Application of constructed wetlands using Vetiveria zizanioides and Phragmites australis in the landfill leachate treatment

Abstract

Constructed wetlands have been widely applied for removing pollutants in the leachate recently. In this study, constructed wetland system combined vertical flow and horizontal flow, using Vetiveria zizanioides L. and Phragmites australis, was set in a laboratory scale to assess the leachate treatment ability. The landfill leachate was added to the system with increasing concentration to evaluate the treatment ability by the time. The results showed that the removal efficiency reached the highest when the COD concentration was 575 mg/L, including BOD5 (96.48%), COD (83.24%), total nitrogen (91.43%), total phosphorus (77.84%), ammonia nitrogen (86.47%), and color (87.91%). Furthermore, the treated effluent quality reached the class A of the Vietnamese standard on industrial wastewater quality. Beside, when physicochemically treated leachate (coagulation – flocculation) (COD concentration was 1255.50 mg/L), was added to the system, the removing efficiencies remained stable by the time, with the efficiency of ammonia nitrogen removing (93.48%), BOD5 (94.86%), total phosphorus (96.67%), total nitrogen (95.81%). Besides, the treated effluent quality reached the class B of the Vienamese standard on industrial wastewater quality. On other hand, COD and color removing efficiencies were also high at the first stage and tended to reduce rapidly by the time. Therefore, the EM called Bayer Pond Plus added to the system could increase and substained the removing efficiencies of COD (66.61%), color (81.40%). The results of this study showed that constructed wetland system had potential in the landfill leachate treatment.