Objectives and problems to be solved:
Based on an existing organic waste treatment hybrid process B.S.F.C., in which the waste is separated in a liquid fraction for anaerobic digestion and a solid fraction for composting, the project objective is to establish an environmentally beneficial process with optimised utilisation of all output mass flows in terms of maximum energy yield and valuable soil fertiliser by performing the following measures:
- improving energy production for different new organic waste materials;
- upgrading of the biogas for use in the natural gas grid and in future in fuel cells;
- depletion of heavy metals and salt in raw material to improve compost quality;
- development of an economically acceptable method to reduce N and P contamination in the liquid digested residues for recycling into the process and environmental protection.
Description of Work:
- For maximum biogas output and cost effectiveness applicability tests of CSTR (continuous stirred tank reactor) and FBR (fluidised bed reactor) for digestion of the liquid fraction will be performed with new waste substrates from the leather industry and slaughterhouse at mesophilic and thermophilic conditions.
- For the upgrading of biogas a small scaled prototype will be constructed and operated at the SME proposer MFN. To fulfil a cost effective cleaning system biological/chemical and physical methods will be combined. Therefore the prototype will consists of a bio trickling filter for removal of H2S, an activated carbon filter for removal of AOX and hydrocarbons, and an gas membrane filter for removal of CO2.
- Variation of separation techniques and parameters in laboratory and technical scale at the waste treatment plant of the SME proposer SESA are necessary to find the key parameters for depletion of heavy metals and salts in the solid fraction, which will be composted to obtain a valuable soil fertiliser.
- For flexible and environmentally friendly management of digested residues solid/liquid separation experiments of digested residues by centrifugation and evaluation of solid digested residues drying systems are necessary. The applicability of composting of digested residues in technical scale has to be examined. To find out the most cost-effective solution for the N- and P-removal from the liquid digested residues investigations of SBR (sequential batch reactor), bio filtration and phosphate precipitation will be done. Hygienic monitoring of the process will be carried out by bacteriological tests.
Expected results and exploitation plans:
- Maximising the energy yield from the digestion of organic wastes
- Biogas upgrading to meet the requirements for the natural gas grid
- Depletion of heavy metals and salts in compost below the limit values for first grade soil fertiliser- Removal of N- and P-contamination from liquid digested residues below the limit values of direct discharge into the environment.
Funding SchemeCRS - Cooperative research contracts
33929 Frieres - Langreo