Treatment of anaerobic digested effluent in biochar-packed vertical flow constructed wetland columns: Role of media and tidal operation
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Three types of vertical flow constructed wetland columns (VFCWs), packed with corn cob biochar (CB-CW), wood biochar (WB-CW) and gravel (G-CW) under tidal flowoperations, were comparatively evaluated to investigate anaerobic digested effluent treatment performance and mechanisms. Itwas demonstrated that CB-CWand WB-CWprovide significantly higher removal efficiencies for organic matter (N59%), NH4 +-N (N76%), TN (N37%) and phosphorus (N71%), compared with G-CW (22%–49%). The higher pollutants removal ability of biocharpacked VFCWs was mainly attribute to the higher adsorption ability and microbial cultivation in the porous biochar media. Moreover, increasing the flooded/drained ratio from 4/8 h to 8/4 h of the tidal operation further improved around 10% of the removal of both organics and NH4 +-N for biochar-packed VFCWs. The phosphorus removal was dependent on the media adsorption capacities through the whole experiment. However, the NH4 +-N biodegradation by microbial communities was demonstrated to become the dominant removal mechanismin the long termtreatment,which compensated the decreased adsorption capacities of the media. The study supported that the use of biochar would increase the treatment performance and elongate the lifespan of CWs under tidal operation.
- Natural Sciences