Methane (55–60%) and carbon dioxide (40–45%) are the two main greenhouse gases that makeup landfill gas. Traditionally, methane emissions from covered landfills were reduced by collecting the gas with an active or passive gas collection system, burning it in a high-temperature flare, or using it as fuel in a CHP plant. But as the landfill ages, the quantity of gas produced and its methane concentration decline, making further effective gas collection, methane removal, and energy recovery using conventional methods, technically and financially unfeasible, as is the case with the old landfill Nienburg/Rehburg-Loccum.
Utilizing a cutting-edge method, BAWN and ISAH intend to mitigate methane emissions naturally, economically, and with low energy consumption. Within the framework of the research project "Oxi-Loc", BAWN and ISAH aim to jointly demonstrate and implement in practice an external biofilter to prove sufficient methane oxidation of the residual gas from old landfills by employing old leachate treatment components installed at landfill sites. Hence, existing infrastructure (landfill gas extraction and collection and existing structural components of the landfill leachate treatment system) are reused, thus further resources could be conserved. Methane oxidation in the biofilter is also to be optimized by the use of biochar. The biochar will be obtained by pyrolysis of the oversize material from the composting process that was previously sent to the thermal treatment. This will close another cycle and reduce climate-damaging greenhouse gases.
Initially, this topic was researched at the ISAH as part of the master's thesis of Ms. Sara Zahedi Nezhad "Development of a concept for the oxidation of residual landfill gas using the example of the old landfill Loccum" (2019), and Mr. Tim Kappmeier "Design and scale-up of a test station for residual methane gas treatment of the old landfill Rehburg-Loccum" (2021) under the supervision of PD. Dr. Ing. Weichgrebe and Dr. Ernst Reuter (IWA engineering association). Both mentioned master graduates are employed at ISAH as research engineers and supervise this innovative project, among others. Furthermore, PD Dr. D. Weichgrebe (ISAH) will scientifically accompany the research project with great enthusiasm.
The Oxi-Loc project is being funded by the state government with more than 400,000 euros. The BAWN will receive 200,000 euros for practical implementation and field research on the new process. The remaining funds will be given to the ISAH for scientific cooperation. The aim is to jointly test a process that can eliminate methane from landfill gas at the old landfill site in Loccum. Oxi-Loc, the project's name, is an acronym for "Methane Oxidation Loccum."
