Optimization of hydrolysis and acidogenesis of food waste for production of organic acid

Abstract The rising of human population in the world leads to the increasing number of food waste annually. To counter this problem, the food waste is suggested to be recycled into value-added product. Anaerobic digestion is one of the ways to recycle the food waste. The main product of a complete anaerobic digestion is methane (biogas). However, methane is very hard to handle since it is in gas form. Hence, this paper has drawn the attention toward the intermediate product of anaerobic digestion, the lactic acid. This paper presents the effect of 3 different variables: (a) pH values, (b) temperature and (c) amount of inoculum, on the hydrolysis and acidogenesis stages of anaerobic digestion of food waste. Besides, the optimal condition was determined. Experimental results show that the optimum, 0.0845 g/mL of lactic acid was obtained at pH value of 7, with 125 g of volatile solid food waste and 100 g of inoculum (Ragi Tapai), and was left in a pre-heated oven at 45°C for four days. This value was higher than the other previous study, and so showing promise in producing green acid from food waste that can be used as an intermediate substance for making other materials.