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As part of its responsible environment policy, Interbrew Belgium (InBev group) has decided in association with Aspiravi, to develop the water treatment plant at its Leuven brewery to generate green electricity from biogas from the anaerobic pre-purification of waste water. The 1,000 kW unit should yield an energy gain of at least 5,000 MWh a year, representing the annual energy consumption of about 1,500 households.

Interbrew built a water purification plant on the site of its Leuven brewery in 1980, regarded at the time as revolutionary by virtue of the degree to which biological processes are applied in the water purification process. Water purification capacity of 15,000 m[sup.3]/day and 30 tonnes COD/day, corresponds to purification capacity for a city of 350,000 inhabitants. Up to 2004, waste water purification was exclusively aerobic: waste water was purified using biological organisms (activated sludge) which feed on and thereby remove waste elements from the water. The water ultimately produced meets quality standards for discharge into surface water. However, this process had the disadvantage of requiring a lot of energy and the production large quantities of sludge.

In order to reduce the impact of water purification on the environment, it was decided in 2004 to further develop the process, which now breaks down into two parts: anaerobic pre-purification with production of biogas and processing of this biogas into electricity and heat. This implies the integration of an additional stage in the process: before being treated in the existing water purification installation, waste water is first purified through an "anaerobic process", in an environment bereft of oxygen. There are three advantages to anaerobic purification: instead of transforming food substances (pollution) into biomass (sludge) and CO2, produced by the breathing of aerobic bacteria, anaerobic bacteria form biogas (composed of CH4 and CO2). This biogas can in turn be put to good use. Since waste water is anaerobicly pre-purified, energy consumption in the ensuing aerobic stage is significantly reduced. Moreover, anaerobic organisms grow much more slowly, cutting down on the production of sludge which must in turn be treated.

Transforming biogas into electricity and heat.

The biogas produced during the anaerobic process can be valorised in various ways. At its Leuven plant, Interbrew has chosen with Aspiravi to use the biogas to produce electricity by means of a biogas motor. Aspiravi is responsible for the development of the project, investment and exploitation of the recycling of biogas. The biogas is initially treated in a rinsing column to meet the motor's quality specifications. Thereafter, a 570m[sup.3] intermediate storage reservoir serves to control fluctuations in biogas production and guarantee stable operation of the motor. Finally, the purified biogas is transformed into electricity and heat in the motor. The estimated quantity of electricity that can be produced is equivalent to the annual consumption of about 1,500 households. This electricity is used fully by production departments at the Leuven brewery. The heat is meanwhile used to optimise anaerobic purification yields. Since mid-2003, significant efforts have been made to ensure intelligent consumption of energy and water. The Leuven brewery has also signed an energy contract with public authorities and has pledged to pursue the optimisation of energy consumption over the coming years. The first fruits of these efforts were reaped in 2004: compared with 2003, water consumption was down 15% and electricity consumption down 14% as a result of anaerobic purification.

* Interbrew Belgium: InBev was established through the merger of Interbrew and Ambev (Brazil) and employs 3,430 staff in Belgium. InBev is the world's largest brewer in volume terms. Interbrew Belgium has a diverse portfolio of 44 brands (notably: Beck's, Jupiler, Stella Artois, Hoegaarden, Leffe and Belle-Vue), four production centres (Leuven, Liege - Jupiler, Hoegaarden and Brussels), 8 distribution centres and 2 distribution hubs.

* Aspiravi: is a Belgian company involved in project development, investment and exploitation of environmentally-friendly renewable energy production installations. The company currently operates 41 wind turbines, 4 biogas motors, 2 small-scale hydro-power plants and 20 co-generation installations in Flanders, Belgium.
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Publication:Europe Energy
Date:Mar 11, 2005

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