Biokinetic coefficients determination of a MBR for styrene and ethylbenzene as substrate base on Andrews model

In this study, a lab-scale membrane bioreactor (MBR) was operated for a period of more than 10 months to determine the biokinetic coefficients of the system under the hydraulic retention times (HRT) of 20, 15 and 10 hrs and sludge retention times (SRT) of 5-20 days. The results revealed that the biological removal efficiency of styrene and ethylbenzene at a solid retention time of 20 day and a hydraulic retention time of 15 hr was higher compared to a SRT of 10 day and at the same HRT. The results also showed that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) for styrene and ethylbenzene as substrate were 0.60 and 0.60 mg/mg, 0.25 and 0.25 day−1, 0.188 and 0.363 h-1, and 0.146 and 2.82 mg /l, respectively. Furthermore, ethylbenzene was more appropriate as a source of carbon to activated sludge in the membrane bioreactor than the styrene which had a lower μmax than ethylbenzene.