air scour demonstrates filter performance and … · • phase 3 - optimize initial low rate...
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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!