Optimization of operation conditions for domestic sewage treatment using a sequencing batch biofilm filter

A sequencing batch biofilm filter (SBBF) was applied to treat domestic sewage. The bioreactor consisted of fibrous filler in the upper part and ceramsite filter media in the lower part. The impacts of the most important factors including dissolved oxygen (DO), water temperature and hydraulic retention time (HRT) were evaluated on contaminants removal during the operation of the SBBF. Changes in DO (1.5-4.0 mg/L) and water temperature (2-30 °C) had little effect on the removal of chemical oxygen demand (COD), but had a greater impact on the removal of total nitrogen (TN) and NH₄⁺-N. Changes in HRT (8-14 h) had little effect on the removal of COD, but had a greater impact on the removal of TN, NH₄⁺-N and total phosphorus. The optimal operating parameters for the SBBF were as follows: DO of 2-3 mg/L, water temperature above 10 °C, and HRT of 10-13 h. Furthermore, a simple kinetic model was developed, reflecting the relationship between COD and HRT.