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EUREKA SWAN - Reduction of water use in the EU Malting Industry - AR0916

The UK malting industry is very conscious of the need to ensure the sustainability of its operations. The production of malting barley, maltsters’ basic material, has strong links to the sustainability of agriculture. UK maltsters have been in the forefront of UK energy efficiency practices since the early 1970’s, and are signatories to a sector Climate Change Levy Agreement. However, whilst energy use in malting has been significantly reduced, there has been no improvement in the very large amount of water used in malting. Since malting officially became a food industry a number of years ago, water use in cleaning malting production equipment has increased.

The EU water framework directive makes it clear that emphasis on more efficient water use will increase, and the cost of water will rise. The current situation on water and effluent costs will change significantly over the coming years, to the extent where the commercial viability of malting in Europe could be placed under considerable pressure.

Malting is the controlled germination of cereals, to ensure a desired physical and biochemical change within the grain, which is then stabilised by the application of heat. Malting makes use of the natural process of change that occurs when grain germinates. The modification changes within the grain naturally take place in grain that has been planted in soil. The embryo commences to grow once the grain moisture content is above 33%, and continues to draw the necessary moisture from the soil to complete the process. To induce this condition in an industrial process the grain must be put to the germination stage with moisture content of around 45%. Raw barley is held in safe storage at below 14% moisture content, so it must be immersed in water to raise the grain moisture content to the required level for malting. This is achieved by a series of periods of immersion in water, followed by a period of drain and rest in air. Almost all modern maltings use the 2 or 3 wet system, which is called ‘steeping’.

At a review that the MAGB carried out amongst UK maltsters in July 2002 it was found that an average use of water in the steeping process was 5.05 m3/per tonne of malt made, this in turn produced an effluent from steep of an average volume of 4.1 m3/per tonne of malt made. The UK malt production in 2001 was 1.56 million tonnes which indicates that around 7.9 million m3 (or 8262 million litres) of potable water was used in malt production in that year and that water effluent from UK maltings totalled around 6.4 m3 (or 6708 million litres). This project intends to help reduce water usage in the steeping operation by no less than 50%, and ideally up to 85%.

This project seeks to explore a way to solve the problems that have prevented the re-use of water in malting, in particular to find a method to treat the effluent from the steeping of grain, to enable its re-use in the steeping process. It is known that when grain is immersed in water to increase its moisture content from 14% to 45%, substances are leeched or washed from the grain, and pass into the resultant effluent. One or more of those substances is known to inhibit grain germination if it is re-applied to steeped grain.
The project will identify and quantify the elements present in the steeping water that cause an inhibition of germination resulting in the production of an inferior quality of malt. The project will attempt, on a pilot and laboratory scale, thereafter an industrial pilot, to produce a viable economic procedure for the re-use of treated water, after isolating the inhibiting agent.

During steeping between 0.5% and 1.5% of the grain’s dry weight dissolves in the steep water. Steeping a 100 tonne batch of dried barley can add around a tonne of solids into the total volume of effluent from the batch (over the 2 or 3 wets during steeping). Biological oxygen demand (BOD) increases with the length of contact time between grain and steep water. Larger volumes of water results in “less strong” effluent. The project must address the issue of effluent strength and costs in relation to the solution required to produce potable water (with the germination inhibitor removed), suitable in the grain steeping process. It is important that the project can address the different site needs in relation to existing water treatment plants. Information on the system, and combinations of systems being used to treat effluent, looking at raw effluent and final effluent analyses will be gathered. Considerations will have to be given as to how the solution for steep water re-use can be most efficiently and cost effectively incorporated into existing plants. Current technologies for the treatment of effluents are capable of producing potable water, which should be reusable at any level of the industrial process, if the inhibitor can be defined and eradicated.

The seven largest UK malting companies will form the UK maltsters’ partnership, operating for the project as MAGB SWAN Ltd
To reduce water usage in the malt steeping operation by no less than 50%, and ideally up to 85%, by treating and re-using steep water.
Project Documents
• Final Report : Recycling of Malting Process Water   (714k)
Time-Scale and Cost
From: 2003

To: 2006

Cost: £174,014
Contractor / Funded Organisations
Climate and Weather              
Climate Change              
Food and Drink              
Food Chain              
Food manufacturing industry              
Process Technology              
Sustainable Farming and Food              
Sustainable Production              
Fields of Study
Arable Crops