Gene S. Shelp, Leonard P. Seed, Daren Yetman and John M. MottoENPAR Technologies Inc., Guelph, Ontario, Canada

Patented AmmEL Process for the Treatment of

Ammonia in Low Temperature Mine

Wastewater; Ammonia Converted to

Environmentally–Friendly Nitrogen Gas

Introduction• Ammonia listed as a toxic substance by

Environment Canada

• One approach employed by the mining industry has been to lower the pH of the wastewater to render it less toxic (due to a shift in the NH3/NH4

+ equilibrium)

• While this approach has assisted in meeting acute lethality discharge requirements, the total ammonia-N released into the environment is not reduced

• Current technology for treating ammonia relies heavily on biological activity (e.g. nitrification) to convert ammonia to nitrate

Introduction• Total nitrogen removal requires additional

biological processes to remove nitrate from wastewater prior to discharge

• Biological treatment systems are adversely affected by cold temperatures and changes in effluent composition

• A novel and patented ion-exchange/electrochemical treatment technology (the AmmEL system) has been developed by Enpar Technologies, Inc. which is not adversely affected by low temperature

The AmmEL Process

ElectrochemicalReactor

IX

Wastewater (NH4)

Loading(Phase 1)

Treated Effluent

Regeneration (Phase 2)

Conversion (Phase 3)

Regenerant Tank

IX

NH4N2

NH4

AmmEL Reactions

2NH4+ → N2 + 8H+ + 6e-

2Cl- → Cl2 + 2e-

Cl2 + H2O → HOCl + HCl

2NH4+ + 3HOCl → N2 + 3H2O + 5H+ + 3Cl-

The AmmEL Advantage

• Eliminates nitrogen loading by converting ammonia directly into innocuous N2

• Does not produce nitrate and the GHG nitrous oxide associated with biological treatment

• Not affected by low temperature

• Intermittent operation -- no start-up delays

• Can be fully automated -- low maintenance

System Applications

• Mining effluent or process streams containing ammonia derived from the use of ammonia based blasting powder and/or the oxidation of cyanide

• Tertiary treatment for municipal waste water treatment plants (MWTP) and lagoon systems

• Process streams related to steel, fertilizer and chemical industries

Pilot StudyThe AmmEL-LC System

AmmEL-LC Pilot Unit Specifications

• 3-20 cm x 3.05m fluidized bed IX columns, BV = 59.3L

• 1.5 kW electrochemical reactor

• The main operating conditions for the system were as follows:– Wastewater flow rate: 18-20 L/min– Recharge brine flow rate: 8-10 L/min– Brine NaCl concentration: 3-4%– Cell current: 150 A

• Designed to allow for single column operation as well as series column operation

• Typical treatment mode was to operate the system with two columns in series in a lead-lag arrangement

• Third column was either involved in a regeneration cycle or was in standby

• Following a regeneration cycle, the regenerated column was rinsed with a small amount of treated water to remove any extraneous brine

• The rinse stream was directed into a 200L holding tank for testing prior to release back into the holding pond

IX 1IX 2IX 3

Reactor

Single Column Results

Breakthrough Curve at 18 L/min

99 98 97 9692

90 88 8684

7975

67

5853

2728 28

29 29

27

3132

31 3130

2928

30

0.3 0.5 0.8 1.22.2 2.7

3.7 4.5 5.16.5

7.69.6

11.6

14.2

0

10

20

30

40

50

60

70

80

90

100

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Am

mon

ia R

emov

ed (%

)

Am

mon

ia C

once

ntra

tion

(mg/

L)

Run Time (h)

% Removed Inlet Ammonia Outlet Ammonia

Typical Single Column Results

Flow rate (L/min) 18.0

Total run time (h) 14

Total volume treated (L) 15,120

Water temperature (°C) 5.7

Inlet pH 7.76

Outlet pH 7.85

Avg inlet ammonia (mg/L) 29.1

Avg outlet ammonia (mg/L) 5.1

Series Column Results

Breakthrough Curve, 18L/min, Columns C2 & C1

96 96 96 96 94 92 9087

85 8480

76

6863

58

50

27

24

2725

2423

24

20

2122

23

21

20

2122 22

1.1 1.0 1.0 1.1 1.5 1.8 2.4 2.53.3 3.6

4.6 5.16.3

7.89.3

11.1

0

10

20

30

40

50

60

70

80

90

100

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Am

mon

ia R

emov

ed (%

)

Am

mon

ia C

once

ntra

tion

(mg/

L)

Time (h)

% Removed Inlet Ammonia Outlet Ammonia

Series Column Results

Breakthrough Curve, 18L/min, Columns C1 & C3

99 99 99 98 97 96 9491

88 9087

8278

72

6624

3032 32 32 32

3032

3032

3332

3332 32

0.1 0.3 0.4 0.6 0.9 1.3 1.92.8 3.5 3.2

4.25.7

7.38.7

10.8

0

10

20

30

40

50

60

70

80

90

100

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Am

mon

ia R

emov

ed (%

)

Am

mon

ia C

once

ntra

tion

(mg/

L)

Time (h)

% Removed Inlet Ammonia Outlet Ammonia

Series Column Results

Breakthrough Curve, 18L/min, Columns C3 & C2

96 97 96 95 9491 90

8582

7982

7673

32 32

35 35 3537

3534

37 37 3735

37

1.1 1.1 1.4 1.7 2.23.2 3.7

5.06.5

7.76.8

8.410.0

0

10

20

30

40

50

60

70

80

90

100

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12 13

Am

mon

ia R

emov

ed (%

)

Am

mon

ia C

once

ntra

tion

(mg/

L)

Time (h)

% Removed Inlet Ammonia Outlet Ammonia

Series Column ResultsC2 & C1 C1 & C3 C3 & C2

Flow Rate (L/min) 18.2 18.1 18.3

Total Run Time (h) 16 15 13

Water Temperature (°C) 5.9 6.0 5.9

Inlet pH 7.79 7.84 7.82

Outlet pH 7.86 7.86 7.91

Average Inlet NH3 (mg/L) 23.0 31.0 35.3

Average Outlet NH3 (mg/L) 4.0 3.4 4.5

Pilot Study Conclusions

• The AmmEL-LC system can readily remove ammonia from mine waste water to below the discharge requirement of 10 mg/L

• No pretreatment of the stream was required

• The efficiency of the AmmEL-LC was not affected by low water temperatures (<6°C)

• Operating costs were relatively low ($0.10/m3 of water treated)

Full-Scale Installation• Full-scale installation commissioned March 10, 2010 in Timmins, Ontario

• Three zeolite filled 30 cm (i.d.) x 6 m ion exchange columns

• Electrochemical reactor → 18 m2 of anode surface area; 16V, 2000A DC rectifier

• Chlorine gas scrubber to comply with Ontario MOE chlorine emission levels

• The system is designed to treat 400 m3 of mine waste per day containing an average of 30 mg of ammonia-nitrogen/L

• Average effluent levels are 10 mg NH3-N/L year round including during the winter months when mine water can reach temperatures slightly above freezing

Ion Exchange Columns

Electrochemical Reactor

DC Rectifier Chlorine Gas Scrubber

Ongoing Developments• New modified zeolite currently under development for use in

IX columns

– Selective in adsorption of ammonium ions vs. calcium and magnesium ions during effluent treatment

– 6-fold decrease in transfer of calcium and magnesium to brine during recharge cycle

– Pilot studies indicate instances of reactor cleaning and brine conditioning significantly reduced

Questions?