TWO-PHASE ANAEROBIC DIGESTION OF SOLID ORGANIC WASTES YIELDING BIOGAS AND COMPOST
The aim of the project was to develop a novel, specific process for the anaerobic digestion of solid organic wastes with biogas and compost as the final products. This novel process can be an alternative to (controlled) dumping, to incineration of organic wastes and to (aerobic) composting. The solid matter is charged into a liquefaction acidification reactor (R1), to be broken down by an anaerobic microflora into soluble compounds: mainly volatile fatty acids (VFA), which are continuously leached by percolating water. The percolate is pumped to a digester (R2), containing methane bacteria, where the dissolved organic matter is converted into biogas, while the treated water is recycled to the R1. The microbiological and technological aspects of this process have been investigated on laboratory scale, in semi technical apparatus and in a pilot plant (two different conceptions of the R1, at about 33 degrees C (mesophilic). A great variety of materials was tested, like waste from sugarbeet and potato processing factories, and organic fractions separated from municipal solid waste. The residues, after anaerobic digestion, were submitted to an (aerobic) after-composting; after a spontaneous initial heating, a compost equal to a usual compost was obtained. The results of the investigation, a technological discussion and a feasibility study are given. The process is considered to be technologically feasible. The economic feasibility is more complex and, has to be judged, for any given situation, in all its aspects, in comparison with the alternatives. In general for the Netherlands it can be concluded that uncontrolled dumping is the cheapest, controlled dumping and anaerobic digestion are more expensive but about equal in price, while incineration is by far the most expensive way of disposal.
Bibliographic Reference: EUR 9942 EN (1985) MF, 60 P., BFR 150, BLOW-UP COPY BFR 300, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989124106500 / Last updated on: 1987-01-01
Available languages: en