Pilot Testing of Zero Liquid Discharge (ZLD) Technologies Using Brackish Ground Water for Inland Desert Communities

Transcription

1 Pilot Testing of Zero Liquid Discharge (ZLD) Technologies Using Brackish Ground Water for Inland Desert Communities Renee Morquecho, Ph.D., Tom Mulvihill Indian Wells Valley Water District Andrew Wiesner, Adam Zacheis, Ph.D., P.E., and Graham Juby, Ph.D., P.E. Carollo Engineers AMTA July 13-16,

2 Presentation Outline Project Background Project Costs Pretreatment Electrodialysis Reversal Reverse Osmosis

3 The Indian Wells Valley Water District is Located in the Mojave Desert Ridgecrest, CA

4 Influent Water Characteristics Present Challenges to Desalting Well Water Quality ph = 7.1 TDS = 1500 mg/l Hardness = 500 mg/l as CaCO 3 Calcium = 140 mg/l Sulfate = 500 mg/l Silica = 50 mg/l Silt Density Index = 1.0 Contaminants of Concern Iron = 40 μg/l Manganese = 46 μg/l Arsenic = 6 μg/l Selenium = 40 μg/l

5 Despite the Many Challenges, Potable Water Can Be Obtained by a Zero Liquid Discharge Treatment Train Pilot Scale Pre-Treatment Reverse Osmosis Stabilization/ Disinfection Electrodialysis Reversal Coagulation Brine Concentrator Pond Full-Scale Plant

6 Pilot Project Objectives 1. Demonstrate feasibility of selected treatment train. RO 2. Demonstrate primary RO and secondary EDR can achieve predicted recovery with minimal fouling. 3. Evaluate the effectiveness of a reversible RO configuration.

7 Pretreatment Project Background Project Costs Pretreatment Electrodialysis Reversal Reverse Osmosis

8 Pretreatment Can Effectively Remove RO Constituents of Concern Fe/Mn Removal Granular Media Filtration Filtronics FV-03 Electromedia I

9 Pretreatment Can Effectively Remove RO Constituents of Concern Concentration (μg/l) Total Iron Manganese Well RO Feed

10 Reverse Osmosis Project Background Project Costs Pretreatment Electrodialysis Reversal Reverse Osmosis

11 The RO Unit was Operated for Over 4,000 Hours

12 The RO Process Can Operate at High Recoveries Recovery (%) 80 Recovery (%) Run Time (Days)

13 The RO Process Produces a Low Total Dissolved Solids (TDS) Product 6000 Concentration (mg/l) Well RO Feed RO Permeate RO Concentrate at 70% recovery

14 The RO Process Can Operate with Minimal Fouling Start of Reversible operation Flow (gpm) Restart Clean #1 Clean # Operation (Days) Stage 1 flow Stage 2 flow Total system flow

15 Reversible RO Configuration Has the Potential to Increase Recovery and Decrease Membrane Fouling

16 Reversible RO Configuration Has the Potential to Increase Recovery and Decrease Membrane Fouling

17 System Normalized Permeate Flow - Reversible Operation vs. Conventional Operation NPF/NPFinitial Reversible Conventional Throughput (gal x 100,000)

18 1 st Stage Normalized Permeate Flow - Reversible Operation vs. Conventional Operation NPF/NPFinitial Reversible Conventional Throughput (gal x 100,000)

19 2 nd Stage Normalized Permeate Flow - Reversible Operation vs. Conventional Operation NPF/NPFinitial Throughput (gal x 100,000) Reversible Conventional

20 RO Concentrate Silt Density Index (SDI) Indicates Particle Removal After Flow Reversal SDI Before Flow Reversal After Flow Reversal

21 Electrodialysis Reversal Project Background Project Costs Pretreatment Electrodialysis Reversal Reverse Osmosis

22 The EDR was Operated Continuously for Over 1,600 hours Cathode -ve Anode +ve Na + Na + Cl - Na + Cl - Cl - Na + Cl - Product Compartment Concentrate Compartment Cationic Membrane Anionic Membrane Cationic Membrane

23 Reduced RO Recovery to Meet EDR Feed Requirements RO Recovery = 60% Pre-Treatment Reverse Osmosis RO Bypass Electrodialysis Reversal EDR Influent Silica Limit = 115 mg/l

24 EDR can Effectively Remove TDS from the RO Concentrate TDS (mg/l) EDR Feed EDR Product EDR Concentrate

25 EDR can Achieve High Recoveries 100% 90% 80% Recovery (%) 70% 60% 50% 40% 30% 20% 10% 0% (-)ve Polarity (+)ve Polarity ,000 1,200 1,400 1,600 1,800 Run Time (hr)

26 EDR Performance has been Stable Pressure (psi) Feed Pressure Stack Inlet Pressure (+) Stack Inlet Pressure (-) Run Time (hr)

27 EDR Performance has been Stable 14.0 Resistance (Ohms) Stage 1 (+) Resistance Stage 1 ( - ) Resistance Stage 2 (+) Resistance Stage 2 ( - ) Resistance Run Time (hr)

28 RO Primary Desalting and EDR Secondary Desalting can Achieve High Overall Recovery Pre-Treatment Reverse 31 gpm Osmosis 28 gpm Electrodialysis Reversal 3 gpm System Recovery = 90%

29 RO Primary Desalting and EDR Secondary Desalting can Produce a Low TDS Product TDS (mg/l) Well Product Concentrate

30 Project Costs Project Costs Project Background Pretreatment Electrodialysis Reversal Reverse Osmosis

31 Limiting the Volume of Brine for Final Treatment Reduces Cost Reverse Osmosis Brine Concentration Capital 1 mgd $2 million $22 million Power (kwh/1000 gal)

32 Impact of Overall Recovery is Significant Example: 1-mgd Plant Brine Flowrate (gpm) 100 Primary RO Brine 174 gpm Secondary EDR Brine 70 gpm 80,000 70,000 60,000 50,000 40,000 30,000 Brine Concentration (mg/l) 50 20,000 10, % 75% 80% 85% 90% 95% Overall Recovery 0

33 Limiting the Volume of Brine for Final Treatment Reduces Cost Full-Scale Facility at 2.7 mgd Capital Cost (MM$/yr) O&M Cost (MM$/yr) Total Cost (MM$/yr) RO + BC RO + EDR + BC

34 Summary and Conclusions 1. Selected treatment train is feasible. RO 2. Primary RO and secondary EDR can achieve predicted recoveries. 3. The reversible function has potential to improve RO performance, but additional testing is needed.

35 Acknowledgements California Department of Water Resources (Chapter 6(a) of Proposition 50) Staff Indian Wells Valley Water District

36 Questions? Questions?

37 Comparing Water Costs Indicates that Costs are Reasonable Given Water Quality and Inland Location Typical Brackish Desalting Ocean Disposal for Brine ~ ~ 500 Total ~ 1,000 This Project Total ~ 1,780 Primary Desalting Step ~ 620 Zero-Liquid Discharge/ Brine Treatment ~ 1,160 Bottled Water Crystal Geyser ~ 974,000 AWWA June 2005 ~ 6,500, $/AF