Anammox, biochar column and subsurface constructed wetland as an integrated system for treating municipal solid waste derived landfill leachate from an open dumpsite

This study aims to treat nitrogen-rich landfill leachate from Karadiyana open dumpsite, Sri Lanka, through an integrated treatment train consists of an anammox process, Municipal Solid Waste derived biochar column followed by a biochar embedded subsurface constructed wetland. Characterization of leachate was done and the leachate pollution index (LPI) was estimated. Meanwhile, leachate was treated through a treatment system comprising an anammox reactor having 140 mm diameter and 250 mm height, a biochar reactor having the same dimensions with 1.3 kg of MSW biochar, and a laboratory-scale constructed wetland of 1 x 0.3 x 0.45 m. The influent and effluent quality was assessed for the samples taken in 24 h intervals. The analysis indicated that the leachate was high in COD (4000-14,000 mg/L), ammonia (760-900 mg/L), nitrate (60-126 mg/L), and phosphorus (33-66 mg/L). Ammonia and nitrite were removed 94 and 99% by anammox unit, respectively. Nitrate, phosphate, COD and conductivity were significantly removed by the constructed wetland system in 78, 70, 65 and 61%, respectively, whereas biochar barricades extended support for removal of the contaminants and color. The combined treatment system demonstrated treatment efficiencies as 100% of ammonia, 98.7% of nitrite, 98.2% of nitrate, 80.9% of phosphate, 79.7% of COD, and 69.9% of conductivity. Thus, it can be concluded that the anammox, combined with biochar embedded treatment train is promising to treat landfill leachate, having a high pollutant index.