NIT Rourkela designs waste water treatment innovation to revitalise India's 'Dhobi ghats'

New Delhi, Dec 4 (PTI) Researchers at the National Institute of Technology (NIT), Rourkela have designed a nature-based wastewater treatment innovation targeted towards revitalising India's "dhobi ghats" and protecting urban water bodies, according to officials.

Dhobi ghats, traditional laundry spaces, still serve as socio-economic support in many Indian cities.

Due to acute water shortages, and drying borewells, the availability of open water has become very limited. Simultaneously, untreated laundry wastewater, laden with synthetic detergents, dyes, and microfibres, contaminates rivers, lakes, and wetlands, exacerbating water scarcity and harming aquatic ecosystems.

To address this challenge, the innovative setup designed by NIT Rourkela research team has created a low-cost, chemical-free, and energy-independent wastewater treatment solution -- Constructed Wetland-Microbial Fuel Cell (CW-MFC) System -- by merging wetland plants, engineered filtration layers, and electricity producing microorganisms.

"The wastewater treatment system developed by our team employed natural things like gravel, sand, soil, plants, and microbes to purify the wastewater. The system is inspired by nature and engineered for clean water," said Kasturi Dutta, Associate Professor, Department of Biotechnology and Medical Engineering, NIT Rourkela.

By leveraging the natural purification processes and generating bioelectricity in the treatment state, the developed system opens a new path for decentralised wastewater management.

Its low operational costs and minimal maintenance make it highly adaptable for deployment in urban slums, peri-urban settlements, and rural laundry setup.

"Being capable of generating real-time bioelectricity, the system can treat unlimited wastewater. With its treatment capacity increasing as the system size and numbers increases, the developed system is suitable for densely populated dhobi ghats such as Mumbai's Mahalaxmi and Bengaluru’s Halasuru facilities.

"The innovation holds significant social significance as the treated wastewater can be reused by washermen, thus easing their dependence on freshwater sources and reducing overall environmental damage.

"Additionally, the developed system offers a sustainable pathway of safeguarding local lakes and drainage systems from chemical contamination," Dutta said.

As a pilot project, the research team tested the developed system at NIT Rourkela’s own Dhobi ghat which produces approximately 1400 litres of detergent-rich wastewater daily. The developed system successfully removed surfactants and chemical oxygen demand (COD) to levels of permissible limits specified by the Bureau of Indian Standards.

The system consists of two cylindrical constructed wetland units integrated with a microbial fuel cell. Each unit is filled with layers of differently sized gravel, followed by sand and soil. A layer of graphite chunks is placed at the bottom between the gravel layers to function as the anode, while another layer of graphite chunks at the top serves as the cathode.

"The wastewater from Dhobi ghat is collected and pumped to an overhead tank which is connected to the developed systems. The wastewater then gets processed and treated resulting in an odourless and colorless water that can be reused for washing purposes," Dutta explained. PTI GJS NB