Feasibility investigation of a multi soil layering bioreactor for domestic wastewater treatment.

In this study, a multi soil layering (MSL) bioreactor was constructed to treat synthetic domestic wastewater. Effects of hydraulic loading rate (HLR) on the performance of the MSL bioreactor for synthetic domestic wastewater treatment were investigated. Results showed that the MSL bioreactor exhibited a strong adaptability on the variation of HLR, when the HLR was adjusted to 400 L·m-2·d-1, average removal efficiencies of chemical oxygen demand (COD), ammonia, total nitrogen (TN), and total phosphorus (TP) reached 93.4%, 94.9%, 80.4%, and 94.7%, respectively, which meet to the 1A discharge standard of the Discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002). In the treatment process by the MSL bioreactor, biological decomposition and biotransformation processes of microorganisms was the most important pathway for COD, ammonia, and TN removal, while TP was removed by the chemical reaction with ferric ion. Nitrobacteria, ciliate, rotifer and epistylis were in large numbers in the operating phase, indicated that the biofilm was matured with a high quality and the MSL bioreactor was effective for domestic wastewater treatment.