BIOGAS PRODUCTION, HEAT RECOVERY AND SIMULTANEOUS ANAEROBIC TREATMENT OF BREWERY WASTE WATER

Ziel

The use of a new anaerobic digestion process called "anodek" to simultaneously purify brewery effluent and produce biogas to heat the hot water circuit. The process is based on R&D carried out at the University of Gent.
The methane fermentation process which is applied in this treatment system is a microbiological process where the substrate, which consists of soluble and insoluble complex organic matter, is finally converted into methane gas and carbon dioxide. The insoluble organic matter is first solubilized and hydrolyzed. Then this soluble organic matter is metabolized and converted into organic acids, ethanol, hydrogen and carbon dioxyde. All these intermediates are formed by a heterogenity of micro-organisms in a first fermentation phase. Then these intermediates are again metabolized and finally transformed into methane and carbon dioxide in a second fermentation phase. In the two stage " Biotim-A" methane fermentation process, the two basically different parts of the fermentation process are operated separately. Thus each part of the fermentation can be operated at its optimum conditions, leading to an improved total treatment efficiency. Accidental toxic discharges can for instance be detected before they reach the more sensitive methanogenic fermentation phase.
In the treatment station the two phases of the anaerobic fermentation process are separated as follows. The wastewater is first treated in the so-called biological conditioning and control reactor (BCCR). This reactor is used as an acidification reactor and as a buffering tank.
The second fermentation phase takes place in the methane reactor. It is a reactor of the CASB type (Captured Anaerobic Sludge Blanket). In this reactor the wastewater first rises through an expanded anaerobic methanogenic sludge blanket and then through a bed of reticulated polymer carrier material. A high concentration of methanogenic bacteria is obtained in the reactor, leading to high yields. The produced biogas can be temporarily stored in a 100 m gasholder before it is burned. The total treatment process is controlled by a computer.
Recently a series of experiments with a PCR (polyurethane carrier reactor) pilot reactor havebeen finished successfully. The parallel experiments on the full scale CASB and also on a UASB pilot reactor were not satisfactory since a constant sludge wash out was observed and because imperfect settling of sludge developed. Contrarely good settling seed sludge broke in pieces and disappeared. As compared with the CASB, this pilot PCR reactor contains more carrier material. Thus a higher amount of active methanogenic bacteria, fixed on and included by the carrier, was obtained. Three temperatures have been used: 22, 32 and 37 deg. C. The pilot plant COD, BOD and VFA (Volatile Fatty Acids) effluent concentrations show a clear correlation with the reactor loading. At increasing loading rates the effluent concentration rises in a nearly linear way between the applied loading interval. An adaptation of the full scale CASB installation to the pilot PCR design is being studied and these changes will be carried out on the full scale installation.
The "anodek" anaerobic digestion process consists of two separated phases :
- a microbial acidification of the organic fraction of the waste water.
- a methanogenic fermentation of the organic acids.
A new suspension of the microbial mass will be used in the anaerobic fermenter: the biogas which is produced is used to fire a hot water circuit.
The first reactor (B.C.C.V. Biological conditioning and control vessel) has a total volume of 540 m3 and retention time of 8 h.
A buffering volume of 240 m3 permits the methane reactor to be fed continuously.
The second fermentation phase takes place in the methane reactor. It is a reactor of the CASB type (Captured Anaerobic Sludge Blanket). In this reactor the waste water first rises through an expanded anaerobic methanogenic sludge blanket and then through a bed of reticulated polymer carrier material.
A high concentration of methanogenic bacteria is obtained in the reactor, leading to high yields. The methane reactor has an active volumeof 320 m3. Of the designed 840 m3 of wastewater, the reactor is actually treating 670 m3 per day.
The produced biogas can be temporarily stored in a 100 m3 gasholder before it is burned. The total treatment process is controlled by a computer located in the control building.
Foreseen biogas production is expected to be 600 m3/d.

Programm/Programme

ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984

Thema/Themen

1.7 - PRODUCTION AND USE OF BIOGAS

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

DEM - Demonstration contracts

Koordinator

BROUWERIJ PALM SA

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STEENHUFFELDORP 3
2901 LONDERZEEL
Belgien

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