Biological treatment of landfill leachate: efford landfill, Hampshire, UK - a case study

Abstract

Demand for of on-site treatment schemes that are capable of treating landfill leachates to highstandards has grown substantially during the last two decades. Increasingly, plants are beingrequired to discharge high quality effluents directly into surface watercourses, or to provide ahigh degree of treatment prior to discharge into the public sewerage system. This trend is certainto continue - primarily driven in the United Kingdom in recent months by the requirements of theEU IPPC Directive, which demands the application of Best Available Techniques (BAT), and bythe EU Water Framework Directive.Aerobic biological treatment of leachate from domestic landfills has widely been shown to be themost appropriate, reliable and successful treatment technique to consistently meet stringentdischarge constraints with minimal operator input. The cost of this technology is also oftenfavourable, when compared with alternative processes. More than 50 plants of this type arecurrently operational in the United Kingdom, making it by far the most widely adopted on-sitetreatment technology, and many other examples exist overseas.This paper provides a detailed case study of the design, construction and commissioning of abiological, Sequencing Batch Reactor (SBR) leachate treatment plant for Hampshire CountyCouncil, at Efford Landfill Site in the New Forest in Hampshire, UK.Since plant commissioning was completed by the authors during early 2003, extensive anddetailed monitoring data have been collected. These are presented for the plant, which is capable 3 of treating up to 150 m /day of strong methanogenic leachate (ammoniacal-N from 600-1 000mg/1), and are compared with treatment performances achieved at other full-scale leachatetreatment plants. The paper shows 80D5 and ammoniacal-N removal efficiencies in excess of99%.Results also show the efficiency of polishing treatment in a reed bed, before discharge of finaleffluent to public sewer.