Home > Bathurst Regional Council supernatant recycling system uses UV disinfection equipment from CST Wastewater Solutions

Bathurst Regional Council supernatant recycling system uses UV disinfection equipment from CST Wastewater Solutions

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article image UV disinfection equipment from CST Wastewater Solutions was installed in a supernatant recycling system designed to recover and disinfect filter backwash water

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CST Wastewater Solutions  has supplied UV disinfection equipment for installation in a supernatant recycling system being introduced into the filtration plant by a major NSW regional council in the town water supply, helping to conserve potable water and provide substantial water savings over the long term.  

Installed by Ted Wilson & Sons of Blayney using UV disinfection equipment supplied by CST Wastewater Solutions, the Bathurst Regional Council recycling system recovers and disinfects the filter backwash water at the plant.  

Serving a population of about 37,000, Bathurst’s water filtration plant currently has a water treatment capacity of 60 million litres per day.  

The filter backwash water, a by-product of the reverse flushing of the sand filters in the filtration plant is discharged into the system’s three sludge lagoons, along with sludge from the sedimentation tank. Previously the supernatant from the sludge lagoons was eventually decanted from the lagoons and discharged.  

Disinfection of backwash supernatant, which is the clear liquid that collects above the sediment, can recover up to 10% of raw water supply while also avoiding the need for discharge flows into river systems.  

The new system involved the construction of a supernatant pumping station to enable the automatic recycling of supernatant from the sludge lagoons into an in-ground well, and then into the first chamber of the rapid mix tank.  

The wastewater to be recovered at the present annual water consumption of about 6000 ML could be as much as 192 ML per year with overall water to be saved estimated to be 13,000 ML over 50 years.  

The contractor installed two submersible motor pumps for the pumping station at the in-ground well in addition to an electrical switchboard at the pumping well and other associated equipment, including a level control for the pumps and lifting chains for raising and lowering them for maintenance.  

A Berson UV disinfection system, supplied by CST Wastewater Solutions was fitted between the pumping station and the rapid mix tank to disinfect the recycled water from the sludge lagoons before returning it to the rapid mix tank. The system fully disinfects up to a flow rate of 60 L/s and has a variable power control to enable the UV dosage to be adjustable to suit operating conditions.  

A PLC/SCADA telemetry system was installed to automatically or remotely control the operation of the recycle pumps and the UV system.  

Highlights of the UV disinfection equipment fitted during the upgrade:  

  • Berson inline Model IL1000+Summit.
  • Four new-generation Summit medium-pressure high output/efficiency lamps, 2.5 kW per lamp with autowipe included
  • Stepless Energy Control (SEC) with variable power matched to the water quality and flow rate
  • PLC-based UVTronic+ controller
According to Michael Bambridge, Managing Director of CST Wastewater Solutions, though the process is not widely used in Australia, backwash supernatant disinfection can help recover up to 10% of the raw supply, which reduces the demand on the water storage system and avoids the need for waste flows into the river system.

Very importantly, UV disinfection is effective against Cryptosporidium and Giardia bacteria present in the backwash water.  

Mr Bambridge adds that the new generation Berson SUMMIT lamps have a higher output power than earlier lamps and a longer life with SEC power control.  

The supernatant recycling project at Bathurst Regional Council was partially funded by the Australian Government’s Water for the Future initiative through the National Water Security for Cities and Towns program.

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