Huang Renhua

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.

Monitoring and long-term prediction of refuse compositions and settlement in large-scale landfill

Settlement and changes in refuse composition for total sugar, raw cellulose, biological degradable matter, volatile solid, organic carbon, were monitored in a large-scale experimental landfill unit and closed landfill units at Shanghai Refuse Landfill from April 1995 through to October 1998. Mathematical simulation formulae between these parameters and refuse age were developed based on the data obtained from the experimental landfill unit and validated by data from landfill units closed in April of 1991, 1992, 1993 and 1994. Long-term predictions for these parameters for the landfill were made using these formulae. It was predicted that the refuse might be fully mineralized and the cumulative settlement might be over 30% of the initial height after around 22 to 30 years. The stabilization process and reuse approaches for landfills based on the compositions and settlement are discussed.