Monitoring for Nitrification CHARLOTTE SMITH CHARLOTTE SMITH

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Monitoring for Nitrification CHARLOTTE
SMITH CHARLOTTE SMITH ASSOCIATES, INC.AWWA
WQTC San Antonio, TexasNovember, 2004
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Presentation Content

• PART I THE PARAMETERS
• WHY is monitoring important?
• WHAT parameters are important to monitor?
• WHERE (Method depends on location)
• PART II - METHODS
• Advantages and Disadvantages of Methods
• PART III INTERPRETING RESULTS
• PART IV QUESTIONS ANSWERS

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WHY is monitoring important?
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Public Health Laws Require Maintenance of
Chlorine Residual in the Distribution
SystemFederal Regulation SWTR
DetectableState Regulations Vary in
definition of detectable
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What?

• Key Process Control Parameters
• Chlorine Residual (free/total)
• Ammonia (free/total)
• Nitrite/nitrate
• Surrogate for AOB HPC-R2A
• pH
• Temperature

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What?

• Related Parameters
• Total Organic Carbon
• Hardness
• Alkalinity
• Dissolved Oxygen

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CHLORINE RESIDUAL
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Total Chlorine Residual Defined
free chlorine

• OCl- NH4 NH2Cl H2O
• NH2Cl HOCl NHCl2 H2O
• NHCl2 HOCl NCl3 H2O
• HOCl organic nitrogen R-NHCl

Organo-chloramine
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Breakpoint Curve(relates to chemical feed)
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6
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Total Chlorine Residual (mg/L)
2
0
0
2
4
6
8
10
12
14
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Chlorine Dose mg/L Cl2 per mg/L NH3-N
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Cl2 Methods
Standard Methods 4500 -Cl2 B - 4500-Cl2
I Technique Amperometric Titration Standard
of Comparison Range ( 0.2 mg/L 2.0 mg/L
) - Clean and condition electrodes for sharp
endpoints - Loss of chlorine due to
stirring - More time consuming than
colorimetric methods Not affected by
oxidizing agents, temp, turbidity Technique
Colorimetric / N,N-diethy-p-phenylenediamine
(DPD) _at_ 515 nm Range ( 0.010 mg/L 2.0 mg/L
under ideal conditions ) - Monochloramine
interferes with free chlorine - Mn, Br
interfere reduced forms (e.g. Br-) dont -
Organochloramines interfere NCl3 reacts as
Clfree (confounds breakpoint curve analysis
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Total Cl2 Methods
Hach (colorimetric/spectrophotometric) Range
(0.02 2.00 mg/L) High range tests use
reduced pathlength or dilution Determine reagent
blank and matrix blank for low concentrations
(e.g. Environmental Discharges) Other Technique
H P L C (Andrews Cheng, 2000)
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Free Chlorine

• Indicates position on breakpoint curve.
• Only measure in the field during breakpoint
  chlorination events or main installation/repair.
• Mn, Br, NH2Cl give false positive results.

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Total Chlorine versus Monochloramine DPD or
Monochlor F Reagent?
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In process control lab at plant calculation and
measurement of monochloramine is useful.In DS
total Cl2 measurement is practical.
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Cl2 Methods Recommendations
Treatment Plants Technique Amperometric
Titration (for instrument calibration or
comparative studies Colorimetric / DPD
Transmission Technique Colorimetric /
DPD Distribution system (TCR taps) Technique
Colorimetric / DPD Storage Facilities
Technique Colorimetric / DPD
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AMMONIA
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Or chemical oxidation
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Ammonia-N Defined
Combined ammonia-N
free ammonia

• OCl- NH4 NH2Cl H2O
• NH2Cl HOCl NHCl2 H2O
• NHCl2 HOCl NCl3 H2O
• OCl - organic-N (amines) R-NHCl

Organo-chloramine
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Ammonia-N Methods
Standard Methods Technique ASE 4500-NH3-D or
4500-NH3 E (known addition) Range (0.03 1400
mg/L) - immerse electrode 2-3 min. for stable
reading Technique Manual / Automated
Phenate Range (0.02 2.0 mg/L) Refrigerate
unacidified Run lt 24 hours Hach
(colorimetric/spectrophotometric) Technique
Salicylate methods ammonia reacts w/ chlorine,
monochloramine reacts with alicylate to form
5-aminosalicylate, 5-aminosalicylate reacts w/
sodium nitroprusside catalyst to form blue, Blue
masked by yellow of excess reagent to form green
_at_ 655 nm Range ( 0.01 0.50 mg/L)
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Fate of Free Ammonia-N in DS

• According to the Breakpoint Curve
• The portion of the ammonia-N dose which does
  not combine with chlorine to form chloramines
  will be present as free ammonia-N.
• Decomposition of chloramines produces free
  ammonia-N.

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Ammonia-N Recommendations

• Total ammonia-N for breakpoint calculations.
• Free ammonia-N at plant (Target lt0.05mg/L).
• Free ammonia-N in distribution system.

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NITRITE
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NO2--N Methods
Standard Methods 4500-NO2--N Technique
Spectrophotometric _at_ 543 nm gt1cm
pathlength Range (0.010 1.000 mg/L) Coupling
diazotized sulfanilamide w/ N-(1-naphthyl)-ethylen
ediamine dihydrochloride (NED dihyochloride)
2 days _at_ 4 degrees Celcius Hach
(colorimetric/spectrophotometric) Technique
Diazotiztion Method _at_ 507 nm Range (0.003 30
mg/L) similar to Standard Methods
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Nitrite Recommendations

• If there is no background concentration of
  nitrite, it is the best indicator of
  nitrification.
• Monitor with total chlorine in distribution
  system.

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NITRATE
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NO3--N Methods
Standard Methods 4500-NO3--N Technique
Ultraviolet screening method 220nm Technique
Nitrate electrode Range (0.14-
1400mg/L) Technique Cadmium Reduction Range
(0.01-1.0 mg/L) Technique Cadmium Reduction
Range (0.001-1.00 mg/L) 2 days _at_ 4 degrees
Celcius Hach (colorimetric/spectrophotometric)
Technique Cadmium Reduction Range (0.01 30
mg/L depending on method) - cadmium is a
hazardous waste Technique Dimethylphenol Range
(0.2 13.5 mg/L)
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Nitrate Recommendations

• Nitrobacter are very slow growers. Increase may
  indicate nitrification but can also reflect
  variability in source water concentration
• Can be useful during evaluation studies of
  nitrification.
• Not necessary for routine monitoring

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AMMONIA OXIDIZING BACTERIA
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Ammonia Oxidizing Bacteria and Heterotrophic
Plate Count
Lieu, N. 1989
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AOB Methods
Methods Technique Multiple Tube Method - 3
week incubation time Technique BARTS - No
published information Technique Rapid
Enumeration Method PCR method FISH method
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Targeting 16S rRNA Gene
Ribotyping suggests single gene in AOB ?
simplifies quantification
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Nitrosomonas TaqMan Probe Design
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Fluorescent In Situ Hybridization (FISH)
Confocal image of AOB-targeted FISH applied to
activated sludge floc
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HPC Methods
Standard Methods Technique 9215C Pour plate
Range (20 200 or gt5700 or gt6500 depending on
plate size) - subject to heat shock Technique
9215D Spread plate no heat shock Technique
9215E membrane filter no heat shock -
possible damage to cells from pressure 8 hours
max holding time or at 4o lt24hr. Compliance with
SWTR 40CRF141.74 PourPlate 35oC 48hrs Highest
counts R2A media 5-7 days 20-28oC Report
xCFU/ml, pourplate, 35oC/48hrs, plate count
agar
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PCA vs. R2A
3.5
3
2.5
Routine Locations
New Mains
2
mean CFU/ml (x 1000)
1.5
1
0.5
0
PCA
R2A
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Source A. Wilczak
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Source A. Wilczak
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TEMPERATURE
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Temperature Methods
Standard Methods 1. Technique Mercury Filled
Thermometer _at_ 0.1 degree intervals or 2.
Technique Reversing Thermometer Technique
Thermophone Technique Thermistor (most
accurate) _at_ 0.1 1 degree intevals
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Is the Tank Thermally Stratified?
Data logger
58.2 o F
Temp probes
Float
58.0 o F
57.7 o F
56.2 o F
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Probes Hanging a Distribution Reservoir
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Water Quality Data
Roof ports
8
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pH
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pH Methods
Standard Methods Technique Electrometric
Method Range (0-14) with temperature
compensation pH log10 ? H H activity
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Example of Graphed Data

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Conclusions

• Regulations only require Total Chlorine residual.
• More work needs to be performed on organic
  chloramines compounds, fate, disinfection
  efficacy, health effects.
• Ammonia field and lab methods require better
  verification for accuracy.

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Conclusions

• Monitoring program critical for nitrification
  prevention and response.
• Methods should be based on location and
  regulatory requirements or process control needs.
• Both field and Standard Methods are useful.
• New ammonia oxidizing bacteria methods show
  promise.

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Questions?

• www.CharlotteSmith.us