Nitrate removal from treated landfill leachate using a mix of vegetable waste and immature compost as a carbon source (simulation) in batches.

Abstract

The aim of this dissertation was to investigate how effective the process of removing nitrates from treated leachate, and if it is possible to apply to a landfill treatment plant. The leachate is high strength landfill leachate from Mariannhill Landfill Conservancy. Nitrates are present in treated and untreated leachate, which emanate from landfill sites. An excess of nitrates are harmful to the environment and poses a risk to health to particularly pregnant women and infants. Thus there is a specific need for nitrate removal and leachate treatment as there are no shortage of landfills and leachate. Most of the waste in South Africa is eventually dumped at landfill sites. A method for nitrate removal does exist. However, this is an expensive process and cheap or more effective method would be very useful for future leachate treatment. The method proposed for the removal of nitrate is the technology that would be used in an anaerobic bio-reactor. It is already known that CGRRAW works as a good substrate, thus various mixes with vegetable waste was investigated in order to improve the effectiveness and conclude which of the mix ratios is the most feasible. Experiments (or lab tests) were carried out for mixes in batch shot bottles. The less time it takes to remove all of the nitrates, the more effective that particular mix, of vegetable waste and immature compost, is as carbon sources for nitrate removal. Other aspects were also judged to determine the feasibility. It was found that combining vegetable waste and garden refuse can significantly improve the effectiveness of the nitrite removal. The result varies depending on the mix ratio. A 100% vegetable waste mix is not efficient at treating nitrates and too far from the standards set by DWAF compared to the other substrates, to be considered as an effective substrate. The most effective mix was found to be 1:3 mix of vegetable waste to CGRRAW (25/75 mix). The 25/75 mix was feasible, considering the DWAF discharge stands. All of the substrates tested would require a polishing treatment if the 25/75 mix applied in a Flat bed reactor.