Scottish-IISc researchers develop wastewater treatment, recycling system

About 200km southwest of Bengaluru is Berambadi, a village nestled between mountains, swathes of agricultural fields, the Hirikere lake, and the Bandipur National Park.

This verdant countryside with tidy roads that borders Karnataka's neighbours Kerala and Tamil Nadu is spellbinding. However, Berambadi, located in the rain shadow side of the Western Ghats, has been hit by drought several times in the last few years.

A study, published in the Journal of Water Process Engineering and carried out in collaboration with researchers in Scotland, shows how the system has, over the past year, enabled the reuse of wastewater and reduced dependence on freshwater resources, IISc said in a statement.

The project, funded by the Scotland government, is a collaboration between IISc, the Ashoka Trust for Research in Ecology and the  Environment, Bengaluru, the James Hutton Institute, Scotland, and the University of Glasgow.

"We have demonstrated for the first time that decentralised wastewater treatment systems can be economically put into practice in a  rural setting," the Centre for Sustainable Technologies, IISc, Assistant Professor and a senior author of the paper Lakshminarayana Rao said, adding that decentralised wastewater treatment system is the way to go.

According to IISc, the research team operated the greywater treatment system for a year and monitored the different physicochemical  and biological characteristics of the greywater at the entry and exit points.

Rao added that the goal was to direct the treated grey water for reuse in toilet flushes and gardening.

"To do this, they designed a  system where grey water is subjected to a series of steps: first is getting rid of the remnant fat and grease in the wastewater using a grease trapper.

Water free of grease is passed through a trickling bed filter (a bed made of gravels of different sizes)  and an aerator, where microorganisms help remove pollutants in the wastewater. This water, after undergoing the final step of disinfection, can be reused," Rao explained.

The performance of every treatment stage was quantified in terms of removal efficiencies (REs) of turbidity, Total Suspended Solids (TSS), nitrate, total phosphorus, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and faecal coliforms (FC), it said.

Overall, the system showed high REs more than 90 per cent for most of the parameters.

About 667 litres of greywater were treated daily using the system, saving around 180,000 litres of water annually, it added.

Such a robust wastewater management system can be replicated in both rural and urban settings after taking into consideration various  factors such as space limitations, baseline greywater quality and daily flow rates, the authors suggested explaining how the system works.

"The people from Berambadi village are very happy with the system. Based on the success of this sustainable wastewater management project,  several other schools in Karnataka have approached us to duplicate it in their schools," Rao claimed.