Using riverbank filtration to ease water supply tensions in India
Using riverbank filtration for irrigation and drinking water abstraction can help ease the pressure on Indian aquifers. The CCRBF joint Indo-German research project investigates the necessary preconditions and advocates the large-scale use of riverbank filtration in India.
India has a population of over 1.3 billion people. It is a great challenge both to supply this vast population with drinking water and to provide sufficient amounts of water for agriculture. While per capita consump-tion of drinking water is relatively low in India compared to Western countries, its agricultural sector re-quires large amounts of water. More than three-quarters of India’s water production is used for agricul-ture. In large parts of the country, rainfalls vary considerably throughout the year, leaving farmers de-pendent on irrigation.
The CCRBF collaborative project
This collaboration is aimed at improving water production in India while also conserving groundwater. To this end, Germany and India will continue to deepen their cooperation on research and education in the areas of water management. The thematic focus of the project is on natural processes such as riverbank filtration and constructed wetlands. Project partners are jointly drawing up guidelines in order to increase the use of these technologies in India and are developing a master plan for riverbank filtration.
The Indo-German Riverbank Filtration Network, which was launched in 2008, will be strengthened and expanded to include 15 partners from both countries, namely seven higher education institutions, four research institutes, two water utilities and two engineering firms. The plan is to establish a Competence Centre for Riverbank Filtration (CCRBF) with headquarters in Dresden and Roorkee. The centre will pro-vide comprehensive counselling services on the use of riverbank filtration as well as practical training courses for those working in the water industry.
Putting the technology to use – riverbank filtration
Riverbank filtration is a natural water treatment technique. It takes advantage of the capacity of subsur-face sediments to function as a natural filter. Water is collected from a well that is installed near a river. The water collected from these wells is sourced partly from groundwater and partly from river water that filters through sediments into the well (bank filtrate). Different physical, chemical and biological processes take place along the water’s flow path through the subsoil. This partly or fully breaks down germs and pollutants and thereby removes them from the river water.
Germany is a global leader in the field of riverbank filtration technology for energy-efficient water pro-duction. The collection of bank filtrate helps to avoid groundwater depletion.
In India, farmers often still use river water to irrigate farmland. This is a problem as the pollutants and pathogens contained in the river water are spread unfiltered on land and crops. Using water produced by riverbank filtration for agricultural irrigation considerably reduces this risk.
Demonstration plants and accompanying research
The collaborative project involves the collection of bank filtrate from demonstration plants along four Indian rivers. The collected water will be analysed in order to demonstrate the potential of riverbank fil-tration for producing clean water. This monitoring not only guarantees the quality of the produced drink-ing and industrial water but also provides Indian project partners with the practical know-how for using the technology.
At another demonstration site, constructed wetlands will be used to treat wastewater. This method is particularly well-suited for decentralized water treatment in rural areas. Constructed wetlands have proven to work well in India and facilitate the management of rising amounts of wastewater produced by a rapidly growing population. Scientists are monitoring the operation of the demonstration plant closely. The plant also serves as a demonstration site for interested authorities and water utilities.
One of the priorities of the Riverbank Filtration Network is to familiarize engineers at Indian water utilities with the two technologies and provide practical training in their use.
Defining the framework and drafting a master plan
One important milestone in the collaborative project is for the network to define the necessary frame-work conditions for making meaningful use of riverbank filtration. Not all riverbanks are suited to this technology. For example, extraction wells should not be installed too close to estuaries because salty seawater would mix with fresh river water at high tide. Riverbank filtration in these areas would firstly produce brackish water that contains too much salt to be used and, secondly cause saltwater intrusion in the subsoil and hence the aquifer.
Another aim is to review the guidelines for the use of riverbank filtration and constructed wetlands in India, together with the institutions involved. These guidelines should lay the foundation for political deci-sion-making and help administrations promote the use of these technologies.
The network brings together practitioners and researchers from the institutions involved to jointly draw up a scientific master plan for riverbank filtration. This master plan will be drafted in cooperation with the research institutions of India’s Department of Water Resources. The goal is to use riverbank filtration to produce up to 5% of India’s drinking water consumption by 2030.