Open degradation kinetics of organic fraction of municipal solid waste

The objective of this study was to determine the time required to achieve stabilization of organic fraction of municipal solid waste and to develop a decay model to describe volatile solid (VS) loss from open degradation of organic fraction of municipal solid waste in open dump sites. The role of soil contact and access to degradation by micro and meso + microorganisms were considered in this study as the driving factors of degradation. The weight loss in the organic fraction of municipal solid waste was monitored during the 30 days of degradation. The moisture content and volatile solids were rapidly lost within 6-8 days of exposure under dry conditions followed by slowing down and stabilization to low levels. The role of micro-fauna in the early stage of degradation was important. The function of micro-organisms was restricted due to the rapid fall in the moisture content of degrading municipal solid waste and this led the rest of the process to be carried out by meso and macro fauna. The degradation followed an exponential decay pattern with two potentially acceptable rate kinetics in two phases. Phase I followed zero-order kinetics, occurred till the 6th day of degradation and after a short transition, it was followed by phase II first-order kinetics. The rate constant of phase I and phase II are 16.6 g/kg/day and 0.024/day, respectively. As most of the waste was dried in the initial phase of degradation, it lowered the decomposition rates drastically.