Kinetics of the organic matter biodegradation in the leachate from a municipal waste landfill

The paper presents results of the research upon leachate from a municipal waste landfill in north-eastern Poland, where a reverse osmosis process with concentrate spraying on the dumped waste to treat leachate was used. The tests include measurements of oxygen consumption for the mineralization of organic matter in the biochemical oxygen demand (BOD). Measurements were carried out in a 25 d period under laboratory conditions at 20 degrees C and 10 degrees C. The test results were used to estimate the rate constant of biochemical decomposition of organic matter in the leachate. To describe the rate of BOD changes, the assumption was made that the decomposition reaction is the first-order reaction. This assumption was correct when dividing the process into two stages: 0-5 d and 5-25 d. On the basis of the test results, the reaction rate constants for biochemical changes for the oxygen demand in both stages were determined separately. In the first step, reaction rate constants k varied between 0.610 and 0.624 d(-1) at 20 degrees C and 0.387 to 0.877 d(-1) at 10 degrees C. In the second stage, they were 0.021-0.090 d(-1) and 0.009-0.055 d(-1), respectively. The R-2 determination coefficient for the calculated values ranged from 0.9903 to 0.9960.