How Rotorflush Filtration Products Are Used to Benefit Habitats and Help Species Recovery.

How Rotorflush Filtration Products Are Used to Benefit Habitats and Help Species Recovery.

Rotorflush Filters Limited produce standard and bespoke self-cleaning water filters and strainers for use on pump suction intakes or gravity fed water intakes. 

These screens are large mechanical strainers with a built-in mechanism for keeping the intake strainer mesh free from debris and particulate while water is being screened. Water is screened as it is drawn through the strainers by a pump or by gravity. 

Their design keeps intake velocity through the mesh low to protect aquatic life, while allowing large volumes of water to be moved. They have applications across many industrial and agricultural sectors, but offer particular benefits for habitat management and fish and eel protection.

This is in keeping with Rotorflush Filters Ltd’s commitment to:

• environmental improvement
• minimising our environmental impact
• enabling our customers to do likewise
• and conserving vital water resources

Eel and Fish Screening

Most new and renewed abstraction licences for raw water in England and Wales are granted subject to compliance with the Regulations for the protection of eels, as determined on a site-by-site basis by the UK Environment Agency. 

Greater protection for fish stocks by protecting fish fry likely in the UK, and some protection for fish at some intakes already exists in the United States.

The reason for Eel protection regulations is the collapse of European Eel populations; any measures that conserve eels and mitigate the impact of human activity will help to improve on eel populations.  Rotorflush self-cleaning eel screens are ideal for eel protection where raw water is being pumped or drawn for use, increasing the young eel population by reducing the losses otherwise attributable to our resource use.

Eel Screens

Measures required to be taken to protect eels and elvers include screening water being abstracted through 2 mm aperture mesh or less to avoid the entrainment of eels in intake systems and equipment.  Eel regulations may also constrain the intake velocity through the mesh. This will vary depending on location but in habitats where there are glass eels the intake velocity could be set as low as 0.1 m / second.

Clearly, then, drawing large amounts of water through 2mm mesh - in the case of water treatment works this could be several MLD (mega litres per day) – presents some challenges in ensuring a continuous supply.

Rotorflush ‘LW’ screens and strainers by design have a low intake velocity and the added benefit of a continuous backwash system to keep the 2 mm or smaller mesh clear, making them ideal for compliance with Eel Protection Regulations.

More information can be found in ‘New Eel protection guidelines LIT 60516 - Screening at intakes - Measures to Protect Eel and Elvers’, and the Environment Agency’s trial of a selection of eel screening methods – ‘2023_EA-Mobile-Screening-Trials-Presentation’.

Fish Screening

There are moves towards protecting fish stocks in UK waters as well, discussions being underway determine what measures might be taken to protect fish fry. These are likely to involve slower water intake velocities and possibly smaller – 1 mm – mesh requirements. 

In North America there is already regulation to protect fish from entrainment when drawing raw water for cooling, under Environmental Protection Agency (EPA) Rule 316(b). Again, compliance is based on intake velocity and screening, making Rotorflush screens ideal for protecting fish populations near pumped intakes.

Water and Habitat Management 

Rotorflush self-cleaning strainers and screens are used in many applications, often where screened water is needed for a particular purpose – for example irrigation, water for heat exchange or cooling, water intake for industrial processes and raw water intake for use as potable water after treatment.

Our screens have also been used to actively improve habitats. The RSPB manages wetland reserves, important destinations for migrating birds and breeding sites for many species.

Climate change has increased the instances of both flood damage to wetlands and drought damage. Good wetland management means keeping water levels as far as is possible within established parameters – and this invariably means moving large amounts of water, while complying with wildlife protection regulations. 

Rotorflush self-cleaning intake screens have been used at several RSPB sites to move water to improve conditions on reserves.  Pumping can be continuous over a number of weeks, so having strainers that protect aquatic life and do not block easily makes this kind of intensive water management feasible.

Rotorflush Filters Ltd is also working on Projects with the Canals and Rivers Trust, again contributing to the better management of water resources as they improve the Canal infrastructure.

And Rotorflush screens have not just helped better management of the natural environment. At Slimbridge – a man-made sanctuary for wildlife as diverse as dragonflies and flamingos – Rotorflush filterpumps and screens are used to maintain the circulation of water across the site. 

Responsible Water Use

Water is fundamental to almost all environments and lifeforms. How water is used, and how it is managed, affects habitats and the wildlife therein. In order to protect our environment and repair the damage we may already have done; water, of all resources, needs to managed responsibly.

This means taking steps to ensure that our use of water does not adversely affect sensitive habitats, and preventing our use of water harming eels and fish so that their populations. Being able to move water harmlessly, screening water for re-use, and good water management with minimal impact on wildlife has a positive and regenerative impact on our environment. 

At Rotorflush Filters Ltd, we are proud of our contribution to these efforts.