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Peristaltic technology is treating chemically disrupted water to help prevent ‘intersex’ fish and other problems associated with pollution.

Male fish in British rivers have recently begun to spontaneously develop female characteristics.

This is caused by the UK’s improved water quality, which allows fish to colonise previously fishless rivers.

This has meant that fish are surviving in the upper reaches of urban river-systems and are more exposed to treated sewage effluent.

It is believed that endocrine disrupting chemicals (EDCs) such as natural and synthetic hormones in the wastewater effluent are causing the intersex effect in male fish such as the appearance of oocytes (egg cells) in the testes of male fish.

EDCs are typically found in waste water at concentrations of less than one part per ten billion and are a minute fraction of all the organic material present.

This means that the processes traditionally used to treat contaminants found in waste water are insufficient for completely removing EDCs.

For example, trickling filters are likely to remove less EDCs than a nitrifying activated sludge plant and processes such as ozone and granular-activated carbon treatment are likely to remove even more.

This makes further research imperative.

The Environment Agency, in collaboration with the UK government and the water industry, has co-ordinated a GBP40m national programme to examine EDCs and assess the effectiveness, costs and benefits of their removal in existing or enhanced sewage treatment.

The programme is gathering data from 13 different types of sewage-treatment works across England and Wales, including a notable project at Ilkeston STW in Derbyshire.

Undertaken by Severn Trent Water, the Ilkeston project requires the company to carry out a side-by-side evaluation of three different advanced treatments for removal.

It also requires them to carry out fish tests using native roach to determine the effects of different waters on the fish.

The experiments include the comparison of river water, treated sewage effluent and dilutions of treated sewage-effluent in tap water.

To make the tap-water useable in the sample tanks, the chlorine in the water must be neutralised.

For this purpose, Severn Trent specified use off Watson-Marlow’s 520SN/R2 peristaltic pumps for dosing of sodium thiosulphate, which dechlorinates the water.

The 520 series of peristaltic pumps can be calibrated either by weight or volume, allowing for precise dosing and metering necessary in the Ilkeston trial.

Severn Trent is also using SPX25 hose pumps, which feed the river water and treated effluent to the tanks.

The benefits of the hose pump for the river water are that the suction lift is good so that the pump can be situated safely inside the work’s perimeter fence, with only the suction hose suspended in the river.

The ability to handle solids also means that only a simple weed-screen is necessary to prevent weed blockages.

Because peristaltic pumps retain the chemical completely within the tube and have no valves that can leak or corrode, they can be used for the closely controlled metering of problematic chemicals such as sodium thiosulphate during treatment processes.

One of the central challenges of the EDC research programme is how to maximise removal efficiency by modifying current treatment technologies, while remaining cost-effective.

Advanced water treatment technologies are often more expensive than conventional treatment.

The cost-effectiveness of peristaltic technology is also aiding EDC removal.

Philip Bolton, water industry specialist at Watson-Marlow, said: ‘The previous engineering solution for this kind of trial used gear pumps to achieve the flow rate and pressure required, but this involved a high level of maintenance, as well as a complicated pressure regulation system utilising bypass valves.

‘By contrast, peristaltic pumps are simpler and more reliable.

‘Decreased maintenance requirements of peristaltic pumps mean that not only are costs lower, but engineers’ time is freed up to be spent elsewhere.

The Ilkeston trial, which finishes in the coming months, should provide knowledge about EDCs and the best methods to keep them out of the surface water system.

The UK’s growing technological expertise is helping to reduce the impact of EDCs on river-dwelling wildlife.

Watson-Marlow Fluid Technology Group

Watson-Marlow Fluid Technology Group (WMFTG) is the world leader in niche peristaltic and sinusoidal pumps and associated fluid path technologies. Founded on nearly 60 years of supplying engineering and process expertise and with over one million pumps installed worldwide, our pumps are tried, tested and proven to deliver.

WMFTG is a wholly owned subsidiary of Spirax-Sarco Engineering plc (LSE: SPX), a global organisation employing approximately 4,800 people worldwide. Watson-Marlow Fluid Technology Group comprises nine established brands, each with their own area of expertise, but together offering our customers an unrivalled breadth of solutions for their pumping applications:

  • Watson-Marlow Pumps: peristaltic tube pumps for biopharm and process industries
  • Watson-Marlow Tubing: precision tubing for pumping and other purposes, in a range of materials
  • Bredel: high flow, high-pressure hose pumps
  • Alitea: unique peristaltic solutions for OEM customers
  • Flexicon: aseptic filling and capping systems
  • MasoSine: gentle sinusoidal pumps for food, chemical and cosmetics applications
  • BioPure: advanced single-use tubing connector systems
  • Asepco: aseptic valves for the biopharmaceutical industry
  • FlowSmart: high purity sanitary gaskets, silicone transfer tubing and reinforced silicone hoses for the biopharmaceutical industry

Watson-Marlow Fluid Technology Group is an international operation based in Falmouth, Cornwall, UK. Watson-Marlow Fluid |Technology Group has offices in Argentina, Australia, Austria, Belgium, Brazil, Chile, China, Canada, Denmark, France, Germany, India, Italy, Japan, South Korea, Malaysia, Mexico, the Netherlands, New Zealand, Poland, Russia, Sharjah UAE, Singapore, South Africa, Sweden, Switzerland, Taiwan, USA and Vietnam.

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