Following construction of the new Regional Water Reclamation Facility and the Beaver Channel Pump Station at the original Plant site, most of the original Water Pollution Control Plant was taken out of service. However, portions of the original plant have been retained for intermittent operation during wet weather as a Wet Weather Retention and Treatment Facility. Peak wet weather flows from the combined sewer system are diverted and pumped separately to the original plant screening, grit removal, and primary clarifiers providing up to 700,000 gallons of storage. The stored volume is then pumped and treated at the new Regional Water Reclamation Facility when flows from the combined sewer system return to normal following wet weather events.
The new Regional Water Reclamation Facility provides a significantly higher level of treatment at more than 1.5 times the capacity of the original plant; providing the capacity for 8 million gallons a day of average dry weather sewage flow and up to 17 million gallons per day of peak hour combined storm and sewage flow. Liquid treatment processes at the new facility include fine screening, grit removal, flow measurement, aeration basins, and secondary clarifiers. Solids handling processes include return activated sludge (RAS) and waste activated sludge (WAS) pumping, rotary drum WAS thickening, aerobic digesters, and rotary press solids dewatering, and dewatered solids cake storage.
New Regional Water Reclamation Facility
At the new Regional Water Reclamation Facility, several levels of sewage and associated solids treatment are provided. Treated effluent is pumped back to the old Water Pollution Control Plant for discharge to the Mississippi River. Treated biosolids are hauled and land applied to agricultural lands as a soil conditioner and fertilizer.
At the Headworks Building, perforated screens remove rags, sticks, plastics, and similar solids. Vortex grit basins also remove sand, coffee grounds, egg shells, bone chips, and similar solids. In both instances, solids are removed to protect downstream equipment from plugging and abrasion, and are washed and compacted prior to landfill disposal.
At the Aeration Basins, microorganisms, collectively referred to as activated sludge, are grown in the three aeration basins containing approximately 2 million gallons each. The microorganisms are kept suspended through a combination of mechanical mixing and aeration.
A series of aerobic, oxic and anoxic zones within the aeration basins enable the microorganisms to convert dissolved contaminants referred to as BOD to biomass and to biologically convert and remove the nutrients nitrogen and phosphorus from the waste stream.
The Secondary Treatment Building contains state of the art high speed turbo blowers that provide the air to the aeration basins for mixing and to provide oxygen in the aerobic and oxic zones. Return sludge pumps recycle the activated sludge (microorganisms) from the clarifiers to the aeration basins and waste excess activated sludge (biomass) to the aerobic digesters.
The Secondary Clarifiers provide a quiet zone to separate the activated sludge from the treated wastewater. The activated sludge settles to the bottom of the three 125 foot diameter by 16 foot deep clarifiers and is recycled to the aeration basins for continued use. Treated wastewater overflows as a clear effluent to the Effluent Pump Station.
At the Effluent Pump Station, up to four 16-inch diameter vertical turbine effluent pumps discharge treated effluent to the old Water Pollution Control Plant for discharge to the Mississippi River through the existing plant outfall.
At the Aerobic Digesters, waste activated sludge (biomass) is reduced in volume and stabilized through a process known as endogenous respiration. Air from high speed turbo blowers mix and provide oxygen to the sludge biomass in the four 800,000 gallon digesters.
At the Solids Processing Building, waste activated sludge is processed prior to storage and land application as biosolids. Water is removed to concentrate the waste activated sludge with two rotary drum thickeners prior to discharge to the aerobic digesters. Additional water is squeezed from the stabilized biosolids using three rotary presses to produce dewatered biosolids known as " cake" biosolids. Polymer is added to enhance both the thickening and dewatering processes.
"Cake" biosolids are conveyed and stored on the Solids Digester Pad. The biosolids, which are an excellent soil conditioner and fertilizer, are seasonally removed from the storage pad and land applied at agronomic rates to crop land in the surrounding rural area. Each year, the process of treating Clinton, Camanche, and Low Moor wastewater produces approximately 1,600 dump truck loads of waste biosolids weighing about 1,400 tons.
The facility's SCADA system is configured to facilitate 8 hour/day staffing.