ANAEROBIC DIGESTION OF THE ORGANIC FRACTION OF WASTE: CORRELATION AMONG DIGESTER ENVIRONMENT, PERFORMANCES AND MICROBIAL ECOLOGY

摘要

The effects of anaerobic co-digestion of waste-mixed sludge with fruit and vegetable waste (FVW) on methane generation of a mesophilic digester was investigated. Organic loading rates (OLR) of 1.46 kgVS/m~3 day, 2.1 kgVS/m~3 day and 2.8 kgVS/m~3 day were used. Increase in the OLR due to FVW co-digestion caused modification of the internal environment of the digester, mainly in terms of N-NH4 (mg/L) and volatile fatty acids (mg/L). Maximum specific bio-methane generation of 435 NLCH4 per kgVS feed was achieved for an OLR of 2.1 kgVS/m~3 day at which corresponded a biomethane generation per kgVS removed of about 1,700 NLCH4. In these conditions methanogenic pathway was dominated by aceticalstic Methanosaeta and aceticalstic and hydrogenotrphic Methanosarcinae Archael genus. Findings showed that a key factor able to generate an internal environment of the digester able to boost methane generation was the ammonium concentration.