The Effect of Water Reuse on Linens


By Rich Fitzmorris

Water reuse and how it can affect textiles via the washing process is the topic in today’s discussion on how to keep linens/textiles white. Water is an important resource world-wide. However, it is a resource that is dwindling – so we in the laundry industry must show good stewardship in our use of this precious resource. Along those lines, many industry facilities are reusing water – but how does that affect linen whiteness? How does it affect the tensile strength of the linens? And what can we do about it?

Laundry owners and managers should understand the pros and cons of a water reuse system and how it can affect your laundry and equipment. Obviously, the pros are clear. A laundry uses vast amounts of water and reuse conserves that resource.

The cons, however, are not as obvious. The wrong system can damage your equipment, affect the quality of laundered textiles – whiteness and tensile strength, and raise the textile replacement costs in your facility.

Acceptable Water Reuse

There are different types of filtration used in the market today. A number of manufacturers install systems that collect all water from washers that would normally be released to the sewer. That water is directed to a separator or in some cases a large ‘shaker’ that removes solids from the wastewater. The finest screening possible without constant plugging is used. The water is then pumped into a series of tanks that continue to filter the water by use of course to finer median materials.

That processed reuse water is added to fresh water which collectively becomes the entire source of water for the laundering processes. There are a number of ratios of fresh water to reuse water that will be acceptable to produce high quality white textiles with no tensile damage. Ultimately, the better the filtration the better the quality of reuse water and therefore the higher the ratio of reuse water to fresh which can be used.

Finally, any reuse system must have a method of killing bacteria that will be present in reuse water. The method must be thorough because adding bacteria to the rinse and final process of sour and softening is unacceptable in any type of laundering.

I believe that the mixture of fresh and reuse water is an acceptable way to conserve. However, in addition to a successful bacteria elimination process, there are specific conditions that must be met by the reuse water.

Conditions for reuse and fresh water combined:

1) The water is by definition “soft” – 0 ppm of hardness.
2) The water does not exceed the pH of 9.0 – no exception.
3) The water does not exceed 125 ppm of TDS (total dissolved solids) or exceed the ppm of TDS that is in the fresh water supply.
4) The water does not exceed 100 ppm of bicarb (bicarbonate) or exceed the ppm of that is in the fresh water supply.
5) The water should be able to withstand the test of clarity. This was explained in Part III of our discussion on Linen Whiteness.
6) The water must be free of bacteria.

The above conditions are very important as some reuse systems do not remove or cannot remove alkalinity or detergents from the reuse water. When this happens, depending on which cycle this water is used in, the reuse water not only affects the ‘whiteness’ of your goods, it affects their tensile strength.

This inadequate process can be very troublesome to proper washing and in particular rinsing during the program cycle. If there is chemistry in the rinse water the only way to neutralize it, is to over sour the textiles. Souring may adjust the pH but the chemistry is not gone from the textiles it remains in chemical salts. This could result in damage to the textile and lose of whiteness quality in a short time.

So know the specific means of filtration for reuse water you are investigating. Ask for tests on the reuse water to see what residue/contaminants are filtered and what, if any, remains in the reuse water.

To overcome this potential issue of textile damage and lose of whiteness – do not try to squeeze the system for every ounce of water. Use the appropriate ratio of fresh water vs. reuse water to balance your water saving without sacrificing quality and replacement cost of the textiles.

STUDY AND COMPARE YOUR OPTIONS

Comparing different water reuse systems can seem daunting. However, if you keep in mind that all water can be compared by the simple method of micron size of water contaminants then choosing your reuse system gets easier. Whatever reuse manufacturer can deliver the smallest micron size through filtration wins!

The most expensive reuse system is a Reverse Osmosis (RO) system. But the end result is worth it. However, it may not be the right choice for all laundries due to its cost. One thing to take in to consideration about cost is how much will you actually be saving and how long it will take for the system to break even.

There are a number of RO manufacturers, but here too – do your homework by researching the manufacturer, finding out how long they have been in business and speaking to their customers.

I cannot stress enough the importance of research prior to purchase of any water reuse system – or equipment with reuse capabilities. Speak with Owners and Laundry Managers, the users of the product you have under consideration. How long have they had their reuse system? What problems if any have they had? Has their system affected the end result of their finished goods? Have their textile replacement costs risen?

But don’t stop there. Verification through testing laboratories is also extremely important. The manufacturer who can deliver the smallest micron size through filtration wins. Has your reuse manufacturer been certified by a legitimate testing laboratory? Get the results. Compare those results with those of other systems under consideration.

Also check the manufacturer’s history, financial stability, customer service and local service available if needed.

Do your homework before purchasing a water reuse system. The results from a poor system, or one that is not used properly, can cause more harm than good by damaging textiles.

Remember, textile replacement is the second most costly item next to labor in a laundry.

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Rich Fitzmorris is a veteran of the laundry industry. Rich retired after 42 years at Sunburst Chemicals. Although he headed up various Sunburst business sectors throughout his career, prior to retiring, Rich was Senior Vice President Professional Textile Chemistry, where he oversaw the company’s Large Laundry Division, laundry product development and chemical technology. Presently, he is putting his experience to work consulting in the areas of industrial and commercial laundry wash processes, chemistry, production, utilities, formulas and cost reductions.

Image caption: (c) Can Stock Photo Inc. / Irabel8