Wastewater Treatment Process

Liquids Process Flow

The flow enters the plant from three main pumping stations. The flow passes through a flow meter, fine screen to remove large debris, sampler, and a grit removal system.
The flow is then divided into two primary settling tanks. The water is slowed down to allow for the heavy solids to settle to the bottom of the tank and the lite solids to float to the surface. The solids that settle to the bottom are pumped out and placed in anaerobic digesters for treatment. The solids that float are skimmed off and put in a dumpster for disposal at a landfill.
The flow is then sent to three selector tanks that are run in a series. In these tanks, the flow from the primary tanks and the bacteria and microscopic organisms are mixed without the addition of oxygen. This allows us to select the type of biomass that produces the best treatment and stresses the biomass which causes a release of phosphorus.
The flow is then divided into two oxidation ditches. Each oxidation ditch contains 1.49 million gallons of water. The oxidation ditches provide the biological treatment of the water. Microorganisms work to remove the solids that remain, biological oxygen demand, ammonia, and phosphorus
The flow is then sent to a secondary clarifier. The microorganisms settle to the bottom of the clarifier and are pumped back to the selector tank. The clean water flows out of the tank and goes to disinfection.
Disinfection is accomplished by UV lights. Disinfection is only required from April 1st thru October 31st.
After disinfection is post aeration. Oxygen is added to the water through floating aerators. We have a minimum Dissolved Oxygen level that we must meet per our permit.
Finally a sample is taken for the lab for testing. We must test 7 days per week.

Solids Process Flow

Solids handling includes thickening, digestion, dewatering and storage.
The waste activated sludge (WAS) is diverted to a gravity belt thickener.
The thickened sludge is then pumped to a digester.
The solids (sludge) that settle to the bottom of the primary tanks are pumped directly to the digesters for treatment.
The sludge is then heated and mixed for over 100 days for treatment. The sludge is then pumped to a holding tank for dewatering.
The sludge is then pumped to a volute screw press to be dewatered. The dewatered material is called a cake.
The cake is stored in a building until it is loaded out. The cake is either land applied on farm ground or taken to the landfill if farm ground is not available.

Limitations of POTWs (Publicly Owned Treatment Works)

As noted, POTWs (Publicly Owned Treatment Works) are not designed to treat toxins in industrial waste. As such, discharges from both industrial and commercial sources can cause serious problems. The National Pretreatment Program, published in Title 40 Code of Federal Regulations (CFR) Part 403, provides the regulatory basis to require non-domestic discharges to comply with pretreatment standards to ensure that goals are attained. The objectives of the National Pretreatment Program are to:

Improve opportunities to recycle and reclaim municipal and industrial wastewaters and sludges
Prevent the introduction of pollutants into POTWs, which will interfere with the operation of a POTW, including the interference with its use or disposal of municipal sludge
Prevent the introduction of pollutants into POTWs, which will pass through the treatment works or otherwise be incompatible with such work

Pre-Treatment Operations

Publicly-owned treatment works (POTWs) collect wastewater from homes, commercial buildings, and industrial facilities and transport it via a series of pipes, known as the collection system, to the treatment plant. Generally, POTWs are designed to treat domestic sewage only, creating the need for a pretreatment operations program.

The program regulates what the industry can send to the treatment plant to ensure the treatment plant can treat the waste that is sent.

The program issues a permit to the industries regulating discharges to meet the sewer use ordinance and samples 4 times per year to ensure compliance.

There is a FOG (fats, oil, and grease) program that regulates restaurants. This program makes sure restaurants have a system to remove the FOG from the waste stream and that proper maintenance of those systems is being completed.

Maintenance

The Wastewater Treatment Utility maintenance and construction personnel are responsible for the regular upkeep of sanitary and stormwater infrastructure throughout Warsaw. With over 120 miles of sanitary, storm, or combined sewer and 50+ lift or pump stations, the maintenance and construction personnel perform vital operations to help ensure the proper functioning of Warsaw’s collection systems. Regularly cleaning pipelines and lift/pump stations, performing pipe locates prior to construction, maintenance of lift/pump stations, repair and replacement of infrastructure, and video inspections of pipes, structures, and lift/pump stations.

The maintenance and construction personnel are also responsible for the treatment plant. They perform repair and replacement of pumps, valves, pipes and other components of the treatment plant. They are also responsible for building and grounds maintenance and preventative maintenance.

Lab Operations

The Warsaw Wastewater Laboratory's primary task is to test the influent and effluent water and report the results to the Indiana Department of Environmental Management (IDEM) in order to demonstrate that the utility is removing pollution before discharging to public waters.

Additionally, tests are performed on treatment process controls for the plant while also testing for the Stormwater Program. Tests are performed on all biosolids that are applied to farm fields in the area. The Tippecanoe River is also monitored above and below outfalls for pollutants.

The Warsaw Wastewater Laboratory has earned the Laboratory Excellence Award yearly since 2003 and has passed all Discharge Monitoring Report Quality Analysis evaluations as required by the State of Indiana since 2004.