1. Electrocoagulation Treatment of Heavy Metals from Mine Impacted Water
Denney Eames, P.E. & Jacob Aylesworth, EIT
IWC 16-45

2. Executive Summary Electrocoagulation (EC) introduction
History of the technology
Overview of the science of electrochemistry
Review three mine water treatment case studies for EC treated water
Underground mine dewatering
Tailings stormwater runoff
Smelter environmental cleanup water
Review the capital and operational costs associated with these treatment process

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

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

5. Electrocoagulation Process
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 absorption
Gas generated at the cathode assists in separating the lighter coagulated particles and forming a stable floc

6. Fe3+ Fe3+ Fe3+ OH- HM CL- CL- OH- OH- OH- CL- CL- CL- HM OH- OH- HM

7. Cathode Anode + Fe3+ Fe3+ Fe3+
OH-
Cathode HM
OH-
OH-
Fe3+ H2 HM
OH-
OH-
Fe3+ HM H2
OH-
Less Competition, Higher Potential Energy

8. Electrocoagulation Effects
Electrocoagulation Makes Particles Larger
Gravity/Floatation Separation
Electrocoagulation

9. Electrocoagulation Targets1.
Coagulation of suspended solids 2.
Precipitation and agglomeration of dissolved metals 3.
De-emulsification
of oil and grease from water

10. Literature Chemical Treatment Electrocoagulation
“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 floc differ dramatically from those generated by chemical coagulation. An electrocoagulated floc 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.

11. Project Process Flow

12. Mine Water Underground Mine Dewatering
Treated at mine surface
gpm
Elevated cadmium, copper, arsenic, lead

13. Data: Underground Mine Dewatering
Analytical
Parameter
Average
ug/L
Standard Deviation
Max/Min
INF
EFF
% Reduced Cd
2.1
0.54
74.5%
0.44
3.7/1.4
1.7/0.14 Cu 22
1.7
92.6%
3.5
1.3
32/16
6.3/0.10 Pb
105
1.4
98.6% 15
1.1
141/60
5.4/0.55 Zn
531 70
86.9% 73 62
660/390
244/10 pH
8.1
0.0%
0.2
8.3/7.9
# of Samples 27
 Total Treated Volume: 2,628,600 gallons

14. Tailings Stormwater Runoff
Mine water storage pond
gpm
Elevated cadmium, copper, arsenic, lead

15. Data: Tailings Stormwater Runoff
Analytical
Parameter
Average
ug/L
Standard Deviation
Max/Min
INF
EFF
% Reduced Cd
0.44
0.20
55.5%
0.33
0.15
1.3/0.13
0.61/0.03 Cu
4.4
1.6
64.3%
0.29
9.3/2.8
2.1/1.1 Pb 27
0.48
98.2% 14
0.40
58/12
2.3/0.18 Zn
130
89.1% 32
6.9
242/104
37/5.6 pH
8.0
0.0%
0.2
8.2/7.8
# of Samples 23
 Total Treated Volume: 1,930,200 gallons

16. Smelter Site Environmental Cleanup Water
Mine water storage pond
gpm
Elevated cadmium, copper, arsenic, lead
pH treatment (raised to 8.6 after EC)

17. Data: Smelter Environmental Cleanup Water
Analytical
Parameter 
Average
ug/L
Standard Deviation
Max/Min
INF
EFF
% Reduced Cd
2,654 12
99.5%
1,755
9.1
7,107/864
34/6 Cu
216
3.8
98.2%
211
1.0
772/34
6/3 Pb
39,932 37
99.9%
40,594 27
147,959/
3,341
105/6 Zn
10,472 36
99.7%
5,465 17
22,981/
2,212
58/15 pH
7.6
8.6
-13.1%
0.3
7.9/7.3
8.9/8.3
# of Samples 10
Total Treated Volume: 375,900 gallons

18. Capital Costs 6,000 gpm: Water Treatment Plant
Capital Cost Item
Cost
Engineering
$425,000
Process Equipment
$8,624,000
Facility, Infrastructure & Installation
$2,493,000
Management, Supervision & Commissioning
$357,000
Total
$11,899,000

19. Operational Costs for a 6,000 gpm: EC Water Treatment Plant
Operational Cost Item
$/1000 gallon
Annual Cost*
Consumables
(EC Cells, UF Membranes, Misc.)
$1.252
$3,255,200
Power ($0.07/KWH)
$0.272
$707,200
Operations Labor
$0.162
$421,200
Total
$1.686
$4,383,600
* Estimated annual cost based on treating 2.6 billion gallons per year

20. Operational Costs for a 6,000 gpm: Chemical Water Treatment Plant*
Operational Cost Item
$/1000 gallon
Annual Cost*
Consumables
(Chemicals, Filters, Misc.)
$0.879
$2,285,400
Power ($0.07/kWh)
$0.215
$559,000
Operations Labor
$0.162
$421,200
Total
$1.256
$3,265,600
Note: Capital cost range was estimated at $10,300,000 to $15,700,000
* Estimated annual cost based on treating 2.6 billion gallons per year

21. Conclusions Capital cost for an EC and chemical plant were equivalent
EC advantages
Full compliance demonstrated in heavy metal reduction
Passed all aquatic toxicity testing
Reduced sludge/tailings production
EC disadvantage cell cost
34% higher operational cost compared to chemical
The cost of the EC cell was the majority of the cost
Designing a less expensive EC cell is the key to lowering operational costs