Ballasted Sedimentation for Water & Wastewater Treatment

Home , Clarifier, Drying, Settling basin

PNWS-AWWA Conference May 5, 2017 Jeff Marrs, Plant Manager, City of Anacortes Water Treatment Plant Jeff Lundt, P.E., King County Tina Hastings, P.E., CH2M Jason Curl, P.E., CH2M

Agenda Technology Overview Water Treatment • City of Anacortes Water Treatment Plant • Woodland-Davis Regional Water Treatment Plant Wastewater Treatment Technology Overview

Ballasted Sedimentation

QMJ, November 2003

3 Ballasted Sedimentation

Process Overview Sludge

Separator

Sand COAG Polymer

Influent Effluent

Clarifier Mixing / Flocculation / Coagulation Maturation

4 Solids RapiSand™ Ballasted Sedimentation Technology Selection

• Veolia/Kruger: Actiflo® • Degremont: DensaDeg® Evoqua: CoMagTM Actiflo® • • WesTech: RapiSandTM

DensaDeg®

5 Actiflo®

6 Sand Pumps

7 Plates vs. Tubes

Plate Tubes Material 316 SST Polystyrene, black UV resistance Good Recommend to submerge in water Expected Life > 30 years 10 - 15 years Hose down < 90 psi < 40 psi pressure Performance Good Slightly better Installation Easier (lighter) Cost + $0.25M for a 35MGD train Applications Optional Standard (most (Salem, drinking water Tacoma, plants, Anacortes) 8 Bremerton) Water Treatment

Case Study: City of Anacortes Water Treatment Plant

9 City of Anacortes Water Treatment Plant

. Project drivers and objectives . Skagit River Basin and Raw Water Quality Characteristics . Treatment process systems . Reliability / Sustained Operations - considerations and features . Optimization . Operator Challenges and Response

10 Anacortes Water System Service Area

Anacortes Tesoro & Shell Oil Refineries Mount Del Mar Vernon

La Conner Swinomish Tribe

Skagit PUD Naval Air Oak Harbor 11Station Project Drivers – Challenges/Limitations

• Floodplain elevation • Challenging Raw Water Quality  Dramatic fluctuation of Turbidity and Color • Ineffective Pre-treatment • Need to Expand Treatment Capacity  2007 max. day demand: 29 MGD  2030 max. day demand: 40.7 MGD • Condition of existing structures • Reliability and Redundancy needed for continuous operations

12 Skagit River Basin

13 Source: Skagit County Source: USDA Forest Service Raw Water Quality (2003-2008)

• Turbidity  Average: 28 NTU  95th-%: 81 NTU  98th-%: 164 NTU  Maximum: 5475 NTU • Color: 1 – 4872 Pt Co • pH: 6.5 - 7.8 • Alkalinity: 16-38 mg/L • TOC 0.5 to 3.0 mg/L

14 Selected Treatment Scheme

• Ballasted sedimentation

• Rapid sand filtration

• Chlorine contacting – CT compliance

• Finished water pH adjustment

15 HIGH SERVICE PUMPS

LOW LIFT / BW / FTW CLEARWELL PUMPS BALLASTED SEDIMENTATION

16 2013 Treatment Process

Ballasted Lagoons Sedimentation Standby High Service (2 trains) Generators Pumps

FW Storage Tank Decant PS Pipe Gallery (Lower), Electrical and Operation Control (Upper) 8 Filters 17 Design Production Requirements

• Treatment capacity – 42 MGD

• Future expansion capacity – 55 MGD

• Emergency conditions treatment capacity – 21 MGD

18 Ballasted Sedimentation Process Microsand Add Coagulant Microsand Particle to Grow Large Particle Floc particles

Large Solid Floc Particles Particle Flocculate

Add Ballast and Polymer Organic Particle

Distance Attach Particles to Ballasted Flocculation Ballast to Increase Settling Ballast Velocity Settling – use plate

19 settlers to enhance separation Time Ballasted Sedimentation - Actiflo

SLUDGE (0.5 to 1%)

HYDROCYCLONE BALLASTED FLOCS TO HYDROCYCLONE POLYMER MICRO-SAND

CLARIFIED WATER

ALUM / CAUSTIC / SODA ASH COAGULANT

RAW WATER INJECTION COAGULATION MATURATION TUBE SETTLER WITH SCRAPER

20 Manufacturer: Kruger Key Design Parameters from Actiflo Pilot Testing

Hydraulic Raw Coagulant Polymer Target Settled Mixing Loading Rate Turbidity Dose Dose Water pH with Speed (HLR) (NTU) (mg/L) (mg/L) Lime Dose (Hz) (gpm/ft2)

Low Not 18 0.4 90 18 - 43 (< 15) Required High (up to 50* 0.5 7.55 90 18 - 43 2200)

21 Treatment Goals for Ballasted Sedimentation

Raw Water Turbidity Range Settled Water Turbidity Less than or equal to 200 NTU Less than or equal to 2 NTU

Between 201 NTU and 500 NTU Less than or equal to 3 NTU Greater than 500 NTU Less than 5 NTU

Settled Water Quality Performance Requirements

Parameters Settled Water Quality Criteria Target: Not greater than 1 NTU Turbidity, 95th percentile: Not greater than 2 NTU* NTU 98th percentile: Not greater than 5 NTU * Washington Department of Health (DOH) Treatment Optimization Program

22 turbidity goal Ballasted Sedimentation System

Two parallel trains with 27 MGD capacity each

23 Ballasted Sedimentation Equipment

Ballasted Sedimentation System – Micro-sand Recycle Pumps

24 Ballasted Sedimentation - Equipment

Ballasted Sedimentation Ballasted Sedimentation System System Hydrocylones Mixer Drives

25 Filtration System – 8 Cells, each with 2 bays

26 Residuals Handling Three lagoons: . Floating decanter each lagoon . One in-service . Decant water booster . One in standby pumps for high river . One out-of-service level conditions

27 Residuals Handling

28 Optimization

29 Optimization

• Aluminum Sulfate – Range from 5 – 40 mg/L depending on river changes. • Coagulant Polymer – Ranges from 0.40-0.50 mg/L – Not frequently adjusted. – Carry over to filters • Caustic Soda – Used for pH control when raw water does not meet treatment requirements. – Ranges from 1.0 – 6 mg/L 30 Optimization

• Microsand

– Maintain 3-6 grains per liter. (manufacturers recommendation) – Rarely add sand due to high sediment in source water – Regular monitoring with infrequent adjustments. – Highest amount of maintenance required. • Soda Ash – Used for alkalinity control – Not regularly used

31 Optimization

• Following year 1 of operation, operators began experimenting with chemical dose ranges. • Resulted in reduced chemical costs with improved results. • Added laboratory analysis for quality control

32 Challenges with Operating a Surface Water Plant

• Frequent Changes in Source Water • Seasonal Challenges • Equipment Failure • Chemical Feed Issues – Late to respond – Over/under dosing – Operator Interpretation

33 Operator Challenges

• Frequent changes in source water conditions • Imbalance in chemical doses in pre- treatment process affects filter operations • Changes can occur in minutes due to short detention time (This is a good and bad thing). • Due to high flow demand and limited storage operators have little time to correct any problems.

34 35 36 Typical Results

• Raw Water – 5 – 1100 NTU – 7.00 -7.40 pH – Alkalinity is 15 – 30 mg/L • Settled Water – Target is less than 1.0 NTU at all times. Typical is less than 0.50 NTU. 95% or greater removal typical. – pH range is 6.80 -7.20 – Alkalinity is 15-25 mg/L

37 Typical Results

• Filtration – Alum is added to aid in filter performance (1.0-1.5 mg/L) – Filter Aid Poly is added for enhanced performance – Typical run time varies but normally is 72-96 hours. – Finished water turbidity is typically 0.020 NTU or less.

38 Results

1050 Raw Water NTU 0.90 NTU Settled 99.9 % Removal

39 Tips For Success

• Operator Training is Essential • Preventive Maintenance Program • Corrective Action Program • Plant SOP’s • Process Instrumentation Maintenance Program • Post Incident Analysis and Review • Communication

40 Water treatment

Case Study: Woodland-Davis Clean Water Agency (WDCWA) Regional Water Treatment Facility

41 Overall Regional System

Length: 4.5 miles Diameter: 36 inches

Location: River mile 70.8 Maximum Combined Diversion: 400 cfs Total Capacity: 30 mgd Woodland: 18 mgd Davis: 12 mgd

Length: 9.9 miles Diameter: 36 inches

42 42 Process Locations Maintenance Operations Solids Drying Bed Chem SBC

Ozone

Backwash Filtration Thickeners Pump Station

Clearwell Clearwell

Solids Drying Effluent Pump Bed Station

43 43 Woodland-Davis Process Flow Diagram

Chemical Addition

Pump Ballasted Sedimentation Ozone Filtration Clearwells Raw Water Station

Gravity Effluent

Thickener Solids Effluent Woodland

Pump Backwash Station

Solids Drying Effluent Davis Beds Pump Station

44 Landfill Sand Ballasted Clarification

• Purpose: Flocculation of destabilized particles into settleable floc and settling of particles • Treatment Criteria: – Turbidity: 85 – 99% removal – DBP precursors: 20 – 35% removal – Manganese: 85 – 99% removal – Iron: 85 – 99% removal – TOC: 20 – 35% removal – Aluminum: 85 – 99% removal

45 SBC – Design Criteria Item Values Units Max Combined Flow* 31.6 mgd Min Combined Flow 7.0 mgd Number of Trains 3 Design Flow per Train 10.53 mgd Coagulation Tank HRT 2 min Minimum Pump Flow 831 gpm Maturation Tank HRT 4.2 min Tube Settler Overflow Rate 30 gpm/ft2 Settling Basin Loading Rate 30 gpm/ft2 Max Settled Water Turbidity 2 NTU Sand Recirculation Flow per Train 225 gpm Sand Recirculation Pumps per Train 1 duty, 1 standby Hydrocyclones per Train 1 duty, 1 standby *Max combined flow based on raw water treatment flow, plus unthickened solids flow, plus backwash supply flow Trains are sized so that max combined flow can be treated with one unit offline. Settled effluent turbidity may increase, requiring more frequent filter backwashing as filter loading increases. 46

Overview – Actiflo® TURBO

• Fundamentals – Coagulation tank – coagulated water mixed to form floc Veolia Water, 2009 – Flocculation/Maturation tank – add polymer and microsand, mix, enhance floc – Settling tank – lamella tubes decrease distance floc needs to fall – Scrapers – moves unthickened sludge, sand recirc pumps withdraw sludge – Hydrocyclones –separate microsand from sludge, sand returned to maturation tank, sludge

47 to thickeners Combined Sewer Overflow treatment

Case Study: Georgetown Wet Weather Treatment Station

48 Brandon and Michigan Outfalls • Control existing South Michigan and Brandon combined sewer overflows (CSO) • Meet County’s CSO Consent Decree schedule • Meet County’s budget objectives

LEGEND City of Seattle CSO Outfall King County WTD CSO Outfall King County WTD CSO addressed by GWWTS 49 System Operation

• Dry Weather Flow

50 System Operation

• Wet Weather Flow (Storage)

51 System Operation

• Dry Weather Flow + Draining Storage

52 System Operation

• Wet Weather Flow (Treatment)

53 System Operation

• O&M Activities for discharge to EBI – Solids Discharge, Flushing & Draining, Commissioning, Training

54 Ballasted Sedimentation Comparison (CSO)

Actiflo® DensaDeg® CoMag™ RapiSand™ Vendor Veolia Water Infilco Evoqua Water WesTech Solutions and Degremont, Inc. Technologies Engineering Technologies, Inc. Clarifier SOR Up to 60 gpm/sf 35 to 50 gpm/sf 30 to 50 gpm/sf 38 gpm/sf (with lamellas) Ballast Microsand Recycled sludge Magnetite and Microsand recycled sludge Ballast 2 to 5 g/L N/A 0.6 to 0.9 g/L 2 to 5 g/L concentration Ballast recovery Hydrocyclone N/A Shear mill and Hydrocyclone technology permanent magnet drum Start time 10 to 20 minutes 15 to 20 minutes Approximately 15 10 to 20 minutes (less than 6 hours minutes idle) Requirement on Most stringent No specific Relatively Most stringent screening (approximately requirement stringent (approximately 10-mm opening (approximately 10-mm opening

55 perforated plate) 20-mm opening) perforated plate) Ballasted Sedimentation Process Overview

56 Process Flow Diagram

To EBI Solids Storage

To EBI

Influent Pump UV Ballasted Sedimentation Regulator Station Disinfection Outfall Screenings / Handling

Chemical Addition Recirc 57 To EBI Cross Section Through Treatment Processes

58 Process Flow Diagram and Sampling Points

Samplers Sample tap Online instrumentation

pH pH pH Turb Tur pH b

Tur b p p H H Tur b

59 Treatment Process

500 - UV Disinfection 600 – Solids Holding Tank

400 - Ballasted Sedimentation

Caustic Storage

800 – Electrical Building Polymer and metering 60 Coagulant pumps Storage Treatment Process

61 Treatment Process Train

Rapid Coagula- Matur- UV C3 Storage \ Settling Mix tion ation UV Pump Room Drop Struct Recirc/ 62 Ballasted Sedimentation UV Disinfection flushing Coagulant Addition