UV treatment improves wastewater quality
A $250,000 investment into a new ultra violet treatment system at the Gore wastewater treatment plant is proving its worth, with e.coli levels at the discharge point being below Ministry of Health recreational limits since its installation.
The UV system was commissioned in October last year and is designed to operate when the Mataura River flows below 60 cubic metres (cumecs). In simple terms, the system consists of 64 UV bulbs housed in a large steel cylinder. Pre-treated wastewater flows past the bulbs, further disinfecting any bacteria.
3 Waters Asset Manager Matt Bayliss said since commissioning the unit, the highest concentration recorded downstream of the unit was 10 e.coli per 100 mls.
A concentration of less that 260 e.coli per 100 millilitres is considered safe for swimming and recreational use.
“In comparison, the median concentration of e.coli in the discharge between February 2014 and April 2020 was 1223 per 100 mls,” said Mr Bayliss.
“This means we have made a marked improvement in the quality of the water being discharged into the river at times of low flow.
“This is in keeping with our vision of providing efficient, quality services and ensuring a sustainable environment for future generations.”