Landfill Leachate Treatment

Almost all landfills produce leachates. In many cases these leachates are unsuitable for discharge to a municipal sewage works, usually due to high BOD/COD levels and/or high ammonia levels.

RPA have worked with a number of landfill operators to identify the most cost effective method of controlling and treating the specific leachate. For example:

1) A large South East Asia landfill produced a leachate which had not only a high BOD but also a very high ammonia content relative to typical European or US experience. We:

• Designed and specified a pilot plant to optimise parameters for ammonia removal using a chemical engineering technique
• Provided on site technical support during part of the pilot plant trials.
• Worked with the local management and their consultants to identify and agree the most economic sizings for a combination of buffer storage capacity and treatment plant capacity.
• Scaled up the ammonia removal test work and integrated it with a biological treatment plant to achieve the required treatment quality.
• Designed and specified the full-scale treatment plant. This occupied much less ground area than a conventional nitrification-denitrification method.
• Carried out costings and provided all necessary details and equipment specifications to allow the Client to proceed with construction.
• This plant is successfully processing 1000 cubic metres of leachate per day.
• Two other plants were designed and specified using this same successfully demonstrated process route.

2) A large and well established UK landfill in a former stone quarry had problems with leachate from the older areas of the site, leachate from recent tipping and contaminated surface water.

The site had discharge consents to both an adjacent canal and to a municipal foul sewer. We investigated a range of biological and physical treatment options for both the methanogenic and the acetogenic leachates from the site and for the surface water run-off issues. Treatment objectives were principally defined by ammonia removal requirements and the need to remove refractory (difficult) COD materials. The assessment provided the Client with a defined strategy for optimum capital investment.

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