Effluent Treatment

Scalewatcher™ ENiGMA Electronic Water Descaling in Fashion with Jeans Finishers

Electronic water descaling has come a long way in the past ten years. The technology itself has developed very little, and, indeed, the majority of scientists still do not fully understand how it works. But work it certainly does, and better than ever thanks to an increased understanding of the applications, limitations and the importance of correct siting, sizing and installation of the equipment.

Due to the massive amounts of lime in use there was one application where the electronic approach had certainly not been the first option to spring to mind. However, it was a resounding success and the considerable savings in effluent charges, man hours and maintenance were hugely welcomed.

Kedgwick Limited, based in Ossett in West Yorkshire, were denim conditioners for numerous UK manufacturers of denim clothing: this involved stonewashing, dyeing and applying special 'finishes' to the garments. Almost all the industrial processes involved water and so all the water entering the works passed through a large softening plant to avoid scaling problems. The problems with scale, however, arose with the effluent water that was produced once the processes were finished.

The culprit? Lime.

The effluent from the denim washing and dyeing process was heavily contaminated with blue dye and pumice stone solids. This effluent was chemically treated with lime, to separate the blue dye from the waste water and other compounds before passing to the on-site effluent treatment plant. Because it contained large amounts of calcium hydroxide and carbonate, the effluent obviously caused considerable amounts of fouling and scaling. This hard scale constricted pipework, scaled up pump impellers and, most seriously, scaled up the filter cloths of the effluent sludge filter press.

Hammers and chisels

Alban Timmons, Chief Engineer at Kedgwick: "This problem has been dealt with in the past by regular jet cleaning of the pipes, mostly during the annual shutdown, manual descaling of the pumps two or three times a year - with hammer and chisel! - and regular replacement of filter cloths."

Alban Timmons was willing to investigate if electronic water descaling could alleviate these problems, therefore a rented Scalewatcher™ ENiGMA Evaluation System was fitted in February 1998. John Thompson is Managing Director of Environmental Treatment Concepts in Fareham, Hampshire, who develop and manufacture Scalewatcher™ ENiGMA : "We fitted four Scalewatcher™ ENiGMA units - to the lime dosing pipe, the main effluent flow, the sludge pipework and the filter press feedpipe. Careful fitting and positioning according to pipe diameters, water flow and temperature are crucial. After more than ten years in the electronic descaling business we know that when you get this right, the results often far exceed expectations. ETC not only understands the technology but has the added unique advantage of being able to demonstrate and measure the effects."

Because of the special circumstances of the application, Alban Timmons anticipated difficulty in quantifying and evaluating results. This would be partly due to the changing nature of the effluent and the varying production levels throughout the year. However, many of the results were surprisingly good and saved the company significant energy, time and money.

Timmons again: "Prior to the fitting of the Scalewatcher™ ENiGMA evaluation equipment we inserted a probe into the effluent pipework and it was left to scale. For the first few weeks of the trial, the amount of scale that accumulated on the probe, before the Scalewatcher™ ENiGMA was switched on, reduced and then built up again. This random pattern continued throughout the period that Scalewatcher™ ENiGMA was working. But then we started to get results elsewhere, including the filter cloths."

Results after just one month

After the Scalewatcher™ ENiGMA had been operating for around one month the built-up hard scale on the filter cloths of the filter press began to come off, so much so that the drains blocked up. Although the calcium deposits return periodically, Kedgwick find it is much less of a problem than in the past. "We still replace the cloths," says Timmons, "but previously, the cloths were literally as stiff as boards and when they were replaced they had to be cut off. Now they retain their flexibility and some of their permeability, too."

"The scale build-up on the pumps is very much reduced. Before, it was common to have the pump completely solid with scale, now there is usually just a 3-4mm layer on the impeller. The static mixer for the pH correction system used to block up with scale and lint about once a month, but it has only had to be cleaned once in the 12 months since the Scalewatcher™ ENiGMA was installed. This has helped us greatly."

Timmons also reported considerable improvements to pipework since the Scalewatcher™ ENiGMA arrived. "The main effluent pipework usually has 40-50mm of scale when it is jetted out during shutdown, but this year there was no more than 10-15mm - that is a 75% reduction."

'The toughest test'

"On a scale of 1-10, Scalewatcher™ ENiGMA would score very highly, especially when you consider that it was not developed for this kind of very difficult application. Kedgwick's has got to be the toughest test you could possibly give a device like this.

Savings

As part of the evaluation process of Scalewatcher™ ENiGMA 's efficiency, and to assess its contribution to any energy saving policies that customers have in place, John Thompson encourages customers to calculate savings in terms of energy, maintenance, time and money.

At Kedgwicks the most significant savings have been in terms of a 63% reduction in solids discharged by the works. This equates to an annual saving of over £6,000. Labour savings amount to around 150 man hours per year. Filter cloths perform much better throughout their working life and although they are not replaced any less frequently, their better condition has meant better overall performance of the effluent treatment plant which has in turn contributed to a 'significant saving' in effluent charges.

Other Applications

Electronic water descaling technology continues to achieve excellent results in a wide variety of applications - the most conventional being on hot water pipework, boilers and calorifiers, cooling towers, chillers (where energy savings can be enormous), swimming pool plant, (chemical savings) and so on. The application within the textile industry was a real challenge but the technology rose to the occasion yet again.

Environmental issues are high on the political and social agenda today and interest, and more increasingly investment, is growing in environmentally-friendly alternatives which reduce or eradicate the need for costly and damaging chemical intervention. Electronic water descaling offers the most effective, environmentally friendly water scale solutions ever.

Kedgwick Limited is just one of the many thousands of industrial, commercial and leisure users who, collectively, are saving millions of pounds each year directly as a result of this technology.

EU Legislation - clean up effluent!

Pressure is mounting within the EU for more stringent legislation regarding the cleaning of effluent prior to discharge from industrial sites such as Kedgwick. At present, in many cases, the authorities are turning a blind eye to colourings and dyes being present in effluent. This is because processes such as those using lime to remove dye are expensive and create costly scale problems. These costs would increase the prices of the end product to the extent that it would prevent these industries from competing with cheaper overseas imports.

Electronic water descaling makes lime processes affordable

In Kedgwick's case the savings in effluent charges, man hours and so on, made from combining the electronic descaling technology with the lime effluent treatment process, has made cleaning the effluent more efficient and affordable. In the long term it is only environmentally friendly industries that will thrive.