Our congratulations go to Sean and all of the other solutions that were submitted by Members in 2023.
The Problem
What was the problem that you experienced?
Determining the exact time to stop a backwash of Lorne’s Dissolved Air Floatation Filtration (DAFF) Water Treatment Plant (WTP) has always been challenging. If stopped too soon the media will be left spoiled and reduce the next filter run time. If let run too long can waste this precious resource (230L/s) and prolong the ripening period of the filter media.
Every second counts!
How did the problem impact you or your work situation?
Previously, backwash samples were taken from the launder every 10 seconds and then later analysed to determine the time required to ensure a properly cleaned filter media. This time-consuming exercise worked well if the raw water quality remained stable.
After a rain event Lorne’s raw water quality can be very erratic causing varied filter performance which effects the backwashing length required.
Probe type turbidity analysers were trialled in varied positions within the filter area but could not provide a stable accurate reading.
How long had the problem been occurring?
Since commissioning of the WTP, operators would prefer to overrun the backwash to avoid an early fouled filter.
The Solution
How did you come up with the solution?
Rays of sunlight streaming through the window on a sunny spring day illuminated the backwash water which helped me to determine when the water had cleared enough to stop the backwash. An underwater dock light would provide a similar light source that could be turned on at any time of the day or night.
Who helped work on the solution?
Assistance was provided by fellow Coastal Treatment team operators, and Barwon Asset Solutions electrical team who completed the required electrical works. Our Technical Service team programmed the light to turn on during the backwash sequence.
Describe the Solution.
Installing an underwater marina dock light into the backwash launder of the filter has allowed the operator to observe in real time when the backwash water quality was clear and, in a way, become the turbidity and colour analyser themselves.
How has it helped at your work?
The installation of a light in the backwash launder allows the operator to make a qualitative assessment that the backwash water and filter media are at a stage to be able to stop the backwash. This improvement has reduced the backwash run time by up to 250 seconds saving 55kL per backwash. Conducting a backwash on average 60 times a year (58 in the past 12 months) equals a saving of up to 3.3ML per year. This water saving initiative has contributed to a shift in the timeframe for when we will be required to augment the Lorne water supply system to meet demand. This initiative directly aligns with our Barwon Water 2030 strategy key objective of “maintaining our efforts to continually optimise our system, so that we can make best use of available water resources and entitlements.”