Variation of concentration of humic-like matter in landfill leachate with landfill age

The difficulty in landfill leachate treatment is probably attributed to high content of humic-like matter. The concentration of humic-like matter as a function of landfill age was established. The parameters were determined using the data from the leachate treatment facilities by means of grid method and solving non-linear eqations using Newton iteration method. Meanwhile, the accuracy of this prediction model was testified by comparing with residual COD values of biologically treated leachate both from the test and the monitoring data in site. The modeling results showed that the concentration of humic-like matter increased first and then decreased with the increase of landfill age, and indicated that biological processes generally cannot reduce the COD sufficiently to be allowed direct discharge during the major part of whole period of landfill stabilization. Thus it could provide basis for humic acid recycling from leachate and guidance in selection of treatment processes for leachate.