Long-term operation with an insight into a newly established green bio-sorption reactor: Can it achieve "1 + 1 > 2"?

An eco-friendly system of green bio-sorption reactor (GBR), constructed by embedding alum sludge-based constructed wetland (AlCW) into a conventional activated sludge process to achieve "1 + 1 > 2", was evaluated under a long-term operation basis. Insight into the pollutants removal, particularly the role of the AlCW in the GBR, was explored and discussed. The results showed that the GBR could achieve 90% and 95% removal for TN and TP (Stage 4), respectively, under the hydraulic and nitrogen loading rate of 2.07 m3 /(m3 ·d) and 166.2 gN/(m3 ·d), respectively. Intriguingly, despite the P adsorption, the AlCW enlarged the size of the activated sludge flocs which benefited the simultaneous nitrification and denitrification. Subversively, the embedding AlCW brings about dual-intensification in both capacity and efficiency. In addition, the GBR as an ecological engineering system can be employed closely to residential area in line with its green and pleasing appearance.