Hector, MN – Wastewater Treatment Plant
Challenge:
Hector’s original wastewater facility was constructed in 1967. In 1993, the facility was expanded to include preliminary treatment, conventional activated sludge biological treatment, final clarification and chlorine disinfection. Most of the equipment in the current wastewater treatment plant hadn’t been updated since the 1993 plant expansion.
The facility’s current preliminary treatment equipment (screening and grit removal) were inadequate. The facility’s discharge permit added a requirement to add de-chlorination provisions if chlorine usage continued for wastewater disinfectant. In addition, the plant began receiving additional waste from a new significant industrial user which nearly tripled the loading the plant receives. The plant’s capacity was limited by the capacity of the aeration basins and biosolids handling. In order to continue providing reliable wastewater treatment, a facility upgrade was in order.
Solution:
Moore Engineering performed a facility plan report to determine the recommended improvements and size of components. The proposed improvements to the facility were constructed in two phases. The first phase of the improvements was completed in 2013 and provided additional aeration capacity. The project involved replacing the aeration basin fine bubble diffusers to provide the biological treatment capacity the facility needed to accept the new industrial waste load.
The second phase of construction began in 2015 and included a new process treatment building which provided fine screening and grit removal of the influent wastewater, new RAS pumps and sludge transfer pumps, variable frequency drive (VFD) additions for the aeration basin blowers, and a new mechanical biosolids thickening equipment.
Other upgrades include conversion of the facility’s chlorine disinfection to ultraviolet light disinfection, biosolids tank mixing equipment, new influent pumps, existing control building improvements, and facility SCADA and control system upgrades.
Outcome:
Hector’s wastewater treatment plant is now fully automated using the new SCADA controls. The facility has upgraded control functions and a system that optimizes the energy use of the treatment processes.
