Self-cleaning filtration cuts bills and saves environment

Merseyside-based Industrial Purification Systems has brought a technology to market that, it says, bridges the gap between conventional water filter systems and the more advanced membrane technology

As the economy slows and the climate changes, companies are increasingly looking at ways to enhance their performance and their green image. Many find it difficult to cut carbon. But the reuse of process water or municipal wastewater, or using alternative water sources such as borehole and rainwater harvesting, can save energy and resources.

There are various strategies that can make this happen but a number of reasons why it has not taken place. For example, for years it has been believed that the filtration of heating or cooling water in open or closed systems is not such a big issue. But the costly damage caused by a build up of contamination, often not even picked up by the human eye, shows this is not the case.

Additionally, substantial energy gains - up to 30% - can be achieved by cleaning dirty process water used in heating or cooling applications.

Most industrial and commercial water sources tested to date show an expected contamination above 20µm. But the distribution and population of particulates is consistently higher at less than 20µm, much of which is biological.

Significantly, this is even more pronounced below 10µm - which is the traditional cut-off point for mainstream filtration technologies and is the key reason why a business can lose this 30% in energy performance on heating, ventilating and air-conditioning systems.

As a further example, the industry's ability to reuse process water for secondary or even primary applications will go a long way to help reduce a global reliance on valuable potable water resources. Such a strategy can give a significant return on investment when taking into account the cost to purchase and dispose of water in its many applications.

Fine contamination
However, until now, there has not been a reliable method of filtering out fine contamination to make the introduction of such a strategy workable, Industrial Purification Systems (IPS) says. According to the company, its new self-cleaning filtration technology will remove contamination to less than 1µm, without the prohibitively high capital or revenue costs normally associated with water-polishing applications. It says its CrossFlowMF1.0 has been developed to filter below 1µm reliably - even achieving down to 0.45µm to ensure cleaner process water, which in turn can reduce a business's carbon footprint. The reuse of process water just once can reduce the carbon footprint on potable water by an impressive 50%, it says.

IPS managing director Steve Cupples says: "It is not only direct energy costs that will be affected, but also secondary costs including: the ability to produce and distribute potable water for non potable application; the reduction in the use of water treatment chemicals; the reduction in electricity bills by improving heating and cooling systems efficiencies.

"Operationally, the CrossFlowMF1.0 filter system utilises a unique patented vortex bed stabiliser, which maintains flat bed filtration with high surface turbulence.

"This ensures that no bio-fouling can be seeded, while holding filtered contamination in suspension above the media bed. This gives lower pressure drops, longer filtration and shorter backwash cycles making direct savings on operational costs," he adds.

The high interstitial void volume of the media allows for greater dirt-holding capacity and contamination interaction for the zeta potential of the media to remove the finer particulates down to 0.45µm. According to the company, compared with conventional media filtration, the inlet configuration allows for high flow rates, these being five times higher than the normal accepted flux rates of conventional filters. Backwash volume used is also significantly lower, especially when the longer operational period is taken into consideration. It is also more effective with backwash times per unit being as low as two minutes.

This new technology has been shown to provide a high efficiency removal rate of over 86% at 1µm in one single pass whereas conventional filters have to undertake multiple passes to get anywhere such efficiency. So, by reducing the load on the filter in this way, it is increasing the cycle between cleaning and reducing the amount of times the process has to stop for the membranes to be cleaned.

In addition, the need for chemical filtration is reduced, which reduces the impact on the environment. It also solves the problem of bacteria build-up when using sand filtration.

Drinking water
In Australia, government departments are currently testing this new technology to pre-filter tertiary sewage for reprocessing back into drinking water. In the Middle East, it has been installed by one of the country's major ethylene plants for the reprocessing of caustic incinerator effluent to allow the plant to discharge the cleaned water back into the sea. The high-efficiency media filtration is being used as a polishing filter as part of a combined technology of coagulation and flocculation mechanical filtration. The effects on industry will be significant.

For example, in their bid to meet quality standards set by major supermarket chains, food growers are using mains water for crop spraying, which is expensive and environmentally unsound. This new technology means that mains water can be reprocessed by cleaning it to meet these quality standards and reused repeatedly.

Cupples says: "Corporations will be able to reap the benefits. The life of a membrane filtration system could be extended considerably, this being anything from 20% to 30%. There will be less backwashing, less chemical use and longer membrane life span. And most importantly, for a relatively small cost, the improvements in efficiency and reduction on environmental impact will be significant.

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