Leachate recirculation shceme for enhancing degradation of organic waste

Abstract

The objectives of this research were to study the leachate recirculation scheme in bioreactor landfill to enhance gas production and reduce stabilization time for organic waste, which is the major element of waste in Thailand. Analysis of the results provides a basis for field application. Three lab scale bioreactor landfills were set up: 1) recycle reactor, based on leachate volume and percent methane at fixed step; 2) recycle reactor, based on COD mass and volume of methane in which the leachate volume was adjusted according to the reactor’s output of yesterday, and 3) non recycle reactor. The results from this research confirmed that the leachate recycling practice showed higher efficiency in landfill stabilization as reflected by gas production rate, methane production rate, percent methane, and leachate indicator parameters, for instance, pH, ORP, and COD. When comparing two leachate recycle schemes, the reactor with recycle based on COD mass and volume of methane had lower percent methane at the final stage. However, it did not mean that the leachate recycle scheme inhibited methane gas production. Since the cumulative methane production from this scheme was higher than those of other reactors. With the significantly high rate of methane gas production from leachate recycle scheme based on COD mass and volume of methane, this scheme is recommended for small-scale landfill and landfill with biogas production purpose. This leachate recirculation scheme required examining these parameters frequently; daily gas production, methane gas percentage, and COD. Therefore, the application of plan B scheme to large-scale landfill might not be justify.