Long-term Monitoring and Prediction for Leachate Concentrations in Shanghai Refuse Landfill

Parameters such as pH, concentrations of Cl-, turbidity,NH3-N, CODCr and BOD5 (simplified as COD and BODrespectively in the following text) in leachate generated inthe large-scale testing landfill unit and closed landfill unitsat Shanghai Refuse Landfill were monitored from April 1995 toOctober 1998. The mathematical simulation formula between theseparameters and refuse age were established based on the dataobtained from the testing landfill unit and justified by thedata obtained at the closed landfill units from 1989 to 1993.The long-term predictions for the leachate concentrations forthe Landfill were made using the mathematical simulation formulaestablished. It was predicted that the COD and BOD may bereached to the strictest standard for pollution control on municipal solid wastes landfill in China, i.e., COD < 100 mg L-1 and BOD < 30 mg L-1, after 15 yr natural attenuation. The time predicted for NH3-N concentrations to reach the discharging standard, 15 mg L-1, was found to be at least 23–26 yr or even longer. The predictions for concentrations of Cl-, turbidity, and pH values in leachate are also given. The natural attenuation of Cl- is the slowest and might be decreased to 200 mg Cl- L-1, the agricultural irritation standard, after at least 58 yr.