Coagulation enhanced high-rate contact-stabilization process for pretreatment of municipal wastewater: Simultaneous organic capture and phosphorus removal

High-rate contact-stabilization is criticized as its unsatisfactory organic elimination performance and failure for the phosphorus removal, which greatly restricts its engineering implementation. In this work, coagulation enhanced high-rate contact-stabilization process was established to realize simultaneous carbon capture and phosphorus removal in a single treatment unit. Results showed that under a molar ratio of 2:1 (metal ion: P), effluent chemical oxygen demand and total phosphorus less than 50 and 0.50 mg.L-1 could be stably achieved, respectively. Under the similar to 8% mineralization efficiency, approximate 80% of influent organic carbon was captured as sludge. Coagulation precipitation and bioflocculation both contributed to carbon removal. Overdosage of coagulants would induce reactive oxygen species accumulation and sludge activity decline. Microbial abundance and redundancy analysis revealed that the dosed coagulants would cause a selective pressure and lead to a reduced microbial richness. For a practical application, an optimized dosing of mixed coagulants was suggested to maximize the carbon capture and phosphorus removal. This work may provide guidance on sustainable carbon management for municipal wastewater sector.

Automated summary

In this study, a coagulation enhanced high-rate contact-stabilization process was established to simultaneously capture carbon and remove phosphorus. The results showed that this process achieved stable removal of carbon and phosphorus under specific molar ratios. Additionally, controlling the dosage of coagulants was found to improve the carbon capture efficiency.