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Guest Post: Why Reducing Water Consumption in the Laundry is So Important

We welcome Steve Anderton for the second in a series of guest blog posts from LTC Worldwide - the UK's leading textile care specialists, regularly seen in the press. LTC offer a wide range of consultancy, training & testing services for the textile services and laundry industry and provide independent expert services to both Government and private institutions. Based in the UK, they work globally, particularly in Europe, North America and the Middle East. Here at Hydrofinity we're committed to reducing the water consumed by commercial laundries - traditionally a water intensive process - but here's an outside perspective on exactly why that is important.

Why is Lowering Water Consumption So Important?

Water consumption in a modern laundry varies from under 5 litre/kg of dry textiles to over 20 litre/kg! Most laundries can improve their consumption simply by employing best practice sound management, before there is any need to invest in water recycling equipment. Is this worthwhile or important? The answer is an emphatic YES!

Why is Expert Water Management Essential?

one The cost of producing enough clean water to meet the demands of growing national populations should, theoretically, include significant interest and depreciation on new reservoir and underground source costs.

In fact, this element of water cost is very small because every type of user has spent the last 70 years improving user efficiency. Consumers have switched from baths to showers. Food and process industries have adopted continuous counter-current rinsing. Where space allows, launderers have brought in tunnel washing for high volumes, and Hydrofinity polymer XOrb washing for smaller tonnages.

Best practice is widely available and well publicised, which enables everyone to follow the market leaders. No-one wants an upward step-change in production costs and thankfully this is avoidable if it continues the trend of reducing consumption (and there is still plenty of scope for further savings). Building of new reservoirs is at an all-time low.

two

The cost of water consumption is increasing, either in-line with inflation or at a slightly greater rate, depending on the extent of historic poor management of national distribution systems, which has led to excessive and unsustainable leakage losses.

When this is coupled with regular demands for better mains water quality, there is absolutely no credible prospect of this rate of cost increases levelling out.

The cost of wastewater treatment is rising at the same rate, frequently because of the extra detergent needed for oil removal, together with the oil itself. Only the Hydrofinity process removes much of the oil into its polymer XOrbs instead of into the effluent. This means it creates less effluent which reduces costs.

To remain competitive, launderers in the hospitality sector, the healthcare sector and the workwear sector, have to implement best practice for water use and effluent quality, or risk being priced out of their respective markets.

three Environmental sustainability: water use is approaching unsustainable limits, with extraction from underground aquifers and surface channels such as rivers having a strong negative impact on reliability of supply (not enough water for those downstream).

This is becoming true, even in countries with a mild climate and apparently abundant rainfall. We are running out of adequate, low-cost water sources.

The tunnel washer is contributing massively at the high volume end of the market, but only the Hydrofinity design is making a significant impact for those laundries where available space, lower volume and/or required wash quality make a tunnel washer unsuitable.

four Failure to manage water effectively is already leading to excessive costs, which are unsustainable. In laundering, for example, failure to rinse properly results in yellowing of white textiles, reduced life of ironer & press cladding, and shortening of textile life.

Each of these can be avoided with just a little knowledge and care.

What This Means for the Modern Launderer | The Golden Rules

For all laundries, including small and on-premise laundries there are eight golden rules:

1. Classify soiled textiles correctly

...and use the right process for each classification. A wash designed for one-night hotel sheets is a waste of time and money for heavily soiled chef’s wear or for a stained rewash.

2. Use the best machine for each classification

For example, a washer-extractor with a large cage diameter but shallow depth will not keep a polycotton coat crease-free as well as a washer-extractor with a smaller diameter and greater depth.

The Hydrofinity design will get the best results because XOrbs prevent the pressing of creases into the particular garment which happens to be at the bottom of the cage during the reversal of rotational direction in the hot wash.

If the textiles are soiled with food oils or fatty proteins, then the Hydrofinity system will get them cleaner, more quickly and with lower chemical dosages than one with an empty cage. The polymer orbs pull the oils and fats off the textile surface to aid significantly the removal of these at low temperature, with minimum chemistry.

3. Check the water level in each washing stage of the process | Minimise it

A pre-wash for a classification which carries much ‘debris’, such as bed linen and towels from a surgical ward, needs a wash dip of around 125mm (measured from the lowest part of the inside the cage to the mean water level during rotation).

Conversely, a classification with protein staining but no debris needs the correct pre-wash temperature (below 40C to avoid stain setting), but a dip of 75mm will probably suffice.

Water use can be cut further (for lightly soiled classifications with minimal debris) by omitting the drain after the pre-wash and going straight to a main wash temperature with no additional water addition (because 75mm will give good mechanical action for the main wash, with maximum chemical concentration). They call this a ‘stepped-wash’.

Launderers who reduce dip levels for the pre-wash and main wash can usually reduce chemical dosages too, maintaining the original concentrations at the new, lower dips.

It's worth mentioning, with all this talk of dip levels, that Hydrofinity machines don't use one - is the primary reason they reduce water consumption so significantly. Imagine the difference between taking a bath (dip wash) and a short shower (spray-based alternative).

4. Check the water level for each rinse

Any chemist versed in the ‘theory of washing’ will tell you that with multiple rinsing, the lowest water demand is obtained with the same dip for each rinse. The knack is to minimise this rinse dip, without getting yellowing (or ‘galling’, caused by incomplete removal of alkali from the wash chemistry). This is best done with the detergent supplier when possible.

The rinse dip is reduced in steps of 10mm until the alkalinity of the final rinse liquor is only 2 gram/litre above the alkalinity of the incoming soft water supply into the laundry.

Where there is no-one available to titrate the final rinse liquor to determine the final alkalinity, some launderers have succeeded by reducing the rinse dips by 10mm each week, until suddenly there is a general problem of (temporary) yellowing! At this point the rinse dips should be put back up by 10mm and the yellowing removed by rewashing.

You will find that light-soil classifications require lower rinse dips than heavy soil ones (because they demand less detergent, leaving less to be rinsed out).

5. Use inter-spins for lightly soiled textiles

An inter-spin is a short (say one-minute), medium speed spin after the first rinse. If this is correctly designed and programmed, the removal of extra water after the first rinse will enable most light-soil classifications to require only two rinses, saving time and up to 5 litres/kg.

6. Invest in a tunnel washer if appropriate for your laundry

The smallest of these can now process down to less than 500 kg textiles per hour and will give a step reduction in water consumption of around 60%, with associated savings in energy and labour.

If you do not have the high volumes for this or require maximum wash performance, then remember that the Hydrofinity design will save up to 80% compared to the traditional washer-extractor’s consumption of water.

7. Use split rinsing in a tunnel washer

This involves an additional pumped recycle of water from the press tank into the centre of the rinse zone and saves a further 2 litres/kg. The tunnel needs designing with split rinsing in mind (for example with a double skin throughout the rinse zone).

8. Maximise water extraction after the last rinse

This will reduce the quantities of chemical residues carried forward to the tumble dryer or ironer and minimise damage to ironed clothing (by alkaline hydrolysis of the ironer cladding) or to the textiles themselves (by abrasion of yarns with crystallising salts).

Pitfalls for the unwary...

Not all water economies are easy to implement

...and intelligent care is needed. After a successful trial with reduced rinse dips for one-night hotel sheets, do not apply this to heavy soil food industry work-wear - they are unlikely to work for dirty overalls.

Modern washers come with computer controls, which permit optimised settings for each classification, and you will need to work systematically through each one to get these just right.

The surprising result is that the first 20% savings in water consumption are usually easy to achieve, with significant effects on productivity (shorter cycle times) and water consumption.

Simple recycling of water must balance demand

...the pre-wash and main wash in a washer-extractor will typically require only 7 litre/kg dry textiles, whilst the rinses could demand another 18 litre/kg. There is no point in collecting and recycling the rinse liquor (using twin dump valves and split drains) if you can only utilise less than half of it.

The most cost-effective recycling in washer-extractor based laundries is to collect the last rinse (because this is the cleanest). This is sufficient for pre-wash and main wash, with a small overflow to remove surface scum from the recycle holding tank. Payback on this scheme is usually excellent and it can often be designed and built in-house. They Hydrofinity system works in this way.

Recycled water may need to meet a quality specification

If the recycled water is for washing only, then the quality of most final rinse liquors will be adequate, with no purification treatment beyond simple screening out of lint and debris.

If the recycle stream is for rinsing, simple screening is inadequate. It may require micro-filtration or reverse osmosis to avoid build-up of laundry chemicals that might cause yellowing or microbial growths which might spread infection.

The Textile Services Association publish a specification for recycled water, consistent with safe re-use, both for washing and for rinsing.

Conclusion

Almost every laundry can make substantial savings in water consumption, by applying the principles of good management and following the guidance given here. There is plenty of low-hanging fruit available. Good hunting!

Topics: Commercial Laundry Sustainability Hotel Laundry Spa Laundry Guest Post

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