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Page 1: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry
Page 2: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Agricultural Mineral Soil Additives for Passive Nitrate

Removal, &

Phosphorus Removal Using Low Energy Electrochemistry

NOWRA Onsite Wastewater Mega-Conference

Christopher Jowett

October 24, 2017

Page 3: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Outline

3

• Talk #1 – Nitrate Removal

• Pilot testing

• Effects on treatment

• HRT results

• Sulphate production

• Talk #2 – Phosphorus Removal

• P removal in natural systems

• Mimicking nature with Waterloo EC-P

• Test results & mineral formation

• Other benefits

Page 4: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Agricultural Mineral Soil

Additives for Passive Nitrate Removal

Page 5: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Residential Nitrogen Removal

1. Single-Pass Waterloo Biofilter

• 25 – 35% TN removal

• Internal carbon source of wastewater

2. Double-Pass Waterloo Biofilter

• 50 – 65% TN removal

• Septic tank carbon source through recirculation

3. WaterNOx Anoxic Filtration Denitrification Add-On

• 80 – 95% TN removal

• Proprietary external carbon source

4. Nox-LS Autotrophic Sulphur-Limestone Add-On

• 90 – 95% TN removal

• Sulphur-oxidizing bacteria reduce nitrate5

Page 6: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• EPA lab study using agricultural sulfur at Cornell University, 1978

• Recent Florida & MASSTC work using wood chips + agricultural sulfur

• FULL-SCALE PERFORMANCE OF A TWO-STAGE BIOFILTRATION SYSTEM FOR REDUCTION OF NITROGEN

Damann Anderson, Josefin Hirst, Richard Otis, Elke Ursin, and Daniel Smith, 2014

• PILOT STUDY OF TWO-STAGE BIOFILTRATION FOR REDUCTION OF NITROGEN FROM OWSJosefin Hirst, Damann Anderson, and Daniel Smith, 2014

Autotrophic So + CaCO3

Denitrification

Damann Anderson at

residential demonstration

site near Tampa Florida

6

Page 7: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Nitrification consumes alkalinity to buffer lower pH

• Adequate alkalinity must exist for thorough nitrification to occur

• Nitrification in soft water areas may require alkalinity chemical

addition

Nitrification is Key

7

Page 8: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Water conservation is a problem – more TKN, not so much alkalinity

Nitrification is Key

Insufficient Alkalinity due to Water Conservation

0

20

40

60

80

100

0 100 200 300 400 500 600

TK

N

mg

/L

Days Lapsed

TKN Total NWaterless urinals

installed Day 80 –

increased TKN

without increasing

alkalinity

Automatic alkalinity

dosing installed

Day 380 –

nitrification back to

normal

8

Page 9: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

NOx-LS Testing

Page 10: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Autotrophic Sulphur Denitrification

Units

• Received 60 – 240 L/day of nitrified

Waterloo Biofilter effluent

• Hydraulic Retention Times of 8 – 34

hours

• NO2,3-N Loading Rate = 3.7 g/day =

13.2 g/m2/day

Pilot Test at Rural School

10

Page 11: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Excellent immediate denitrification

• Consistent very low TN

• No increase in TSS

• Marginal increase in BOD

• Monitor SO4 to keep <500 mg/L; though 1000-1500 mg/L is upper limit

Pilot Test at Rural School

1.1S0 + NO3- + 0.76H2O + 0.4CO2 + 0.08NH4

+ =

0.08C5H7O2N + 1.1SO42- + 0.5N2 + 1.28H+

S0 + O2 + H2O = H2SO4 sulphuric acid

S0 + NO3 + H2O = N2 + H2SO4

CaCO3 + H2SO4 = HCO3- + OH- + CO2 + Ca+2 + SO4

-

Ca+2 + SO4- + 2H2O = CaSO42H2O gypsum ?

Acid produced, pH buffered by dissolving limestone.

Sulphate produced, monitor for aesthetic purposes.

Nitrogen gas is non-reactive. Can form

insoluble bubbles that impede hydraulic flow.

11

Page 12: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Evolution of nitrogen species and sulphate through the treatment train

Pilot Test at Rural School

Erin Lift Station Raw Sewage

pH DO Temp cBOD TSS TKN Sulphate Alkalinity

mg/L ˚C mg/L mg/L mg/L mg/L mg/L

Mean 7.1 1.1 13.6 124.0 41.9 66.9 119.1 --

Median 7.1 1.0 14.0 112.0 33.5 65.1 120.0 --

Biofilter Effluent

pH DO Temp cBOD TSS TKN NO3-N NO2-N TN Sulphate Alkalinity

mg/L ˚C mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

Mean 7.1 7.53 14.2 4.4 2.1 1.7 32.7 0.15 34.5 119.6 --

Median 7.1 7.84 14.5 4.0 2.0 1.3 27.1 0.03 30.0 120.0 --

Limestone + Sulphur Effluent

pH DO Temp cBOD TSS TKN NO3-N NO2-N TN Sulphate Alk'y

mg/L ˚C mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

Mean 6.9 0.93 16.6 9.3 2.7 1.73 1.68 0.19 3.59 418 192

Median 6.9 0.85 16.5 4.0 2.0 0.90 0.06 0.03 2.22 405 177

N = 35-5012

Page 13: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• NOx-LS minimal effect on TSS

Treatment Effects

1

10

100

0 200 400 600 800

TSS

mg/

L

Days Lapsed

Biofilter TSS

WaterNOx-LS TSS

Raw Sewage TSS

13

Page 14: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• NOx-LS marginally increases cBOD; easily removed in limestone polisher

Treatment Effects

1

10

100

1000

0 200 400 600 800

cBO

D m

g/L

Days Lapsed

WaterNOx-LS cBOD Raw Sewage cBOD Limestone Polisher

14

Page 15: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Total Nitrogen depends on sewage TKN + Biofilter NO3-N + Nox-LS HRT

• Generally TN < 10 mg/L when HRT > 12 hours

TN Removal

0.1

1.0

10.0

100.0

1000.0

0 100 200 300 400 500 600 700

Tota

l Nit

roge

n m

g/L

Days Lapsed

Biofilter TN NOx-LS TN Raw Sewage TKN

15

Page 16: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• TN% removal was high and remained consistent until HRT was lowered to

8.4 hours

• Performance improved immediately when HRT was increased again

HRT Analysis

16

Page 17: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Linear relationship between mass of sulphate produced and mass of nitrate +

DO removed

Sulphate Production

y = 1.43x + 9.32R² = 0.915

0

20

40

60

80

0 10 20 30 40 50

Sulp

hat

e P

rod

uce

d g

/day

NO2,3 + DO Removed g/day

17

Page 18: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Basic reaction:

2.5 S0 + CO2 + NO3 + H2O + 2.5 O2 = CH2O + 1/2 N2 + 2.5 SO4

2.5 SO4 = 2.5 S0 + CO2 + NO3 + H2O + 2.5 O2 – (CH2O + 1/2 N2)

SO4 = (2.5 S + CO2 + NO3 + H2O + 2.5 O2 - CH2O - 1/2 N2)/2.5

Mass SO4 = 96

Mass (NO3 + DO) = 56.8

Slope = SO4/(NO3 + DO) = 96/56.8 = 1.69

Sulphate Production

Theoretical Slope = 1.69 with intercept = 0.0

Actual Slope = 1.43 with intercept = 9.32

Actual Slope = 1.77 if set intercept = 0.0

Values from influent & effluent only, not within the reactor

(likely need to include CO2 + NH3,4) 18

Page 19: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Suction lysimeters sampled internal pore water at 20” + 10” depths

• Internal reactor data fits theoretical slope = 1.69 if intercept is artificially set to

zero (more data needed)

Internal Reactions

y = 1.691xR² = -0.236

0

10

20

30

0 5 10 15 20

Sulp

hat

e P

rod

uce

d g

/day

NO2,3 + DO Removed g/day

Pore Water Results

19

Page 20: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• 10” depth sample shows

peaks in

• cBOD (biomass?)

• TSS

• Alkalinity

• TKN

• NH4

• SO4

• sulphide

• Corresponds with a low of

pH and nitrate

• Shows reactions occurring

that are lost looking at just

influent & effluent samples

Internal Reactions

20

Page 21: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Before use showing smooth surface

SEM of Media

Pristine S0 surface at 50 μm SEM scale Agricultural S0 pastille ~ 3 mm diameter

21

Page 22: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• After use showing dissolution pits indicating biochemical reaction with oxygen

and nitrate-rich water

SEM of Media

Corrosion ‘caries’ texture common in

S0 at depth = 20” near source of NO2,3

Caries texture rare in S0 at depth = 10”

further from source of NO2,3

Different 50 μm SEM scale

22

Page 23: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Agricultural sulfur and limestone successful at high

levels of TN removal

• HRT of 8 – 12 hours minimum needed without

substantial nitrate breakthrough

• pH fully neutralized and little TSS/BOD addition

• Internal reactions analogous to ‘oxidation-reduction roll-

front deposit’ in the natural environment

• Nitrate advances through ‘rock’ both nitrate and DO

reduced as sulphur oxidized

Conclusions

23

Page 24: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Phosphorus Removal Using

Low Energy Electrochemistry

Page 25: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Phosphorus Removal

• Industry issue

• A lot of discussion

• Not a lot of action… so far

• Technology exists now

Lake Erie algae bloom, 2013

Freshwater Lake Northern Ontario, 2015

Lake Okeechobee FL algae bloom, 2016

Lake Okeechobee FL outflow to the coast,

2016

25

Page 26: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Natural Removal of Phosphorus in Soils

• Iron rich B Horizon soils, yes

• Preferential pathways

• Unknown when iron is used up

• Clean sand and iron poor soils, somewhat

• Low levels ~20-25% TP

• Loosely adsorbed & easily leached out

• Clean sand or filtration medium, yes

• If Fe ions added by EC-P

26

Page 27: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Natural Soil Processes in ‘B horizon’

Ferric minerals:

Goethite α-FeOOH – yellowish brown

Hematite α-Fe2O3 – bright red

Lepidocrocite γ-FeOOH – bright orange

Maghemite γ-Fe2O3 – red to brown

Ferrihydrite 5Fe2O39H2O – reddish brown

Strengite FePO42H2O

Ferrous minerals:

Siderite FeCO3

Vivianite Fe3(PO4)28H2O

Pyrite FeS2

Phosphorus is leached down and adsorbed onto Fe-hydroxides, then mineralized as

insoluble FeSO4 crystalline mineral cements

27

Page 28: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Replicating B Horizon Soil in Clean Sand

Sand Filter Foam Filter

Go straight to the ‘mineralization’ step in otherwise non-reactive media:

What we are trying to do is bring together soluble ions to react together:

3 + 2PO43- = (PO4)2 (vivianite) or

+ PO43- = (PO4) (strengite)

28

Page 29: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Phase Diagram for Fe-PO4 minerals

High

O2

Low

O2

Biomat

Septictank

Groundwater Likely pathway is septic tank, anaerobic biomat, to

aerobic groundwater, leaving Fe-PO4 minerals

scattered in soil or filtration medium

29

Page 30: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Waterloo EC-P & Testing

Page 31: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Replicating Nature with EC-P

31

Page 32: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

EC-P Electrodes

Early Retrofit Testing at School in Ontario

Commercial Installation at

Provincial Park in Manitoba Residential Installation at Lakefront Cottage

32

Page 33: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Smart Panel Control

EC-P Control

• Variable intensity settings

• Variable operational schedules

• Controls rest of the system as well

• Automatic ‘away‘ shutdown mode (pump

required)

Smart Panel Benefits

• Remote control & live monitoring

• Instant email notifications

• Cellular or Ethernet connections

• Reduced O&M costs

• Peace of mind33

Page 34: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Waterloo EC-P Field Study Results

1. Compare to Single-Pass Sand Filter no EC-P

TP >3.6 mg/L after 24” C-33 sand = 20-25% removal

2. Generic Recirculating Sand Filter with EC-P;

TP = 1.1 mg/L at lower iron dissolution = 82% removal

TP = 0.51 mg/L at higher iron dissolution = 92% removal

TP = 0.58 mg/Lin a second study = 91% removal

3. Residential Biofilter with EC-P;

TP = 0.61 mg/L = 96%

4. Public School Biofilter with EC-P;

TP = 0.53 mg/L = 92%

5. Septic Tank + Soil Leach Field with EC-P;

TP = 0.11 mg/L after 300 mm of sandy loam soil = 98%

TP = 0.05 mg/L after 600 mm of sandy loam soil = 99%

TP = 0.03 mg/L after 900 mm of sandy loam soil > 99%

Arithmetic averages34

Page 35: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Ontario-style leachfield with pan lysimeters at 12”, 24”,

36” depths

Multi-Year Testing at MASSTC

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

TP m

g/L

Days Lapsed

300 mm pan lysimeter results

35

Page 36: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

EC-P + Soil Depth Removal

0.01

0.1

1

10

0 100 200 300 400 500 600 700 800

TP m

g/L

Days Lapsed

C3 Septic 12" PAN 24" PAN 36" PAN

36

Page 37: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Mimicking Nature?

Al chemicals produce Al + K + P concentrations, but no apparent

crystallinity in SEM

37

Page 38: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Mimicking Nature?

EC-P Fe addition forms octahedral crystalline structures

38

Page 39: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Mineral Formation SEM & XRD scans identify CaC2O4

oxalate mineral weddellite (left) and Fe-PO4 mineral vivianite (right)

39

Page 40: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Mineral FormationXRD scans identify CaC2O4 oxalate mineral

weddellite and Fe-PO4 mineral vivianite

40

Page 41: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

It’s nice to see chemistry theory predict what reactions will occur, in this case formation of vivianite

High

O2

Low

O2

Biomat

Septic

tank

Groundwater

41

Page 42: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Other Benefits

Page 43: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Conventional Strategy – Separation as Sludge

• Dose chemicals to separate out & concentrate P in sludge

• High P sludge pumped out & treated again at WWTP

• pH buffering chemical normally required

• Waterloo EC-P Strategy – Precipitation of Fe-P Minerals

• No chemicals

• Allow FE-P ions to bond meet in anaerobic environment

• Form insoluble crystalline minerals in aerobic environment

• No additional sludge, no subsequent re-treatment

New Strategy

43

Page 44: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

No pH Impact

1

10

0 100 200 300 400 500 600 700

pH

un

its

Days Lapsed

School Septic, Polisher & Area Bed – pH

Polisher Area Bed

Septic Tank Raw Sewage

EC-P Day 372

44

Page 45: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Will this method plug the leachfield?

Long Term

To estimate the volume of Fe-P minerals precipitated in a soil leach field, an Ontario example is used of a 4-person residence with ~2.63 kg TP loading per year.

Assuming that all P is removed in the leach field as oxidized strengite FePO4·2H2O (16.6% P & density of 2840 kg/m3) and none in the anoxic septic tank, this technology will crystallize out 15.8 kg strengite per year or 15.8 ÷ 2840 = 0.0056 m3 of Fe-P minerals.

Field experience shows that the iron staining on sand grains penetrates to at least 0.3 – 0.5 m depth in sandy soil and assumed somewhat less in clay-rich soils.

In 100 m of 0.6-m wide trench in sandy loam soil of ~30% porosity, this technology will occlude 0.0056 m3 or 1 – 2% of the available 7.2 m3 pore space in the upper 0.3 – 0.5 m of leach field over a period of 20 years.

In 500 m trench in clay-rich soil, only 0.2 – 0.4% of the available ~30% porosity will be occluded.

For 1.0 m depth of synthetic filtration media such as peat, foam or textile, Fe-P minerals will occupy less than 5% of available porosity over a 20-year period at peak flow rates.

45

Page 46: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Silicate material used as filtration media receiving septic tank

effluent + EC-P

• Removed and mixed with soil as fertilizing soil amendment

• Greenhouse corn growth & soil leaching studies performed

• Soil only (control)

• silicate material

• super phosphate

• STE + silicate + EC-P

• STE + silicate

15 plants of each 5 treatments

Potential for Recovery

46

Page 47: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Potential for Recovery

0

4

8

12

16

20

Soil(control)

Soil + vsm Soil +Mineral P

STE-EC-P +Soil

STE + vsm +Soil

Tiss

ue

Ph

osp

ho

rus

Per

cen

t D

iffe

ren

ce

1 2 3 4 5

EC-P Highest P uptake

0

20

40

60

80

100

Soil(control)

Soil + VSM Soil +Mineral P

Soil + VSM(STE/EC-P)

Soil + VSM(STE)

Hei

ght

cm

1 2 3 4 5

EC-P Tallest plant height

47

Page 48: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Potential for Recovery

EC-P Most biomass

0

20

40

60

Soil (control) Soil + vsm Soil +Mineral P

STE-EC-P +Soil

STE + vsm +Soil

Dry

Bio

mas

s Pe

rcen

t D

iffe

ren

ce 1 2 3 4 5

48

Page 49: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

• Clean sand removes up to 35% TP (loosely)

• Iron-rich soils remove more

• Possible to mimic iron-rich soils using clean sand or

other filtration medium such as foam

• Insoluble vivianite crystals formed with EC-P

• Suitable for individual homes with other benefits

including potential for resource recovery

Conclusions

49

Page 50: Agricultural Mineral Soil Additives for Passive Nitrate Annual Conference...Agricultural Mineral Soil Additives for Passive Nitrate Removal, & Phosphorus Removal Using Low Energy Electrochemistry

Thank you for your attention!