Lucknow: A team of engineers at IIT-Kanpur has developed a system to treat industrial wastewater by using locally available sand, solar radiation and zinc oxide.The team tested the innovative system at a treatment plant in Jaipur and got it patented. The team used photocatalytic treatment process embedded within the treatment plant ecosystem that improved the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) – the two key water quality tests used to measure organic pollution.Before the photocatalytic treatment (that uses solar radiation), the team of researchers led by Prof Shantanu Bhattacharya decoloured the water in a coagulation-flocculation unit designed by them to maintain the pH level. The coagulation-flocculation unit is a green tank in which the researchers put chemicals to allow the sludge in wastewater to settle down.The researchers then used a sand filter for further filtration before putting the water into the main photocatalysis tank that is embedded with zinc oxide grown over a galvanised plain sheet. Here, through solar radiation, the water is treated for two to three hours after which the BOD and COD levels come down from 156mg/litre to 10mg/litre and 2400mg/litre to 125mg/litre, respectively.Research scholar Suraj Kumar said this automated system uses sensors which can detect the pH, total dissolved solids (TDS), and colour of the water at different treatment stages. “This plant is currently installed in a textile industry in Jaipur. With this technology, the treated wastewater is being used for washing clothes and plantation,” he said.Prof Bhattacharya said that after the photocatalytic treatment, the water is further filtered using a carbon filter to remove smaller particles that are not separated through sand filtration process. “Beyond the textile and steel industries, we have recently used this technology in treating food wastage water. We are now exploring the use of the treated wastewater for hydrogen production,” he said.GFXGreen Treatment TechLow operating cost: Utilises solar radiation and locally available sandReduces COD, BOD, TOC, TSS and brings pH level within safe limitEnables reuse of treated effluent in the industrial process, reducing industry’s freshwater demand
