Ferric Sulfate Success Story - OWASA s Switch to Ferric Sulfate Leads to a Reduction in Disinfection Byproducts

Transcription

1 Ferric Sulfate Success Story - OWASA s Switch to Ferric Sulfate Leads to a Reduction in Disinfection Byproducts NC AWWA-WEA CONFERENCE NOVEMBER 13-16, 2016 Orange Water and Sewer Authority A public, non-profit agency providing water, sewer and reclaimed water services to the Carrboro-Chapel Hill community.

2 Orange Water and Sewer Authority Public, non-profit agency Provide water, wastewater and reclaimed serves to the Carrboro-Chapel Hill Community Serve over 83,300 customers Partnership for Safe Water Phase IV Excellence in Water Treatment (5 Years Consecutive) Area-Wide Optimization Program (AWOP) (5 Years Consecutive)

3 Water Treatment Plant Process 20 MGD Capacity average 7.2 MGD Surface Water Treatment Coagulation Flocculation Sedimentation Conventional Super Pulsators Filtration Disinfection Optional Permanganate Feed Primary Coagulant Coagulant Aid Potassium Permanganate Powder Activated Carbon Sodium Hydroxide Pulsators

4 Our Journey Managing Change Research & Evaluation Consulting with State Regulators Community Engagement Making Plant Process Changes Communicating Results OWASA Jones Ferry Water Treatment Plant Staff

5 Reasons for Resisting Change No reasons to change Fear of the unknown Fear of failure Fear of the loss of security Lack of resources

6 Successfully Implementing Change Clearly communicate the need for the change Clearly communicate the path forward Have backup plan Get people involved Find ways to build confidence in the team Be supportive Regularly communicate those positive results through the process

7 Research & Evaluation Jar Tests Research Articles Visit other Utilities Chemical Distributors

8 Consult with State Regulators! Approved for a 2-Year Trial Developed a Water Quality Sampling Plan Turbidity Total Organic Carbon/Dissolved Organic Carbon Disinfection By-Products Water Quality Parameters (Corrosion Control) Temperature ph Alkalinity Conductivity Calcium Hardness Ortho-Phosphorous Chloride to Sulfate Ratio Lead and Copper Robert Herring (OWASA Laboratory Analyst) performing water quality testing.

9 Community Engagement News Releases Water Quality Report Card Newsletters Bill Inserts

10 Process Changes Caustic Feed Additions Raw Water Individual Filters Created Target phs Flash Mix Individual Filters > 6.5 Raw Water Caustic Addition Individual Caustic Addition

11 Trending Pulsator Turbidity vs. ph Pulsator Turbidity ph Turbidity (NTU) ph /1/2015 2/4/2015 2/7/2015 2/10/2015 2/13/2015 2/16/2015 2/19/2015 2/22/2015 2/25/2015 2/28/2015

12 Ferric Sulfate Advantages Ferric Sulfate is a low cost iron salt. Ferric Sulfate more versatile works at a wider range of raw water conditions. Ferric produces a heavier floc that settles better during the colder months. Ferric Sulfate is better at removing more total organic carbon. Disadvantages x Requires a larger dose. x Requires additional ph adjustments within the treatment process. x Produces more solids, due to the increased amount of solids removal. x Harsher on equipment and structures. x Staining

13 Total Organic Carbon (TOC) Removal Percent Removal Increased Total Organic Carbon Removal by 10%

14 Finished Water Total Organic Carbon Average Finished Water TOC decreased from 2.14 to 1.33 mg/l Concentration (mg/l)

15 Trihalomethanes (THMs) Reductions Overall Reduction of 42% Average Concentration (mg/l) Alum Ferric - Year 1 Ferric - Year % 54% 40% 49% May August November February

16 Haloacetic Acids (HAAs) Reductions Overall Reduction of 51% Average Concentration (mg/l) Alum Ferric - Year 1 Ferric - Year % 67% 47% 67% 0.0 May August November February

17 1.2 Solids Disposal 13 14% Increase in Solids 1.0 Wet Tons per Million Gallons Treated

18 125 Alum and Ferric Coagulant Dose mg/l Alum Ferric Note: Switched from Alum to Ferric in March 2014.

19 40 Caustic Caustic Dose mg/l Post Caustic Pre Caustic

20 30 Carbon 20 Carbon Dose mg/l

21 5 Potassium Permanganate 4 Potassium Permanganate Dose mg/l

22 Chemical Cost Comparison Chemical Alum Ferric Cost Difference Primary Coagulant $125,000 $272, ,000 Caustic $64,300 $204, ,600 Carbon $319,100 $221,300-97,800 Potassium Permanganate $183,300 $41, ,300 Total Cost $691,700 $739, ,500

23 In Closing Thank you to our Team of dedicated people and their commitment to continuous improvement! Interact with other Utilities Seek guidance and leadership from State Regulators Inform and Engage your Community Regularly Communicate Results ORANGE WATER AND SEWER AUTHORITY A public, non-profit agency providing water, sewer and reclaimed water services to the Carrboro-Chapel Hill community.

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25 0.06 Compliance Lead Results 90th Percentile Concentration (parts per million) EPA Action Level ppm < < <0.003 <0.003 <0.003 < Year

26 0.06 Compliance Lead Results Individual Sites Concentration (parts per million) EPA Action Level ppm Not Detectable Year

27 0.06 Customer Requested Lead Results Individual Sites Concentration (parts per million) EPA Action Level ppm Not Detectable 0 Year