Residents near the Village’s Waste Water Treatment Plant may be experiencing rather unpleasant odours from the plant. We apologize for this, however, necessary maintenance work has stirred up the ponds and racetrack causing the malodourous wafts of stinky air. As the system is new, it takes time to fine tune it and resolve issues that arise. The crew are working as fast as possible to help the water and sludge settle back down and we are looking to introduce more O2 into the racetrack system which will increase microbial activity and decrease odour, as will natural settling.
How the System Works
Air is injected via the two aerators in the race track. The current system has never at anytime during its operation been able to put enough air in the water to bring our dissolved O2 to acceptable levels. However, the current aerators are more efficient than the old paddle system power wise. Last week we found all the old operator manuals from the original plant build that confirmed our suspicions of low DO’s contributing to odour. The notes and operator manuals advised purchasing a blower-diffuser. This was never done.
To get the dissolved O2 up in our racetrack to support healthy aerobic zones will require air to be blown (with a blower) in to the bottom of the racetrack through piping and diffused to achieve the right bubble size for maximum O2 conversion, i.e. raising the dissolved O2. This will create the aerobic zones that promote healthy bugs and solids digestion in the racetrack and prevent filamentous bacteria outbreaks that cause odour due to the racetrack being in an anaerobic state. We currently run a DO of .15 -.50 mg/l and we need to be at 1 – 3 mg/l of dissolved O2 to attain a healthy environment in the racetrack. A healthy racetrack has three zones, aerobic, anoxic and anaerobic, but ours was only in an anaerobic condition and, before the upgrade, we had SVI testing that confirmed that we had a dangerously high solids volume and sludge retention times that are way too long. The new plant design took this into consideration but didn’t go far enough into addressing the issue.
The crew has confirmed their suspicions about the issue and solution by talking with very experienced Level 4 operators at other facilities and they unanimously stated our problems have been O2 related the whole time. Regretfully, the engineers did not include adding a diffuser to inject more O2 into the system as part of the recent plant upgrade.
A Long-term Solution is in the Works
We are currently in talks with several companies that do O2 injection and a solution should be found very soon. In the meantime, the racetrack and ponds are now into the process of resettling and the odour should decrease.
Why Activating the Second Racetrack Won’t Help
The WWT plant has two racetracks but putting the second race track online would do nothing but burn more power and the dissolved O2 would not come up, which we have been able to confirm through the old notes and paperwork from the original system. Not only that but, another anaerobic racetrack would contribute to the odour not reduce it as it would be twice as much surface area to gas off odour. Not only that but the second race track running would require more solids than we have to get running correctly.
Again, our apologies for the smell. Please bear with us as we resolve the issue.
O2 = oxygen
DO = dissolved Oxygen
SVI = Sludge Volume Index