Green Washing Saves Water

Sept. 24, 2020
Conservation procedures can both cut down on water used for cleaning and recover some of it for reuse.

“Greenwashing” is a pejorative term that denotes phony efforts by businesses to appear environmentally sound.

But green washing, two words, is something else entirely – something that food processors might have to do to be environmentally sound.

Cleaning and sanitizing is, in almost all food and beverage plants, the operation that uses the most water. (The two terms are often used interchangeably, but in general, cleaning means ridding a surface of extraneous material; sanitizing usually means applying a biocide like bleach to a clean surface.) But the more water a plant uses, the greater the strain on local resources, both to supply it and to accommodate it when it becomes wastewater.

The stakes can be high, especially when a plant comes online or its water requirements suddenly rise. That’s what Kraft Heinz found when, in 2017, it started making string cheese in its facility in Lowville, N.Y., about 60 miles northeast of Syracuse.

The plant had been producing cream cheese, but the cleanup required after making string cheese was harder and more water-intensive. The plant’s water use shot up, to the point where it took up more than 80% of the town’s typical daily water supply. At one point in 2017, Lowville had to tell its approximately 3,500 residents to restrict car washing and other water usage. (Kraft Heinz did not respond to a request for comment.)

A comprehensive plant audit is the first step of each of Veolia Water Technologies' projects. Every piece of water-using equipment is evaluated for how much water is used, how much is discarded and the water qualities of both the incoming and effluent streams. 

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Strategies for saving water basically break down two ways: using less of it in the first place, and recovering as much as possible from what does get used. The first step is to figure out just how much water is being used, where, and for what – something that a surprising number of plants don’t do.

“Not nearly enough facilities have flowmeters or really have any idea of how they’re using water throughout their entire process,” says Matthew Howard, director of the Alliance for Water Stewardship in North America. “Companies today really need to start with simple water audits and a better understanding of where they’re using water, how they impact water resources and of course the associated costs.”

When Veolia Water Technologies takes on the job of reducing a food processor’s water usage, the first step is a comprehensive plant audit, says Ted Lawson, director of strategic marketing. Every piece of water-using equipment is evaluated for how much water is used, how much is discarded and the water qualities of both the incoming and effluent streams.

“Then you can literally map the facility as to their water in, where it goes, how it’s used, water out, and then ultimately how it’s treated,” Lawson says.

Many plants would need to install flowmeters at strategic points to get an accurate picture of where their water is going – something they should not hesitate to do, says Glen Giersch, senior technical manager at Hydrite Chemical, a cleaning chemical supplier.

“Accurate flowmeters that do not require piping modification or cutting are available,” Giersch says. “With the ever-increasing focus on water usage, they are worth the investment.”

Specialized equipment can sometimes help. Sanitation-services provider PSSI, for instance, has designed, in conjunction with a third-party engineering firm, a meter that can be installed in individual hoses to measure pressure and temperature as well as volume.

Strategizing savings

Once water usage is accurately mapped, the hard work of strategizing water savings can begin. When deciding on ways to save water used for cleaning and sanitation, its purpose must never be lost sight of: keeping the plant clean and its products safe. That’s why arbitrary reduction goals, like a 10% overall savings, are a bad idea.

“The goal is to identify and correct areas of water waste without negatively affecting product quality,” Giersch says. “This requires actual usage measurements and not an uncontrolled approach. Do not arbitrarily cut water usage without identifying all potential impacts.”

The initial audit will often uncover obvious instances of waste, in what amounts to low-hanging fruit. These could include inefficient cleaning practices such as using hoses to “chase” bits of contamination to a distant drain, water supplies being left on and unattended, major leaks and problems with clean-in-place tanks – either overflowing or an excessive demand for makeup water.

Dealing with these is a logical first step, but it will only go so far. Meaningful water reduction is often a matter of small victories – finding incremental savings in disparate places that add up.

“The thing with water usage is, they’re all small wins, in terms of using less gallons here, less gallons there,” says Jared McClintock, business development engineer for engineering firm Barnum Mechanical. “The trick is to be able to find and add up as many of those wins throughout the plant as possible.”

Sprayers that apply cleaning chemicals directly to equipment like fillers can cut down on the amount of water used to clean them. Photo: Barnum Mechanical

Possibilities for such savings include:

  • Proper preparation of the area to be cleaned. Brooms, squeegees, catch pans and even pressurized air can remove loose soil from a surface effectively without water.
  • Proper use of cleaning chemicals. Too little means cleaning won’t be done effectively; too much can require extra rinsing to remove the chemical and its foam, as well as wasting the chemical in the first place. Chemical quantities for each major task should be predetermined; in plants that require frequent use, automatic dispensing should be considered. (This not only standardizes chemical use, but, by tracking usage, can provide a crude metric as to the speed and effectiveness of cleaning.)
  • Use of water-saving equipment and chemicals. Certain kinds of sprayers, valves, etc., have the potential to save water while maintaining effective cleaning. Spray nozzles and other equipment with low flow and high impingement can do this, as can dry steam cleaning for things like conveyor belts, such as systems available from Goodway Technologies. Alcohol-based chemicals can sanitize surfaces without water.

Pumps that can run at varying speeds are better suited to handle the surges and ebbs required by sanitation. Photo: Grundfos

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In many cases, it’s possible to decrease pressure with increasing temperature to save water while maintaining sanitation, says Jared Gabel, water treatment market development manager for Grundfos. Doing so requires pumps that can handle varying loads; this can be done better with pumps powered by motors with variable frequency drives, allowing them to modulate their speeds, Gabel says.

  • More efficienct clean-in-place (CIP) systems. These need to be monitored by programmers and controls personnel to make sure that rinses are effective without being excessive. Instrumentation like flowmeters and conductivity sensors, which determine that chemicals are at proper strength, can help fine-tune CIP for maximum efficiency. In CIP operations that begin with a prewash to loosen soil, water for the final, sanitizing stage of one cycle can be used for the prewash of the next.

Dirtier water

When reducing the amount of water used for cleaning, plant managers must be aware of a potential unintended consequence: dirtier wastewater. The volume of water will be reduced but the overall count of soil and cleaning chemicals will stay about the same, increasing the water’s degree of contamination. This might require more intense treatment before discharge to avoid triggering fines over releasing wastewater with excessive chemical oxygen demand, suspended solids or other pollution metrics.

“Many food processing facilities that have successfully and significantly cut water usage have, in turn, developed issues with treating their wastewater,” Giersch says. “This is due to the resultant wastewater stream being more concentrated.” That’s another reason for incremental reductions, which will mitigate this effect.

For cleaning and sanitation, wastewater can be a resource as well as a problem. Recovery and reuse of wastewater can cut overall water use considerably and, in areas where water is expensive, preserve supplies of potable water for applications where it’s necessary.

When it comes to treatment and recovery, many companies treat wastewater as a single stream of wastes, mixed together from all the plant’s various sources and coming out a pipe at the end. That can be a mistake, Veolia’s Lawson says.

Often the best strategy is to use what Lawson calls “point-source reduction” – that is, to understand wastewater as it is generated from a plant process, instead of dumping it into an overall waste stream. “It’s much easier to treat the quality of water coming off a boiler blowdown or a cooling tower bleed or a piece of production equipment in the plant than it is to treat all of them when they get combined at the wastewater plant,” Lawson says.

Technology exists to make wastewater potable, but this treatment is often cost-prohibitive, as well as culturally unacceptable in most North American markets. However, it often pays to make wastewater clean enough for other plant applications, such as prewash for a CIP cycle or makeup water for boilers or cooling towers.

The bottom line is, to save on water volume going into a plant, cut down on water going out by tightening up high water-using processes, looking for in-plant reuse opportunities, and designing wastewater recycling systems where possible.

“Anytime you can take a current effluent from a water-using system and reuse it someplace else,” Lawson says, “you ultimately reduce the total volume going down the drain, which then results in a reduced water influent on the front end of the plant, reducing the overall water footprint.”

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