Recovery of protein and carbohydrate from dairy wastewater using ultrafiltration and forward osmosis processes

Abstract

The presence of protein, carbohydrate, and lipids in dairy wastewater reduces its biological treatment efficiency. However, separating these compounds before wastewater treatment will have economic benefits for the dairy industry, (i) protein and carbohydrate could be used as an alternative nutrition source of farm animals, and (ii) the efficiency of the existing wastewater treatment facilities will be improved. Membrane technology (ultrafiltration UF, nanofiltration NF, and reverse osmosis RO) in combination (UF-NF or UF-RO) has been used for the treatment of dairy wastewater. However, these technologies are pressure driven and energy intensive, further the presence of protein and carbohydrate results into fouling in NF and RO. The present study reports the application of UF and forward osmosis (FO) membrane processes. FO is a concentration driven membrane process which involves migration of water through a semi permeable membrane from low osmotic pressure (feed solution) to high osmotic pressure (draw solution). It results into less fouling than NF or RO. The present study involves an integrated treatment process with UF followed by FO, it has resulted into 65% of carbohydrate retention and 98% of protein retention.