Aggregates as a Biological Support in Wastewater Treatment

The Moving Bed Biofilm Reactor (MBBR) has been recently used in industrial and municipal wastewater treatment. MBBR is a kind of Bio-Filter with light packed bed. In this study, a mineral packing bed called Leca, a light expanded clay aggregate, was used as a biological support in the treatment of wastewater. The main objective of this study was to evaluate packed media for preparation of suitable beds for biological activity. Seventy percent of the reactor volume was filled with the packing media. Synthetic wastewater was made using sugar beet factory effluent. The influent COD in the range of 800 to 3200 mg/L was injected into the reactor at retention times of 12.16 and 24 hours. The results show that MBBR reactor is capable of removing 82% of soluble COD at a loading rate of 1.766 kg COD/m2. However, it was found that reducing the retention time from 24 h to 16 h and 12 h, reduces COD removal efficiency from 82% to 76% and 66%, respectively. It was also found that 78.2% of the overall COD removal is due to biofilm activity and the rest is related to the activity of the submerged microorganism.