected to continue after project end, in particular as most pilots have been implemented in institutional settings.”

Keywords

Saraswati 2.0, India, water, treatment, decentralised, system, urban, household, monitoring, evaluation, collaboration

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