Effect of recycle flow on performance of an anaerobic baffled reactor (ABR) in batch condition

The anaerobic baffled reactor (ABR) is a cubic structure that contains a mixed anaerobic culture segregated into compartments. ABR is divided by a series of vertical baffles which baffles form a number of upflow and downflow compartment to make wastewater flow under and over them as it passes from the inlet to outlet. In this study, performance of ABR reactor was studied by four recycle flow rates in batch condition. Each batch operation lasted four days and olive mill oil wastewater (OMW) was added equally into ABR compartments. Operations were started at initial COD concentration of about 3000mgCOD.l-1. In different recycle flow rate in the first day of process, COD removal efficiency reached about 30% that increased between 10-20% after four days. Performance of ABR involved with a critical state when recycle flow rate 35cm3.min-1 (upflow velocity about 1cm.min-1) had been created. Meanwhile maximum biomass washout and minimum COD removal efficiency occurred. This upflow velocity can be useful for designing and operation in steady state condition. A second order model fitted well to obtained results with correlation coefficient of 99%. The ratio of gram-positive bacteria to gram-negative bacteria increased at the end of experiment.

Keywords:

Anaerobic baffled reactor , Recycle flow rate , Mathematical modeling , Olive mill oil wastewater (OMW)