Research Library: Documents & Publications
Over the last 20 years, the Resource Recovery Section of King County's Wastewater Treatment Division has been investigating and assessing wastewater treatment processing technologies for ways to reduce or reuse energy, water and nutrient sources during wastewater processing, benefiting ratepayers and the environment.
Each project description is followed by links to project reports with related information, when available. You can download and view documents (PDF files) using a PDF Reader.
An investigation of alternative approaches to optimize biogas management and energy utilization facilities at the South Treatment Plant.
View report (6.8 MB)
A detailed study investigating the feasibility of importing brown (restaurant) grease to WTD's South Treatment Plant and co-digesting with sewage solids to enhance production of renewable biogas.
View report (5.8 MB)
This report summarizes the results of a two-year project to demonstrate whether a molten carbonate fuel cell power plant could be adapted to use anaerobic digester gas as a fuel source and still achieve a power output target of 1 megawatt.
This report summarizes an initial investigation on the feasibility of implementing a food waste importation program at South Plant in order to increase methane production.
View report (54 KB)
A variety of studies to evaluate and/or improve the operation of West Point's solids digestion process are summarized below:
- Digester Tracer Studies – to evaluate mixing effectiveness. Initial testing was inconclusive.
- Temperature profiles – to evaluate mixing effectiveness by looking for temperature gradients within the digester.
- Solids profiles – to evaluate mixing effectiveness by looking for solids concentration gradients within the digester.
- Vmax/Acetate uptake rates – to evaluate health of a digester tank by measuring how it responds to a known artificial feed source.
- Digester survey – to establish how actual operating conditions of 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 and online gas composition and liquid stream parameters.
The studies ultimately resulted in a multi-phase capital project designed to improve the stability of the digesters. Results of the studies are summarized in this PowerPoint presentation.
View report (244 KB)
This report summarizes a demonstration of the VERTAD™ digestion process to provide Class A pathogen reduction through an aerobic deep shaft design.View report (17.6 MB)
This study examined temperature-phased anaerobic digestion to improve volatile solids destruction and/or to accommodate reduced hydraulic residence time in existing digesters.
View report (134 KB)
This demonstration project determined that the Centridry™ biosolids drying process was capable of producing biosolids of 50 to 60 percent solids content in a mechanically reliable and operator-friendly manner but also revealed serious issues of odor, and hence product acceptability and siting issues.
View report(41 MB)
The reclaimed water comprehensive planning process explored if, when, where, and by what funding mechanisms King County's existing reclaimed water program should expand over the next 30 years. It examined potential reclaimed water uses and evaluated strategies for serving these uses.
The Washington State Department of Ecology has determined that portions of south Puget Sound do not meet Washington State water quality standards for dissolved oxygen. Ecology is concerned that algal growth stimulated by nitrogen loadings to Puget Sound is causing DO depression in near-bottom regions. The Technology Assessment Program conducted this study to evaluate the impact (e.g. costs, footprint, energy, greenhouse gas emissions) of a range of potential future nitrogen removal requirements on the West Point Treatment Plant. The West Point Treatment Plant is a high-purity oxygen (HPO) activated sludge process (non-nitrifying) on a very constrained site with no possibility of expansion.Report (5 MB)
The Washington State Department of Ecology has determined that portions of south Puget Sound do not meet Washington State water quality standards for dissolved oxygen. Ecology is concerned that algal growth stimulated by nitrogen loadings to Puget Sound is causing DO depression in near-bottom regions. The Technology Assessment Program conducted this study to evaluate the impact (e.g. costs, footprint, energy, greenhouse gas emissions) of a range of potential future nitrogen removal requirements on the South Treatment Plant. The South Treatment Plant is a conventional activated sludge process (non-nitrifying) with significant space available for future expansionReport (9 MB)
View report (785 KB)
This demonstration assessed various emerging wastewater treatment technologies designed to produce Class A effluent. This project was awarded the 2002 National Environmental Achievement Award for Research and Technology by the National Association of Clean Water Agencies.Learn more.
For more information about resource recovery, please contact us at:
- 201 S. Jackson Street, KSC-NR-0512, Seattle, WA 98104