Abstract:
This research was a study on efficiency of EGSB system in treating domestic wastewater from Jarernvidsavagum Building, Faculty of Engineering, Chulalongkorn University. The research examined the effects of influent flow rate to recirculation flow rate ratio and upflow velocity on efficiency of system. The research was divided into 2 experiments. The first experiment controlled standing upflow velocity at 4.5 m./hr. and the influent flow rate to recirculation flow rate ratios were varied at 1:3, 1:7, 1:11 and 1:15. The second experiment selected one suitable influent flow rate to recirculation flow rate ratio at 1:11 and the upflow velocities were varied at 3.5 and 5.5 m./hr. The results obtained from the first experiment was found that at influent flow rate to recirculation flow rate ratios at 1:3, 1:7, 1:11 and 1:15, the efficiencies of COD removal were 69.2, 72.6, 76.3 and 74.6 percent, respectively, efficiencies of BOD removal were 72.7, 73.5, 76.6 and 75.6 percent, respectively and efficiencies of suspended solid removal were 74.0, 77.4, 81.7 and 73.3 percent, respectively. It could summary that the influent flow rate to recirculation flow rate ratio at 1:11 had best efficiency for treatment of overall parameters. The results obtained from the second experiment was found that at upflow velocities 3.5 and 5.5 m./hr., The efficiencies of COD removal were 72.5 and 79.3 percent, respectively, efficiencies of BOD removal were 74.6 and 78.1 percent, respectively and efficiencies of suspended solid removal were 82.0 and 79.7 percent, respectively. It could summary that the upflow velocity had significant effects on efficiency of EGSB system. This research could not measure biogas amount since wastewater had low COD concentration and it could also dissolve in wastewater and then go with effluent. The effluent quality from EGSB system could comply with building effluent standard. Therefore, the EGSB system is an alternative system for treating domestic wastewater