Proceedings

On site Landfill Leachate Treatment: Investigations into Economical and Environmental sustainable systems for Northern Ireland

Devlin, Y.1, Nicholl, G.1, McRoberts, C.1, Johnston, C.1, Rosinqvist D.2, Svensson B.M.3 and Mårtensson, L.3
1Agri-Food and Biosciences Institute, UK, 2Laqua Treatment AB, Sweden, 3Kristianstad University, Sweden

(free)

Abstract:

This paper presents the potential for the Swedish Laquaâ system to be used as a sustainable method for on-site landfill leachate management in Northern Ireland, specifically the potential to use locally sourced filter materials from Northern Ireland as part of the filter system. Four carbon containing ashes and four types of peat were tested over a 24 hours period by a shaking test with untreated landfill leachate. Considering the results of this screening test, and the economical and sustainable supply of filter materials, one combination of ash and peat was selected to be column tested. Column testing with artificial leachate containing 7 organic pollutants (3 PAHs and 4 PCBs) and 9 inorganic pollutants showed that locally sourced filter materials effectively removed both organic and inorganic pollutants. A subsequent column test with landfill leachate for 13 weeks demonstrated it was feasible to apply the Laquaâ system with economical locally sourced filter materials.

Keywords

Artificial leachate, Carbon-Containing Ash, Filter treatment, Landfill leachate, Peat, Wastewater treatment

Introduction

In the 21st century we are becoming an increasingly ‘throw-away society’; consuming produce and generating significant volumes of waste materials for disposal immediately after use. For example, many mothers in the UK no longer wash baby nappies, instead using disposable products which are ultimately destined for landfill. These products are not just made of simple materials such as paper, but also contain complex materials that include polymers, adhesives, dyes and perfumes.

While there is some public concern about these waste materials entering landfill and polluting the soil, there may be less concern or knowledge about the dissolved pollutants that may leave the landfill via leachate. Over time, waste material decomposes producing leachate which has to be managed and treated to prevent it from entering ground water sources. Without proper treatment of the leachate, it can pollute not only around landfills, but also rivers, lakes and the ocean.. However, even after a landfill site has been closed to further waste, the treatment of leachate is often required for decades.In 2015, there were approximately 30 authorised landfill sites in Northern Ireland which were estimated to handle 1.4 million tonnes of municipal waste a year (NIEA, 2015). According to Met Office data (Met Office, 2017) rainfall in Northern Ireland ranges between 800 – 2000 mm per annum, and subsequent ground water replenishment can result in large volumes of leachate being generated on landfill sites. On-site, the landfill leachate receives primary treatment to reduce the levels of Biological Oxygen Demand and Ammonia and adjust the pH/acidity, before being transferred to waste water treatment facilities for further treatment before final safe discharge to the environment.

One Northern Irish landfill site recorded their leachate volume to be up to 40,000m3 per year, equivalent to transportation of three water tankers per day (110m3 /day). So, it is easy to estimate the high economic costs solely for leachate transportation, let alone the additional costs of the final leachate treatment. In Sweden, some commercial landfill sites have introduced an “on-site landfill leachate management” system named Laquaâ. The Laquaâ system and methodology is a simple filter-based system where leachate is filtered through a mixed layer of specific peats and ashes to remove potential contaminants (Figure 1).

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