Dipankar Sen, PhD, PE
Santa Clara Valley Water District
Professor, Virginia Tech Civil & Env Engr
Outline Changes in wastewater in our industry
How it affects the wastewater treatment plant
Advanced Wastewater Treatment Configurations and their Operation
Recycled water production
Configurations
Managing Risk – how will operations change?
Ways to plan for the future
Climate change, drought cycle, wet weather
Upgrade for Nitrogen Removal Nitrogen removal is typically required for discharge to
sensitive Bays
Chesapeake Bay
Ocean discharges and Estuaries have not required this
In biological systems, typical pathway is:
Nitrification
Denitrification
Alternate pathways
Nitritation, Annamox mediated denitrification
What do you have to do to Nitrify at your plant?
MCRTMLSS TemperatureOxygen requirementAlkalinity requirement
What do you have to do to Denitrify?
Organic Carbon requirementCreate anoxic conditionAmount of biomass Supplemental C?
Upgrade for Nitrogen Removal –Santa Rosa
Source: Google Maps
Activated SludgeTank
MembraneTank
Upgrade for N Removal - Redlands MBRSlide: Courtesy of City of Redlands;Dave Commons; Membrane GE Zenon
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Slide: Redlands MBR Plant
Slide: Courtesy Redlands Dave Commons; Membrane – GE Zenon
GE ZenonMembranes
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Phosphorus Removal Chemical P Removal
Biological Excess P Removal
Westminster WWTP, MD
Anaerobic
Anoxic
Source: Google Maps
IViewOps Screen, Westminster
Ref: WEFTEC 2013, 2016
Four Tanks, two different types of diffusers serviced by one or two blower systems
View of Tank with Parkson Panel Diffusers
Setup at a Plant (adjacent to SCADA computer)
Westminster – secondary effluent
Plant was able to remove P through BEPR alone when effluent permit was 1 mg/L
Tertiary Effluent – BNR, to be upgraded to ENR (4 mg/L TN, 0.3 TP)
Wet Weather Operations Management Even if you have upgraded your plant for recycled
water production to adapt for climate change, you have to manage for wet weather operations
Santa Rosa, CA
Wants to avoid discharge to stream because it requires operating to a more stringent TP permit
Westminster, MD
Wants to be able to sustain nutrient removal, septage and sludge processing operations during wet weather
Plant has flows from areas served with combined sewers
Provide intelligence to anticipate, plan and adapt for wet weather operations
Upgrade for N Removal – Impact of Solids Handling Can your solids dewatering operations affect effluent
ammonium-N and nitrate-N?
42 mgd AADF54 mgd MMDF75 mgd PWDF128 mgd PDF185 mgd PIF
UOSA Millard H. Robbins, Jr.Water Resource Recovery Facility
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PE Flow, MGD
SE NO3N, mg/L
PE NH4N mg/L
Centrate, gpm
No Centrate RecycleCentrateRecycle
CentrateRecycle
Flow weighted average = 15.1 mg/L
CentrateRecycle
No Centrate Recycle
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PE Flow, MGD
PE NH4N, mg/L
SE NO3N, mg/L
Centrate, gpm
Measured valuesSimulated trend
Fluctuation Error - NO3N probe readings tend to fluctuate more widely than lab readings
Note how timing of peaks & valleys of simulation match Data from probe. Based on this, simulator used for optimizationCentrate recycle causes values to increase
Figure 6. Fifteen minute Secondary Effluent Nitrate-N, Actual and Simulated for Calibration Periods in Table 2Simulation matches the roller coaster effect on effluent NO3N. Modelling identified the causes of the roller coaster effects. Simulations can determine if probes need calibration; after calibration can test ways to improve effluent nitrate.
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Nitrate-N Probe Average Error –Probe = 10.2; Model =15.1 ; Lab Sec Eff 15.9 mg/L .
IViewOps Application at UOSA
Plant Simulation Scenarios, Views, Sub Views in IViewOps3 CSS
CDSESS
Winter Opt
ViewsMainHWETWTSCSH
Are there other effects of digestion and dewatering operation on recycled water? Dewatering
Polymer
Coagulant
Refra ctory organic nitrogen
Anaerobic digestion
Thermal hydrolysis
What helps generate better water quality for recycled water production?
Higher MCRT?
Nitrification?
Denitrification?
Type of coagulant?
Alum, ferric
PPCPs?Consistency in TSS?For Agricultural reuse?Groundwater recharge?RO operation?Carbon filter operation?