Moving Bed Biofilm Moving Bed Biofilm Reactor Reactor

Retrofit for Ammonia Retrofit for Ammonia and Nitrate Removaland Nitrate Removal

B&VB&V SACWSD SACWSD

Lela Parsons, P.E.Lela Parsons, P.E. Greg Fabisiak Greg Fabisiak

Mark Maxwell, P.E.Mark Maxwell, P.E. Joan Chavez Joan Chavez

2002 RMSAWWA / RMWEA ANNUAL 2002 RMSAWWA / RMWEA ANNUAL CONFERENCECONFERENCE

Phase 2 Project ComponentsPhase 2 Project Components Wastewater Collection System Wastewater Collection System

Master PlanMaster Plan Utility PlanUtility Plan Preliminary Design ReportPreliminary Design Report Detailed Plans & SpecificationsDetailed Plans & Specifications Contract AdministrationContract Administration

Utility Plan GoalsUtility Plan Goals Provide information required by Provide information required by

DRCOG and for SRF FundingDRCOG and for SRF Funding– Evaluation of existing facilitiesEvaluation of existing facilities– Population & flow projectionsPopulation & flow projections– Environmental assessment to support Environmental assessment to support

FNSIFNSI– Alternative analysis and recommendationsAlternative analysis and recommendations– Implementation and financial plansImplementation and financial plans– Public participationPublic participation

Determine necessary wastewater Determine necessary wastewater facilities for capacity and regulatory facilities for capacity and regulatory compliance through 2020compliance through 2020

Site LayoutSite Layout

WM WWTP Existing Unit WM WWTP Existing Unit ProcessesProcesses

MechanicalScreenings

PrimaryClarifiers

EastTrickling

Filter

FinalClarifiers

Chlorination

Dechlorination

Chlorination

Raw Wastewater

WestTrickling

Filter

FinalClarifier

DegrittingGravity

ThickenerAnaerobicDigesters

Deskins“Quick-Dry”

Filtration SystemTM

Discharge to South

Platte River

Combined Primary &

MBBR Sludge

Accelerated Air Drying of Dewatered Biosolids Prior to Ultimate Disposal

of Class A Product

RotatingBiologicalContactors

P

P

P

P

Flow Splitter

WM WWTP Existing Unit WM WWTP Existing Unit Process CapacitiesProcess Capacities

7.88.4

8.8

4.4

8.3

2.82.4

10.0

4.2

7.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Scree

ning

Raw W

aste

wat

er P

umpin

g

Primar

y Cla

rific

atio

n

Tric

klin

g Filt

ers/

RBCs

Final

Cla

rific

atio

n

Chlorin

atio

n

Dechlo

rinat

ion

Sludge

Thicke

ning

Anaero

bic D

iges

tion

Bioso

lids

Disposa

l

Treatment IssuesTreatment Issues Regulatory ComplianceRegulatory Compliance

– Reclassification of the South Platte River Reclassification of the South Platte River requires additional disinfectionrequires additional disinfection

– Updated model of Segment 15 of the South Updated model of Segment 15 of the South Platte River resulted in imposition of Platte River resulted in imposition of effluent ammonia limiteffluent ammonia limit

Current and Future Water Quality Current and Future Water Quality ConcernsConcerns– Dissolved oxygenDissolved oxygen– AmmoniaAmmonia– NitratesNitrates– NutrientsNutrients

South Platte DischargersSouth Platte Dischargers

Centennial

SACWSD

Brighton

MWRDCentral Plant

Future Sand CreekSatellite WWTP

Littleton-Englewood

Bear

Cre

ek

C

lear

Cre

ek

Sand C

reek

BurlingtonDitch Diversion

Glendale

Segment 14 Segment 15

ChatfieldReservoir

South Platte River

Segments 14 & 15 of South Platte River(Not shown are non-point sources, diversion dams, reaeration structures etc.)

Cherr

y C

reek

Treatment Issues (con’t)Treatment Issues (con’t) WM WWTP Treatment CapacityWM WWTP Treatment Capacity

– Surge in residential and commercial Surge in residential and commercial activity in the service areaactivity in the service area

– Current treatment capacity of 4.4 mgd Current treatment capacity of 4.4 mgd forecasted to only be sufficient through forecasted to only be sufficient through 20032003

– Limited room for additional expansion at Limited room for additional expansion at the existing sitethe existing site

SACWSD Future PlanSACWSD Future Plan Complete Phase 2 expansion at WM Complete Phase 2 expansion at WM

WWTP by 2004 WWTP by 2004 Phase 2 will provide capacity until Phase 2 will provide capacity until

2008 2008 New WWTP will be needed by 2009- New WWTP will be needed by 2009-

could be regional WWTP or SACWSD could be regional WWTP or SACWSD WWTPWWTP

Upgrade WM WWTP when Upgrade WM WWTP when appropriate to meet future water appropriate to meet future water quality regulationsquality regulations

Increase treatment capacity from 4.4 Increase treatment capacity from 4.4 to 7.0 mgdto 7.0 mgd

Notice to proceed issued September Notice to proceed issued September 20022002

Short-term - capacity expansion Short-term - capacity expansion allows growth while new WWTP is allows growth while new WWTP is designed and constructeddesigned and constructed

Long-term - WM WWTP will continue Long-term - WM WWTP will continue to serve the to serve the southern area southern area of the Districtof the District

WM WWTP ExpansionWM WWTP Expansion

Phase 2 ImprovementsPhase 2 Improvements Major ExpansionsMajor Expansions

– Secondary Treatment ProcessSecondary Treatment Process– Solids Handling ProcessSolids Handling Process

Additional ImprovementsAdditional Improvements– Replace Manual Bar ScreenReplace Manual Bar Screen– Demolish RBCsDemolish RBCs– Upgrade Disinfection FacilitiesUpgrade Disinfection Facilities– Add Stand-by Power CapacityAdd Stand-by Power Capacity– Expand Administration Building/GarageExpand Administration Building/Garage

Treatment AlternativesTreatment Alternatives

Activated SludgeActivated Sludge– Anoxic/oxic basinsAnoxic/oxic basins

WAS Pumping WAS Pumping Station and Blower Station and Blower BuildingBuilding

New Aerobic Sludge New Aerobic Sludge HandlingHandling– CentrifugeCentrifuge– Aerated sludge Aerated sludge

holdingholding Biological Nutrient Biological Nutrient

Removal (future)Removal (future)

Fixed FilmFixed Film– MBBRMBBR– Anoxic/oxic basinsAnoxic/oxic basins

Blower BuildingBlower Building Additional Anaerobic Additional Anaerobic

Solids ProcessingSolids Processing– Convert secondary Convert secondary

digester to primary digester to primary digesterdigester

– New secondary digesterNew secondary digester Chemical Phosphorous Chemical Phosphorous

Removal (future)Removal (future) Post Denitrification Post Denitrification

(future)(future)

Alternative A Alternative B

Alternative EvaluationAlternative Evaluation Alternative A slightly less expensiveAlternative A slightly less expensive Alternative A more operationally Alternative A more operationally

complex- requires separate solids complex- requires separate solids handling processhandling process

Alternative B will require chemical Alternative B will require chemical addition for future phosphorous addition for future phosphorous removalremoval

SACWSD has always utilized and SACWSD has always utilized and prefers fixed film processesprefers fixed film processes

Selected Alternative: Selected Alternative: Moving Bed Biofilm Moving Bed Biofilm ReactorsReactors Fixed film process manufactured by Fixed film process manufactured by

KaldnesKaldnes Employs high-density polyethylene Employs high-density polyethylene

plastic media, coarse bubble plastic media, coarse bubble aeration, and sievesaeration, and sieves

Biofilm grows on inside of the mediaBiofilm grows on inside of the media Specific gravity Specific gravity

of 0.96of 0.96 150 ft150 ft22/ft/ft33 media media

surface areasurface area 0.93 %/ft clean 0.93 %/ft clean

water oxygen water oxygen transfer ratetransfer rate

Design ConditionsDesign Conditions 100 mg/L influent BOD100 mg/L influent BOD 2 anoxic and 2 oxic reactors in 2 anoxic and 2 oxic reactors in

seriesseries 60% fill in each reactor60% fill in each reactor Coarse bubble diffuser system in oxic Coarse bubble diffuser system in oxic

reactorsreactors Submersible propeller mixers in Submersible propeller mixers in

anoxic reactorsanoxic reactors 4 mg/L summer DO concentration4 mg/L summer DO concentration 5 mg/L winter DO concentration5 mg/L winter DO concentration 200% internal recycle for nitrate 200% internal recycle for nitrate

removalremoval

Treatment RequirementsTreatment Requirements East Plant EffluentEast Plant Effluent

– BODBOD55 reduction <10 mg/L reduction <10 mg/L– Total ammonia reduction <2 mg-N/L Total ammonia reduction <2 mg-N/L

(complete nitrification)(complete nitrification)– Total nitrate reduction <10 mg-NOTotal nitrate reduction <10 mg-NO33/L /L

(partial denitrification)(partial denitrification)

Blended Effluent (East and West Blended Effluent (East and West Plant)Plant)– CBOD reduction <25 mg/LCBOD reduction <25 mg/L– Total ammonia reduction <10 mg-N/L Total ammonia reduction <10 mg-N/L

Selected Alternative Flow Selected Alternative Flow SchematicSchematic

MechanicalScreenings

PrimaryClarifiers

EastTrickling

Filter

AnoxicMBBR

OxicMBBR

FinalClarifiers

Chlorination

Dechlorination

Chlorination

Raw Wastewater

WestTrickling

Filter

FinalClarifier

DegrittingGravity

ThickenerAnaerobicDigesters

Deskins“Quick-Dry”

Filtration SystemTM

Discharge to South

Platte River

Combined Primary &

MBBR Sludge

Accelerated Air Drying of Dewatered Biosolids Prior to Ultimate Disposal

of Class A Product

Existing Facilities

Phase 2 New

Phase 2 Modified

P

P

P

P

P

Flow Splitter

Operational IssuesOperational Issues Portion of primary effluent must be Portion of primary effluent must be

bypassed around existing trickling bypassed around existing trickling filterfilter– Requires construction of a new flow Requires construction of a new flow

splitter structuresplitter structure– Prevents hydraulic surcharging of Prevents hydraulic surcharging of

underdrainsunderdrains– Assures sufficient soluble BOD for Assures sufficient soluble BOD for

denitrificationdenitrification– Allows ETF pumping station to be taken Allows ETF pumping station to be taken

out of serviceout of service

Trickling filter snail accumulationTrickling filter snail accumulation– Installed an automatic, self-cleaning Installed an automatic, self-cleaning

strainer with 1/8- inch openings at the ETF strainer with 1/8- inch openings at the ETF pumping stationpumping station

Total Project CostsTotal Project Costs

Engineer’s ConstructionEngineer’s Construction

Cost OpinionCost Opinion

Low Bid PriceLow Bid Price

Difference Between High Difference Between High

and Low Bidsand Low Bids

$13,283,00$13,283,0000

$12,774,00$12,774,0000

$475,300$475,300