ONSITE TREATMENT METHODS FOR REMOVAL AND RECOVERY OF MACRONUTRIENTS (N/P) FROM WASTEWATER

Global Innovation Imperatives, IWSWQ, Delhi, Jan. 17-20, 2011

ONSITE TREATMENT METHODS FOR REMOVAL AND RECOVERY OF

MACRONUTRIENTS (N/P) FROM WASTEWATER

Sukalyan SenguptaProfessor & Chairperson

Civil & Environmental Engineering Department University of Massachusetts Dartmouth



SOME I/A SYSTEMS TO REDUCE NITROGEN IN ONSITE EFFLUENT

Heterotrophic Denitrification

Requires an organic carbon source for energy metabolism and cell synthesis:

C in wastewater + NO3- N2 + C5H7O2N


Waterloo Biofilter


Aquapoint Bioclere

TechnologyInfluent Total Nitrogen (mg/L) as N

Effluent Total Nitrogen (mg/L as N)

% Of Nitrogen Removal

Conventional Title 5 System

34.6 26.6 23

Waterloo Biofilter 35.1 12.5 64

Amphidrome 35.3 12.1 66

Biomicrobics MicroFAST

34.1 14.6 57

ECO-RUCK 34.8 34.9 UP

Influent Total Nitrogen = NH4+ + NOx + DON + PON

UP = Unsatisfactory Performance BOD5 - Average = 180 mg/LTotal Suspended Solids – Average = 150 mg/L

Hydraulic Loading Rate = 0.74 gal/ft2/day – Based on NSF 40 protocol

Nitrogen Removal Efficiencies of a Title 5 System and 4 I/A Techs.


SULFUR-OXIDIZING DENITRIFICATION

• High nitrate removal efficiencies• Elemental sulfur, which is a by-product of oil processing, is less expensive than ethanol

or methanol • No external carbon source is required, minimizing the possibility of carry-over of excess

organic carbon into the effluent • Sulfur oxidizing denitrification can take place under aerobic conditions, no need to

deoxygenate the influent• Less sludge produced due to lower biomass yields • Autotrophic sulfur oxidizing denitrifying bacteria produce less N2O (a greenhouse gas)

than heterotrophic denitrifying bacteria

55S0 + 20CO2 + 50NO3- + 38H2O +4NH4

+ 4C5H7O2N + 55SO42- + 25N2 + 64H+

ADVANTAGES:



SOLID-PHASE SOURCES OF ALKALINITY

• Limestone• Marble Chips• Crushed Oyster Shell

Both laboratory-Scale and Field-Scale Tests Performed

Massachusetts Alternative Septic System Test Center (MASSTC)

• At Otis ANG Base Sandwich, MA.

• Assessment of Innovative/Alternative on-site wastewater technologies.

• Pilot scale bioreactor tests run for 18 months.


MASSTC Pilot Tests




FIELD - SCALE TEST RESULTS

0

5

10

15

20

25

30

35

0 100 200 300 400 500

Day of Sampling

Nitr

ate

(N0 3

- - N

as

mg/

L)

Inf luent

Marble Chips Eff luentOyster Shell Eff luent



020406080

100120140160

0 100 200 300 400 500

Day of Sampling

TALK

(mg/

L as

CaC

O 3)

Inf luent Marble Chips Eff luentOyster Shell Eff luent



050

100150200250300350400450

0 100 200 300 400 500

Day of Sampling

Sulfa

te (S

O 42-

) mg/

L

Inf luentMarble Chips EffluentOyster Effluent



33.5

44.5

55.5

66.5

77.5

8

0 100 200 300 400 500

Day of Sampling

pH

Inf luentMarble Chips Eff luentOyster Shell Eff luent



05

101520253035

0 100 200 300 400 500

Day of Sampling

BOD

(mg/

L) Influent

Marble ChipsEffluentOyster ShellEff luent


CONCLUSIONS• High denitrification rates could be achieved in a sulfur-oxidizing

bioreactor system treating nitrified wastewater with an EBCT of eight hours and sufficient pH buffering .

• Crushed oyster shell is the most suitable solid-phase buffer in sulfur-oxidizing autotrophic denitrification systems based on the criteria of (i) dissolution rate, (ii) effluent turbidity, and (iii) economics..

• Material characterization studies (SEM, EDX, and XRD) clearly demonstrate that in crushed oyster shell, (i) the presence of various crystalline phases of calcite (CaCO3), (ii) nano-flakes of calcite, and (iii) the binding action of shell proteins to calcite, contribute to controlled release of buffer and its suitability for this application scenario.

• pH and alkalinity can act as process-control variables.


USE OF BIORETENTION SYSTEMS TO CONTROL

NONPOINT SOURCES OF NITROGEN

Stormwater Structural Best Management Practices*

SwalesWetlandsInfiltration

basins

Media filtersPorous pavementBioretention

systems• Data available on flow reduction, travel time

delays, solids and organics removal• Little data on nutrient removal• Conventional bioretention systems:

– 70-85% P, 55-65% TKN, < 20% NO3- /NO2

-

*UNH stormwater center 2007 annual report


Five Distinct Regions:

Ponding: maintains hydraulic loading

Top Soil & Mulch Nitrification: aerobic

sand layer Denitrification

1. Autotrophic (Sulfur + Oyster)

2. Heterotrophic (wood chips and sand mix – Denyte)

Stone


• Inorganic electron donor (NH4+)

• O2 is electron acceptor

• Carried out in aerobic sand layer

• Autotrophic metabolism (inorganic C source – CO2)

• Alkalinity consumed during process

NH4+ + O2 + CO2 NO3

- + H+ + H2O + new cells

Nitrification


Heterotrophic Denitrifying Bioreactor

• Organic electron donor

• Wood chip/sand mixture

• NO3- electron acceptor

• Process generates alkalinity

• High growth and denitrification rates

Organic carbon + NO3- + H+ N2 + CO2 + H2O + new cells

55S0 + 20CO2 + 50NO3- + 38H2O +4NH4

+

4C5H7O2N + 55SO42- + 25N2 + 64H+

Autotrophic Denitrifying Bioreactor

Mixture of Sulfur and Crushed Oyster Shell Autotrophic metabolism Low biomass generation Excellent packing material Process consumes alkalinity – oyster shell

provides alkalinity source


Methods: Laboratory Storm Events

Application Rate 4 ml/secApplication Duration 6 hrs

Total Applied Volume 86.4 L

Feed CompositionNO3

--N 2 mg/L as NNH4

+-N 2 mg/L as N

Organic N 4 mg/L as NHPO4

2- 0.6 mg/L as P

• Feed – literature values based on urban runoff (Davis et al., 2001; Hsieh and Davis, 2005)

• Application – average W Mass storm event & 0.75% bioretention surface area

• Influent & effluent: pH, TALK, BOD, COD, TSS, VSS, TN, NH4

+, NO3-, NO2

-


Total N Removal in Simulated Storm Event

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.00

1

2

3

4

5

6

7

8

Simulated Rain Event #3: Total Nitrogen Concentration vs. Sample Time

Influent S:OS Effluent Denyte Effluent

Sample Time After Start of Rain Event (hr)

Tota

l N C

once

ntra

tion

(mg/

L)


Nutrients: Simulated Storm Event

Analyte Influent Denyte Sulfur/OS Units

pH 7.08 6.7 7.60

Alkalinity 10.5 280 163.3 mg/L as CaCO3

NO3--N 1.93 ND ND mg/L as N

NH4+-N 3.52 0.3 0.5 mg/L as N

PO43--P 2.4 0.1 0.2 mg/L as P

SO42- 1.4 2 48.9 mg/L SO4

2-

Excellent N and P removal similar to those observed in other studies.


Organics & Solids: Simulated Storm Event


COD 13 88 61 mg/L

BOD5 7 29 13 mg/L

TSS <1 8 2 mg/L

VSS <1 8 2 mg/L

Some generation of organics and solids due to leaching from organic material, production of soluble microbial products.

Field Site: Putnam CT• Dairy farm in Putnam, CT• Runoff from barn conveyed to detention

pond• Reactors used to treat detention pond

water

Lagoon Characteristics

Average Detention Pond Composition

pH 7.8TN 90 mg/L

NO3--N ND

NH4+-N 22 mg/L

PO43--P 27 mg/L

BOD5 200 mg/L COD 2080 mg/L


Influent 2 hours 4 hours 6 hours0

10

20

30

40

50

60

70

Denyte

S/OS

Tot

al N

itrog

en (m

g/L

)

Total Nitrogen Removal

Concentration of TN over time during typical field test

CH4CO2

NPBODTSSCH4


Field Tests – Nutrients


pH 7.9 6.5 7.0

Alkalinity 890 615 470 mg/L as CaCO3

NO3--N ND ND ND mg/L-N

NO2--N 23.56 ND ND mg/L-N

NH4+-N 13 0.78 3.24 mg/L-N

Total N 57.56 3.97 5.57 mg/L-NPO4

3--P 28.8 ND ND mg/L-P

Total P 53 20 17 mg/L-PSO4

2- 85 90 260 mg/L


Field Results – Organics, Solids & Metals

Analyte Influent Denyte Sulfur/OS UnitsCOD 1216 790 695 mg/LBOD5 144 95 50 mg/LTSS 252 68 31 mg/LVSS* 222 55 25 mg/LCopper ND ND ND mg/LZinc ND ND ND mg/L

* Approximately 56% TN, 14% TP and 55% COD removal due to removal of solids

Hydrolysis of dissolved and particulate organic N appears to be rate limiting. Current research focused on pretreatment to remove organic C, and

hydrolyze organic N. ND =Non-Detect, Detection Limit = 0.10 mg/L by AA flame method.


Change in Sampling Procedure

A battery operated timer was installed to control the influent flow to the field reactors for dosing the units at scheduled intervals for better activation of the microbial community and to more closely simulate conditions expected of a bio-retention system.

• Flow Rate: 100 ml/min• Days of Operation: Tuesday, Thursday, Saturday• Time of Operation: 8:00 , 9:00, 10:00, 11:00,12:00• Duration: 21 minutes on 39 minutes off• Loading Rate: 0.035 cm3/cm2-min• Sample Collection: 11:00, 12:00

Operating Parameters


Field Tests – Nutrients


pH 7.6 7.03 7.34

Total Alkalinity 286 385 284 mg/L as CaCO3



NH4+-N 11.5 ND 0.44 mg/L-N

Total N 37.13 6.20 7.00 mg/L-N

PO43--P 18.23 9.11 14.71 mg/L-P

SO42- 16.02 6.30 99.70 mg/L


Field Tests – Organics, Solids, & Microbial Contaminants


COD 434 208 208 mg/L

BOD5 86 17 27 mg/L

TSS 129 21 16 mg/L

VSS 111 16 12 mg/L

Total Coliforms 1.1x106 8.4x104 9.13x104 mg/L

E.Coli 1.03x105 2.01x103 1.35x103 mg/L


Conclusions – Bioretention Systems• Initial steps taken in developing a low cost, low

maintenance, passive system for total N removal in stormwater.

• Laboratory results indicate >90% TN removal achievable for runoff from developed land, fertilized fields.

• Treatment of runoff from livestock operations challenging – low rates of organic N hydrolysis.

• Bench scale tests currently focused on increasing ammonification rates.


Selective Removal of Phosphorus from Wastewater Combined with Its Recovery as a Solid-Phase Fertilizer


P Limits:70µg/L – Boise42 µg/L – Spokane10 µg/L - Everglades

Chemical Precipitation:Moles Al/Fe/Mole P100 – 200Sludge disposal??


Phosphorus Supplies

• Phosphorus is being consumed faster than geological cycles can replenish it.

• Approximately 80% of global phosphorus deposits are concentrated in three countries: Morocco, China, and the US.

• Some studies predict global supplies of phosphorus may start running out at the end of this century.


Physical-Chemical Adsorption/ Sorption

• Removal mechanisms:– Electrostatic interaction– Lewis acid-base interaction/Ligand exchange

• Materials Studied:– Metal hydroxides (Al, Fe, Zr, etc.)– Alum sludge– Blast furnace slag– Fly-ash– Gas concrete


• Oxides of polyvalent metals exhibit strong ligand (Lewis bases) sorption properties (Lewis acids) through formation of inner sphere complexes.

• Ortho-phosphate molecules containing one or more lone pairs of electrons in the highest occupied molecular orbital depending on the degree of dissociation are strong ligands.

Ligand Exchange


Development of Polymeric Ligand Exchangers (PLEs)

• Limitations faced:– Granular metal oxides lack the mechanical strength and

attrition resistance properties for prolonged operation.– Commercial anion exchangers show poor selectivity for

phosphate over other competing anions, like sulfate.

• Development of PLEs:– PLEs combine the sorption affinity of these metal oxides

with the durability and mechanical strength of the ion exchanger.

Characteristics HAIX DOW-HFO DOW-HFO-Cu

Structure Macroporous Polystyrene-Divinylbenzene

Macroporous Polystyrene-Divinylbenzene

Macroporous Polystyrene-Divinylbenzene

Appearance Brown spherical beads Tan to dark brown opaque beads Tan to dark brown opaque beads

Functional group Quaternary ammonium Bis-picolylamine Bis-picolylamine

Iron content 75-90 mg as Fe/ g resin 45 - 60 mg as Fe/ g resin 40 - 50 mg as Fe/ g resin

Bulk density 790 - 840 g/L 673 g/L 673 g/L

Particle size 300 - 1200 µm 297 - 841 µm 297 - 841 µm

N

H

N N

N

H

N N

Cu2+

Iron-Oxide-Impregnated PLE


Schematic of Complexation of Phosphate

Competing sulfate and chloride ions only form outer sphere complexes due to Coulombic interaction. This reverses the tendency of preferential uptake of sulfate over phosphate by the resin.


0 100 200 300 400 500 600 7000.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00Breakthrough Curve of PO43- and SO42- for HAIX

Phosphate (mg P/L) Sulfate (mg/L)

Bed Volumes (BV)

Con

cent

ratio

n

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent CharacteristicspH = 8.0;Cl- = 2.77 mg/L;SO4

2- = 161.61 mg/L;Phosphate = 4.20 mg/L as P


Effect of SO42- Presence on PO4

3- Sorption

0 100 200 300 400 500 600 700 8000.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Comparison of Effluent Phosphate (PO43-) profiles in Exhaustion Run [Influent Concentration ≈ 2.75 mg/L]

Sulfate Concentration = 20.00 mg/LBed Volume (BV)

Conc

entr

ation

(in

mg/

L as

P)

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent CharacteristicspH = 8.0


Effect of Increase in SO42- Concentration on PO4

3- Sorption

0 100 200 300 400 500 600 7000.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

Breakthrough curve of PO43- for HAIX at different SO42- concentration

Phosphate (mg P/L):Sulfate (mg/L) = 1:40 Phosphate (mg P/L):Sulfate (mg/L) = 1:60

Bed Volumes (BV)

Con

cent

ratio

n (m

g P/

L)

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent CharacteristicspH = 8.0;Cl- ≈ 2.77 mg/L;Phosphate ≈ 4.0 mg/L as P

SO42- = 245.90

mg/L

SO42- = 161.61

mg/L


0 100 200 300 400 500 6000.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00Breakthrough Curve of PO43- and SO42- for DOW-HFO


Bed Volume (BV)

Con

cen

trat

ion




0 100 200 300 400 500 600 700 800 900 10000.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00Breakthrough Curve of PO43- and SO42- for DOW-HFO-Cu


Bed Volumes (BV)

Con

cen

trat

ion




N

H

N N

Cu2+

H2PO4-/HPO4

2-= Coulombic

= LAB


0 100 200 300 400 500 600 700 800 900 10000.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00Comparative Breakthrough Profile of PO43- for Different Sorbents

HAIX

DOW-HFO

DOW-HFO-Cu

Bed Volumes (BV)

Con

cen

trat

ion

(m

g/L

)

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent CharacteristicspH = 8.0;Cl- ≈ 3.50 mg/L;SO4

2- ≈ 130.00 mg/L;Phosphate ≈ 4.25 mg/L as P

0 5 10 15 20 250.0

50.0

100.0

150.0

200.0

250.0

Bed Volume (BV)

Con

c. (

mg

P/L

) Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent Characteristics2.5 % NaCl + 2.0% NaOH

0 5 10 15 20 250.00

50.00

100.00

150.00

200.00

250.00

300.00

Bed Volumes (BV)

Conc

entr

atio

n (m

g P/

L)

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent Characteris-tics2.5 % NaCl + 2.0% NaOH

Regeneration Profiles

HAIX

DOW-HFO


0 5 10 15 20 250

100

200

300

400

500

600

700

800

900

1000

Bed Volumes (BV)

Con

cent

ratio

n (m

g P/

L)

Flow Condition:EBCT: 3.0 min;Loading Rate: 200 L/m2-hrInfluent Characteris-tics2.5 % NaCl + 2.0% NaOH

DOW-HFO-Cu


Fertilizer from Regenerant Solution Standard

Element Weight % Atomic % Weight % Atomic %

Oxygen 49.35 68.96 53.57 72.87

Sodium 1.82 1.71 - -

Phosphorus 17.74 12.36 19.60 13.18

Chlorine 3.11 1.89 - -

Calcium 27.99 15.07 26.82 13.94

Fertilizer from Regenerant Solution Standard

Element Weight % Atomic % Weight % Atomic %

Oxygen 66.19 75.56 56.67 65.92

Phosphorus 16.99 10.02 22.12 13.29

Magnesium 13.60 10.21 13.12 10.04

Nitrogen 3.23 4.21 8.10 10.76

Magnesium Ammonium Phosphate Mg(NH4)PO4 - Struvite

Calcium Phosphate Ca3(PO4)2


0 5 1 0 1 5 2 0 2 50. 0

50. 0

100. 0

150. 0

200. 0

250. 0

Fresh regenerantReecycled regenerant

Bed Volume (BV)

Con

cen

trat

ion

(m

g P

/L)

Regeneration Efficiency: 97.0 %

Regeneration Efficiency: 93.0 %

Recycled Regenerant Performance



Process Flow Scheme


Conclusions HAIX, DOW-HFO, & DOW-HFO-Cu can be used for selective phosphate

uptake, and all three showed high selectivity towards phosphate when compared to sulfate.

Lewis acid-base interaction (between the anionic ligand and the central metal atom forming inner-sphere complexes) accompanied by the electrostatic attraction (i.e. ion-pair formation) is the core mechanism leading to high sorption affinity toward phosphate. This mechanism was supported by thermodynamic data.

Each sorbent is amenable to efficient regeneration. Single step regeneration with 2.5 % NaCl and 2.0 % NaOH consistently recovered more than 95.0 % of sorbed phosphate within 10 bed volumes. Only minor capacity drop (about 1.5 %) was observed after 10 cycles of exhaustion-regeneration.


Conclusions (contd.) The spent regenerant may be reused after supplementing for the hydroxide

lost in regeneration.

Phosphate could easily be recovered from the spent regenerant as calcium phosphate or struvite with addition of calcium chloride or magnesium chloride + ammonium chloride.

No significant bleeding of iron was found in the regenerant, negating any need for supplemental addition of iron to the sorbent media during its life cycle.

Intraparticle diffusion is the rate limiting step for phosphate sorption.

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ONSITE TREATMENT METHODS FOR REMOVAL AND RECOVERY OF MACRONUTRIENTS (N/P) FROM WASTEWATER

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