Food processing consumes more water than any other manufacturing process.
According to Sydney Water, of the 90 million litres of water used by industry every day, 39% is consumed by food manufacturing.
By contrast the next most water-intensive industry, metal products, uses only 12%.
With the cost of water rising and likely to increase further to fund investment in alternative water supplies as weather patterns change and dams dry up, it is not surprising that food companies are looking at ways to reduce water consumption in their manufacturing processes.
Although many of these technologies are well proven, Busch Vacuum Pumps and Systems’ systems manager Alexis Lim says a large part of the problem is food manufacturers’ conservatism. “For a long time water has been so cheap that it was essentially free,” he said.
However, Lim believes that companies are slowly coming around and are starting to look at technologies such as Busch’s waterless vacuum pumps and other ways of saving water.
Water-saving initiatives
Reducing water use is a complex business, particularly in food manufacturing where waste water can contain life-threatening pathogens.
Some of the main areas where work is being done to reduce water used in manufacturing include installing water efficient devices and appliances, harvesting rainwater, and reusing water (greywater or blackwater recycling).
Of these technologies, the easiest and often the cheapest to implement is some form of demand management by installing water saving devices and appliances, says Energetics principal consultant Peter Holt.
“On a very simple level it’s technology such as dual flush toilets, cap aerators and machines that use low levels of water, as well as modifying washdown procedures on the factory floor to use less water,” he explained.
“Cooling systems can be changed from water-based to air-based cooling systems.”
Cleaning process equipment can account for between 50% and 70% of a manufacturing facility’s total water use so, for organisations that have not already done so, installing a clean-in-place (CIP) system can be an effective initial step towards saving water.
Reuse and recycle
Beyond basic demand management, the next step for an organisation is to look at reuse or recycling.
Reuse is about using water that would otherwise be wasted — waste water, stormwater, rainwater, and greywater — instead of using fresh drinking water.
Recycling water involves going a step further to treat waste water or stormwater to a standard fit for purpose.
Beyond this, alternative water sources such as groundwater or sea water may be used.
When considering these measures, cost and complexity need to be taken into account.
Rainwater for example, needs very little treatment whereas sea water must be desalinated before it can be used.
Reuse and recycling are often used in concert with a cascading hierarchy of uses.
For example, if water is in contact with food it needs to be high quality but for washdown purposes in some factories it would be acceptable to use rinse water from another process.
Trade offs
One final factor that needs to be taken into account is energy consumption.
The technology exists to take low quality water such as stormwater, groundwater, salt water, blackwater, or sewerage, and recycle it so it is drinkable.
The trade off is that the process used to do this, reverse osmosis, uses a lot of electricity, said Holt.
“A more intensive water recycling process may mean that you’re saving water but at the expense of more energy.
“It can also lead to more concentrated effluent which can cause waste management challenges,” he said.
Case study
National Foods faced all these issues when it decided to reduce water usage at its Penrith, NSW, milk processing factory.
“The basic process was simple,” National Foods spokesperson Julian Caples said.
“We started with an intensive metering program at the site with the help of Sydney Water.
“It installed some remote logging water meters to look at the usage patterns in the factory so we could see where the big uses were, where the peak uses were, and then gradually modify the processes.”
Some of the measures National Foods implemented were big changes, says Caples.
“We designed a water recycling system to wash milk crates with recycled rinse water instead of new water.
“There were also some changes with the CIP where we experimented a lot with wash times and sequences, water pressures and flow rates which made substantial differences to water use and chemical use.
“We made some operational changes to key equipment such as pasteurisers and bottle washers and instead of having simple hoses for washdown we moved to high-pressure, low-volume spray systems where we could.”
“You can’t do that in all places because of microbiological contamination,” he continued.
National Foods also found a lot of small housekeeping changes made a surprising amount of difference.
Filters were fitted with water seals on valves to make sure they were not continuously running and overflowing, and leaking pipes and dripping taps were eliminated.
The company also implemented water saving operating disciplines discouraging operators from leaving hoses running on the floor.
“Once we got started and put the technical changes in place, reinforcing that with behavioural changes was comparatively straightforward,” Caples said.
“It needs constant reinforcing but once people saw that we were serious about water reduction by doing things like changing the crate wash, it helped put all the other changes in place and by the end of it we’d saved 30 million litres [by the] end of 2006.
“Over a three year period that’s 20%.”
Water is going to become a greater issue in the future, as climate change continues and Australia’s droughts wreak havoc, causing the cost of water to increase still further.
This is a cost food manufacturers could well do without. Addressing the issue now will save time and money later on, allowing those that are prepared to jump ahead of their competiton reap the rewards.
www.buschpump.com
www.energetics.com.au