Effect of enzymatic pretreatment on acid fermentation of food waste

Although food waste is a valuable carbon source for biological nutrient removal systems with low organic wastewater because of high ON and C/P ratios, it must be pretreated to promote the hydrolysis of particulates, which is considered as a rate-limiting step. This study investigated the effects of enzymatic pretreatment on hydrolytic solubilization of food waste with commercial enzyme. Both acidification efficiency and volatile fatty acid (VFA) production potential of enzymatically pretreated food waste were examined under controlled laboratory conditions. Experimental results indicated that protease exhibited the highest VSS reduction rate among three types of enzymes: carbohydrase, protease and lipase. A mixed enzyme treatment showed better reduction efficiency than a single enzyme treatment, and the highest volatile suspended solids (VSS) reduction was observed at an enzyme mixture ratio of 1:2:1 with carbohydrase:protease:lipase, respectively. It has been noted that pretreatment resulted in both maximum VFA production and the highest VFA content of soluble chemical oxygen demand at an enzyme mixture dosage of 0.1% (v/v). VFA production at this dosage revealed a 3.3 times higher rate than that of no-enzyme added fermenter. The dominant VFAs were n-butyrate followed by acetate. (c) 2006 Society of Chemical Industry.