Event Title
Presentation Abstract
Wapato Lake in Tacoma, WA is a 23-acre urban lake that has had problems of eutrophication and toxic algae blooms for over a hundred years. Inputs of phosphorus from both environmental and anthropogenic sources contribute to this problem. Much of the 900-acre watershed consists of residential or commercial development, increasing the amount of stormwater containing increased levels of phosphorus. Past management efforts designed to control eutrophication at Wapato included constructing a diversion structure to route phosphorus rich stormwater around the lake. This plan increased the retention time of Wapato to ≈ 8.5 years. We have been tasked by the City of Tacoma to research the prospects of introducing filtered stormwater runoff into the lake to reduce retention time. Our plan includes creating a media filter using a waste product from the drinking water industry “Water Treatment Residuals” (WTR) as an amendment to a sand filter to adsorb and trap phosphorus. To determine WTR’s viability as a media filter we have compared WTR from three drinking water facilities with commercial stormwater filtration media. The WTR and media mixes were compared using a series of experiments including kinetic and batch adsorption isotherm tests to determine the contact time and maximum adsorption of phosphorus as well as tests looking into and dissolved metals in the leachate. In phase 2 of this experiment we will compare the best working WTR mixture to proprietary mixes in terms of its physical filtration capabilities, total and ortho-phosphorus removal using water from Wapato Lake.
Session Title
Session S-10B: Cleaning Our Waters: Moving Forward on Green Infrastructure
Conference Track
Stormwater
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
2-5-2014 1:30 PM
End Date
2-5-2014 3:00 PM
Location
Room 608-609
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Water treatment plant residuals--Biotechnology--Research--Washington (State)--Tacoma; Phosphorus compounds--Decontamination--Research--Washington (State)--Tacoma
Geographic Coverage
Salish Sea (B.C. and Wash.); Tacoma (Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Assessing Water Treatment Residuals as a Filtration Media for Phosphorus Removal at Wapato Lake - Tacoma, WA
Room 608-609
Wapato Lake in Tacoma, WA is a 23-acre urban lake that has had problems of eutrophication and toxic algae blooms for over a hundred years. Inputs of phosphorus from both environmental and anthropogenic sources contribute to this problem. Much of the 900-acre watershed consists of residential or commercial development, increasing the amount of stormwater containing increased levels of phosphorus. Past management efforts designed to control eutrophication at Wapato included constructing a diversion structure to route phosphorus rich stormwater around the lake. This plan increased the retention time of Wapato to ≈ 8.5 years. We have been tasked by the City of Tacoma to research the prospects of introducing filtered stormwater runoff into the lake to reduce retention time. Our plan includes creating a media filter using a waste product from the drinking water industry “Water Treatment Residuals” (WTR) as an amendment to a sand filter to adsorb and trap phosphorus. To determine WTR’s viability as a media filter we have compared WTR from three drinking water facilities with commercial stormwater filtration media. The WTR and media mixes were compared using a series of experiments including kinetic and batch adsorption isotherm tests to determine the contact time and maximum adsorption of phosphorus as well as tests looking into and dissolved metals in the leachate. In phase 2 of this experiment we will compare the best working WTR mixture to proprietary mixes in terms of its physical filtration capabilities, total and ortho-phosphorus removal using water from Wapato Lake.
