Biotransformation of cheese whey effluent: A dual approach for wastewater treatment and polyhydroxyalkanoates production using mixed microbial cultures

Abstract

Cheese whey wastewater (CWW) generated during cheese manufacturing poses an environmental issue due to its high concentration of organic matter and contaminants, including nitrogen and phosphorus. These can lead to eutrophication and represent hazards to human health. The objective of this study was to develop a biological method for the sustainable and efficient treatment of CWW using native bacterial pure isolates and mixed cultures. This method also aims to enhance circular economy practices in the dairy industry by adopting a biorefinery approach to produce biopolymer from the treated biomass. Hence, the objective was to decrease the contaminants in the wastewater that would allow its reuse in agricultural activities. CWW was obtained from a dairy farm in India and used as a substrate for the growth of bacteria. In this work, three promising isolates were screened from a pool of nineteen microorganisms for CWW treatment based on their growth in cheese whey effluent. After 7 days of CWW treatment with mixed culture cells, it was approximated that the procedure could achieve a removal efficiency of 89.10 % for COD, 78.35 % for total nitrogen, and 83.77 % for total phosphorus in CWW. Polyhydroxyalkanoates (PHA) were isolated from the bioremediated biomass and the mixed culture (CW₁₂₃) generated 389.23 mg/L of PHA. Analytical analysis has revealed that the extracted PHA have properties similar to commercial PHA. Hence, this strategy has demonstrated the capacity to reduce contaminants in CWW and provide a sustainable source for producing PHA, promoting a circular economy in the dairy sector.