Effect of Operation Conditions on Performance of Treating Actual Domestic Wastewater Bioreactor at Ambient Temperature

Abstract

To determine the operation parameters of the expanded granular sludge bed (EGSB) reactor treating actual domestic wastewater at ambient temperature of 15-26°C, the effects of influent flow, HRT, recycle ratio,Vup and temperature on the performance of the EGSB reactor were investigated in this paper. The results indicated that when treating actual domestic wastewater, the EGSB reactor could support high influent flow and low HRT. For 9L.h-1, 11L.h-1, 15L.h-1, 24L.h-1 influent flow, with the optimal recycle ratios of 1.6-2.5, 1.2-1.6, 0.4-0.8, 0.0, the COD removal efficiencies could attain to 86-90%, 88-89%, 83%, 83%, respectively. For lower influent flow, higher Vup could slightly increase COD removal, but accordingly higher recycle ratio need to supply. Meanwhile, for higher influent flow, higher Vup will damage the granular characteristic and thus cause the decreasing of COD removal, and thus for the EGSB reactor treating actual domestic wastewater, 2.7-3.0m.h-1 optimal Vup should be employed. The EGSB reactor could work well at ambient temperature of 15°C-26°C. The optimal influent flow and Vup were 15-24L.h-1 and 3.0m.h-1. High average OLR of 18.6kgCOD.m-3.d-1 and high average COD removal efficiencies of above 81.4% could achieve, and only very low recycle ratio of 0.0 to 0.4 need employ.