Ricerc@Sapienza

Although the organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) originate from the same urban area and contain similar organic matter, they are collected separately and handled with different technologies. In this work, a combined treatment of OFMSW-SS mixture was investigated at pilot scale, by using a three-step mixed microbial culture (MMC) process in order to produce polyhydroxyalkanoate (PHA) as final high value biobased product.

In recent years, the attention to organic wastes as a new feedstock for the production of PHA is increased based on the idea that this is the only way to reduce their high cost and to increase their sustainability. For this reason, a pilot platform has been designed to produce PHA from the source-sorted organic fraction of municipal solid waste (OFMSW). The cost-effective system consists in the three-steps anaerobic-aerobic process: the fermentation step was performed in a 200 L CSTR (OLR 20.0 kgVS/m3.d, HRT 3.3 d) in thermophilic conditions (55°C).

Three different experimental sets of runs involving batch fermentation assays were performed to evaluate the influence of the experimental conditions on biological hydrogen production from the source-separated organic fraction of municipal solid waste collected through a door-to-door system. The fermentation process was operated with and without automatic pH control, at a pH of 5.5 and 6.5, food-to-microorganism ratios of 1/3 and 1/1 (wet weight basis) and with different working volumes (0.5 and 3 L).