IMPACT ASSESSMENT OF CONCENTRATE RE-CIRCULATION ON THE LANDFILL GAS PRODUCTION

This paper explores the impact of concentrate re-circulation, as a product of leach ate treated by reverse osmosis plant, on the production of landfill gas at the real scale landfill for municipal solid waste. In an effort to come up with results, experimental measurements were carried out at the landfill in city of Bijeljina, Republic of Srpska, Bosnia and Herzegovina. All performed measurements were divided into three groups. The aims of two groups of measurement were to determine landfill gas and methane yield from concentrate, and leachate in laboratory conditions (1st group), and to find out concentrations of oxidizing matters (chemical and biochemical oxygen demand) present in leachate and concentrate at different points of treatment as well as its variability over the time (2nd group), which could be used to calculate the potential of landfill gas and methane generation from concentrate by re-circulation, theoretically. The 3rd group of measurements, carried out in parallel, has goal to determine the quality and quantity of the collected landfill gas at wells throughout the landfill. The results of analysis carried out in this experimental research show the clear evidence of concentrate re-circulation impact on methane production by increasing the landfill gas flow, as well as its concentration within the landfill gas composition, at the nearby well. Although results indicated relatively high impact of concentrate re-circulation on landfill gas production, comparing to its theoretical potential, the influence on the landfill at whole, is negligible, due to relatively low volumes in re-circulation with respect to its size and objectively low potential given by organic matter present in concentrate.