Hybrid electrocoagulation reactor for dairy wastewater treatment and methodology for sludge reusability for the development of vermicompost.

Abstract

The dairy industry is a high-water-consuming sector, making water conservation crucial, especially in countries like India that are top milk producers and have large populations. This research evaluates the performance and effluent characterization of dairy effluent treatment systems in Kerala using modern, cost-effective technology to address this issue. A hybrid electrocoagulation reactor (HECR) is designed to operate simultaneously in coagulation, and the electrocoagulation process is proposed in this study. The wastewater treatment parameters of the HECR with those of six existing dairy effluent treatment plants using geological mapping and geographic information system (GIS) were studied. According to inverse distance weighted (IDW) interpolation findings, HECR's effluent treatment profile is comparable to existing technologies, with a minimum required retention time of 9.58 h. The results show the HECR treatment efficiency, removing up to 75.15% of turbidity and 94.5% of COD. Moreover, the sludge generated from HECR is transformed into nutrient-rich vermicompost by adding suitable fillers in the ratio of 5:1:3:1 (industrial dairy sludge/HECR sludge: cow dung, dry leaf, and seed vermicompost). The optimal conversion times for vermicompost developed from dairy industrial sludge are 40 days, with nitrogen, phosphorus, and potassium (NPK) values per gram vermicompost of 8.86%, 3.18%, and 3.6%, respectively. For HECR sludge, on the 60th day, the observed NPK value for the developed vermicompost is at 4.76%, 1.46%, and 5.1%. Overall, this research offers a promising solution to treat dairy wastewater and transform generated waste sludge into a valuable resource, highlighting the importance of technology adaptation in the dairy industry.