silicon valley advanced water purification center...
TRANSCRIPT
SILICON VALLEY ADVANCED WATER PURIFICATION CENTER
WATER QUALITY
Steve R. Twitchell T-5 Santa Clara Valley Water District
Nov 21, 2014
Overview
2
SVAWPC treatment processes
SVAWPC product water quality and monitoring
Current recycled water quality in the South Bay Water Recycling (SBWR) system
Benefits of improved recycled water quality
SVAWPC process schematic
3 3
WPCP Secondary Effluent (TDS = 700 ppm)
Highly purified water (TDS ~40 ppm)
Microfiltration Reverse osmosis
Ultraviolet light
SVAWPC location
4
San Jose-Santa Clara Regional Wastewater Facility
Silicon Valley Advanced Water Purification Center
SVAWPC layout
5 5
SA
TI
NAOH
RO CIP
MF CIP
NOCL
NHOH
Influent Pumps
IPST
RO Transfer Pumps &
CFs MF RF Pumps
RO
#3
#2
#1
UV
Decarbination
Waste Equalization
Wetwell
PWST
MF
Control Room
Influent pumps
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Autostrainers
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SVAWPC treatment processes
9 9 Recycled Water Customer Workshop – May 17, 2013
Microfiltration (MF) Units
Produces high quality feed water for RO membranes:
<0.5 NTU instantaneous turbidity, <4 Silt Density Index at any time
Microfiltration
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Microfiltration
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Interprocess storage tank and RO pumps
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Cartridge filters
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Reverse osmosis feed pumps
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Reverse Osmosis (RO) Units Remove aqueous salts, metal ions, viruses, etc. Lower TDS to <60 mg/L
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Recycled Water Customer Workshop – May 17, 2013
SVAWPC treatment processes
Reverse osmosis units
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Reverse osmosis module
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Reverse osmosis video
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Decarbonation towers
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Ultraviolet disinfection
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Ultraviolet (UV) Disinfection UV irradiation is used for disinfection / inactivation of pathogens meeting CDPH disinfection requirements UV also addresses NDMA (N-Nitrosodimethylamine), a probable carcinogen (Notification Level=10 ng/L)
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RO Permeate UV Effluent to Product Water Storage Tank
Ultraviolet disinfection
Product water storage tank
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Chemical additives
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Sodium Hypochlorite Aqua Ammonia
Sodium Hydroxide Citric Acid
Sulfuric Acid
Threshold Inhibitor Sodium Bisulfite Phosphoric Acid
Hydrogen Peroxide RO CIP Chemicals
Current SBWR recycled water quality
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Water Quality 2014 Parameter Average Minimum Maximum TDS, mg/L 609 467 856
Turbidity, NTU 0.6 0.3 1.2
TSS, mg/L <1.0 <1.0 <1.0
pH 7.7 7.4 8.0
Alkalinity, mg/L 156 128 204
Ammonia, mg/L 1.4 1.0 2.5
Conductivity, umhos/cm 1,070 846 1390
Nitrate, mg/L 11.0 8.8 15.2
Nitrite, mg/L <0.23 0.03 1.1
Hardness, mg/L 216 172 293
Bicarbonate, mg/L 156 128 204
BOD, mg/L 2 0 7
Temperature, °F 71.8 61.5 79.5 Total Coliform Count, CFU/100ml <1 <1 2
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Current SBWR recycled water quality cont…
0
100
200
300
400
500
600
700
800
Jan/ Feb Mar/Apr May/Jun Jul/Aug
787
629
516 513
TDS
2014 SJ/SC Water Pollution Control Plant Average TDS Levels
SVAWPC water quality
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PARAMETER TREATMENT GOAL pH 6.5 ≤ pH ≤ 8.5 Chlorine Residual 5 – 10 mg/L (at any time) Dissolved Oxygen >1.0 mg/L (at any time) Dissolved Sulfide <0.1 mg/L (at any time) Total Dissolved Solids (TDS) <60 mg/L (at any time) Total Coliform 2.2 MPN/100 mL (7-day median)
23 MPN/100 mL (any sample) Turbidity <0.2 NTU (average 24 hours)
<0.5 NTU (at any time) Maximum Filtered Water Silt Density Index (SDI)
<3.0 (98% of the time) <4.0 (at any time)
Blended Product Water 500±50 mg/L
Total dissolved solids in perspective
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Benefits of improved recycled water
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Save $$$ - Customers can save by reducing impacts to vegetation and reducing the levels of pretreatment needed for industrial purposes
Increase use of recycled water by making it more suitable for irrigation, commercial and industrial purposes
Protect the region’s high-quality groundwater supplies
Reduce freshwater discharge to the San Francisco Bay
Preserve the natural tidal habitat
Questions ?