The automation team at Melbourne Water is analysing historical and real-time data to change the water treatment process at the Eastern Treatment Plant (ETP), saving hundreds of thousands of dollars and lowering energy use.
ETP uses ozone as part of its water treatment process. Ozone is a powerful oxidising agent which when dissolved in water, destroys all bacteria. The ozone used is produced at the site via generators that are fed oxygen from one of two sources.
The first is from the on-site Vacuum Pressure Swing Absorption (VPSA) oxygen generation units, and the second source is from the Liquid Oxygen (LOX) storage tanks, also onsite. The storage tanks are filled with product trucked in from an external manufacturer which makes it quite expensive.
Melbourne Water Automation Leader, Russell Riding, said this prompted the search for a more efficient operating system.
“We engaged employees James Lloyd (Wholesale Services) and Chamila Withana (Business Enablement) to assess historical data using Internet of Things (IoT) tools and systems, and to create a dashboard to enable easier analysis of the data,” Mr Riding said.
“That analysis showed that using VPSA generated oxygen over LOX is cheaper, and that there was also a potential to lower energy demand by reducing the ozone concentration set point for the entire process.
“Less energy and less ozone would equal a reduction in operational costs. By generating oxygen on site rather than using liquid oxygen, and realising we could lower the set point of the amount of ozone needed in our water treatment meant we achieved that.”
The IoT dashboard was manually used as a decision support tool by the ETP operational team in 2019. The trial supported the premise that reducing the ozone set point would favour the use of VPSA over LOX and not compromise the quality of recycled water.
The manual trial delivered over four months achieved a $100,000 reduction in ozone generation costs and was the catalyst to automate the existing control system with the altered control regime. The plant is now running successfully with the new automated controls, and the lower ozone set point is favouring the VPSA production of ozone.
The new automated controls will see up to a 12 per cent cost reduction in ozone generation, translating to around $365,000 savings a year for Melbourne Water.