Impact of Alternative Daily Cover Materials Derived from Waste on Leachate Quality and Waste Degradation in Bioreactor Landfills

Bioreactor landfills are proven technology for rapid stabilization of waste by recirculation of generated leachate back into the landfills. To prevent flies, birds, windblown litter, odors, rainwater infiltration, and the spread of diseases, a layer of soil is placed above the waste at the end of each working day. This practice, known as daily cover, is used in landfills to also improve the aesthetic appearance. As the soil becomes scarce, there is a need to find an alternative daily cover material (ADCM) to satisfy all the requirements of a daily cover. The main aim of the study is to use waste materials amended with soil as an alternative daily cover and to evaluate the effect of ADCM on leachate quantity, quality, and settlement in a bioreactor landfill. In this study, biochar, coir pith, compost, and sewage sludge modified with 30% coir pith is amended with soil and used as ADCM. Five reactors of size 1.5 × 1 × 1.2 m were operated under ambient atmospheric conditions for three years. Leachate was collected and analyzed at two weeks intervals. From the study, it is concluded that coir pith-amended soil as alternative daily cover in the ratio 1:1 showed improvement in leachate quality followed by biochar-amended soil in the ratio 2:1. Percentage degradation was high (97.11%) in the bioreactor with soil: modified sewage sludge in the ratio 1:1 as cover material and percentage settlement was high in the bioreactor with soil: biochar in the ratio 2:1 as cover material.