Slow Sand Filter Amendments for Clay Removal and Corrosion Control Stephen J. Rooklidge...
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Transcript of Slow Sand Filter Amendments for Clay Removal and Corrosion Control Stephen J. Rooklidge...
Slow Sand Filter AmendmentsSlow Sand Filter Amendments forfor
Clay Removal and Corrosion ControlClay Removal and Corrosion Control
Stephen J. RooklidgeBioengineering Department
Oregon State UniversityJune 23, 2003
OutlineOutline Filter DescriptionsFilter Descriptions Research OriginResearch Origin Laboratory ExperimentsLaboratory Experiments Field ExperimentsField Experiments SummarySummary
ObjectivesObjectivesExpand Slow Sand Filter use by:Expand Slow Sand Filter use by:
evaluating roughing filter pretreatment evaluating roughing filter pretreatment
evaluating limestone amendmentsevaluating limestone amendments
Slow Sand and Roughing FiltersSlow Sand and Roughing Filters
““Passive” treatment methodPassive” treatment method
RF/SSF - physical and biological processesRF/SSF - physical and biological processes
Appropriate for rural regions and developing nationsAppropriate for rural regions and developing nations
RawWater
Waste
Effluent
Roughing Filter Slow Sand Filter
Limestone AmendmentsLimestone Amendments
RawWater
Effluent
Roughing Filter
LimestoneContactor
SlowSandFilter
Two experimental and one EPA-approved limestone amendment positions to alter filter performance and effluent corrosion control
Research filter media materials are basalt, calcite, and dolomite limestone
Research OriginsResearch Origins Slow sand filters of the City of Salem, OR provide drinking Slow sand filters of the City of Salem, OR provide drinking
water for 155,000 residents from the Santiam Riverwater for 155,000 residents from the Santiam River
Research OriginsResearch Origins Santiam River produces filter effluent with pH < 7 Santiam River produces filter effluent with pH < 7
SSF were unable to treat water with > 140 ntu claySSF were unable to treat water with > 140 ntu clay turbidity during the flood of 1996turbidity during the flood of 1996
Research QuestionsResearch Questions
Will roughing filters amended with Will roughing filters amended with limestone enhance clay removal?limestone enhance clay removal?
Will a SSF amended with limestone Will a SSF amended with limestone enhance effluent corrosion control?enhance effluent corrosion control?
Laboratory ExperimentsLaboratory ExperimentsBench-scale RF clay turbidity challenge tests:Bench-scale RF clay turbidity challenge tests:
Compared clay removal of basalt and calcite media Compared clay removal of basalt and calcite media
Calcium Dissolution
48-minute Detention
Ca2+ (mg/L)
BASALT 1.55
CALCITE 8.42
X-Ray DiffractionX-Ray DiffractionQualitatively examined clay removal using changes in Qualitatively examined clay removal using changes in kaolinite and montmorillonite XRD peak area ratios (K/M)kaolinite and montmorillonite XRD peak area ratios (K/M)
Kaolinite ~ 25Kaolinite ~ 25o o / Montmorillonite ~ 27/ Montmorillonite ~ 27oo
0200400600800
100012001400160018002000
22 23 24 25 26 27 28 29 30
2-Theta (degrees)
Inte
nsit
y (c
ount
s)
Clay Removal TrendsClay Removal Trends
BASALTBASALT
CALCITECALCITE
0
1
2
3
4
5
6
7
8
K/M
Influent Effluent
012345678
0 100 200 300 400 500 600 700Time (minutes)
K/M
Pilot-scale ResearchPilot-scale Research Three RF/SSF configurations: Three RF/SSF configurations:
Basalt, Calcite, Calcite-amended Basalt Filter MediaBasalt, Calcite, Calcite-amended Basalt Filter Media 60-day study & 150 NTU clay challenge tests60-day study & 150 NTU clay challenge tests
Flow
To Waste
Overflow
Raw wa ter
Sample Tap
CalciteLimestone
Layer
EffluentPump
SSF
P1P2
P3
Roughing Filter Research ResultsRoughing Filter Research Results
Parameter River BRF/SSF CRF/SSF CBRF/SSFTurbidity (ntu) 150 -88.0 -95.3 -99.6
pH 7.3 -0.4 +14.4 +0.2
Ca2+ (mg/L) 4.1 -0.2 +73.4 +0.4
Alkalinity (mg/L as CaCO3) 30.1 -1.3 +47.8 +13.7Conductivity (S/cm) 36.6 +1.0 +43.7 +12.5
% change during challenge study
SSF Corrosion ControlSSF Corrosion Control
Effluent pH decreased by:Effluent pH decreased by: Microbial activityMicrobial activity COCO22 conversion conversion
Increase effluent pH by:Increase effluent pH by:
Installing dolomite layerInstalling dolomite layer
48 cm from schmutzdecke48 cm from schmutzdecke
EffluentTap
Sand
Dolomite
Sand
GravelWaste Waste
SampleTap
PolyethyleneTank
RawWater
Overflow
Corrosion Control ResultsCorrosion Control Results Effluent met OHD pH requirements for majority of 60-day study Effluent met OHD pH requirements for majority of 60-day study
Saturation Index, alkalinity, and hardness raisedSaturation Index, alkalinity, and hardness raised
5.5
6.0
6.5
7.0
7.5
8.0
8.5
0 10 20 30 40 50 60Time (days)
pH
Active LayerSSF Effluent
Mineral Service Life CalculationMineral Service Life Calculation Constant flow rateConstant flow rate Filter areaFilter area Range of dolomite packed densityRange of dolomite packed density Assumption of stoichiometric dissolutionAssumption of stoichiometric dissolution
CaMg(COCaMg(CO33))2 2
CaCa2+ 2+ + Mg+ Mg2+ 2+ + 2CO+ 2CO33
Verified by:Verified by: EDTA titration hardnessEDTA titration hardness vs. vs. Hardness by Calculation Hardness by Calculation
(P > 0.12)(P > 0.12)
7
8
9
10
1200 1300 1400 1500 1600 1700
Dolomite Density (kg/m3)
Serv
ice
Life
(yea
rs)
Effluent Limestone ContactorEffluent Limestone Contactor
Research study limestone media acquired from:
Ashgrove Rivergate Lime Plant, Portland, Oregon
Contactor Feasibility Decision TreeContactor Feasibility Decision Tree Design contactor length using EPA DESCON program Design contactor length using EPA DESCON program
Parameters needed:Parameters needed: pHpH Alkalinity (DIC)Alkalinity (DIC) CalciumCalcium IronIron ManganeseManganese
Available at Raymond Letterman’s website http://web.syr.edu/~rdletter/Available at Raymond Letterman’s website http://web.syr.edu/~rdletter/
Research ResultsResearch Results
Slow sand filters pretreated by calcite-amended roughing Slow sand filters pretreated by calcite-amended roughing filters comply with regulatory requirements for raw water filters comply with regulatory requirements for raw water clay turbidity <1 to 150 NTU, while enhancing effluent clay turbidity <1 to 150 NTU, while enhancing effluent corrosion control characteristics.corrosion control characteristics.
Dolomite-amended slow sand filters enhance effluent Dolomite-amended slow sand filters enhance effluent corrosion control, and amendment layer service life corrosion control, and amendment layer service life appears acceptable for engineering applications.appears acceptable for engineering applications.
Limestone contactors are an applicable corrosion control Limestone contactors are an applicable corrosion control engineering design for surface waters of the Pacific engineering design for surface waters of the Pacific Northwest.Northwest.
AcknowledgementsAcknowledgements Environmental & Water Resources Institute (ASCE)Environmental & Water Resources Institute (ASCE)
Oregon State University, Oregon State University, Dr. J. Ronald MinerDr. J. Ronald Miner
University of Notre Dame, University of Notre Dame, Dr. Lloyd H. Ketchum, Jr.Dr. Lloyd H. Ketchum, Jr.
City of Salem water operations and engineering staffCity of Salem water operations and engineering staff
Publications:Publications: Rooklidge, S., Ketchum, L., Burns, P. 2002. Clay Removal in Rooklidge, S., Ketchum, L., Burns, P. 2002. Clay Removal in
Basaltic and Limestone Horizontal Roughing Filters. Basaltic and Limestone Horizontal Roughing Filters. Advances in Advances in Environmental ResearchEnvironmental Research, 7/1, 231-237., 7/1, 231-237.
Rooklidge, S., Ketchum, L. 2002. Corrosion Control Rooklidge, S., Ketchum, L. 2002. Corrosion Control Enhancement from a Dolomite-amended Slow Sand Filter. Enhancement from a Dolomite-amended Slow Sand Filter. Water Water ResearchResearch, 36/11, 2689-2694., 36/11, 2689-2694.
Rooklidge, S., Ketchum, L. 2002. Calcite-Amended Roughing Rooklidge, S., Ketchum, L. 2002. Calcite-Amended Roughing Filtration for Clay Turbidity Removal. Filtration for Clay Turbidity Removal. Journal of Water Supply: Journal of Water Supply: Research and Technology- AquaResearch and Technology- Aqua, 51/6, 333-343., 51/6, 333-343.