Nitrogen modeling and performance of Multi-Soil-Layering (MSL) bioreactor treating domestic wastewater in rural community

Abstract The multi-soil-layering (MSL) bioreactor has been considered in the latest research as an innovative bioreactor for reducing the level of pollutants in wastewater. The efficiency of the MSL bioreactor towards nitrogen pollution is due to the mineralization of organic nitrogen in aerobic layers to ammonia, and reactivity of ammonia nitrogen with soil and gravel by its adsorption into soil layers followed by nitrification and denitrification processes when the alternating phases of oxygenated/anoxic conditions occurs in the filter. In this study, we have examined the performance of the MSL bioreactor at different hydraulic loading rates (HLRs) and predicted the removal rate of nitrogen. To improve the prediction accuracy of the models, the feature selection technique was performed before conducting the Neural Network model. The results showed a significant removal (p  4 3−, 91%), and total coliforms (TC, 1.62 Log units). However, no significant change was observed in the nitrite (NO2−) concentration as it's an intermediate nitrogen form. The MSL treatment efficiency demonstrated a good capacity even when HLR increased from 250 to 4000 L/m2/day, respectively (e.g., between 64% and 86% for BOD5). The HLR was selected as the most significant (p   0.93) and could help to investigate the MSL behavior.