Wastewater quality index (WWQI) as an indicator of secondary treated wastewater quality and sustainable water reuse

The purpose of the present study was the assessment of secondary treated wastewater of dairy industry effluent treatment plant as sustainable water resource in terms of wastewater quality index (WWQI). The results revealed that treatment process and discharged effluent is following the environment protection standards of Indian standards for discharge and irrigation. BOD values of 67% samples are higher than permissible limits of FAO and inland surface waters standards (30mg/l) (IS2490-Part I-1981). The other 15 measured physico-chemical parameters are within permissible values of Indian standards (IS2490-Part I-1981).  The calculated WWQI values ranging from 43.77 to 68.97 are indicative of excellent to good quality of treated water in terms of physicochemical parameters. Still, the treatment process should be regularly monitored and improved to reach a better level of BOD and WWQI and hence better water quality.