Effect of recirculated leachate volume on MSW degradation

Landfilling represents the most economical method for the disposal of municipal solid waste (MSW). After depletion of the limited volume of air available in void spaces of a waste bed, decomposition in a landfill takes place under anaerobic conditions. Anaerobic digestion requires moisture and a lack of water is generally responsible for retarding degradation of MSW in conventional landfills. Furthermore, the moisture that may be present is seldom uniformly distributed. Bioreactor landfills are being researched as a means to provide a rapid and predictable stabilisation of waste and landfill gas production. This is achieved primarily by control and management of the liquid flow within the landfill. The moisture content of waste and moisture movement through a waste bed are two distinct factors that affect MSW decomposition. A moist environment is critical for microbial activity; and flow of moisture is essential to mobilize nutrients and evenly distribute microorganisms through a waste bed. The movement of moisture through a waste bed also provides improved mass transfer and prevents the development of stagnant zones. Experiments were carried out to understand how the amount of recirculated leachate effects waste degradation in coupled pairs of stabilised and fresh waste reactors, Higher recirculation rates are shown to both improve solubilisation of fresh waste, and also establish the methanogenic microbial Copulation more quickly. In the best case, the organic fraction of the waste was essentially entirely degraded within 2 months.