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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
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.
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
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
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
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
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
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)
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
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