AIR SCOUR DEMONSTRATES FILTER PERFORMANCE AND ECONOMIC BENEFITS

IN QUEEN LANE WATER TREATMENT PLANT

Jamie Shambaugh, Lori Kappen (GF)Jerry Kuziw, Shiju Kuriakose, Kate Guest, Ya-Chi Tsao

(PWD)

Acknowledgement

• Queen Lane WTP– Processes raw water from the Schuylkill River– Ferric chloride coagulation, flocculation, and sedimentation– 40 dual-media filters– Average of 62.7 mgd processed (2015)– Median filter surface loading rate 1.1 gpm/sf– Average 63 hour filter run time (2015)

• Full-scale filter air scour demonstration test – Assess advancing filter backwash performance – Quantify potential filter system efficiency improvements

• Field optimization and data collection to evaluate:– Technical and economic benefits of air scour enhanced BW– Comparison of air scour test filters to remaining 38 baseline filters

Introduction and Objectives

• Focus of evaluation:– Improve filter media cleaning– Reduce backwash water usage– Reduce process wastewater production– Extend filter runtimes– Reduce power usage, and– Enhance operations and stormwater relief

• Evaluate potential economic and environmental benefits• Limited opportunity to improve filter effluent quality

– Consistently <0.10 NTU• Maintaining filter effluent quality critical

– Partnership for Safe Water participant– LT2 Bin 2 requirements

Objectives

• Removed surface wash equipment and installed Aries® air scour system from Filters 17 and 19

• Installed temporary electrical equipment, blower, and air piping• Collected additional field samples:

– Baseline filters 18 and 20– Experimental filters 17 and 19

Test Arrangement

Baseline Filters No.18 and 20 Test Filters No.17 and 19

Air Scour Blower and Air Supply Header

Air Supply Header, Flow Meter, Blower Control

Air Scour Timer and Filter Air Supply Isolation Valve

Filter Air Supply Isolation Valve, Air Header, and Drop Pipes

Air Scour Drop Pipes and Air Distribution Grid

Operating Air Scour System

Air Scour Test Protocol - Data Collection

• Filter operating performance– Filter effluent turbidity– Filter effluent particle counts

• Filter Backwash– Filter pre- and post- headloss– Run time– Backwash protocol– Power usage– Backwash water usage– Media expansion

• Filter cleaning efficiency– Backwash turbidity profiles– Acid solubility– Floc retention

• Filter Media Characteristics

• Mechanical Performance Test• Phase 1 – Baseline Operation

– Baseline and Test Filters Backwashed same (except air scour)• Phase 2 - Optimize High Rate Backwash Duration

– Incremental reduction from 8 to 4 minutes• Phase 3 - Optimize Initial Low Rate Backwash Duration

– Incremental reduction from 4 to 2 minutes• Phase 4 - Optimize Air Scour Duration

– Compare 5 minute and 2.5 minute air scour• Phase 5 – Optimize High Rate Backwash Rate

– Incremental reduction of rate by 2,000, 2,500, and 3,000 gpm• Phase 6 – Optimize Backwash Procedure

– Reduce high wash rate, increase final low wash duration

One-Year Test Plan

Filter Effluent Turbidity Performance

• Pre-test turbidity– <0.1 NTU

• Turbidity varied over test period (all filters)

• Air scour resulted in no discernable turbidity impacts– Very low turbidity produced

by baseline filters– Goal was no negative

impact Partnership LT2

Typical Filter Effluent Particle Counts (2µ- 5µ)

Post-Backwash Particle Count Spike Duration (2µ- 5µ)

Phase 1 - Baseline OperationBackwash Turbidity Profile

Phase 1 - Baseline OperationBackwash Turbidity Profile (Linear Scale)

Phase 2 – Reduced High Rate Backwash DurationBackwash Turbidity Profile

Phase 3 – Reduced Initial Low Rate Backwash DurationBackwash Turbidity Profile

Phase 4 – Reduced Air Scour DurationBackwash Turbidity Profile

Phase 5 – Reduced High Rate Backwash Flow RateBackwash Turbidity Profile

Phase 6 – Additional Backwash Protocol OptimizationBackwash Turbidity Profile

Estimated Material Removed During Backwash

Air Scour Test

PhaseBackwash

DateFilter

Number

Duration (minutes)

High Rate Backwash Flow Rate (gpm)

Approximate Material Removed

(kg)Air Scour

Initial Low Rate Wash

High Rate Wash

Final Low Rate Wash

Phase 1

12/9/2015 18 5.0 4 8 1 16,500 16.51/7/2016 17 5.0 4 8 1 16,500 23.91/7/2016 19 5.0 4 8 1 16,500 22.6

1/22/2016 18 5.0 4 8 1 15,000 14.01/27/2016 17 5.0 4 8 1 15,000 19.91/27/2016 19 5.0 4 8 1 15,000 16.8

Phase 3

4/4/2016 17 5.0 4 4 1 17,000 23.24/18/2016 17 5.0 4 4 1 17,500 30.84/29/2016 20 5.0 4 8 1 19,000 20.1

5/3/2016 17 5.0 3 4 1 18,500 28.25/19/2016 17 5.0 3 4 1 18,500 30.9

6/2/2016 20 5.0 4 8 1 20,000 21.56/2/2016 17 5.0 2 4 1 20,000 30.0

6/21/2016 17 5.0 2 4 1 20,500 30.3

Phase 5

9/16/2016 17 2.5 2 4 1 21,500 19.99/16/2016 19 2.5 2 4 1 19,000 18.79/27/2016 18 2.5 4 8 1 21,000 11.29/28/2016 17 2.5 2 4 1 21,000 18.19/28/2016 19 2.5 2 4 1 18,500 14.2

10/20/2016 17 2.5 2 4 1 19,500 11.310/20/2016 19 2.5 2 4 1 16,500 10.9

Post-Backwash Filter Bed AppearanceAugust 16, 2016

Filter 17 – Air Scour Filter 20 – Surface Wash

Filter Headloss Accumulation Rate

Pre-Test Data

Test Data

Filter Run Length Comparison

• Improve the overall integrity of filters• Lower post-backwash turbidity peak• Less usage of backwash water pump • Higher operation runtime flexibility

• Better response to challenged source water quality (drought)• Maintain filter performance (headloss, runtime, filter-to-waste)

• Less maintenance • Less parts replacement and labor

Ease of Operation

Existing

Backwash

Procedures

Air Scour

Backwash

Air Scour

Backwash –

Extended Run

Times

Power

kWh/backwash 68.2 45.8 45.8Annual Cost $ 28,000 $ 19,000 $ 15,000

Washwater Production and Wastewater Transfer

Washwater/Backwash, gal.

245,000 156,000 156,000

Annual Cost $ 308,000 $ 196,000 $ 157,000Maintenance $ 110,000 $ 50,000 $ 50,000Total $ 446,000 $ 265,000 $ 222,000

Annual Operating Cost ComparisonSurface Wash and Air Scour

Present Worth Comparison of Filter Wash System Options

Backwash Method Capital Cost Annual Operation and Maintenance

Costs

20-year Present Worth of

Annual Costs

Total Present Worth

Baseline $ 3,800,000 $ 446,000 $ 6,490,000 $ 10,290,000

Air Scour $ 4,800,000 $ 265,000 $ 3,860,000 $ 8,660,000

Air Scour -

Extended Run Time$ 4,800,000 $ 222,000 $ 3,230,000 $ 9,790,000

Compared to Surface Wash Backwash, Filter Air Scour Backwash:• Improves removal of material from filter bed• Allows reduced backwash flow rates

– High wash rate reduction of up to 3,000 gpm• Allows reduced backwash durations

– High wash duration reduction of 50%• Reduced washwater use and wastewater production by 35%• Could allow for extended filter run times

– Additional water and energy savings• With extended low wash duration (ETSF BW), can reduce post-BW

turbidity spike• Consistent with PWD’s reliability, regulatory compliance, and

environmental stewardship mission

Conclusions and Recommendations

Thank You!