Treatment of hypersaline hazardous landfill leachate using baffled constructed wetland system: Effect of granular packing media and vegetation.

Constructed wetland is an engineered system that attains more attention as a feasible technology for the treatment of municipal landfill leachate. However, its feasibility for treatment of toxic, hazardous and hypersaline leachate remains unexplored. This study aimed to investigate the feasibility of using baffled constructed wetland (BCW) system for the treatment of hypersaline hazardous landfill leachate (HHLL). Furthermore, the effects of granular packing media, toxicity, and hyper salinity conditions on the removal efficiency of COD fractions (CODt, CODs, and CODp), nitrogen, heavy metals and coarse solids was extensively investigated. Our findings indicated that BCWs were highly effective in removing heavy metals particularly Cu(2+), Mn(2+), Fe(2+), Zn(2+) and exhibited moderate efficiency for other contaminants (e.g., COD fractions, solids, and nitrogen species). Furthermore, use of the sand and gravel mixture for bed materials demonstrated higher performance over sand alone. However, we found that Phragmites australis is not tolerant enough to extreme toxicity and salinity conditions, and this reed could not survive for more than 27 and 33 days in sand BCW and sand/gravel BCW, respectively. Consequently, survivorship of reed and efficiency of treatment using vegetation were limited in the long-term operation with high salinity and toxicity conditions.