Treatment of Landfill Leachate at a Remote Closed Landfill Site on the Isle of Wight

Abstract

Safe treatment and disposal of leachates is an important issue at many old landfill sites, where the ingress of rainfall or groundwater is a significant issue requiring consideration. Such leachates may typically be relatively weak, but flows are often characterised by large seasonal variations, in response to winter rainfall. This paper compiles and presents long-term data from a case study on the Isle of Wight, UK. This paper highlights how a successful treatability trial using representative leachates can help predict the effectiveness of a large-scale treatment plant when treating landfill leachates biologically. Bleakdown leachate treatment plant effectively removes all concentrations of ammoniacal-N within the weak leachate generated by the site, ensuring that the discharge consent set by the Environment Agency is achieved consistently. The site is completely unmanned and remote, where monitoring technicians are only required to attend site twice per month in order to assess the success of the biological process. Through an online SCADA control system, operation of the treatment plant can be monitored and controlled remotely, trends in results can be observed, and daily data and treatment records downloaded. This treatment plant is an example of how leachate from old closed landfills can be effectively managed, with very low costs of operation, maintenance and site attendance. This paper presents comprehensive analytical and volumetric treatment data from the Bleakdown LTP, before presenting practical steps that would enable this success to be replicated at similar remote closed landfill sites.