Efficiency control of landfill leachate irrigation on energy crops

Abstract

Leachate constitutes the major long-term em1ss1on from landfills. A possible treatment
method is collection and subsequent irrigation on short rotation coppice during the growing
season, for example onto willow stands (salix). Theoretically, irrigation allows both a volume
reduction and a reduction of potentially hazardous leachate contents, such as nitrogen, organic
carbon and heavy metals. In this work, both hydraulic and reductive efficacy of leachate
irrigation at the municipal solid waste landfill Ronneholm, in Southern Sweden, have been
investigated by means of a water and a mass balance. For the latter, the emission values of
copper, chromium, nickel, zinc and total nitrogen were used, This study covers the period
from November 2002 until December 2003. The water balance and the mass balance were
modelled with a straight-forward box-model. The results suggest the importance of favourable
irrigation schemes and the importance of sedimentation for leachate heavy metal reduction.
Water balance calculations pinpointed potential for improving the efficiency of the leachate
volume reduction. In addition, the susceptibility of emission values for short term water level
changes was checked by daily sampling during a week, at a across section of the landfill.
Initial results suggest that measured heavy metal concentrations fluctuate with water levels in
the landfill body. This might be utilised to optimise irrigation schemes. A simple water and
mass balance model has proved to be an effective method to both control leachate treatment
and to serve as a starting point to develop leachate reduction schemes.