CENTRAL KITSAP COUNTY WASTEWATER FACILITY PLAN ...

Central Kitsap County Wastewater Facility Plan
8: Wastewater Treatment Improvements …
Process
identifier
GR-3
GR-4
Technology
Rectangular gravity
horizontal flow
Square horizontal flow
chamber
Table 8-1. Identification of Liquid Stream Alternatives
Description
Designed to maintain 1.0-foot-per-second velocity and to provide sufficient time for the grit
to settle to the bottom of the channel.
Designed based on a controlled horizontal velocity developed by feed and effluent control
devices.
GR-5 Vortex system Screened raw wastewater is introduced tangentially into a small-diameter circular basin.
Aided by slow speed mechanical impellers, a low-velocity vortex pattern develops in the
basin. The heavy grit particles are collected on the basin floor and migrate to the center of
the basin and drop into a sump.
Flow equalization
FE-1 No flow equalization Current practice.
FE-2 Flow equalization
Primary treatment
PS-1 No primary clarification
PS-2
Conventional primary
clarification
Current technology. Organic solids settle by gravity and are incorporated into a sludge
blanket for solids/liquid separation in the clarifier.
PS-3 Dissolved air flotation Air is pressurized and dissolved into a carrier fluid. The carrier fluid is introduced to the
thickener and ambient pressure causing bubbles to rise and float the solid particles.
PS-4 Inclined plate settlers Settling of primary solids occurs in multiple inclined parallel small-diameter tubes.
PS-5
Chemically enhanced
primary clarification
(CEPT)
Addition of low doses of ferric or alum salt and in some cases polymer in conventional
primary sedimentation basins to increase solids and BOD5 removal by causing solids to
flocculate for better settling and removal at higher surface overflow rates (and thus increase
capacity for the same tankage).
PS-6 Ballasted processes Similar to CEPT, except higher doses of chemicals are used, a ballasted material
(microsand or sludge) is used to improve settling, and is a vendor process (e.g. Actiflo,
DensaDag).
Secondary treatment
ST-1 Anaerobic lagoons Lagoons simulate biological stabilization processes naturally occurring in lakes but at
different and controlled loadings. Anaerobic lagoons do not include any supplemental
aeration (either via surface aerators or diffusers) and anaerobic conditions prevail.
ST-2 Facultative lagoons Lagoons with or without supplemental aeration, with the bottom layer of solids undergoing
anaerobic digestion.
ST-3 Aerobic lagoons Lagoon with supplemented aeration designed to maintain aerobic conditions throughout the
liquid depth.
ST-4 Wetlands Inundated land areas with water depths typically less than 2 ft that support the growth of
emergent plants.
ST-5 Slow-rate land treatment Controlled application of wastewater to land surface. Treatment occurs in plant-soil-water
matrix. Slow-rate system meets the growth needs of the vegetation.
ST-6
ST-7
Overland flow land
treatment
Rapid infiltration land
treatment
Pretreated wastewater is distributed across the upper portions of carefully graded,
vegetated slopes and allows to flow over the slope surfaces to runoff collection ditches at
the bottom of the slopes.
Pretreated wastewater is applied on an intermittent schedule usually to shallow infiltration
or spreading basins.
ST-8 Oxidation ditch Wastewater is treated with a suspended sludge (activated sludge) in a biological reactor in
the shape of a racetrack.
8-3
DRAFT for review purposes only.
Use of contents on this sheet is subject to the limitations specified at the end of this document.
P:\132857 Kitsap WW Facility Plan Ph II\600 Facility Plan\Revision 3 Draft Final Facility Plan\Chapter 8\Chapter 8_draft(BP).doc