Enhancement of performance of uasb reactors treating domestic wastewater under tropical conditions using effective microorganisms

Up flow Anaerobic Sludge Blanket (UASB) reactors have received widespread acceptance in the treatment of various wastewaters despite its incapability to produce the final effluent without the need for post treatment. In this study a microbial Consortium known as Effective Microorganisms (EM) was inoculated in the UASB reactor to enhance its performance so as to produce better effluent quality. The study was conducted using laboratory and pilot scale UASB reactors operated under tropical conditions at both steady state and shock loading conditions. In addition, the advantage of EM inoculated coconut shell charcoal in the UASB (UASBcsc-EM) reactor was also assessed The UASB reactor inoculated with EM (UASB-EM) showed better performance where removal efficiencies of COD and TSS were 85±10% and 91±9% compared to 76±12% and 83±13% in the UASB control reactor respectively. Likewise, total coliform (TC) were removed at 95±5% and 66±14% while faecal coliforms (FC) were 96±4% and 80±13% in the UASB-EM and UASB-control, respectively. NH4-N. PO4-P and NO3-Nwere better removed at 63±14%, 65±12% and 70±17% in the UASB-EM compared to 54±16%, 55±1 1 % and 55±19% in the control UASB reactor correspondingly. Biogas production was also influenced by EM consortium whereby daily methane production was higher in the UASB-EM reactor (135±66ml/day) compared to the control (62±49ml/day). The percentage content of methane in biogas produced was relatively higher in UASB-EM (78±4%) While concentrations of H2S and NH3 impurities were relatively lower (1 .05±1 .54 mg/L and 80.1±52.73 mg/L respectively) compared to control whereby methane content and concentration H2S and NH3 were 72±6%>100 mg/L and ˃200 mg/L respectively. During both organic and hydraulic shock loads, the UASB-EM reactor depicted significantly higher percentage removal of COD of 65±23% und 38±22% compared to 41±21 % and 20±14% of control respectively. Similarly, TSS was removed at62±26% and 48±25% during organic shock load and 30±28% and 6±21% during hydraulic shock load correspondingly. The percentage removal of COD and TSS did riot significantly differ between the UASB-EM reactor and UASBCSC-EM reactor. Yet. the UASBCSC-EMreactor performed better in removing COD and TSS by 86±5% and 92±2% compared toUASB control reactor of 73±5% and 85±2% respectively. This study shows that, EM can significantly enhance the performance of the UASB. However, further study is recommended to ascertain the impact of EM consortium on microbial diversity along with its treatability mechanisms in the UASB reactor in treating domestic wastewater under tropical conditions.