Last updated: (February 2005)
Introduction
The food and drink sector is a large user of water. Increasing costs for purchase and disposal make it important to consider whether water is being used wisely. This Reference Note offers guidance to those in the food and drink industry sector who want to minimise the use of water on industrial sites.
Incentives for Minimising Water Use
Water is a key natural resource that is often taken for granted. In the manufacture of food and drinks, water has an enormous variety of uses, for example in:
- flume transport
- raw materials cleaning
- cooking / blanching
- formulation of final products.
Aside from the product processing line itself, water is also used for a variety of diverse activities such as:
- cleaning of equipment
- provision of services such as steam, vacuum and cooling water
- operation of hygiene stations
- provision of staff amenities such as canteen facilities.
The cost of water from the mains in the UK is typically between 46-86 p/m3 (1999/2000 figures). Before use, of course, food and drinks processors may need to treat water to ensure appropriate quality for their process, adding further costs to the business.
Using water gives rise to costs not only for supply, but also for disposal. For example, charges will be payable if wastewater is discharged to a sewer for off-site treatment. The rate will normally depend on the basis of the volume flow and strength of the effluent. Discharging to the natural environment, where permitted, may also give rise to an annual charge, for example from the Environment Agency in England and Wales.
Combined charges of water supply and disposal can easily reach between £1 and £2 per cubic metre at 1999 prices – and for individual sites this means that annual water and sewage bills of hundreds of thousands of pounds are not uncommon.
In addition to the "visible" costs of water bills, there are other reasons for saving water:
- limits on supply or discharge of water can physically limit the growth potential of a business
- local environmental damage can bring bad publicity or legal problems if use and discharge of water are not carefully managed
- the secondary costs of water use and disposal, such as capital and operating costs for pumping and treatment, may be significant.
By saving a few per cent of annual water charges, some businesses could realise significant savings. The examination of water can, and has, led to significant savings when approached in a logical and structured way.
Tracking Water Use
The ETBPP( Environmental Technology Best Practice Programme)advocates a six step approach to reducing water costs:
| Getting Commitment |
Securing support from senior management, perhaps by:
- highlighting current costs
- demonstrating some quick "low cost/no cost" ways of saving water
- suggesting the scope of potential savings |
| Preliminary Review |
Gathering information, identifying gaps and setting the scope/details
of subsequent work |
| Drawing the Picture |
Developing a simple block flow diagram of sources and fates
of water, which shows the major users of water for the site
Adding known data to produce a first, simple account of water source and fate |
| Adding the Detail |
Generate all details of:
sources: areas served, any treatment, storage, transfer means, use and frequency and quantities supplied
users: develop a diagram linking these to sources
effluents: develop a diagram to show the means of disposal of wastewater, distinguishing between different types of drainage system
any others?: "think around" the process to note leaks, evaporation etc.
Then quantify flows of water onto and off the site. Reconcile differences to establish a "water balance". |
| Using the Water Balance to Save Money |
Now, with an account of major users and effluent generators,
"brainstorm" for suggestions of how to minimise.
For more complicated sites, it may be necessary to develop maps of pollutant loads (mass flowrates) as well as volume flows, in order to set priorities for savings measures. |
| Continuous Improvement |
Review the water balance, say every three to six months. It
can be updated as time passes, to reflect your improvements in both cost
savings and knowledge of your site. As changes are implemented, new priorities
for savings will naturally arise! |
Common Areas
A number of water-saving measures and practices are common to all businesses. For example, it is good practice to keep drains for foul sewage, stormwater and process effluents separate, so that high sewage or trade effluent charges are not incurred for "cleaner" water flows. Dry methods should be considered prior to those which use water, to minimise water use and effluent generation. When a hose is used to spray equipment or floors, care should be taken that large quantities of solid or soluble materials are not sent to drain if they can first be removed by sweeping or scraping. In staff toilets, the installation of percussion taps or automatic flushing devices for urinals could be considered.
Food And Drink
There are, however, a number of measures which have particular relevance to
the food and drinks sector. These include:
| raw materials cleaning: |
consider alternatives to batchwise bath immersion such as:
- water recycling/reuse
- spray washing
- countercurrent washing |
| cleaning of equipment: |
consider:
- non-stick surfaces to reduce contamination
- dry cleaning before water washing
- automatic detection of product/water interfaces
- effective spray nozzles
- automatic shut-off hoses
- optimised "clean-in-place" technology
recycle detergents/rinses
product/vessel-specific programming
- optimisation of "hygiene" shutdowns
- optimisation of product changeovers |
| provision of services: |
steam:
examine losses and potential for condensate recovery
vacuum:
consider recycling seal water or use of dry vacuum pumps
cooling water:
consider automatic blowdown, reducing loads by process changes, and using alternative means of cooling |
| operation of hygiene stations: |
examine:
- exact cleaning requirements
- tap water pressures
- forms of tap head (spray etc)
- automatic shut-off of water supply |
Potential For Benchmarking
Compiling a water balance for a site gives a site-specific initial "benchmark" of water use performance. In some instances or industry sectors, water use is calculated on the basis of use per unit of production. This form of measure can be very useful for monitoring the performance of an individual site with respect to time.
Following a survey of the soft drinks industry, the Environmental Technology
Best Practice Programme published a guide EG126 Water Use in the Soft Drinks
Industry. This provided some industry-wide data for water use and wastewater
discharges by product type.