EFFECT OF EM ON BIOGAS PRODUCTION IN UASB REACTOR TREATING DOMESTIC WASTEWATER UNDER TROPICAL CONDITIONS

摘要

Anaerobic processes in the UASB reactor are concluded by biogas production that has a great potential for energy recovery. This study aimed at investigating the impact of Effective Microorganisms (EM) consortium on biogas production (quantity and quality) when inoculated in the UASB reactor during treatment of domestic wastewater under tropical conditions.Two laboratory scale UASB reactors of 4 L effective volume, made of PVC pipe with internal diameter 100mm were run for 30 days to establish comparative study with and without EM consortium. Liquid displacement method was used to measure the gas quantity produced, and the gas analyzer was used to measure the content and composition of the biogas. The average biogas production and yield were higher in the UASB-EM reactor than the UASB control reactor. The latter produced methane for at 0.062±0.049 L/day with a yield of 0.018+0.012 L/g COD per day. Meanwhile in UASB-EM methane production was 0.135±0.066 L/day with a yield of 0.034±0.019 L/g COD per day. Likewise, UASB-EM reactor depicted higher methane content (78±4%) compared to 72±6% of the UASB control. Furthermore, EM consortium improved the quality of biogas by producing relatively lower H_2S and NH3 of 1.05±1.54 mg/L and 80.11 ±52.73 mg/L respectively. The control were over 100 mg/L and over 200 mg/L respectively.This study indicates that EM consortium not only enhances biogas production but also improves the biogas quality in the UASB reactor during the treatment of domestic wastewater. Further studies are needed to investigate the mechanisms of EM consortium to augment biogas quantity and improve its quality in UASB reactor.