MEETING NEVADA DEP-BMRR PROFILE II PARAMETERS WITH ELECTROCOAGULATION BASED TREATMENT SOLUTIONS B. DENNEY EAMES, BRYAN NIELSEN, CHARLES LANDIS IWC-14-20 International Water Conference 2014
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
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
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
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
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
Electrocoagulation Targets 1. Coagulation of suspended solids 2. Precipitation and agglomeration of dissolved metals 3. De-emulsification of oil and grease from water
Electrocoagulation Process Electrocoagulation Makes Particles Larger Gravity Separation Electrocoagulation
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
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
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. 212. **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
Project Background Nevada Profile II standards introduction Analytical Parameter Description Units Limit Value Aluminum mg/l 0.2 Antimony mg/l 0.006 Arsenic mg/l 0.010 Barium mg/l 2.0 Beryllium mg/l 0.0004 Cadmium mg/l 0.005
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 0.015 Magnesium mg/l 150 Manganese mg/l 0.10
NV Profile II Standards (cont.) Analytical Parameter Description Units Limit Value Mercury mg/l 0.002 Nickel mg/l 0.1 Nitrate + Nitrite (as N) mg/l 10 Nitrogen, Total (as N) mg/l 10 ph (standard units) s.u. 6.5 8.5 Selenium mg/l 0.05 Silver mg/l 0.1 Sulfate mg/l 500
NV Profile II Standards (cont.) Analytical Parameter Description Units Limit Value Thallium mg/l 0.002 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.
Targets: Arsenic and Antimony Dissociation of Arsenite [As(iii)]
Targets: Arsenic and Antimony (cont.) Dissociation of Arsenate [As(v)]
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
PERIODIC TABLE
ARSENIC POURBAIX DIAGRAM Arsenic (v) Arsenic (iii)
ANTIMONY POURBAIX DIAGRAM Antimony (v) Antimony (iii)
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 -
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
Treatment Methods Untreated raw influent Aerated and ORP raised with EOX EC cell treatment, settling, and filtration
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
Sample #1 Results Parameter Description Units NV PII Influent Effluent Aluminum mg/l 0.2 ND<0.2 ND<0.2 Antimony mg/l 0.006 0.017 ND<0.005 Arsenic mg/l 0.010 1.5 ND<0.003 Barium mg/l 2.0 ND<0.05 ND<0.05 Beryllium mg/l 0.0004 ND<0.004 ND<0.004 Cadmium mg/l 0.005 ND<0.004 ND<0.004 Chloride mg/l 400 14 170 Chromium mg/l 0.1 ND<0.01 ND<0.01
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 4.0 0.15 0.13 Iron mg/l 0.6 ND<0.56 ND<0.56 Lead mg/l 0.015 ND<0.015 ND<0.015 Magnesium mg/l 150 3.5 3.5 Manganese mg/l 0.10 ND<0.011 ND<0.011 Mercury mg/l 0.002 ND<0.0005 ND<0.0005 Nickel mg/l 0.1 ND<0.05 ND<0.05
Sample #1 Results (cont.) Parameter Description Units NV PII Influent Effluent Nitrate+Nitrite (N) mg/l 10 0.49 0.52 Nitrogen, Total (N) mg/l 10 1.08 0.94 ph (standard units) s.u. 6.5-8.5 7.45 6.57 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 500 150 150 Thallium mg/l 0.002 ND<0.002 ND<0.002
Sample #1 Results (cont.) Parameter Description Total Dissolved Solids Units NV PII Influent Effluent mg/l 1,000 250 400 WAD Cyanide mg/l 0.2 ND<0.005 ND<0.005 Zinc mg/l 5.0 ND<0.05 ND<0.05
Sample #2 Results Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Aluminum 0.2 0.09 ND<0.056 0.0126 Antimony 0.006 0.03 0.0042 0.0053 Arsenic 0.010 0.28 ND<0.003 0.0021 Barium 2.0 0.0959 0.0810 0.0789 Beryllium 0.0004 ND<0.0014 ND<0.0014 ND<0.0014 Cadmium 0.005 ND<0.0002 ND<0.0002 ND<0.0002 Chloride 400 69.9 190 204.4 Chromium 0.1 ND<0.0006 ND<0.0006 ND<0.0006 Copper 1.0 0.0034 0.078 0.0069 Fluoride 4.0 0.5 ND<0.02 ND<0.02
Sample #2 Results (cont.) Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Iron 0.6 0.27 0.20 0.25 Lead 0.015 0.052 0.0056 0.0047 Magnesium 150 30.1 27.4 30.3 Manganese 0.10 0.047 0.076 0.079 Mercury 0.002 ND<0.0001 ND<0.0001 ND<0.0001 Nickel 0.1 0.0066 0.0028 0.0208 Nitrate+Nitrite (N) 10 0.05 ND<0.02 ND<0.02 Nitrogen, Total (N) 10 0.69 0.72 1.37 ph (standard units) 6.5-8.5 8.22 6.96 7.29 Selenium 0.05 0.0046 0.0106 0.0086
Sample #2 Results (cont.) Parameter Description NV PII Influent Effluent Lab #1 Effluent Lab #2 Silver 0.1 ND<0.0002 ND<0.0002 ND<0.0002 Sulfate 500 61 59.6 55.7 Thallium 0.002 0.0025 ND<0.002 ND<0.002 Total Dissolved Solids 1,000 403 590 585 WAD Cyanide 0.2 ND<0.005 ND<0.005 ND<0.005 Zinc 5.0 0.0556 0.0569 0.0571
Sample #3 Results Parameter Description Units NV PII Influent Effluent Aluminum mg/l 0.2 11 ND<0.11 Antimony mg/l 0.006 0.059 0.0058 Arsenic mg/l 0.010 6.3 ND<0.0033 Barium mg/l 2.0 0.23 0.1100 Beryllium mg/l 0.0004 ND<0.002 ND<0.002 Cadmium mg/l 0.005 ND<0.004 ND<0.004 Chloride mg/l 400 47 53 Chromium mg/l 0.1 0.017 ND<0.010
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 4.0 0.55 NS Iron mg/l 0.6 7.4 ND<0.050 Lead mg/l 0.015 0.0055 ND<0.001 Magnesium mg/l 150 17 12 Manganese mg/l 0.10 0.13 ND<0.010 Mercury mg/l 0.002 0.0075 ND<0.0005 Nickel mg/l 0.1 0.05 ND<0.050
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 10 0.246 NS ph (s.u.) s.u. 6.5-8.5 9.29 6.64 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 500 590 470 Thallium mg/l 0.002 0.0087 ND<0.0019 TDS mg/l 1,000 810 790
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 5.0 0.055 ND<0.050
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