South Kitsap Water Reclamation Facility (SKWRF)
Cleaning the water we use and protecting the environment we live in.
West Sound Utility District operates the South Kitsap Water Reclamation Facility that serves both the City of Port Orchard and the District. The City and District each manage their own collection systems. The City of Port Orchard and West Sound Utility District jointly own the South Kitsap Water Reclamation Facility. Cost effective operations and oversight is accomplished by the Sewer Advisory Committee comprised of City Council members and District Commissioners.
Prior to 1984, the City and District each had their own primary treatment plants which encompassed their respective service areas. When the State and federal law mandated secondary treatment for wastewater, the two agencies cooperated and constructed the Joint Wastewater Treatment Facility. As the mission shifted from wastewater treatment to sustainable reclamation, the Facility changed its name to the South Kitsap Water Reclamation Facility.
The South Kitsap Water Reclamation Facility is an award winning facility. It is staffed by nine highly trained professionals who treat the wastewater for more than 25,000 people. The facility was expanded in 2006 and it has the capacity to serve the urban areas in the South Kitsap Community, all of the McCormick Woods ULID area, South Kitsap Industrial Area, and selected rural communities.
An overview of the facility and its processes:
- Receiving water body: Sinclair Inlet, Puget Sound
- Main Facility Online in May of 1985
- Solids handling upgrades 1987
- Membrane Bioreactor upgrades online March 2006
- Annual Average Flow 1.93 MGD (2016)
- Design Flow 4.2 MGD
- Peak Wet Weather Flow 16 MGD
- 3 Primary Clarifiers 90,525 Gallons Each
- 6 Aeration Cells with a capacity of 77,792 Gallons each
- 2 Secondary Clarifiers with a capacity 279,897 Gallons each
- 2 Membrane Bioreactor Filtration trains. Current capacity of 1.7 MGD, upgradeable to 2.5 MGD.
- 1 High Rate Clarifier with a capacity of 10 MGD
- 2 Anaerobic Digesters with a capacity of 255,000 each
- Number of Fulltime Staff is nine working varying shifts
- Staffed 7 Days a week 365 days/ year
Removing Large Debris and Grit
Rotary screens remove large debris from the wastewater as it enters the facility. After screening, wastewater travels to vortex grit removers to remove sand and other inorganics. The waste stream then travels to the primary clarifiers.
Wastewater settles in long tanks called primary clarifiers. Heavy material settles to the bottom, and light material floats to the top. All settled material removed in "Primary Treatment" is pumped onto the solids handling process to be thickened and sent for further processing in the anaerobic digesters. The primary treated water (primary effluent) now flows to the Secondary Treatment processes. The two Secondary Treatment processes are Conventional Activated Sludge and Membrane Bioreactor"
Secondary Treatment (Biological Process)
The primary treatment effluent flows to aeration basins where oxygen is added to encourage growth of useful bacteria and microorganisms naturally present in the wastewater. Microorganisms and bacteria consume organic material (food) in the wastewater aeration system/basin which goes to secondary clarifiers.
The clarifiers are large round sedimentation tanks where the microorganisms settle to the bottom of the tank. Some of the settled organisms are returned to the aeration basins to again be introduced to oxygen and a food source to become ‘activated’ to consume more organic material. The excess secondary sludge is pumped to the Solids Handling process to be thickened and sent for further processing in the anaerobic digesters. The water (effluent) from the secondary clarifiers (Final Settling) flows to the disinfection channel for disinfection.
A regulated flow is introduced to the Membrane Filtration process. The process has two tanks in which microorganisms and bacteria consume organic material (food) in the water. One tank is anoxic (contains little dissolved oxygen) and an aerobic tank (contains dissolved oxygen). Membranes are contained in the aerobic tank. Filtration is achieved by drawing water to the inside of the membrane fiber under low vacuum pressure. The hollow-fiber membranes have nominal and absolute pore sizes of 0.02 and 0.1 microns respectively. The small pore size excludes particulate matter including solids, bacteria, pathogens and certain viruses. The excess process sludge is pumped to the Solids Handling process to be thickened and sent for further processing in the anaerobic digesters. The treated water (permeate) is conveyed to the main permeate collection pipes, and then is blended with the effluent from the Secondary Clarifiers in the disinfection channel. This highly treated water is also used for the purposes of water reclamation which is distributed for landscape irrigation uses.
Keeping Pathogens in Check
The Secondary Treatment effluents conveyed to the disinfection channel are chlorinated with Sodium Hypochlorite (NaOCL) which is a concentrated ‘bleach’. This destroys most pathogens, or disease-causing bacteria. The effluent is then de-chlorinated before it is released through an outfall pipe and diffused into the receiving water body, Sinclair Inlet, Puget Sound.
Wet Weather Capacity
High Rate Clarification
A high rate clarifier uses chemical addition to quickly settle out solids. This process may be used during continuous high flow periods over 6 Million Gallons per day (MGD) through the treatment plant. The High Rate clarifier can handle flows up to 10 MGD. High flow conditions are caused by intrusion of ground water into the older sewer conveyance system lines during heavy rains. After removing the solids the treated water is conveyed to the disinfection channel and combined with the secondary effluents.
Solids Handling, Biosolids
Solids Dewatering/ Biosolids Production
Digested Sludge from the digester is removed and conveyed through a centrifuge. The centrifuge spins at a high rate of speed and removes excess water from the solids in the sludge. The dewatered solid material is nutrient-rich Biosolids which are utilized as a soil amendment. Additionally Biosolids can be used for land reclamation where soils no longer have the required nutrient levels to sustain vegetation. The SKWRF belongs to the Northwest Biosolids Management Association. Further information on Biosolids use and benefits can be found on their site at www.nwbiosolids.org
Thickened solids are blended in a large tank called a Digester. In the Digester a decomposition process occurs further breaking down the microorganisms and bacteria. One of the by-products of this process is the production of bio-gas (methane) which is utilized for energy recovery in the facilities boilers to heat the digesters and facility buildings.
The treatment of odors is one of the top priorities of the facility. A natural soil filter media is used to treat the odors. Bio-filters use microorganisms to remove odor causing compounds. The air flows through a packed bed and the compounds transfer into a thin biofilm on the surface of the filter media. Microorganisms, including bacteria and fungi, comprising the biofilm, degrade the compounds which cause odors.
The laboratory is an essential part of the facility. The laboratory functions on a daily basis in analyzing the waste stream that flows through the facility. Samples are taken at different stages of the process and through the examination from skilled laboratory staff, vital data is generated.
Reliable, quality analytical services are required to accurately determine the concentrations of the contaminants that the wastewater plant discharges into the Puget Sound. These contaminant concentrations are limited by the Department of Ecology by an NPDES permit which the plant must meet. Much of the generation and documentation of this important data is done in the laboratory. Additionally, many of the operator’s process changes and decisions are based on the data provided by the analysts.
The lab provides general chemistry and microbiological analyses, and manages all other required analyses through contracted lab services. The staff is committed to continuous process improvement. The laboratory maintains accreditation through the Department of Ecology and follows specific quality assurance processes. A list of the lab's accredited methods is available through Ecology's Laboratory Accreditation website