A life cycle assessment of conventional technologies for landfill leachate treatment

Abstract

Abstract Landfilling of municipal solid waste is still one of the most diffused practices worldwide, generating long-term heavily polluted gaseous and liquid (i.e. leachate) emissions, causing environmental and especially human health concerns. Improvement of the methods for treating these emissions, particularly the leachate, is mandatory for increasing the sustainability of the entire waste management system. For this aim the environmental impact of conventional off-site technologies, based on co-treatment of leachate with civil sewage in wastewater treatment plants, was compared with advanced on-site technologies based on reverse osmosis and evaporation in a life cycle perspective. The model was built using mainly experimental and technical data from full-scale facilities. Human toxicity and freshwater ecotoxicity were the impacts most affected by the scenarios analysed. Average impacts were higher for the conventional off-site co-treatment in wastewater treatment plants, whereas impacts were lower for the advanced on-site treatment based on reverse osmosis. This result was largely influenced by the high incidence due to leachate transport for the off-site management scheme. Due to the high consumption of energy (i.e. 40 kWh/m3 electricity and 18.5 kWh/m3 thermal heat) and chemicals (mainly HCl) the impact for the on-site evaporation system was always higher than for reverse osmosis and in some cases also for the conventional co-treatment with civil sewage sludge. The uncertainty analysis showed that pollutant emissions to water and emissions due to transport were affected by the highest errors, influencing in a major way the uncertainty of the impacts considered.