Continuous Deflection Separators (CDS®) And Their Role In Stormwater Recycling

Continuous Deflection Separators (CDS®) play an important role in any stormwater system but are particularly important in stormwater recycling systems. In this post we explain how a CDS® Unit works, what Continuous Deflection Separation technology is, why CDS® Units are important in stormwater recycling systems, and look at some successful CDS® Unit installations.

How Continuous Deflection Separation Technology Works

Continuous Deflection Separators are components within gross pollutant traps (GPT) in stormwater recycling systems. GPTs per se are designed to remove pollutants (contaminants and rubbish) from the water so it can be recycled either into natural drainage systems, or for human use. Those with a CDS® unit incorporated are typically far more effective than those without, particularly for removing very fine particulate matter.

A CDS® unit has:

  • An inlet or diversion chamber – this is where water flow is diverted into the CDS® There may be screens or racks at or before the initial diversion point to prevent large debris and rubbish, like logs and similar items, from getting into the system and blocking or damaging it.
  • A screening chamber – this is where Continuous Deflection Separation technology works its magic by removing larger pollutants whilst a specially designed screen separates smaller particulate matter from the water and allows it to flow into the outlet chamber.
  • An outlet chamber – clean water is returned to the water / stormwater recycling stream.

Market leading Continuous Deflection Separators from Civilmart incorporate CDS® direct screening technology, a system that makes use of basic fluid mechanics principles to direct incoming water into the chamber in a way that sets up a vortex. Debris and contaminants are then drawn into the centre of the vortex, where they lose momentum and drop into a collection chamber below.

A specially designed deflective mesh screen then keeps smaller contaminants remaining in the water flow away from the tiny drainage holes in the mesh. The clean water flows unimpeded through these holes into a separate compartment, where it exits the CDS® and continues its journey along the stormwater recycling system.

The Benefits Of Using Continuous Deflection Separators For Sorting And Separating Materials

Continuous Deflection Separation technology, and particularly CDS® direct screening technology, is very effective at sorting, separating, and removing a range of contaminants from most types of stormwater recycling systems. This has many benefits.

  • More efficient stormwater recycling means much cleaner water is discharged into the environment. This significantly reduces the amount of pollution getting into natural water bodies and contributes to environmental sustainability. In areas prone to flooding or heavy rainfall, this is a very important consideration when managing potentially polluted storm water runoff.
  • CDS® technology in stormwater recycling systems allows stormwater to be recycled for non-potable applications like irrigation, industrial processes, and cooling systems. This reduces demand on our valuable and finite potable water sources.
  • Continuous Deflection Separators are low maintenance. Well-designed units, like Civilmart’s CDS® Gross Pollutant Trap have self-cleaning curved screens and efficient pre-screening mechanisms that reduce the need for frequent maintenance.
  • CDS® units can be installed underground as part of space-efficient stormwater recycling systems in urban situations.
  • Continuous Deflection Separation technology is scaleable, and components within the units can be customised to suit flow rates and stormwater volume depending on whether it is intended for residential, small, or large commercial stormwater recycling applications.
  • Continuous Deflection Separators that meet or exceed required stormwater recycling quality standards ensure councils and businesses comply with stormwater quality regulations.
  • Stormwater pollution events are often expensive and time consuming to manage and rectify. CDS® units reduce these costs and risks by effectively managing and removing most of the contaminants from the water before they cause major problems.
  • CDS® units also contribute to reduced waste disposal, lower water treatment costs, and increased water resource recovery.

Successful CDS® Installations For Stormwater Recycling

There are many successful installations for stormwater recycling systems utilising CDS® units of varying capacity across Australia. Here are 4 of them:

  • The Melbourne Airport Stormwater Recycling System is probably one of the largest and best known. The first CDS® Gross Pollutant Trap was installed in 2012, and has removed over 100,000 tonnes of debris, pollutants, and sediments from the airport’s stormwater runoff. It has also been credited with reducing fish deaths in the Yarra River. Today the airport’s total stormwater recycling system incorporates Civilmart 2000, 3000, and 4000 CDS® units and other systems, and has a daily recycling capacity of over 1 million litres of stormwater. It has been fully operational since 2016, has significantly recycled stormwater for use around the airport, and prevented pollutants from entering the Yarra River.
  • The University of Technology Sydney Stormwater Recycling System also incorporates a Civilmart 3000 CDS® The unit can recycle over 100,000 litres of stormwater a day. It started operating in 2017 and has been extremely successful in recycling stormwater and reducing the amount of pollutants entering the local environment. The recycled water is used for irrigation and in the ablution blocks.
  • Also implemented in 2017, the Royal Botanic Gardens Melbourne Stormwater Harvesting System incorporates a Civilmart 4000 CDS® unit and can recycle over 100,000 litres of stormwater per day. The recycled water was used to build a new pond and is currently used to irrigate the gardens.
  • The Astrolabe Park stormwater recycling system in Sydney’s eastern suburbs uses two Civilmart 3000 CDS® units arranged in a series. This ensures a very effective removal of pollutants and particulate matter. The entire system can remove over 100 tonnes of solids from stormwater runoff annually, and contributes significantly to the improved water quality of the Cook River.

Further to these, CDS® units have a range of applications in stormwater recycling systems of many different capacities, and situations.

Continuous Deflection Separation Technology Revolutionising The Stormwater Treatment Process

Ever since Australia’s first GPT with Continuous Deflection Separation technology was installed in 1995, the CDS® Unit has continued to outperform all other types of stormwater recycling systems both locally and internationally. Its ability to successfully capture and remove 95% of contaminants down to 1mm in size plus high volumes of even smaller particulate matter is unparalleled. This has revolutionised stormwater treatment by producing a far cleaner, safer, and environmentally sustainable product that can be safely used in non-potable applications or returned to the environment.

Additionally, CDS® Units:

  • Can remove at least 30% of phosphorus in stormwater, and
  • Are capable of capturing free-floating oil and grease spills. However, most grease and oil in stormwater recycling systems tends to attach to particulate matter, which is very effectively removed by Continuous Deflection Separation technology. CSIRO noted in 1999 that “In the category of “attached pollutants” CDS® Units were the only GPT device to even be considered capable of capturing anything.”

The Importance Of Continuous Deflection Separation Technology In The Recycling Industry

With increasing focus on environmental sustainability and climate change, it’s more important than ever to ensure all available readily renewable water resources, like stormwater, are utilised to their full capacity to reduce the demand on less accessible sources. At the same time, there is a growing requirement to ensure stormwater that does flow back into natural water systems from urban environments is as clean and contaminant free as possible to guarantee the ongoing health of our aquatic systems.

Products like CivilMart’s CDS® Gross Pollutant Trap and Continuous Deflection Separation technology: 

  • Makes possible a very high standard of stormwater recycling that significantly improves the quality of stormwater runoff either for release back into the environment, or as a valuable resource for various industrial processes. This in turn reduces use of valuable potable water for non-potable applications.
  • Ensures those responsible for stormwater recycling compliance can better meet their obligations by producing treated stormwater that meets or exceeds regulated environmental protection standards. This helps reduce the environmental and health impacts of polluted stormwater getting into natural water systems, or being used in applications that have potential to impact human health.
  • Provides a dependable source of high quality, environmentally compliant, treated stormwater for various industrial applications and reduces weather event disruptions to these water supplies. 

Why Choose Civilmart for Your CDS® And Stormwater Recycling And Drainage Technology?

If you are looking for a reliable and experienced partner for your stormwater recycling and drainage system, consider Civilmart’s years of experience in the industry. As a leading supplier of CDS® and Stormwater Drainage Technology in Australia, our team of experts is well equipped to provide the expertise and guidance you require for a successful installation. Contact us today for a quote, or assistance with all your stormwater recycling requirements.

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