A survey on characteristics of leachate pond in an offshore municipal solid waste disposal site

Leachate from a landfill is collected and flowed in leachate accumulation pond, and sent to treatment facility. However, leachate in the pond can be a source of complaints from residents due to off coloration or odor, particularly near heavily populated urban areas. In this study, for the purpose of appropriate control of leachate pond, pond water and sediment were sampled in an offshore municipal solid waste disposal site 2 years after the disposal site was closed, and analyzed some parameters to estimate their properties. The pond water had high alkalinity due to the disposal of incineration residues, and EC and COD_Mn were also high. On the other hand, Cr, Mn, Fe, Cu, Zn, Cd, and Pb did not exceed the Japanese effluent water standards. Total sulfide was detected from all sediment samples during the sampling period, and values in the summer were slightly higher than at other times. To investigate the stabilization of targeted disposal site, the relationships among cumulative liquid/solid ratio (L/S) with pH and Cl^? elution after closing the site were examined. Both parameters showed a direct relationship with cumulative L/S ratio, which can be anticipated to continue increasing in the future.