Biogas Production from Modified Starch at the Anaerobic Digester

摘要

Since 1997, PT Lautan Warna Sari (LWS) has produced cassava-based modified starch raw materials to a total capacity of 200 tons/day or 40 tonnes of product. Tapioca industrial effluent is derived from a variety of existing processes in the production system. Because of this high production capacity, a large effluent treatment facility is required (six equalization basins, 3,000 m~2 each). The percentage of organic compounds in the effluent is relatively high, thus representing a high economic value when processed into biogas. However, untreated waste causes environmental pollution in the form of a bad odor in the vicinity of the plant. Earlier waste handling merely removed the smell. In fact, from field observations, formation of gas occurred, which is characterized by the emergence of gas bubbles that arise from an equalization basin. This suggested the idea for management and processing of effluent into biogas. Further study also found that in addition to the liquid waste, the industry generates solid waste, such as the epidermal tissue, solids, and cassava. Epidermal tissue and solids (soil and groats cassava) result from the initial washing of cassava, while cassava is produced from the starch-making process. Epidermal tissue and solid impurities have been dumped untreated to date. Cassava in the form of fiber could theoretically be processed into bioethanol through hydrolysis and fermentation. Also, to produce biogas, solid debris and sludge left behind in this process can be used as a fertilizer (Buren and Arnott 2004; Reese and Thompson 2008), and a plan was developed to integrate this with the epidermal tissue and solid debris.