ABSTRACT
The influence of organic loading rate (OLR) on a two stage integrated bioreactor was investigated in this study. The bioreactor consisted of two biological zones (aerobic and anoxic), a clarifier after the biological zones and an effluent zone, operated as a unit compartmental post-anoxic system. The aerobic zone was integrated into the anoxic zone and the anoxic zone was integrated into the clarifier. A 10 layer hollow rectangular and circular acrylic made submerged materials were installed in the aerobic and anoxic zones, respectively. A synthetic wastewater simulating a low and medium strength domestic wastewater with biochemical oxygen demand (BOD) concentration of 115 and 260 mg/L, corresponding to two different OLR of 0.33 kg BOD5/m3/m2.d−1 (phase 1) and 0.75 kg BOD5/m3/m2.d−1 (phase 2), was used at a fixed HRT of 12 days. The performance of the bioreactor was monitored by the BOD5 removal. Results show that BOD5 removal was stable at 97.3% with increasing OLR from 0.33 kgBOD5/m3/m2.d−1 in phase 1 to 0.75 kgBOD5/m3/m2.d−1 in phase 2. The BOD5 removal rate increased from 0.314 kgBOD5/m3/m2.d−1 in phase 1 to 0.73 kgBOD5/m3/m2.d 1 in phase 2. However, the residual effluent concentration increased from 3 to 7 mg/L with increasing OLR. The aerobic zone was more prominent for BOD5 removal throughout the study. NH+ 4-N and NO3-N was also monitored and was found to reach 98% and 73% removal in phase 2. This study, therefore shows that OLR did not cause any decrease of the bioreactor performance at the operating conditions investigated.
