Increased Wastewater Strength in Arizona Recent Trends and Impacts to Facility Design

Transcription

1 Increased Wastewater Strength in Arizona Recent Trends and Impacts to Facility Design Presented by: Carlos Lopez and Andrew Gilmore October 20, 2015 Stronger Wastewater Affects Plant Capacity, Operation, and Planning 1. Wastewater concentrations have increased by how much? Where? Why? 2. Plant capacity and operation are affected by stronger wastewater 3. How do we address these changes in the biological treatment process? 2 1

2 Stronger Wastewater Affects Plant Capacity, Operation, and Planning 1. Wastewater concentrations have increased by how much? Where? Why? 2. Plant capacity and operation are affected by stronger wastewater 3. How do we address these changes in the biological treatment process? 3 Wastewater Strength Is Defined by Constituent Concentrations Organics BOD or COD Solids TSS Nutrients TKN 4 2

3 Textbook Wastewater Concentrations Vary Widely Low Medium High BOD TSS TKN Source: Metcalf & Eddy, Wastewater Engineering: Treatment and Reuse, 4 th Ed, Typical BOD / TSS / TKN: 200 / 200 / 40 mg/l 5 Wastewater Database Includes 20 Facilities Throughout Arizona 6 3

4 Facilities in Arizona Experience Medium to High Concentrations Low Medium High BOD TSS TKN Arizona Plants See High BOD Concentrations Avg BOD = 292 mg/l 500 BOD 400 Conc. (mg/l) 300 High 200 Medium

5 Arizona Plants See High TSS Concentrations Avg TSS = 324 mg/l 500 TSS 400 Conc. (mg/l) High Medium Arizona Plants See Textbook TKN Concentrations Avg TKN = 43 mg/l High 50 TKN Conc. 40 (mg/l) 30 Medium

6 Growing Communities Show Increasing Concentrations Trends 12 AADF AADF Trend 10 8 Flow (mgd) Growing Communities Show Increasing Concentrations Trends Conc 500 (mg/l) BOD COD TSS BOD Trend COD Trend TSS Trend 12 6

7 Growing Communities Show Increasing Concentrations Trends Conc (mg/l) TKN TKN Trend 13 Non-Growing Communities Show Stable Wastewater Concentrations Flow (mgd) AADF AADF Trend 14 7

8 Non-Growing Communities Show Stable Wastewater Concentrations 600 BOD COD TSS BOD Trend COD Trend TSS Trend Conc 300 (mg/l) Non-Growing Communities Show Stable Wastewater Concentrations Conc 20 (mg/l) NH3 NH3 Trend 16 8

9 Residential Water Conservation Can Account For Increased Concentrations Residential Use Plumbing Fixtures Residential Wastewater Flow Production Water Conservation Reduction Overall Reduction in Wastewater Flow Toilet 40% 54% 22% Shower 20% 44% 9% Faucets 7% 50% 4% Others 33% 0% 0% Total 100% 35% 17 Other Factors Contribute to Changes in Wastewater Concentrations Contribution of commercial/ industrial flows Proportion of newer construction Behavioral practices Use of food grinders Use of water softeners Point-of-use RO units Reduced infiltration into the collection system 18 9

10 Stronger Wastewater Affects Plant Capacity, Operation, and Planning 1. Wastewater concentrations have increased by how much? Where? Why? 2. Plant capacity and operation are affected by stronger wastewater 3. How do we address these changes in the biological treatment process? 19 Treatment Capacity Depends on Flow AND Wastewater Strength PRIMARY SECONDARY TERTIARY Raw Wastewater Preliminary Treatment Biological Treatment Secondary Clarification Filtration Disinfection Recharge Reuse Primary Sludge Waste Sludge To Solids Treatment Flow based capacity Load based treatment capacity Flow based capacity 20 10

11 Permitted Capacity Does Not Reflect Changes in Wastewater Strength Permit Capacity Treatment Capacity Flow Based Unit Processes Loading Based Unit Processes BOD = 200 mg/l 10 MGD 10 MGD 10 MGD 16,680 PPD BOD = 300 mg/l 10 MGD 10 MGD 6.7 MGD 16,680 PPD 21 Stronger Wastewater Affects Plant Capacity, Operation, and Planning 1. Wastewater concentrations have increased by how much? Where? Why? 2. Plant capacity and operation are affected by stronger wastewater 3. How do we address these changes in the biological treatment process? 22 11

12 City of Chandler Case Studies OWRF Improvements OWRF Expansion 23 City of Chandler OWRF Improvements 24 12

13 OWRF Influent Characteristics Are Challenging for MLE Process Sufficient Carbon Influent BOD/TKN Ratio Insufficient Carbon 0.0 Jan-09 Jan-10 Jan-11 Jan-12 Jan-13 Jan Existing MLE Configuration 26 13

14 10/16/2015 Operational Adjustments to Existing MLE Configuration 27 Convert B Basins to Swing Zones 28 14

15 4 Stage NdN Process Provides Better Performance Than MLE Effluent conc. (mg/l) Org N NH3 NOx MLE 4 Stage 29 Chandler OWRF Expansion 30 15

16 Design Influent WW Criteria Current LB Current OWRF Airport WRF OWRF Design Criteria BOD TSS TN BOD/TN Bioreactor Operation Baseline Design (4 Stage) 32 16

17 Bioreactor Operation Larger De-Aeration Volume 33 Bioreactor Operation No De-Aeration Volume 34 17

18 Bioreactor Operation Larger De-Aeration Volume & Anoxic Volume 35 Bioreactor Operation Larger 2 nd Anoxic Volume 36 18

19 Bioreactor Operation MLE with De-aeration 37 Bioreactor Operation 5-Stage Bardenpho with De-aeration 38 19

20 Stronger Wastewater Affects Plant Capacity, Operation, and Planning 1. Wastewater concentrations have increased by how much? Where? Why? 2. Plant capacity and operation are affected by stronger wastewater 3. How do we address these changes in the biological treatment process? 39 Acknowledgements Municipalities/plant staff of all plants included in this survey and analysis 40 20

21 Statements of fact and opinion expressed are those of the author(s) / presenter(s). AZ Water, AZAWWA, and AZWEA assume no responsibility for the content, nor do they represent official policy of the Association