Performance and Mechanism of Improved Soluble Organic Carbon Recovery from Municipal Wastewater through the Coagulation-Enhanced High-Rate Contact Stabilization Process

High-rate contact stabilization is promising to capture organic carbon from municipal wastewater; however, its engineering application is restricted due to its poor capability of removing soluble organic matter (particle size < 0.1 μm). In this work, the carbon capture efficiency and robustness of the coagulation-enhanced high-rate contact-stabilized process for treating municipal wastewater with a varied content of soluble organic matter was comprehensively evaluated. Results showed that the high-rate contact stabilization process did not perform well in the removal and capture of influent organic substances with a high proportion of soluble components. Adding coagulants into the above process favored organic carbon capture, whose recovery efficiency could reach up to 60% even under the 90% influent soluble chemical oxygen demand condition. Mechanism analysis revealed that the hydrolyzed product of the coagulant would adsorb dissolved components to form colloid and subcolloid particles, which was favored for further capture by sludge. The fitting result of the neutral community model indicated that both deterministic environmental factors and random processes influence the succession of sludge community. This work implied that the coagulation-enhanced high-rate contact stabilization process is feasible to recover organic carbon from municipal wastewater, which may shed a promising light for sustainable carbon control and management.