Basic Nutrient Removal from Water

Beta Edition Presented by Paul KrauthUtah DEQ

Salt Lake CountywideWatershed SymposiumOctober 28-29, 2008

Presentation Outline

Salt Lake County waters / 303(d) listings

Nutrient Control

Phosphorous Removal

Nitrogen Removal

Potential Costs

Salt Lake CountyWatershed

Salt Lake CountyWatershed

303(d) listed waters 2008

TP,TDSPS3B396,900 acresUtah Lake Jordan River / Utah Lake

4.2Total PhosphorusNS3BJordan River from North

Temple to 2100 SJordan River-3Jordan River/Utah Lake

4.2Dissolved OxygenNS2BJordan River from North

Temple to 2100 SJordan River-3Jordan River/ Utah Lake

4.46Dissolved OxygenNS3B

Jordan River from Davis County line upstream to North Temple Street.

Jordan River-2Jordan River/Utah Lake

7.6Dissolved OxygenNS3B

Jordan River from Farmington Bay upstream contiguous with the Davis

County line.

Jordan River-1Jordan River/ Utah Lake

MilesSupportClassNameNameUnit

StreamPollutantUseUseUnitUnitManagement

BeneficialAssessmentWatershed

Salt Lake CountyWatershed

Wastewater TreatmentPlants

Magna – 3.3 MGD

Salt Lake – 56 MGD

Central Valley – 75 MGD

South Valley – 38 MGD

- 48 MGD

≅ 182 MGD

What are nutrients ?Chemical elements/compounds needed by organisms to survive, grow, and reproduce.

Nitrogen1-5% dry weight

found in proteins

nitrate (NO3-)

ammonium (NH4+)

natural fixation

decomposition

Phosphorus0.1-1% dry weight

found in lipids, DNA

phosphate (PO43-)

mineral weathering

decomposition

Carbon25-40% dry weight

found in everything

natural fixation

decomposition

Measured ratio of C:N:P can indicate organisms needsSlide courtesy Dr. Michelle A. Baker - USU(106:16:1)

Nitrogen vs. PhosphorusIf enough phosphorus is presentCyanobacteria can fix nitrogen fromthe air.

Nitrogen control is needed for ammonia toxicity, for nitratereduction in drinking water, and forwaters where phosphorus levels arenormally low.

So Now You Want Me To Treat for

NUTRIENTS!

Why remove phosphorusEutrophication

Excess nutrients

Nitrogen, phosphorus

Algal blooms

Hypoxic conditions

Why remove phosphorusEutrophication

Phosphate is the main cause of eutrophication as it accumulates with time, while nitrate, tends to denitrify with time and so does not accumulate to the same extent

Phosphorus forms11th most abundant mineral

Highly reactive so NOT found as P

Particulate

Soluble

Gaseous – not of any significant

Phosphate formsOrganic phosphates – ATP-ADP

Inorganic phosphates

Orthophosphates – PO4-3

Pyrophosphates – P2O7-4

Tripolyphosphate – P3O10-5

Tota

l Pho

spho

rus

mg/

LWastewater Influent

1971 1991

8

76

4

5

3

0

1

2

9

10

Orthophosphate

Tripolyphosphate

Pyrophosphate

Organic phosphate

Treatment technologiesPhosphorus removal rules

Assume no gaseous forms

100% goes out as a solid or liquid

Must be converted or attached to a solid to be removed from the liquid stream

Treatment technologies

Soluble P

Particulate P

Particulate P

Soluble P

Treatment technologiesConverting soluble P to particulate P

Biologically

Chemically

Biological P RemovalSome bacteria store higher levels of phosphorus than normal

“Excess” phosphorus stored as polyphosphates

These bugs are called phosphorus accumulating organisms PAOs

Biological P RemovalProcess “discovered” in 1974

Anaerobic phosphorus is released

PAOs uptake in aerobic zone

Fat man on a diet

ONLY the activated sludge process

Biological P RemovalAnaerobic Zone

Biological P RemovalAerobic Zone

Biological P RemovalO

rtho

phos

phat

e c

once

ntra

tion

Anaerobic Aerobic

Luxury uptake

Chemical P Removal

Metal ions + PhosphateMetal Phosphate + Acid

Basic Reaction

Side Reaction

Metal ions + BicarbonateMetal Hydroxide + Carbon Dioxide

Chemical P RemovalCa+2 lime

Al+3 alum, sodium aluminate

Fe+3 ferric chloride, ferric sulfate

Fe+2 ferrous sulfate

Chemical P SolidsCa+2 Ca3(PO4)2, Ca5(OH)(PO4)2

Al+3 AlX(OH)Y(PO4)Z

Fe+3 FeX(OH)Y(PO4)Z

Fe+2 Fe3(PO4)2

Chemical P Curve

How low can we go ?EBPR best case 0.5 mg/L

Reliably 1.0 mg/L

Chemically best case 0.01 mg/L

Reliably 0.05 mg/L

Why Remove Nitrogen ?Ammonia, Nitrite and Nitrate can

be toxicAmmonia exerts an oxygen demandAmmonia and nitrate stimulate

growth of algae and aquatic plants

Forms of Nitrogen in WaterAmmonium and Ammonia ( NH4

+ , NH3 ) ( ionized, un-ionized )

Organic Nitrogen ( -N )

Nitrite and Nitrate ( NO2-, NO3

- )

Total Kjeldahl Nitrogen ( TKN ) ( ammonia forms + organic nitrogen )

Total Inorganic Nitrogen ( TIN ) ( ammonia forms + nitrite + nitrate )

Total Nitrogen

0%

20%

40%

60%

80%

100%

6 7 8 9 10 11 12 13

pH

perc

enta

ge

NH4+ - N

ammoniumionized ammonia

NH3 - Nammonia gas

unionized ammonia

Ammonia form depends on pH

Some ChemistryAmmonia is the third most produced

chemical in U.S.

Detectable odor from 25 to 50 mg/L

NH3(aq) + H2O(l)

NH4+(aq)

NH4+(aq) + OH-(aq)

NH3(aq) + H+(aq)

NitrificationThe major method for ammonia removal

Conversion of ammonium to nitrite and nitrate by autotrophic bacteria

Is an AREOBIC process ( Oxygen needed )

Nitrification DefinitionsAll bacteria need carbon for growth

Heterotrophic bacteria – “bugs” that use organic compounds (BOD5) for their carbon source

Autotrophic bacteria – “bugs” that use CO2 as their carbon source ( nitrifiers )

Nitrification DefinitionsHeterotrophic bacteria will always out

compete Autotrophic bacteria

Carbon oxidizers are the top of the food chain (CBOD)

So if a system is nitrifying it must have a LOW CBOD

Some Chemistry

2 NH4+ + 3 O2 2 NO2

- + 4 H+ + 2 H2O

Typically a 2 step process ( peel the orange! )

Nitrite formation ( Nitroso-bacteria)

Nitrate formation ( Nitro-bacteria )

2 NO2- + O2 2 NO3

-

2 NH4+ + 3 O2 2 NO3

- + 2 H+ + 2 H2O

Nitrite - NitrateCon 10 mg/L drinking water

Nitrite - NitratePro Estrogen removal

17 α-ethinylestradiol (EE2)

2,4-nitro EE2

De-nitrification The major method for nitrate removal

Conversion of nitrate to nitrogen gas by heterotrophic bacteria

Is an ANOXIC process ( Carbon needed )

De-nitrificationSince it is heterotrophic growth, organic

carbon is used

Substrate consumption ratio (SCR)

Theoretical SCR is 2.86 g COD/gram nitrate nitrogen

Typical influent has about 4.2 g COD/gram nitrate nitrogen

De-nitrificationOxygen equivalent of NO3

- is 2.86 mg

Alkalinity produced due to the consumption of the nitric acid

Alkalinity equivalent of NO3- is 3~3.2 mg

Wait till you see the costs of low nutrient

removal !

What are the Costs ?DWQ needs to know

EPA needs survey curves

Numerous white papers

Conduct Statewide study

2000 CWNS Results138 wastewater projects next 20 yearsNo nutrient projects793 million dollars neededAverage cost 5.7 million (2000 dollars)

Capacity MGD

Unit Cost of TP for existing facilities (2005)for 1 mg/L

$ /

kg T

P

White Paper ExampleQ = 182 MGD

TPi = 5.0 mg/L

TPe = 1.0 mg/L

Load Reduced ≅ 3.00 tons/day

Costs ≅ 250 million

Costs ≅ $25/person

State StudyDWQ plans to evaluating the feasibility and economic impacts of establishing state-wide discharge standards for the nutrients phosphorus and nitrogen in treated wastewater discharged to surface waters

State StudyTreatment facilities and nutrient removal treatment costs will be assessed with respect to the need to treat wastewater to a range of nutrient standards. The following discharge standards will be considered for each facility:

State Study

0.1 ppm & 10 ppm0.1 ppm1.0 ppm & 20 ppm1.0 ppm

Total Phosphorus & Total Nitrogen

Total Phosphorus Only

Effluent Nutrient Requirement Scenarios

State StudySelected consultant – CH2M Hill

Data gathering from POTWs

Schedule meetings with POTWs

Complete report

Presentations to Councils/Boards

Questions ?