At first glance, it seems inconspicuous. Since August, the new drinking water plant is up and running in the Indian fishing village of Rasui near the town of Chatra. Previously, the only publicly accessible source of drinking water was untreated groundwater contaminated with arsenic. After years of research, planning and political wrangling, the new plant is now in a twelve-month test operation and shows that the natural-biological process implemented in it works better in this environment than other solutions applied so far.
The adelphi water engineers developed this new form of water treatment in a joint research project with Jadavpur University in Kolkata and the Technical University in Berlin. They extended the pre-treatment stage by two additional stages, and improved the main treatment stage with an additional oxygen supply. This demonstrably removes impurities and micropollutants more efficiently than conventional processes. As a result, the plant has reached the main criteria for drinking water quality after only a few days of operation. Berliner Wasserbetriebe is also testing a similar process.
Rainwater, and seasonally also the nearby Padma River, is collected in a pond built for this purpose, which functions as the water source for the treatment plant. A dynamic intake -filter followed by a four-stage horizontal roughing gravel filter, a slow sand filter and an activated carbon filter purify the sedimented water.
Not only the near-natural treatment process, but also the environmentally friendly construction follows the principles of sustainable use of local resources. Local craftsmen assembled the entire system, including filter media, on site. Photovoltaic power operates the three DC pumps during the day to pump the water into buffer tanks, from where it passes through the continuous filtration process by gravity.
Another highlight of the plant is that it is managed by a village water committee and specially trained operators. Together, they incentivise organic farming in the catchment area and constantly monitor water quality levels. The government of India is introducing this community-owned form of drinking water supply throughout the rural areas of the country. The plant also serves as a pilot for this process.
Planning and construction were not without difficulties. Some local political forces were very much in favour of the project, while other forces, some of them religiously motivated, politicised it. But a participatory process and continuous lobbying on the part of our team on site worked out. Pragmatic solutions also helped. For example, the team won over a neighbouring community for the project at short notice after reaching a political impasse in the location originally planned for it.
Eventually, and with the help of a local NGO and engineering company MAB Inc., construction could be completed and the plant will soon provide drinking water to about 150 families. Over the next two years, adelphi plans to optimise the plant, transfer it to the community for sustainable operation, and also develop a distribution network and suitable wastewater treatment.
This would not have been possible without the strong support of Indienhilfe e.V. and the municipality of Herrsching in Bavaria. Indienhilfe provided financial support to the technical implementation by adelphi and the socio-economic support on site. And the municipality of Herrsching financed the construction as it is the twin city of Chatra.
A doctoral thesis supervised by adelphi now evaluates and optimizes the plant. Jadavpur University Kolkata supports this work within a research project funded by the Indian Ministry of Science and Technology.