Is dairy wastewater safe for production of edible microbial biomass: A case study of Saras dairy plant at Jaipur, India

Abstract

Mismanagement of wastewater at large scale may lead to catastrophic environmental and health consequences. Microbial remediation of wastewater is one of the most effective low-cost solutions. There are also initiatives to use wastewater for production edible biomass as an alternative for protein diets. While much researches were oriented towards maximum recovery of biomass and applications, less were focused on mutagenicity of dairy wastewater. In this study, we examined wastewater of one of the largest dairy industries in Rajasthan for its suitability for microbial biomass production and mutagenicity. Influent wastewater was collected from Saras dairy plant, Jaipur, for over a week. Physiochemical properties of wastewater were examined, such as; temperature, pH, salinity, TSS, TDS, turbidity, conductivity, BOD, COD, total carbon, and total nitrogen. SOS chromotest and Salmonella fluctuation test (TA 98, TA 100 and TA 102) were carried out at variable concentration of wastewater to assess mutagenic activity. Results indicated ideal pH, temperature and salinity, for microbial remediation. High TOC and TKN were also observed in the investigated wastewater, which is few of the prerequisites for single cell production. The ratio of BOD and COD was between 0.3-0.4, making the wastewater ideal for microbial growth. No mutagenic activity was observed by SOS chromotest, all three concentrations (C 0.01, C 0.1, and C 0.2) investigated in this study were <1.5 IF. Likewise, mutagenic ratio for all three types of Salmonella revertants were below 1.2 threshold, for investigated concentrations (C 0.5, C 1, and C 10) of wastewater. Conclusively, examined influent wastewater is less likely to induce mutagenic activity at the investigated concentration. Through physiochemical analysis, the investigated wastewater assumed to be candidate substrate for microbial biomass production.