The influence of moisture enhancement on solid waste biodegradation

The objective of this study was to assess the influence of moisture enhancement strategies on biodegradation of municipal solid waste (MSW) in laboratory-scale reactors. Moisture enhancement strategies were varied with respect to dose volume (40, 80, 160, and 320 L/Mg-MSW) and dose frequency (dosing every ½, 1, 2, and 4 weeks). Biodegradation was evaluated based on methane generation to assess (i) the lag-time between the start of liquid dosing and onset of methane generation and (ii) the first-order decay rate for methane generation. In general, the decay rate increased with an increase in dose volume for a given dose frequency. In addition, trends of increasing decay rate and decreasing lag-time were observed for an increase in dose frequency for reactors operated with dose volumes of 40, 80, and 160 L/Mg-MSW. A key conclusion from this study was that reactors with more aggressive moisture enhancement attained more rapid methane generation that initiated at shorter elapsed times following the onset of dosing. An assessment of liquid dosing per month indicated that there were more pronounced impacts of increasing decay rate and decreasing lag-time as moisture enhancement increased from 40 L/Mg-MSW/month to 320 L/Mg-MSW/month as compared to the impact on both variables for an increase in liquid dosing above 320 L/Mg-MSW/month.