Anaerobic Digestion of Tofu Liquid Waste Using Upflow Anerobic Sludge Blanket for Producing Biogas

• Main Author: Putera, Utomo
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/38490
• Institution: Institut Teknologi Bandung

Tofu is favored by almost all levels of Indonesian society. Based on data from the Secretary General of the Ministry of Agriculture of the Republic of Indonesia, tofu consumption in 2002-2015 reached 7.26 kg / capita / year. From 1 kg of soybean, 3.3 kg tofu can be produced with waste consisting of 2.0-2.2 kg tofu pulp and 17 L liquid waste per kg of soybean processed. Tofu liquid waste contains Chemical Oxygen Demand (COD) of 30,000-40,000 mg/L and approved to be the raw material for producing biogas. Therefore, to overcome this waste is by using anerobic decomposition. This study discusses about determining the residence time of tofu liquid waste decomposition on biogas production and the level of COD content reduction in waste by using 1,5 litre Upflow Anaerobic Sludge Blanket (UASB) with PET material and a fed-batch feed system. The changed variables are waste residence time in the reactor or hydraulic retention time (HRT), which are 6, 7, 8, and 9 days. The determining parameters consisted of the composition of COD and pH on the feed and reactor output, the rate of production and the composition and calorific value of biogas. The characteristics of tofu wastewater used in this study had a COD level of 14,600-18,450 mg/L, pH 4, and TSS of 1035 mg / L. Based on the study results, the variation of 8-day HRT produced the highest COD reduction rate with COD reduction percentage of 51,32% and COD value reduction from 16.525 mg/L to 8.045 mg/L. The highest biogas production achieved in 6 days HRT variation with rate production of 0.11 L/day and biogas content consisting of Methane (13,08%-mol), Carbondioxide (33,34%-mol), and other compounds (53,58%-mol) with biogas heating value of 4,68 MJ / m3.