An economic analysis of leachate purification through willow-coppice vegetation filters

In this study an economic analysis of the purification of integrated solid waste treatment facility leachates through a willowcoppice (Salix) vegetation filter in southern Sweden was carried out. Calculations were based on the use of two computer models that were initially used in estimating a pump-and-pipe irrigation system for a 36-ha willow-coppice plantation to purify an average annual quantity of 195,000 m3 of leachate with an average nitrogen content of 24 g/m3. Results showed that facility leachates could be purified at US$0.34/m3 compared with US$0.62/m3 for that of conventional leachate treatment at a wastewater treatment plant. Furthermore, results revealed that the increased income from willow growing and sale of the biomass chips represented only a small factor in the overall cost of the purification technique––decreasing purification costs to US$0.326/m3. Sensitivity analyses also demonstrated that, because of the large leachate holding pond expense, only a fraction of facility leachate should be treated through a vegetation filter.