Assessment of the performance of a down-flow hanging sponge system for treatment of agricultural drainage water

Abstract

AbstractThe performance of down-flow hanging sponge (DHS) system for the treatment of agricultural drainage water has been investigated for six months. The reactor was operated at a hydraulic retention time (HRT) of 2.0 h, sludge residence time of 88.5 d, and food to micro-organism ratio of 0.24 kg COD/kg MLVSS/d. The results obtained showed that the average total chemical oxygen demand (CODtot) and biochemical oxygen demand (BOD5) concentrations measured in the final effluent of the system were 62.4 and 17.1 mg/l, respectively, corresponding to the overall removal efficiency of 73.1% for CODtot and 86.7% for BOD5. The reactor provided a final effluent containing a low concentration of 14.7 mg/l for total suspended solids (TSS). Moreover, 84% of ammonia–nitrogen was eliminated at organic loading rate (OLR) of 3.0 kg COD/m3 d. The calculated nitrification rate of the DHS system according to the nitrate and nitrite production amounted to 0.16 kg NH4–N/m3 d. Based on these results, the reactor achieved an ef...