MEETING NEVADA DEP-BMRR PROFILE II PARAMETERS WITH ELECTROCOAGULATION BASED TREATMENT SOLUTIONS

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1 MEETING NEVADA DEP-BMRR PROFILE II PARAMETERS WITH ELECTROCOAGULATION BASED TREATMENT SOLUTIONS B. DENNEY EAMES, BRYAN NIELSEN, CHARLES LANDIS IWC International Water Conference 2014

2 Executive Summary Electrocoagulation (EC) introduction History and basics Overview of the Science of Electrochemistry Review three Mine water treatment case studies for EC treated water meeting Nevada Profile II targets

3 Introduction to Electrocoagulation First patented in 1906 by A. E. Dietrich Original patent was used to treat bilge water from ships Multiple attempts have been made to commercialize the technology with varying degrees of success New regulations have put pressure on industries to explore innovative solutions Electrocoagulation has reemerged as a viable technology

4 Electrocoagulation Today Electrocoagulation is used in many industries today Stormwater Treatment Environmental Remediation Marine Pollution Prevention Automotive Cleaning Food and Beverage Mining Oil & Gas International Water Conference 2014

5 Electrocoagulation Principles Electrocoagulation is a process utilizing sacrificed anodes to form active coagulants which are used to remove pollutants by precipitation and flotation in-situ. Compared with traditional chemical coagulation, electrocoagulation has, in theory, the advantage of removing the smallest colloidal particles; the smallest charged particles have a greater probability of being coagulated because of the electric field that sets them in motion. -MF Pouet, 1995

6 Electrocoagulation Principles The electrical current releases positively charged metal ions that attract a disproportionate quantity of negatively charged contaminants Small particles agglomerate into larger particles through precipitation and adsorption Gas generated at the cathode assists in separating the lighter coagulated particles and forming a stable floc

7 Electrocoagulation Targets 1. Coagulation of suspended solids 2. Precipitation and agglomeration of dissolved metals 3. De-emulsification of oil and grease from water

8 Electrocoagulation Process Electrocoagulation Makes Particles Larger Gravity Separation Electrocoagulation

9 Coagulation of Suspended Solids Coagulation is one of the most important physiochemical reactions used in water treatment Coagulation is brought about by the reduction of the net surface charge where the colloidal particles (previously stabilized by electrostatic repulsion) can approach closely enough for Van Der Waals forces to hold them together and allow aggregation

10 Coagulation of Suspended Solids Coagulation can be achieved by chemical or electrical methods Metals salts like Aluminum Sulfate and Ferric Chloride have been used for over 100 years in water treatment In the EC process, the coagulant is generated in-situ by electrolytic oxidation of an anode Ions are removed from water by reacting other ions of opposite charges, or through floc of metallic hydroxides generated within the effluent

11 Literature Chemical Treatment Alum, lime and/or polymers tend to generate large volumes of sludge with high bound water content that can be slow to filter and difficult to dewater. These treatment processes also tend to increase the total dissolved solids (TDS) content of the effluent, making it unacceptable for reuse within industrial applications. * Electrocoagulation The characteristics of the electrocoagulated flock differ dramatically from those generated by chemical coagulation. An electrocogulated flock tends to contain less bound water, is more shear resistant and is more readily filterable. ** *Benefield, Larry D.; Judkins, Joseph F.; Weand, Barron L. (1982). Process Chemistry for Water and Wastewater Treatment. Englewood Cliffs, NJ: Prentice-Hall. p **Woytowich, David L.; Dalrymple, C.W.; Britton, M.G. (Spring 1993). "Electrocoagulation (CURE) Treatment of Ship Bilge Water for the US Coast Guard in Alaska". Marine Technology Society Journal (Columbia, MD: Marine Technology Society, Inc.) 27 (1): 92. ***MF Pouet, 1995

12 Project Background Nevada Profile II standards introduction Analytical Parameter Description Units Limit Value Aluminum mg/l 0.2 Antimony mg/l Arsenic mg/l Barium mg/l 2.0 Beryllium mg/l Cadmium mg/l 0.005

13 NV Profile II Standards (cont.) Analytical Parameter Description Units Limit Value Chloride mg/l 400 Chromium mg/l 0.1 Copper mg/l 1.0 Fluoride mg/l 4.0 Iron mg/l 0.6 Lead mg/l Magnesium mg/l 150 Manganese mg/l 0.10

14 NV Profile II Standards (cont.) Analytical Parameter Description Units Limit Value Mercury mg/l Nickel mg/l 0.1 Nitrate + Nitrite (as N) mg/l 10 Nitrogen, Total (as N) mg/l 10 ph (standard units) s.u Selenium mg/l 0.05 Silver mg/l 0.1 Sulfate mg/l 500

15 NV Profile II Standards (cont.) Analytical Parameter Description Units Limit Value Thallium mg/l Total Dissolved Solids mg/l 1,000 WAD Cyanide mg/l 0.2 Zinc mg/l 5.0 Note: All analyses for the dissolved fraction.

16 Targets: Arsenic and Antimony Dissociation of Arsenite [As(iii)]

17 Targets: Arsenic and Antimony (cont.) Dissociation of Arsenate [As(v)]

18 ARSENIC PRECIPITATION Arsenic (III) As (iii) Fe 3 + No Attraction Oxidation Created As OCL - Negatively (iii) As (v) Charged As (V) Arsenic (V) As (v) Fe 3+ Attracted and Bound to Ferric Precipitate

19 PERIODIC TABLE

20 ARSENIC POURBAIX DIAGRAM Arsenic (v) Arsenic (iii)

21 ANTIMONY POURBAIX DIAGRAM Antimony (v) Antimony (iii)

22 FERRIC CHLORIDE COAGULATION CL - Fe 3 + OH - CL - As (v) - OH - CL - OH - CL - OH - As (v) - OH - Fe 3+ CL - As (v) - CL - Fe 3+ OH - CL - OH - CL - Lot s of Competition CL - OH -

23 Anode + Cathode EC COAGULATION Fe 3 + As (v) - OH - H 2 OH - OH - H 2 Fe 3+ As (v) - OH - Fe 3+ As (v) - OH - H 2 OH - Less Competition, Higher Potential Energy

24 Treatment Methods Untreated raw influent Aerated and ORP raised with EOX EC cell treatment, settling, and filtration

25 Site Characteristics Mine Water Sample #1 Mine surface water/rain simulated stormwater mix Elevated arsenic and antimony Mine Water Sample #2 Mine water storage pond Elevated arsenic, antimony, and thallium Mine Water Sample #3 Mine water storage pond Elevated arsenic, antimony, aluminum, iron, sulfate, thallium, and ph level

26 Sample #1 Results Parameter Description Units NV PII Influent Effluent Aluminum mg/l 0.2 ND<0.2 ND<0.2 Antimony mg/l ND<0.005 Arsenic mg/l ND<0.003 Barium mg/l 2.0 ND<0.05 ND<0.05 Beryllium mg/l ND<0.004 ND<0.004 Cadmium mg/l ND<0.004 ND<0.004 Chloride mg/l Chromium mg/l 0.1 ND<0.01 ND<0.01

27 Sample #1 Results (cont.) Parameter Description Units NV PII Influent Effluent Copper mg/l 1.0 ND<0.02 ND<0.02 Fluoride mg/l Iron mg/l 0.6 ND<0.56 ND<0.56 Lead mg/l ND<0.015 ND<0.015 Magnesium mg/l Manganese mg/l 0.10 ND<0.011 ND<0.011 Mercury mg/l ND< ND< Nickel mg/l 0.1 ND<0.05 ND<0.05

28 Sample #1 Results (cont.) Parameter Description Units NV PII Influent Effluent Nitrate+Nitrite (N) mg/l Nitrogen, Total (N) mg/l ph (standard units) s.u Selenium mg/l 0.05 ND<0.005 ND<0.005 Silver mg/l 0.1 ND<0.02 ND<0.02 Sulfate mg/l Thallium mg/l ND<0.002 ND<0.002

29 Sample #1 Results (cont.) Parameter Description Total Dissolved Solids Units NV PII Influent Effluent mg/l 1, WAD Cyanide mg/l 0.2 ND<0.005 ND<0.005 Zinc mg/l 5.0 ND<0.05 ND<0.05

30 Sample #2 Results Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Aluminum ND< Antimony Arsenic ND< Barium Beryllium ND< ND< ND< Cadmium ND< ND< ND< Chloride Chromium 0.1 ND< ND< ND< Copper Fluoride ND<0.02 ND<0.02

31 Sample #2 Results (cont.) Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Iron Lead Magnesium Manganese Mercury ND< ND< ND< Nickel Nitrate+Nitrite (N) ND<0.02 ND<0.02 Nitrogen, Total (N) ph (standard units) Selenium

32 Sample #2 Results (cont.) Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Silver 0.1 ND< ND< ND< Sulfate Thallium ND<0.002 ND<0.002 Total Dissolved Solids 1, WAD Cyanide 0.2 ND<0.005 ND<0.005 ND<0.005 Zinc

33 Sample #3 Results Parameter Description Units NV PII Influent Effluent Aluminum mg/l ND<0.11 Antimony mg/l Arsenic mg/l ND< Barium mg/l Beryllium mg/l ND<0.002 ND<0.002 Cadmium mg/l ND<0.004 ND<0.004 Chloride mg/l Chromium mg/l ND<0.010

34 Sample #3 Results (cont.) Parameter Description Units NV PII Influent Effluent Copper mg/l 1.0 ND<0.020 ND<0.020 Fluoride mg/l NS Iron mg/l ND<0.050 Lead mg/l ND<0.001 Magnesium mg/l Manganese mg/l ND<0.010 Mercury mg/l ND< Nickel mg/l ND<0.050

35 Sample #3 Results (cont.) Parameter Description Units NV PII Influent Effluent Nitrate+Nitrite (N) mg/l 10 <0.02 <0.02 Nitrogen, Total (N) mg/l NS ph (s.u.) s.u Selenium mg/l 0.05 ND<0.025 ND<0.025 Silver mg/l 0.1 ND<0.020 ND<0.020 Sulfate mg/l Thallium mg/l ND< TDS mg/l 1,

36 Sample #3 Results (cont.) Parameter Description Units NV PII Influent Effluent WAD Cyanide mg/l 0.2 ND<0.005 ND<0.005 Zinc mg/l ND<0.050

37 Conclusions Increasing challenges in mine wastewater New approaches must target multiple pollutants EC advantages Full compliance demonstrated Breadth of pollutants targeted Lack of trade-offs with other contaminants