Recovery of proteins and lipids from dairy wastewater using food grade sodium lignosulphonate

Abstract

Dairy manufacturing sector generates large quantity of nutrient-rich wastewater which requires treatment before it can be released into the environment. This study aimed to use a low-cost food grade sodium lignosulphonate (Na-lignosulphonate) to recover proteins and lipids from dairy wastewater and reduce the BOD. The colloidal particles of wastewater sample were precipitated with varying the concentration of Na-lignosulphonate (0.002–0.032%, w/v) and pH of medium (1.0–3.5). Experiments were conducted at ambient (22 °C) and mildly elevated (40 °C) temperatures. At the optimum concentration (0.016%, w/v) of Na-lignosulphonate, the highest turbidity removal (98%) was achieved at pH 3.5 and at both temperatures. This method recovered 96% lipids and 46% proteins (mostly caseins) and reduced the BOD by 73% at 22 °C. Na-lignosulphonate is found to be an effective coagulant owing to its ability to readily complex with positively charged colloidal particles at acidic pH. Keywords: Dairy wastewater, Sodium lignosulphonate, Proteins, Lipid, Complexation, Coagulation, Recovery