The use of extended aeration and in-series surface-flow wetlands for landfill leachate treatment

Abstract

Recently in the USA, the Solid Waste Industry has undergone specific changes in landfill regulations. The Federal Resource Conservation and Recovery Acts (RCRA); and EPA subtitle D regulations, as well as stringent State regulations, impose minimum criteria for municipal solid waste facilities in the areas of location, operation, groundwater monitoring, and leachate management. In conjunction with these State and Federal mandates the University of West Florida developed a leachate treatment technique utilizing extended aeration and surface-flow constructed wetlands. Sampling of water quality has occurred monthly since February 1992. Parameters examined include: Nitrogen (NH3,), Total Suspended Solids (TSS), Total Phosphate (TPO4), Total Organic Carbon (TOC), pH, Alkalinity, and Chlorides. Chemical Oxygen Demand (COD), Total and Fecal Coliforms, Priority Pollutant Metals, and limited organic analytes are sampled on a less frequent basis. Samples are collected at a raw leachate site (L0), primary aerated lagoon (L1), and 6 stations within the 1.1 hectare constructed wetland complex (S1; W1; W3; W5; W7; W9) and one sandfilter (SF) location. Results thus far indicate removal percentages of the tested analytes average between 64% and 99%. This data suggests various physical, microbiological and chemical processes occurring within the aerated lagoon and constructed wetlands can provide an effective alternative to standard techniques for landfill leachate treatment and disposal. The methods as described have proven to be ideal for the circumstances occurring at the Perdido Landfill.