RECENT STATE-OF-THE-ART LEACHATE TREATMENT PLANTS IN EASTERN ENGLAND

Abstract

The paper presents detailed design and performance data for two full-scale leachate treatment plants that have been designed and operated in Eastern England during recent years, in which reliable performance has been achieved for an extended period. The first plant is a modified Sequencing Batch Reactor system, treating relatively diluted leachate (COD about 500 mg/l, ammoniacal-N about 180 mg/l) from a closed landfill site, to provide complete nitrification of ammoniacal-N and degradation of all degradable COD, in a manner requiring minimal site attendance. This is made possible by means of reliable and robust operational software, which can run the plant in a completely automated manner, but nevertheless alerts the operator to any issues. The second state-of-the-art leachate treatment plant was designed and built at the Masons Landfill Site in Ipswich. It was designed to treat 160 m 3 /day of strong methanogenic leachate, often containing more than 2000 mg/l of ammoniacal-N. Discharge of treated leachate is to sewer, under a consent in which the main parameters that are limited are ammoniacal nitrogen, and COD. Treatment comprises full biological nitrification, with ultra-filtration membranes providing additional removal of COD, to achieve challenging consent limits. Taken together, the two case studies provide valuable, robust and real, full-scale data, for the degree of treatment which can realistically be delivered, by well-designed and operated, aerobic biological leachate treatment plants, where each plant has succeeded in treating leachates to well below the consented quality limits for discharge.