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Emergency Peak Flow Management Alternatives - South Treatment PlantThis work was initiated by project staff at King County in 2009 as part of preparations for a potential flood emergency in the Green River Basin (which is tributary to King County’s South Treatment Plant ) due to concerns about instability of abutments to the Howard Hansen Dam. The objective of this study was to evaluate potential strategies to maximize flow capacity through the secondary system at the South Treatment Plat during a flood event without putting the secondary process at risk of failure after the flood event. This study was limited to evaluation of process effects. View report (PDF - 785 KB) |
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Digestion System Improvements - West Point Treatment PlantThe West Point Digestion System Improvements Evaluation was initiated as a result of digester instability issues occurring in 1998 and 2002. A variety of digestion-related studies were implemented to evaluate and/or improve the operation of the West Point digestion process. These are summarized below: - Digester Tracer Studies – designed to evaluate mixing effectiveness. Initial testing was inconclusive.
- Temperature profiles – designed to evaluate mixing effectiveness by looking for temperature gradients within the digester.
- Solids profiles – designed to evaluate mixing effectiveness by looking for solids concentration gradients within the digester.
- University of Washington Research: Vmax/Acetate uptake rates – analytical laboratory procedures to evaluate health of a digester by measuring how it responds to a known artificial feed source.
- Digester survey – to establish how the actual operating conditions of the West Point and South Plant digesters compare to similar systems in other parts of North America.
- Recirculation gas monitoring – to determine mixing energy input by establishing the flow of digester gas delivered to each mixing draft tube.
- Evaluation of instrumentation to better monitor digester operation – online gas composition and liquid stream parameters.
Results of the studies are summarized in the PowerPoint presentation below. The studies ultimately resulted in a multi-phase capital project designed to improve the stability of the digesters. View report (PDF - 244 KB) |
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Co-Digestion of Food WasteIn 2006, King County began looking at opportunities to increase methane production at its South Treatment Plant in Renton, Washington. This report summarizes an initial investigation by the Wastewater Treatment Division with input from the Solid Waste Division on the feasibility of implementing a food waste importation program at the South Treatment Plant. View report (PDF - 54 KB) |
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Food Waste StudyThe objective of this 1995 study was to document the status of food waste management in the Wastewater Treatment Division service area and the current impact on wastewater treatment facilities, and to develop and compare alternatives for managing food waste in a more cost effective way. The study included analysis of available data on food waste management. Collection and laboratory testing of food waste samples was also included to determine the effect of food waste on wastewater treatment process unit loading. View report (PDF - 5.3 MB) View report appendix (PDF - 4.4 MB) |
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Nitrogen Removal Study at South and West Point Treatment PlantsSummary of nitrogen study here. View report (PDF - 54 KB) |
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Grease CoDigestionSummary of grease study here. View report (PDF - 54 KB) |
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Combined Sewer Overflow Treatment Systems TestingPilot-scale operation of two potential combined sewer overflow (CSO) treatment technologies: chemically enhanced primary clarification (CEPC) and CEPC combined with lamella plates. The test facility allowed for concurrent operation of both CEPC and CEPC with plates in a single unit with a common flocculation zone. The study used primary influent diluted with secondary effluent to simulate CSO water. View report (PDF - 3.8 MB) |
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Water Reuse Technology DemonstrationThe objective of this 2001-2002 award winning pilot testing program was to assess the ability of emerging wastewater treatment technologies to produce effluent quality that meets either Class A reclaimed water standards or more stringent water quality standards associated with water reuse opportunities being considered by King County. Following an in-depth screening of the individual treatment processes, technologies selected for pilot testing were Biological Aerated Filter (BAF), Membrane Bioreactor (MBR), Fuzzy Filter, ballasted flocculation (Actiflo and Densadeg) microfiltration and reverse osmosis. This project was awarded the 2002 National Environmental Achievement Award for Research and Technology by the National Association of Clean Water Agencies. Learn more. |
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Fuel Cell Demonstration - South Treatment PlantFuel cells produce electric power directly through electrochemical reactions (like a battery). By avoiding the two-step process of conventional combustion technology, where fuel is first burned and then heat is used to produce power, fuel cells are more energy efficient. In June 2004, King County began a two-year demonstration of a fuel cell power plant to be fueled by gas produced through anaerobic digestion of treatment solids produced at the South Treatment Plant. The project was the first application in the country to use digester gas to fuel a molten carbonate fuel cell. Molten carbonate is one of the most efficient of the fuel cell technologies under development. King County’s fuel cell power plant was sized to produce 1 megawatt (MW) of electricity and was designed to capture waste heat from the fuel cell exhaust and return it to the treatment plant. The project successfully demonstrated that molten carbonate fuel cell technology can be adapted to use anaerobic digester gas as a fuel source and can achieve a power output target of 1 MW using either digester gas or natural gas. Learn more and view final report. |
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Membrane Bioreactor Pilot StudyMembrane Bioreactor (MBR) technology works by converting screened sewage to clean effluent (treated water) in a single process - eliminating the need for separate primary, secondary and advanced treatment. It produces a very high quality effluent, meeting Class A criteria (after disinfection). MBR technology has the potential to significantly reduce treatment plant footprint (the amount of land land / space needed for treatment facility) while producing improved effluent quality. From 2000 – 2007, King County pilot-tested multiple membrane bioreactor technologies in order to evaluate their potential use at small satellite plants (e.g. water reuse facilities) as well as large regional wastewater facilities. The technology is now being used at King County’s Carnation Treatment Plant and the Brightwater Treatment Plant. View report 1 (PDF - 917 KB) View report 2 (PDF - 1.2 MB) View report 3 (PDF - 248 KB)
View report 4 (PDF - 651 KB) View poster 5 (PDF - 2.6 MB) View report 6 (PDF - 1.7 MB) |
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Centridry DemonstrationCentridry™ is a biosolids drying process developed by Humboldt-Decanter of Germany. The process uniquely combines centrifuge dewatering with flash air drying to produce a solids product with 50 to 60 percent solids, or drier. A five-month demonstration project was completed in 1998 at King County’s South Treatment Plant to evaluate the technology. The results of the testing indicated that the process was capable of producing biosolids of 50 to 60 percent solids content in a mechanically reliable and operator-friendly manner. On the other hand, the results also indicated that there could be serious issues of odor, and hence product acceptability and siting issues, associated with the Centridry™ product. View report (PDF - 41 MB) |
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Vertad DemonstrationThe objective of this investigation was to construct and operate a VERTAD™ reactor for the purpose of digesting mixed primary and secondary wastewater treatment solids. The 350-foot deep VERTAD™ reactor (pipe within a pipe) is an aerobic thermophilic digestion process with the ability to transfer large quantities of oxygen and to circulate and mix thickened wastewater solids. The process can provide Class A pathogen reduction and a stable biosolids product in a small footprint (small space). The 2001 project report provides an assessment of the development and performance of the VERTAD™ process through the initial investigation. View report (PDF - 17.6 MB) |
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Thermophilic-Mesophilic DegestionThis study examined the use of temperature-phased anaerobic digestion at the West Point Treatment Plant in order to improve volatile solids destruction and/or to accommodate a reduced hydraulic residence time in the existing digesters. A pilot study was conducted with two, 1900-L (500 gal) digesters. The pilot study was initiated in July, 1999, and operated for more than a year at loadings that were selected based on projected future loads and the removal of an existing digester. View report (PDF - 134 KB) |
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