The use of short rotation coppice (SRC) willow for the bioremediation of landfill leachates

• Main Author: Farrar, Siân Marjorie
• Published: Queen's University Belfast 2016
• Subjects: 628.4
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705916

Landfill leachate is a growing problem in both Ireland and the rest of U.K. Methods of treating landfill leachate are often costly and ineffective but SRC willows are extremely capable of the bioremediation of landfill leachate. When screening Salix genotypes (120 in total) with landfill leachate, the majority of genotypes, responded well, with minimal stress. The data suggests that a number of genotypes maybe more suited to leachate than others. Commercial genotypes such as Nimrod and Olaf were particularly tolerant to leachate application. Various loading rates of leachate were applied to eight selected genotypes. The application rates were based on nitrogen content of the leachate. When evaluated, rates of around 1000 kg - 2000 kg N/ha/yr were optimal for biomass production with minimal phytotoxic effects. Application equivalent to 4000 kg/ha/yr produced a significant reduction in biomass yield and led to increased potassium concentration in the soil. Risk evaluation of the technology using simulated rainfall confirmed that the presence of willow actively reduces risk of N leaching and P run-off. Sulphate concentration was elevated in the willow planted plots. The application of leachate produced a small but significant effect on the combustion of the lignocellulosic biomass produced by willow. The minor changes to combustion did not significantly reduce the overall combustibility of the material. This suggests that pairing the bioremediation with methanogenic leachates with biomass production may be possible. This technology could be the sustainable and cost effective solution to a growing leachate problem, provided it is made accessible to landfill operators and local authorities. To increase uptake, it is necessary for policy to support bioremediation as a credible solution. Possibly, incentivising the use of phytoremediation in the way green technologies have been incentivised in recent years, could insure that landfills are not left with leachate treatment issues in the future.