Chemical oxygen demand reduction and pretreatment method of dairy industry sludge waste for lactic-acid fermentation purpose.

Food industry is one of the three largest waste water sources. Dairy industry is one of major food industry that generates approximately 0.2 - 10 L of wastewater per liter of processed milk. The dairy industry wastewater and its sludge are characterized by high biological oxygen demand (BOD), chemical oxygen demand (COD) and nutrients level. The most popular facilities for sewage sludge dewatering are filter presses and centrifuges and finally, sludge is used as fertilizer. In another hand, the large proportion of sludge at dairy industry waste water is a potential resource. Dairy sludge contains casein, lactose, fat, and valuable Nitrogen (N), Phosphor (P), Potasium (K), and organic matter. Industrial dairy sludge also predicted to be suitable for another microorganism media such as lactic acid bacteria. This research lays the foundation of the usage of dairy sludge as lactic acid fermentation resource to aim the best method for its COD reduction and pretreatment. The method of COD reduction is adsorption using four-layer media included coarse zeolite adsorbent, sand, fine zeolite, and activated charcoal arranged in 1: 1: 1: 1 ratio and coagulation using Poly Aluminum Chloride (PAC) 5% and Alum Sulfate 5% with 3 replications for each treatment. Then, hydrolyses was done using HCl 21%, H2SO4 1 M and H2SO4 1 M while steamed by autoclave. This research concluded that the best treatment to reduce COD levels in dairy waste is the adsorption method which can reduce COD for 10.8 x 106mg/L. The best hydrolysis method is using H2SO4 1 M that can yielded 17.43% reducing sugar. [ABSTRACT FROM AUTHOR]