Use of a novel operation strategy in constructed wetland for high strength wastewater treatment

This paper describes a research attempt to employ a novel operation strategy, i.e. the first stage anaerobic-up flow (with effluent recirculation) plus the remaining stages tidal flow, into an alum sludge-based constructed wetland system (CWs) for the purpose of enhancing the high strength wastewater treatment performance with special focuses on organics and nitrogen removal. Analysis of the system's performance showed that tidal flow strategy enhances the oxygen transport and diffusion, improving organics and NH
₄
-N reduction. Effluent recirculation could further increase organics elimination by extending interaction time and benefit denitrification process. In addition, denitrification could be further enhanced by anaerobic-up flow in the first stage. Therefore, even under high organic loading of 58-146 g BOD
₅
/m
²
d, prominent performance of the system for the removals of COD (82%), BOD
₅
(91%), SS (92%), NH
₄
-N (94%), TN (82%) and TP (95%) was achieved.