A council wastewater treatment plant contains a large amount of industrial trade waste inputs. The current treatment process is: screening, anaerobic pond, aerated lagoon, settlement, chemical dosing, followed by conventional submerged lamp UV.
The chemical dosing removes phosphorus and is needed to improve the UV transmittance (UVT) of the effluent so that the conventional UV system can treat it effectively. For most of the year the council irrigate their wastewater to land where the key requirement is E. coli <1,000 MPN/100mL. During this time phosphorus removal is not required for their consent, however the chemical dosing is still used to ensure the UVT is high enough to enable their conventional UV disinfection to work effectively.
NovoLabs™ was invited to the site to prove that their Supercritical UV™ (SCUV) technology could achieve the same level of disinfection without the need for any chemical treatment. NovoLabs™ mobile testing unit was installed immediately before the chemical dosing and operated from start of December 2020 to end of January 2021. During this time the UVT before the chemical dosing ranged from 12% to 42%. A comparison of the E. coli removal achieved by the conventional system with chemical dosing (UVT average 70%) and NovoLabs™ SCUV system without any chemical dosing (UVT average 30%) is shown in Figure 1.
Figure 1: Average E.coli removal through a conventional UV with chemical dosing system and NovoLabs™ SCUV system.
E.coli concentration well below the consent requirement
As shown in Figure 1, both systems reduced the E.coli concentration to well below the consent requirement of 1,000 MPN/100mL. However, NovoLabs™ SCUV technology effectively disinfected the effluent without the need for any prior chemical dosing in an effluent that had UVT’s as low as 12%.
Avoiding chemical dosing is estimated to save over $1,600/day in chemical costs alone, with further significant savings in the elimination of chemical sludge disposal.
An additional significant environmental benefit of NovoLabs™ SCUV technology is that by eliminating the need for chemical dosing prior to irrigation, the valuable nutrients are recycled back to land. It is estimated that an equivalent of over 100 tonnes of superphosphate per year could be recycled back to the land, as opposed to it becoming forever locked up and wasted in a chemical sludge.
Novolabs™ Supercritical UV™ Disinfection — UV Treatment for Low Clarity Liquids