Leachate production and disposal of kitchen food solid waste by dry fermentation for biogas generation

Abstract

This laboratory research, which applies anaerobic digestion for a solid phase batch system using kitchen food solid waste (KFSW), is concerned with optimizing leachate production under different conditions. The solid-phase digestion process is expected to be superior to slurry-phase digestion and the so-called “dry fermentation” process. A batch system solid waste reactor was used in the present study. The performance of the reactor was tested under the conditions of constant temperature of 35°C and the reactor active volume was 12 l. On operation day 10, chemical oxygen demand (COD) for leachate extraction parameters such as COD rate, COD loading rate (LR) and COD concentration reached maximum values, and were 135 g COD/d, 11 g COD/1.d, and 214 g/l of COD, respectively. On day 25, accumulative leachate COD reached the top value of 1509.4 g. The pH value of leachate was kept around 4. However, volatile fatty acid (VFA) concentration of leachate fluctuated, especially in the initial period. A high concentration of VFA on day 5 inhibited gas production, but with the decrease of VFA concentration the gas production rate was increased gradually and the sludge acclimated to VFA gradually. The process can be operated at a profit and no unfavorable environmental impact is expected for this type of plant production of biogas using the leachate from dry fermentation. These considerations make it a viable alternative in most countries as a source of energy.