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

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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?