Techno-economic evaluation of landfill leachate treatment by hybrid lime application and nanofiltration process

Abstract

Leachate treatment is a major issue in the context of landfill management since solutions have not been yet developed, resulting in more satisfactory technical and economic results concerning leachate treatment. In this paper, the technical and economic factors concerning lime application and nanofiltration for the treatment of leachate from the Seropédica landfill (Rio de Janeiro State, Brazil) were evaluated. The results indicate that the application of 30 g lime L-1, under optimum conditions, followed by air stripping, was able to place the effluent within the ammonia nitrogen discharge standard imposed by local legislation. The use of nanofiltration produced a clear and colorless permeate and has proved to be very effective at removing all pollutants. Regarding cost estimates, considering a means leachate generation flow of 1000 m3, recovery of 60% and average permeate flux of 12 L m-2 h-1. The total cost per m3 of treated effluent was estimated in two scenarios, using different types of membrane and therefore different membrane costs per m2. Considering that the landfill would operate for 25 years and after closing, the leachate treatment station would maintain its activities for another 15 years, totaling 40 years, the cost to treat leachate would be of US$ 10.54 and US$ 11.33 m-3. In both evaluated scenarios, with regard to process operation costs, the percentage value relative to membrane exchange was emphasized. It is noteworthy that, a treated effluent at a lower cost to that currently presented by the landfill was obtained through the applied hybrid process.