Northside Wastewater Treatment Plant Tour
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| The Northside Wastewater Treatment Plant began its operation in March of 1988. The plant had an initial treatment capacity of 4.0 million gallons per day, based on an annual average flow. The facility was expanded in 1996 and presently has a treatment capacity of 6.25 million gallons per day. |
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A Pretreatment or Headwork's Area
Raw, untreated wastewater is pumped to the facility for treatment. This raw wastewater enters the treatment plant via this Pretreatment Structure. The Pretreatment Structure performs several preliminary treatment tasks, such as debris removal, inert material removal and odor control.
For a review of the master pumping stations that delivers the raw wastewater to the Northside WWTP, click Here.
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Mechanically Cleaned Bar Screens
An important part of the preliminary treatment process is screening. The Northside facility operates two (2) mechanically cleaned bar screens. A screening process removes roots, rags, cans and large debris from the raw wastewater. This improves the treatability of the water and also helps prevent the plugging of pumps and/or pipelines.
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Grit Removal Process
A Grit Removal Process removes inert, non-organic materials from the raw wastewater. Common materials removed include sand, pebbles, egg shells, etc. The Northside Facility has two (2) Vortex type grit removal systems.
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Activated Sludge System: Aeration Basins
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The Northside Treatment Facility has four (4) Aeration Basins. Each basin contains 2.1 million gallons of wastewater and has two (2) two surface aerators that force the air into the tank contents via mechanical means. With dissolved oxygen being added, the activated sludge process establishes a heterotrophic bacterial population, i.e. organisms that will utilize and assimilate the complex organic matter that is in the wastewater. Also, another group of specialized organisms goes to work nitrofiers. Nitrofing bacteria take the ammonia in the wastewater and oxidize it to nitrate (NO3). This nitrate is then utilized in the Anoxic Process that is described in the next section.
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Activated Sludge System: Anoxic Basins
Activated sludge that contains high levels of nitrates (see Aeration Basins) is pumped by internal recycle pumps to an Anoxic Basin to be mixed with the incoming raw wastewater. An Anoxic Basin consists of a tank mixer which keeps the solids contained in the tank from settling. No aeration (added air) is performed within this tank. The tank has an abundance of food for the hungry organisms in the activated sludge. The tank has no dissolved oxygen available to allow the organisms to assimilate the food. To satisfy their oxygen needs, the organisms remove the oxygen (O3) from the nitrate supply (NO3) that is within the recycled activated sludge. Then, all that is left is a nitrogen molecule (N), which is insoluble in water. This free nitrogen enters the air and, thus, nitrogen is removed from the wastewater.
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Secondary Clarifiers
Following treatment in the Aeration/Anoxic Basins, the bacteria mass that is produced is separated from the cleaned-up water (effluent) by a tanks called clarifiers. These tanks place the biomass in a relatively quite zone for a two (2) plus hour time. This allows gravity to settle out the biomass, which is removed from the bottom of the tank and pumped back to the beginning of the process. There the bacteria begin to do their work again. The cleaned (clarified) effluent exits the tanks, ready for disinfection.
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Effluent Disinfection
Effluent from the secondary clarifier process is disinfected by adding a chlorine solution to the water and maintaining the total chlorine residual of >0.5 mg/L after 30 minutes of contact time. Chlorine residual in the plant effluent is monitored continuously to insure disinfection. effectiveness.
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Effluent Pumping Station
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Effluent leaving the secondary clarifiers flows to this pumping station wet-well. The effluent is then pumped by these pumps to the effluent storage tank.
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Sludge Thickening Process
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Waste activated sludge from the Northside WWRF is pumped to a sludge holding tank daily, in order to maintain a desired "Sludge Age" within the activated sludge system. This "Waste Sludge" has a typical concentration of 1-2% total solids. The sludge thickening process is operated weekly to thicken the "Thin Sludge" to a 4-6 percent total solids concentration. This "Thick Sludge" is discharged to a "Pre-ATAD" holding tank and is the raw material source for the ATAD digestion process. The sludge thickening equipment utilized at the Northside WWTP is the "Aqua Belt System", by Ashbrook, Inc.
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Sludge Digestion Process
The Northside WWTP utilizes the ATAD process (Auto Thermal Thermophylic Aerobic Digestion) to convert waste activated sludge into a "Class AA" stabilized wastewater residual product, suitable for land application on agricultural sites. The ATAD process relies on aerobic microorganisms to carry out the reduction of organic substances within the feed sludge. These reactions also produce heat, which allows the reactors to maintain a temperature of between 50-60° C. The ATAD process produces the required time temperature function, vector attraction reduction and pathogen reduction to produce a "Class AA", stabilized residual product, as defined in 62-640 F.A.C.
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Effluent Storage Tank (Crom Tank)
The Northside WWTP has a 1,500,000 gallon effluent storage tank that acts as a reservoir, allowing for industrial reuse of the plants effluent at the McIntosh Power Plant.
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Industrial Reuse Pumps
This pumping station delivers effluent from the Northside and W. Carl Dicks WWTPs to the McIntosh Power Plant, to be utilized as cooling water within the power generation operation.
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Internal Reuse Pumps
The Northside Wastewater Treatment Plant uses very little potable (public) water within its operation. Plant effluent is utilized instead.
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By-Pass Pumps
Any effluent that is not able to be utilized as industrial reuse water at the power plant (example during spring outages) is pumped back to the Glendale WWRF facility and then pumped to the Lakeland Artificial Wetlands Treatment System for final AWT and ultimate disposal.
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