In light of recent issues centered on the Mansfield wastewater plant, we felt the community needed to see for themselves, rather than hear a prepared report.
At first glance, you’d suspect that all is well. But, that hasn’t been the case until recently. If you will remember, Braden Purcell who was hired as an operator has taken responsibility of the inherited mess, and is in the process of cleaning house, literally speaking.
With limited funds, and a lack of leadership, Purcell has gone to work on correcting the ADEQ violations, as well as ensuring future stability within the plants operating structure.
Follow along as we take you through the process from start to finish.
As wastewater enters the Mansfield plant from Hartford, it’s held in this diversion station. Purcell believes the recent foul smells could be due to the excessive amount of grease build-up in the basin.
To remedy this, the grease would have to be pumped out of the basin, a grease eating bacteria block added, and FOG (Fat, Oil, and Grease) enforcement implemented.
If you’ll notice the ground around the diversion station (basin), Purcell and Clay Davis worked extensively to clean-up a previous Sanitary Sewer Overflow left at the plant.
Coming from the diversion station wastewater enters the headwords where large solids pass through a grinder and are screened, rinsed, and removed. The removal of these solids from the treatment process ensures that the pumps run more efficiently.
The auger at the headwords station is missing a brush that would help in the removal of solids from the treatment process. Purcell submitted a quote to the city on January 30th, but the brush has yet to be ordered.
As the wastewater continues its cycle, it is then passed onto, and through the Hydro-Grit vortex system that spins the wastewater at a high rate of speed. Fine particles of grit settle and are then filtered and removed by the Grit-Classifier before the wastewater moves on to be treated.
Wastewater then enters the SAM (surge/anoxic mix) tank. The SAM tank provides flow and nutrient equalization to provide treatment at a full range of flows and loadings. Mixed liquor (bacteria) is maintained in the SAM tank by being recycled from the top of the SBR (sequencing bach reactor) and mixes with incoming raw sewage to suppress odor and initiate carbon and nitrogen reactions.
Wastewater is treated in the SBR tank through nitrification (adding of dissolved oxygen) and denitrification (lowering of dissolved oxygen) then a timed settle phase before being decanted.
Currently the plant is not running efficiently due to a SBR feed pump needing replaced.
The last step in the process involves a narrow channel where the wastewater passes through a baffle plate to slow flow before a series of twenty four UV lights sterilizes the effluent water being discharged into the creek. The pneumatic cylinders that automatically clean the UV lights need to be replaced due to a lack of maintenance. Purcell gave a quote to the city on February 8th, however the parts have yet to be ordered. The UV lights have to be changed every 12,000 hours to remain effective. Before Purcell started working at the wastewater plant they had not been changed per manufacturer recommendation.
We would like to thank Braden Purcell for his time, and sharing of knowledge to make this article educational, and informational for the people whom this plant effects.