February, March and April 2018

Julie Sievers
Iowa DNR Field Office 3
 Available on the IRWA website
 Go to www.iowaruralwater.org/
 Then Resources
 Then Downloads
 You will find the presentation there
 Introductions
 Chlorine Chemistry, Ammonia Sources and Impact
 Nitrification – The Good, the Bad, and the Ugly
 Testing, Indicators, and Specific Examples

 Flint Lead Event

 Roundtable Discussion
 Monochloramine, NH2Cl
 Dichloramine, NHCl2 Combined Chlorine
 Trichloramine, NCl3
 Free Chlorine, OCl- (hypochlorite) or HOCl
(hypochlorous acid) – dependent on pH
 Free Chlorine = Free Available Chlorine
 Total Chlorine = Free + Combined
 Chlorine Residual = Dose - Demand
Do you know which are present in your system?
 Ammonia, NH3 or Ammonium ion, NH4
◦ In neutral or acidic natural waters, ammonia is
present as ammonium ion
 Nitrite, NO2
 Nitrate, NO3
 Kjeldahl Nitrogen, TKN
◦ TKN = Organic nitrogen + ammonia
 For systems adding ammonia
◦ Ammonium sulfate (LAS), ammonium hydroxide, or
others
 Naturally occurring in Iowa
 When the nitrogen present in the well is ammonia
it is not from surface source
◦ Surface source is converted to nitrate before reaches
aquifer = nitrate in well, not ammonia
 Ammonia is from the mineralization of organic
material present from when aquifer was formed
◦ Mineralization of organic matter to ammonium by
microorganisms in presence of organic carbon sources in
an anaerobic (without oxygen) environment
◦ Most of Iowa was shallow seas
 Found in all aquifers
 Levels of 1 to 5 mg/L common
◦ DNR/UHL study
◦ GSB data
◦ USGS data
◦ Ambient water quality data
Ammonia Molecule
◦ DNR 2013 study 3 hydrogen and 1
◦ Raw water monitoring nitrogen atoms

 Levels as high as 11 mg/L

 Ammonia is NOT regulated in Iowa in drinking water
 Ammonia has a huge chlorine demand (10 – 12 mg/L of
chlorine per 1 mg/L of ammonia)
 Need to know what form of disinfectant you are using
◦ Must meet minimum levels to protect public health
 Taste and odor issues
 Nitrification
 Disinfection byproducts violations or issues
◦ TTHM/HAA5 for free chlorine; Nitrosamines for chloramines
 Water quality impacts

Do you know the ammonia level in your system?

From Bob Spon, OpFlow Article, June 2008
 Chlorine typically added as gas chlorine or
sodium hypochlorite (liquid chlorine)
 Disassociates based on pH (and temperature)

Chlorine Hypochlorous Acid Hypochlorite Ion

If you add ammonia or have it present in the raw water, these
reactions occur:

Formation is
dependent
on the pH
and chlorine
to ammonia
ratio
Monochloramine Dichloramine Trichloramine
AKA Nitrogen trichloride
 There are competing reactions

NaOCl + H2O → HOCl + NaOH Liquid chlorine

Cl2 + H2O → HOCl + Cl- + H+ Gas chlorine

NH3 + HOCl → NH2Cl + H2O Monochloramine

NH2Cl + HOCl → NHCl2 + H2O Dichloramine

Trichloramine
NHCl2 + HOCl → NCl3 + H2O
 For typical, traditional chloramination, the system
adds chlorine and ammonia
◦ The system can control both chlorine feed rate and
ammonia feed rate
◦ Typically, chlorine is added first, then ammonia
 In systems with naturally occurring ammonia,
chloraminating due to ammonia in source water
◦ System can control chlorine feed rate BUT have no to
limited ability to change or control ammonia level
Do you have ammonia in your raw water?
Do you add ammonia?
 Ammonia reacts with chlorine to form monochloramine,
dichloramine, and trichloramine
 Formation is dependent on the pH and chlorine to
ammonia ratio
 Monochloramine, dichloramine, and trichloramine are
measured as a part of the total chlorine residual and are
weak disinfectants
 Trichloramine = Nitrogen trichloride
 Monochloramine and dichloramine exist together at pH
of 6.5 to 7.5
◦ Chlorine to ammonia ratio determine which is formed
 Dichloramine and trichloramine cause taste and odor
problems
 Small amounts of trichloramine (nitrogen trichloride)
may exist past the breakpoint and may also cause taste
and odor problems
From Bob Spon, OpFlow Article, June 2008
 Ammonia results from a certified lab are for total
ammonia
 Free ammonia testing must be done immediately and
is done on-site
◦ Free ammonia and monochloramine are measured as a two
step test
 Total chlorine = free + combined
 Combined chlorine = monochloramine +
dichloramine + trichloramine
 Free chlorine in the presence of chloramines is “false”
free
 Minimum levels dependent on where you are at on
the curve
◦ Levels throughout the distribution system
 Minimum of 0.3 mg/L free chlorine residual if on
the breakpoint side of the curve
 Minimum of 1.5 mg/L total chlorine residual if
chloraminating

 Maximum of 4.0 mg/L total chlorine

◦ Based on Running Annual Average (RAA) = MRDL
 Minimum = 1.5 mg/L total chlorine Min = 0.3 mg/L free

From Bob Spon, OpFlow Article, June 2008

Determine where you are at on the curve
 Measure free chlorine immediately and at 30
second intervals to 2 minutes after adding reagent
◦ Are the readings stable or do the readings increase?
◦ If the free residual increases more than 0.1 mg/L, you
are on the chloramine side of the curve & do NOT have
free chlorine.
 This is often referred to as “false” free
 Measure total chlorine residual
◦ Rule of thumb is if the free residual is stable and about
80% of total, you are on the breakpoint side and have
“true” free residual
 “False” Free Chlorine Residuals
All in mg/L

The rate of
interference is
dependent upon:
• the
concentration
of the
chloramine
Zero Immediately = 0.08 30 seconds = 0.20 • the chloramine
compound
present
• and the
sample
temperature

60 seconds = 0.36 90 seconds = 0.52 120 seconds = 0.76

 Where are You on the BP Curve?
Test Results = 3.0 mg/L total chlorine

Courtesy of Hach disinfection series

http://www.hach.com/DisinfectionSeries06
 What else do you need to know?

From Bob Spon, OpFlow Article, June 2008

 What do we need to measure?
 Where is the best spot to test for it?
 What results are we looking for?
 What do we do if we don’t get them?
All Systems:
 Free chlorine residual
◦ Determine if true or false free
 Total chlorine residual
 Chlorine dosage
 Total ammonia
◦ In systems with naturally-occurring ammonia, to measure raw
water fluctuations
◦ Seasonal changes
◦ Water levels
◦ Usage, pumping rates
◦ Well rotation
 If no total ammonia but indications, test TKN
Chloraminating Systems:
 Free Ammonia
◦ To determine location on the curve
 Monochloramine
◦ This is the target disinfectant for chloraminating systems
◦ Total residual = Monochloramine
◦ In systems that add ammonia, you can achieve this
 Nitrite and nitrate
◦ Important to determine if nitrification is occurring
◦ Measure nitrite and nitrate separately
◦ More on this later, including locations where to measure
 For systems adding ammonia, measure free chlorine prior
to ammonia addition to determine how much ammonia to
add
 Testing Along the Curve
Assume a 1 mg/L ammonia-N dose

Courtesy of Hach disinfection series

http://www.hach.com/DisinfectionSeries06
 Dependent on system and location of chlorine addition
 Always measure at the SEP
 Always measure in the distribution system
◦ Important to know residuals and levels at different water age
locations
 May need to measure at specific treatment processes
◦ More on this later
For chloraminating systems:
 The key is the chlorine to ammonia ratio
◦ In systems that add ammonia, chlorine typically is added first,
then ammonia
 Free chlorine residual (not dose)
 Ammonia dose
◦ In systems with natural ammonia, minimizing free ammonia as
much as possible
◦ Chlorine dose – target is monochloramine
 Other factors
◦ pH
◦ Temperature
 Minimum total residual of 1.5 mg/L
◦ If can show consistent treatment, may not be required to
measure free chlorine (false) – discuss with DNR FO
Systems that add ammonia can control the dosage of
chlorine and ammonia
 Measure Free Chlorine before ammonia addition
◦ Target Monochloramine (NH2Cl) level

After ammonia addition:

 Free Ammonia 0.04 – 0.1 mg/L
 Monochloramine (NH2Cl) at the target
 Total Chlorine = Monochloramine (NH2Cl)
 Know your raw water ammonia levels
◦ If you blend or rotate wells, do this is a way to get the most
consistent ammonia levels possible OR
◦ May need to have different chlorine dosages for different
wells or combination of wells
 Goal is to either chloraminate or use free chlorine –
NO yo-yoing back and forth
 Determine target chlorine residuals based on your
system and work to meet them
 Consistent chlorine residuals throughout the
distribution system
For free chlorine systems:
 The key is to always stay on the free
chlorine side of the curve (past breakpoint)
 Free chlorine residuals are stable
 Free chlorine residuals within 80% of the
total residuals throughout the system
 Minimum free residual of 0.3 mg/L
throughout the distribution system
 I Am Here!

NH2Cl = TC NH2Cl < TC NH2Cl = 0

F NH3N > 0 F NH3N = 0 F NH3N = 0
FC = stable
FC=80% TC

Courtesy of Hach disinfection series TC = Total Chlorine

http://www.hach.com/DisinfectionSeries06 F NH3N = Free Ammonia
 Chloramination Free Chlorine

 Monochloramine is equal to  No remaining ammonia

Total Chlorine  True free chlorine
residual (reading does
 Free Ammonia of 0.04 to 0.10
not increase)
mg/L
 Free chlorine is at least
 Minimum of 1.5 mg/L total
80% of total
chlorine residual throughout the
◦ Optimal is > 85%
distribution system  Minimum of 0.3 mg/L
free chlorine residual
throughout the
distribution system
Factors to consider:
 Change in chlorine levels
◦ What are the two reasons why chlorine residuals change?

 Remember: Residual = Dose - Demand

 Factors to consider: Dose
Calculate the chlorine dose, has it changed, if so, why?

Chlorine Gas Dosage, mg/L = Chlorine Used, lbs/day__

(Flow, MGD) (8.34 lbs/gal)

Liquid Chlorine Dosage, mg/L = (lbs of chlorine) (% available chlorine as decimal)

(Flow, MGD) (8.34 lbs/gal)

OR

Liquid Chlorine Dosage, mg/L = (gallons of chlorine) (% available chlorine as decimal)

(MGD)
Factors to consider: Demand
 Change in ammonia levels
◦ Have the ammonia levels changed?
 Changes in chlorine residuals after regeneration of softeners
◦ Often see residuals change due to formation of chloramines rather
than free chlorine
 Decrease in the chlorine residuals or areas where the
minimum levels cannot be maintained
◦ Nitrification or the bacterial conversion of ammonia to nitrite to
nitrate
◦ Chloramine decay in distribution, especially in low use and dead
end areas
 Others
 Changes in other chlorine demand

Free Chlorine Demand

Water Quality Parameter Multiplier x (Factor)
Iron 0.64 mg/L
Manganese 1.3
Hydrogen Sulfide 0.2 - 2.5
Nitrite (as N) 5
Ammonia (as N) 10 to 12
Organic Nitrogen 1
TOC 0.1
  Example of changes in chlorine demand due to ammonia
Free Chlorine
Water Quality Demand Multiplier Input Water Demand per Input Water Demand per
Parameter x (Factor) Quality Parameter Quality Parameter
Iron 0.64 mg/L 1.2 0.768 1.2 0.768
Manganese 1.3 0.24 0.312 0.24 0.312
Hydrogen Sulfide 0.2 0 0 0 0
Nitrite (as N) 5 0 0 0 0
Ammonia (as N) 10 to 12 2 24 2.5 30
Organic Nitrogen 1 0 0 0 0
TOC 0.1 0 0 0 0

TOTAL Chlorine Demand 25.08 31.08

  Example of changes in chlorine demand due to iron &manganese
Free Chlorine
Water Quality Demand Multiplier Input Water Demand per Input Water Demand per
Parameter x (Factor) Quality Parameter Quality Parameter
Iron 0.64 mg/L 1.2 0.768 1.8 1.152
Manganese 1.3 0.24 0.312 0.34 0.442
Hydrogen Sulfide 0.2 0 0 0 0
Nitrite (as N) 5 0 0 0 0
Ammonia (as N) 10 to 12 2 24 2 24
Organic Nitrogen 1 0 0 0 0
TOC 0.1 0 0 0 0

TOTAL Chlorine Demand 25.08 25.594

Free chlorine residuals are higher than total residuals
 False free
 Reaction not complete
◦ Consider chemical feed location to sample tap location
 Using same sample vials
◦ Dedicated sample vial for free chlorine
◦ Another dedicated sample vial for total chlorine
◦ Zero each before analysis
 Alkalinity and pH interference
◦ According to Hach: After adding the DPD reagent, the sample pH
should measure 6.3 Samples with pH of 7.6 or above and alkalinity of
250 or above may not have pH of 6.3 after adding the reagent, causing
small bubbles to form which increases the reading. After 1 minute the
free residual will decrease as the bubbles dissipate.
• NH2Cl too high • FAA too high
• Reduce NH3 • Reduce NH3
• Reduce Cl2 • Increase Cl2

IT’S A BALANCING ACT

• TC dropped after • TC > NH2Cl
NH3 addition • Reduce Cl2
• Increase NH3
• Reduce Cl2
From Bob Spon, OpFlow Article, June 2008
 Drop in total chlorine residuals in storage
and distribution
 Free ammonia can convert to nitrite and
nitrate
 Taste and odor issues if form di or
trichloramines
 Hypochlorous Acid 20 mg/L
 Monochloramine 5 mg/L
 Dichloramine 0.8 mg/L
 Trichloramine 0.02 mg/L

 Typically “swimming pool” or other “chemical” or

“chlorine” type smell
 “Burning” of eyes, particularly in shower or other hot
water uses
Break Time…
Then on to nitrification…
 Ammonia, NH3
 Ammonium ion, NH4
◦ In neutral or acidic natural waters,
ammonia is present as ammonium ion
 Nitrite, NO2
 Nitrate, NO3
 Kjeldahl Nitrogen, TKN
◦ TKN = Organic nitrogen + ammonia
Pidwirny, M. (2006). "The Nitrogen Cycle". Fundamentals of Physical Geography, 2nd Edition.
Ammonia Treatment Storage and
in Well Plant Distribution
Ammonia, Ammonia,
Nitrite or Nitrite or Nitrate
Nitrate depending on
depending on conditions
conditions

Nitrosomas and Nitrobacter

 Can be a result of surface activities or
contamination
◦ When you find nitrite or nitrate in raw water samples
(directly from well) indicates it is a result of surface
activity
 Can be a result of bacterial nitrification of
ammonia within the water system
◦ Often find ammonia, nitrite and nitrate present in the
same SEP or system sample if nitrification is
incomplete
 Result of contamination from surface activities
◦ When found in raw water samples (directly from well) indicates
close source of contamination or recent contamination
 Result of bacterial nitrification of free ammonia
◦ Conversion within transmission line, treatment plant, storage or
distribution system
◦ Up to one nitrite formed for each ammonia
 1 mg/L of ammonia can form 1 mg/L of nitrite
 MCL in drinking water of 1.0 mg/L - ACUTE health
concern
 SDWA requirement is “one time only” sampling at SEP
 Iowa DNR protocol implementation includes SEP and
distribution system monitoring – more on these later
 Result of contamination from surface activity
◦ Find nitrate in raw water samples
 Result of bacterial nitrification of nitrite
 MCL of 10 mg/L - ACUTE health concern
 Often find present with ammonia and nitrite if
nitrification is incomplete
 Up to one nitrate can be formed from each nitrite
 Sampling at SEP:
◦ 1/year
◦ 1/quarter if >5.0 mg/L <10
◦ 1/month if > 10
 Health concerns the same for each but at different
levels, both are ACUTE contaminants
◦ Nitrite = 1.0 mg/L
◦ Nitrate = 10 mg/L
 Blue baby syndrome
◦ Difficult to identify
 Failure to thrive
 Many times appears to be formula intolerance
◦ Change to premade formula and symptoms disappear
 Some links to bladder and other cancers
 Nitrosomonas convert ammonia to nitrite
 Nitrobacter convert nitrite to nitrate
 Present in treatment plants
◦ Aerators, detention tanks, filters
 Present in transmission lines, storage and
distribution systems
◦ Biofilm
 Common in soil and environment
 Not detected as part of total coliform test
 Not always detected as part of HPC
(heterotrophic or other total plate count)
 Nitrosomonas
◦ Convert ammonia to nitrite
◦ Resistant to chloramines
◦ Less sensitive to chlorine
◦ If established, can protect themselves in presence of high
chlorine residuals
 Nitrobacter
◦ Very sensitive to ammonia
 Any ammonia not consumed by Nitrosomonas will inhibit
Nitrobacter
◦ Very sensitive to chlorine and chloramines
 Will be dormant (hibernate) in presence of chlorine or
chloramines, usually will not be killed except at high levels
◦ Thrive in narrow pH range – 7.6 to 7.8
 Ammonia can convert to nitrite at 1:1 ratio
 Nitrite can convert to nitrate at 1:1 ratio
 IF no limiting factors present

 Highest risk during low water use and warm water

temperatures
◦ Spring and fall when warm water due to time in tower/storage and
low use
◦ Last few years in the summer: issues with nitrification in systems
that had not had previous problems due to low water use and
warm temperatures
 Same bacterial action as in wastewater systems –
conversion of ammonia to nitrate
Factor Nitrosomonas Nitrobacter
pH 5.8 – 9.5 5.7 – 10.2
Optimum pH 7.5 – 8.0 7.6 – 7.8
Temperature 5 – 30 C 5 – 40 C
Optimum Temp 30 C 28 C
Chlorine Less sensitive Very sensitive
Ammonia Consume Very sensitive
 Amount of  Microbial community
dissolved oxygen composition
(DO)  Alkalinity
 Chlorine residuals  Phosphate level
 Temperature  Carbon or TOC levels
 Detention/retention  Type of filter media
time
 Backwash water –
 Amount of free
ammonia present chlorinated or
nonchlorinated
 pH
 Light  Others
 For complete nitrification (conversion of ammonia to nitrate),
4.57 mg/L of oxygen is consumed per each 1 mg/L of
ammonia
◦ This is in addition to the oxygen needed for oxidation of iron and other
contaminants
◦ Often this is the limiting factor – conversion stops at nitrite leading to
nitrite MCL violations
 For complete nitrification, 7.1 mg/L (as CaCO3) of alkalinity is
needed for each 1 mg/L of ammonia
◦ Used to build cell walls by nitrifying bacteria
 Drop in total chlorine residuals or no chlorine
residual in ends or portions of the distribution
system
◦ May also be in the middle of a loop (water moving from both
directions with oldest water in the middle of the loop and
little water movement)
 Fluctuations in chlorine residuals with no apparent
cause or reason such as changes wells or high
service pumps
 Decrease (drop) in pH and/or alkalinity in areas of
distribution system
 Changes in nitrogen compounds through system
◦ No nitrite or nitrate in raw water but nitrite or nitrate at SEP, in or after
storage, or in portions of distribution system
◦ Look at historical data
 Taste and odor complaints
 Dirty water complaints
 Changes in chlorine residuals (demand) after change of filter
media or shock chlorination of filter media, particularly in iron
removal plants
 Disinfection depletion (drop in residuals)
 Nitrite/nitrate formation
 Dissolved oxygen (DO) depletion
 Reduction in pH
 Reduction in alkalinity
 DBP formation changes
 “Dirty water” complaints
 Corrosion issues, commonly seen as lead and
copper exceedances
On to control options…
1. Ammonia removal
Running filters in “bio” mode, also called
biological ammonia removal treatment
2. Breakpoint chlorination
No ammonia to nitrify
3. Combination of oxidants
4. Chloramination with operational control
 Biological removal of ammonia through nitrification
 Ammonia to nitrite to nitrate
◦ No ammonia or nitrite in finished water
◦ Free chlorine residuals – past breakpoint on curve
 Typically occurs in filters but may occur in aeration,
detention – before SEP
 No chlorination prior to filters
 Care must be taken during establishing to protect
nitrifying bacteria
◦ Backwash rate
◦ Backwash water – chlorinated or not chlorinated
 Typically takes 8 – 12 or more weeks to establish
Limiting factor!
 Dissolved oxygen
◦ If ammonia is greater than ~2 mg/L, there will not be enough oxygen
for complete nitrification
◦ About 4.5 mg/L of oxygen is needed to completely nitrify 1 mg/L of
ammonia
◦ Conversion stops at nitrite if not enough oxygen
◦ Often have nitrite MCL violations at SEP as not enough oxygen to get
from nitrite to nitrate
 Systems with higher ammonia levels now operating with air
injection to get ammonia removal in contactors (new
treatment step)
 Destroys all ammonia so no “food” for the nitrifying
bacteria
◦ Ammonia to nitrogen gas
 Disinfection by free chlorine – past breakpoint on
free side of curve
 Requires large dose of chlorine
◦ In practice, 10 to 12 mg/L (or more) of chlorine per 1
mg/L of ammonia is common
 TTHM/HAA5 concerns
◦ Many systems with raw water ammonia have high raw water
TOC levels
 Free chlorination may not be possible
◦ Often cannot add enough chlorine to meet demand
 May not be enough reaction time
◦ Reaction time dependent on pH and temperature
◦ Must go through all reactions to get to free chlorine
(past breakpoint)
◦ If reaction not complete, unstable water entering the
system
 Taste and odor complaints
 Dirty water and corrosion issues common
 Combination of oxidants
◦ Consider use of multiple oxidants
◦ Permanganate, chlorine, others
 Other oxidants
◦ MIOX (Mixed oxidants) is in use in some systems
◦ Uses a salt mixture and DC cell to form oxidants,
including ozone, hydrogen peroxide, chlorine, chlorine
dioxide, etc.
 Not common practice to control as has many
operational challenges
 Addition of sodium chlorite
◦ Very specific monitoring requirements
◦ Must do pilot and show operational control
 Minimize free ammonia as much as possible
◦ For systems adding ammonia, target 0.04 – 0.1 mg/L free
ammonia
◦ For systems with natural ammonia, target consistent
ammonia levels and maximum chlorine to ammonia ratio
 Target disinfectant
◦ Monochloramine = Total Chlorine
 Increase residuals to control nitrifying bacteria
◦ Necessary levels vary by system – typically 2 mg/L or
higher (total chlorine residual)
◦ May need to go to breakpoint for a few weeks each
spring and/or fall to kill biofilm and then maintain
higher chloramine residuals to inhibit growth
 Notify customers and DNR FO if change disinfection
practice
 May still have free ammonia present so may have
nitrite formation in low use areas, dead-ends, and
storage facilities
◦ Reversion to ammonia (breakdown of chloramines)
 Other changes in operation to control
depending on where nitrification is taking
place, such as
◦ Changes to backwash
◦ Increased flushing program
◦ Addition of booster chlorine/ammonia feed
◦ Loop deadends
◦ Periodic forcing of water to move one direction
through looped areas
◦ Changing to free chlorine periodically
 Frequency and duration varies
 Nitrosamine formation
◦ Nitrosamines are DBPs in chloraminating systems
◦ N-nitrosodimethylamine (NDMA) is most common
◦ Much on-going research
◦ Formation from reaction of natural organic matter (NOM),
use of quaternary amine-based coagulants and anion
exchange resins, or wastewater-impaired source waters
 EPA is currently reviewing the existing microbial
and disinfection byproducts regulations as part of
the six year review process (SY3)
 Very specific to each system
 No magic fix that will work for all
systems
 Must know what disinfection practice
you are using and where you are on the
curve!
 Many factors impact decision on how to
control ammonia
 Work with your engineer and/or technical
service provider
 Need to weigh all of the options and
consequences – many unintended
consequences such as nitrification, L/C
corrosion, chlorine residuals, etc.
 Communicate with DNR
 Minimum = 1.5 mg/L total Minimum = 0.3 mg/L free

From Bob Spon, OpFlow Article, June 2008

On to DNR protocols, testing and system specific examples…
 Systems have naturally occurring ammonia in their
groundwater (source water)
 Systems adding ammonia to form chloramines
 Significant potential exists for conversion of ammonia to
nitrite and nitrite to nitrate
◦ MCL nitrite 1.0 mg/L
◦ MCL nitrate 10 mg/L
 Nitrite levels at SEP and/or distribution found ranging from
ND (no detection) to 3.5 mg/L
 A number of systems have not been meeting minimum
disinfection residuals
 Protocols for use:
◦ During sanitary surveys
◦ Investigations of nitrite MCL violations
◦ Complaint investigations
◦ System not meeting minimum residual requirements
 Training of all DNR staff in Nov. 2015
 Protocols are being implemented
 Systems are encouraged to sample each well or
source if ammonia levels are not known
 To determine if there is a need to sample
 Assignment of monitoring determined classification:
◦ Systems with complete nitrification at SEP and/or using free chlorine
for disinfection
◦ Systems with the potential for nitrite formation
◦ Systems with nitrite MCL exceedances
◦ Systems adding ammonia
◦ Consecutive systems using chloramines or not meeting minimum
chlorine residuals
 Interpretation of results
 Any required monitoring will be included in a WS operation
permit
 Systems with Complete Nitrification at SEP and/or using
Free Chlorine for Disinfection
◦ Free and total chlorine residuals
◦ SEP ammonia 1/year for systems with ammonia >0.7 mg/L in
combined raw water
 Systems with the Potential for Nitrite Formation
◦ Ammonia >0.7 mg/L in combined raw water and chloraminating or
nitrification occurring at any site
◦ Free and total residual - total only with FO approval
◦ SEP ammonia, SEP and distribution nitrite
◦ Self-monitoring for nitrite at SEP and distribution system
◦ Frequency dependent on if nitrification has occurred
 Systems with Nitrite MCL Exceedances
◦ For systems with current or historical nitrite MCL exceedances
◦ Free and total residual - total only with FO approval
◦ Quarterly SEP ammonia, monthly SEP and distribution nitrite
◦ Weekly self-monitoring for ammonia and nitrite at SEP and
distribution system
 Systems Adding Ammonia
◦ For systems adding ammonia for chloramination
◦ Total chlorine residual, monochloramine, free ammonia, pH
◦ Distribution system nitrite
◦ Self-monitoring for nitrite
◦ Monitoring Plan with Alert and Action Levels
Consecutive Systems Using Chloramines
 Systems purchasing water containing chloramines
 If the producing system has naturally occurring ammonia:
◦ Free and total residual - total only with FO approval
◦ Distribution system nitrite
◦ Self-monitoring for nitrite
 If the producing system adds ammonia to chloraminate:
◦ Total chlorine residual, monochloramine, free ammonia, pH
◦ Distribution system nitrite
◦ Self-monitoring for nitrite
 Required for systems with monthly or quarterly distribution
system monitoring
 No template as system specific
 Select location(s) with highest risk of nitrification
 Often deadend or low use areas
◦ May be in the middle of a loop
 Use chlorine residuals, monochloramine, free ammonia, and
pH levels; temperature; and taste and odor complaints as
guide
 Select locations with the highest potential for nitrification
◦ Lowest total chlorine residual
◦ Largest separation between total chlorine and monochloramine
◦ Highest free ammonia levels
◦ Lowest pH (drop in pH indicates nitrification)
 Submit to FO and use this location(s) for certified lab
sampling
◦ Remember to test this sample as part of self-monitoring (paired
samples)
Several options depending on:
 Colorimeter/spectrophotometer model
 Needed range of the system
 Be aware of disposal requirements
◦ Nessler reagent for ammonia contains mercury
 Samples for nitrite need to be at room temperature for
accurate results
 Protocols require “paired” samples
◦ Self-monitoring testing and certified lab testing of the same sample
◦ Results should be comparable, if not need to determine why
◦ Use self-monitoring to indicate when something has changed so
results must be accurate and representative
 Guidelines for systems changing from Chloramine to Free
Chlorine or vise versa
◦ Pre-Transition
◦ Water Plant Activities
◦ Distribution Activities
 Customer Notification Samples
 Post Transition Strategy
On to System Specific Examples…
 Curve is specific for each system
 First example is from a system that Dale and Joe worked with
to develop the curve for the system
 Chlorine was added (dosed) after all treatment
 Treatment = aeration, detention, filtration, ion exchange

Water dosed:
 Iron 0.02, Manganese 0.044, Ammonia 0.39 (all mg/L)
Dose (mg/L) Free Chlorine Total Chlorine Monochloramine Free Ammonia Total Ammonia
0.00 0.00 0.00 0.00 0.00 0.39
0.25 0.00 0.05 0.00 0.38 0.40
0.50 0.00 0.29 0.22 0.37 0.40
0.75 0.00 0.46 0.40 0.35 0.41
1.00 0.00 0.62 0.58 0.33 0.41
1.25 0.00 0.74 0.66 0.30 0.41
1.50 0.00 0.85 0.74 0.26 0.40
1.75 0.00 0.98 0.85 0.23 0.40
2.00 0.00 1.11 0.95 0.19 0.39
2.25 0.00 1.24 1.07 0.20 0.39
2.50 0.00 1.37 1.18 0.21 0.39
2.75 0.00 1.48 1.29 0.16 0.38
3.00 0.00 1.58 1.39 0.11 0.38
3.25 0.00 1.61 1.40 0.08 0.39
3.50 0.00 1.63 1.41 0.06 0.38
3.75 0.00 1.66 1.41 0.03 0.37
4.00 0.00 1.68 1.42 0.00 0.27
4.25 0.00 1.65 1.32 0.00 0.25
4.50 0.00 1.62 1.22 0.00 0.24
4.75 0.00 1.58 1.11 0.00 0.22
Dose (mg/L) Free Chlorine Total Chlorine Monochloramine Free Ammonia Total Ammonia
5.00 0.00 1.55 1.01 0.00 0.20
5.25 0.00 1.44 0.90 0.00 0.18
5.50 0.00 1.34 0.80 0.00 0.16
5.75 0.00 1.23 0.69 0.00 0.13
6.00 0.00 1.12 0.58 0.00 0.11
6.25 0.00 1.05 0.51 0.00 0.10
6.50 0.00 0.97 0.43 0.00 0.09
6.75 0.00 0.90 0.36 0.00 0.08
7.00 0.00 0.82 0.28 0.00 0.07
7.25 0.00 0.90 0.25 0.00 0.07
7.50 0.00 0.98 0.21 0.00 0.07
7.75 0.00 1.06 0.18 0.00 0.06
8.00 0.00 1.14 0.14 0.00 0.06
8.25 0.00 1.21 0.12 0.00 0.03
8.50 0.91 1.28 0.09 0.00 0.00
8.75 1.05 1.34 0.05 0.00 0.00
9.00 1.18 1.40 0.00 0.00 0.00
9.25 1.51 1.74 0.00 0.00 0.00
9.50 1.84 2.08 0.00 0.00 0.00
9.75 2.17 2.42 0.00 0.00 0.00
10.00 2.50 2.76 0.00 0.00 0.00
Chloraminating or Breakpoint
mg/l SEP Mid-point End

Initial – 1 Initial – 1 Initial – 1

Free Cl2 minute minute minute
1.16 – 1.35 0.47 – 0.47 0.19 – 0.20
Total Cl2 1.39 0.62 0.26
Mono-
1.37 ND ND
chloramine
Free Ammonia ND ND ND
Total Ammonia 0.23 ND ND
0.005 (0.004
Nitrite ND ND
min)
 Determination of
Chlorine Curve –
System A

Courtesy of Mikael Brown, Bartlett and West, Inc.

Raw water ammonia
= 1.69 mg/L

pH = 7.6

Cl2 dose = 23.9

mg/L

Fe/Mn demand =
1.2 mg/L
Plant A

Courtesy of Mikael Brown, Bartlett and West, Inc. Raw Water NH3 = 1.69
Plant A

• Chlorine demand
measured over time
• At pH of 7.6, reaction
90% complete in 20
minutes
• At pH of 10.5,
reaction 90%
complete in 600
minutes (10 hours)

Courtesy of Mikael Brown, Bartlett

and West, Inc.
 Plant B

Raw water ammonia

= 0.36 mg/L

Iron = 6.96 mg/L

Mn = 0.41 mg/L

Free Chlorine Demand

Water Quality Parameter Multiplier x (Factor)
Iron 0.64 mg/L
Manganese 1.3
Hydrogen Sulfide 0.2
Nitrite (as N) 5
Ammonia (as N) 10 to 12
Organic Nitrogen 1
TOC 0.1

Courtesy of Mikael Brown, Bartlett and West, Inc.

 Plant B

Courtesy of Mikael Brown, Bartlett and West, Inc.

Plant B

Courtesy of Mikael Brown, Bartlett and West, Inc.

 3 Dakota Aquifer Wells

 Wells are within about 2 blocks of each other

◦ Common to see variation in ammonia levels in wells in same aquifer
 Lime softening
 Nitrification occurring in filters and distribution system
 Plant 1 – Natural Ammonia
3 Dakota Aeration
Wells
NH3 = 1.2 - 2.2 Lime Softening
NO2 = <0.02 NH3 = 1.1
NO3 = <0.1 NO2 = <0.02
NO3 = <0.1

Bottom of Filters Top of Filters

NH3 = 0.7 - 0.9 NH3 = 1.1
NO2 = 0.26 - 0.46 NO2 = <0.02-0.12
NO3 = <0.1 NO3 = <0.1
 S/EP High Usage
NH3 = 0.4 Area in
NO2 = <0.02 - 0.24 Distribution
NO3 = 0.27
System
NH3 = 0.4
NO2 = 0.32
NO3 = 0.26
Dead End
NH3 = 0.1
NO2 = 0.19
NO3 = 0.72
 Data - Plant 1
Location Ammonia Nitrite Nitrate

Raw 1.2 <0.02 <0.1

After lime 1.1 <0.02 <0.1

softening
Top of Filters 1.1 – 1.2 <0.02 – 0.12 <0.1

Bottom of 0.7 – 0.9 0.26 – 0.46 <0.1

Filters
S/EP 0.4 <0.02 – 0.24 0.27

End of System 0.4 0.32 0.26

High Usage
Deadend 0.1 0.19 0.72

All results in mg/L

 Initially using raw water to backwash
 Now using chlorinated water to backwash filters
 Flushing system regularly
 Frequent monitoring (self-monitoring) to determine
nitrite levels
 Nitrite levels now typically <0.1 mg/L
◦ During low use, warm temps 0.1 to 0.3 mg/L
 Total chlorine ~2.2 – 3.0 in system
 “False” free chlorine
 Disinfection = chloramination
 Jordan Wells
 Treatment = Aeration, filtration, zeolite softening,
chlorination, caustic soda addition
 Saw significant decrease in chlorine levels when
filter media was changed
◦ No free, low total residual
 Nitrifying bacteria re-established and conversion
to nitrite to nitrate in filters
 Total chlorine ~0.8 - 1.2 in system
 Free chlorine ~ 0.6 - 1.1 in system
 Disinfection = Free chlorine
Location Ammonia Nitrite Nitrate
Well 7 2.1 <0.1 <0.5
Well 8 2.1 <0.1 <0.5
Well 9 2.2 <0.1 <0.5
Well 10 1.9 <0.1 <0.5
S/EP <0.05 <0.1 1.62
 Testing indicated no ammonia
 No nitrite or nitrate in wells
 Nitrate in SEP result
 Nitrification occurring in the filters
 Disinfectant = Free chlorine
Location Ammonia TKN Nitrite Nitrate

Well 3 <0.2 2.0 <0.1 <0.5

Well 4 <0.2 1.8 <0.1 <0.5

Filter <0.2 Not tested <0.1 1.6

Effluent
S/EP <0.2 Not tested <0.1 1.6

All results in mg/L

 2 Dakota wells
◦ Naturally occurring ammonia
 Iron removal
◦ Aeration, detention, gravity filtration
 2 Dakota Aeration
Wells NH3 = 3.5
NO2 = <0.02
NH3 = 3.4 - 3.8 NO3 = <0.1 Detention
NO2 = <0.02 NH3 = 3.6
NO3 = <0.1 NO2 = <0.02
NO3 = <0.1
S/EP
NH3 = 2.5 After Filters
NO2 = 0.29
NO3 = 0.55 NH3 = 2.5 - 2.9
Free chlorine = 0.3 NO2 = 0.66 - 0.85
Total chlorine = 2.6 NO3 = <0.1 - 0.10
 Dist System -
After Tower
NH3 = 2.1
Near Tower
NO2 = 0.41 NH3 = 2.0
NO3 = 0.72 NO2 = 0.70
Free chlorine = 0.1 NO3 = 0.59
Total chlorine = 1.2 Free chlorine = 0.2
Total chlorine = 1.4
Dist System - Dist System -
Dead-end Looped Line
NH3 = 0.51 - 1.1 NH3 = 2.2
NO2 = 1.1 - 2.1 NO2 = 0.44
NO3 = 0.54 - 0.59 NO3 = 0.67
Free chlorine = 0.1 Free chlorine = 0.2
Total chlorine = ND – 0.4 Total chlorine = 1.4
 Tower with 2½ average day capacity
 Tried breakpoint chlorination to control - could not
feed enough chlorine to reach breakpoint, could not
get reaction to be complete in plant/clearwell
 Used MIOX to eliminate ammonia until unit failed
 Exceeded lead and copper action levels
 Now injecting air into contactors for biological
ammonia removal
 Complete nitrification in the plant
 Free chlorine for disinfection
 Treatment is an in-line air stone (atomerator), liquid chlorine
addition, and pressure sand filtration
 The water flows to the tower with splash aeration in the tower,
then to the distribution system
Line to Tower
2 Buried NH3 = 3.4
Sand & NO2 = <0.02
NO3 = <0.1
Gravel Wells Total Chlorine = 2.7
NH3 = 3.3 - 3.6
NO2 = <0.02
NO3 = <0.1
S/EP
NH3 = 3.0
NO2 = <0.02
NO3 = <0.1
Total Chlorine = 2.0
 Dist System - Average
NH3 = 2.1
NO2 = 0.59
NO3 = <1.0
Total chlorine = 1.7

Dist System - Dead-end

NH3 = 1.8
NO2 = 1.2
NO3 = <1.0
Total chlorine = 0.64
 Tried breakpoint chlorination to control - could not feed
enough chlorine to reach breakpoint with the time they have
for the reaction
 Too high of ammonia to get ammonia removal through
nitrification in the plant
◦ Did not have enough oxygen present in the filters to be able to sustain
complete nitrification
 Aggressive flushing program to control nitrite formation
 Surface Water
Surface Water Plant
Clearwell Plant SEP
Free NH3 = 0.43
Prior to NH3 Add Monochloramine =
Free Chlorine = 3.00
0.8 – 1.0

Pump Station 1
Consecutive System
Total NH3 = <1.0
NO2 = 1.0
NO3 = 0.9
Total Chlorine = 2.7
 Dist System - Downstream
Total NH3 = 0.34
Free NH3 = 0.28
NO2 = >0.69
Total chlorine = 0.63
Monochloramine = 0.21

Dist System - Dead-end

Total NH3 = 0.17
Free NH3 = 0.10
NO2 = >0.69
Total chlorine = 0.17
Monochloramine = <0.12
 Tried flushing – could not get velocity to strip biofilm and did
not increase chlorine residuals
 Switched to breakpoint chlorination to control nitrification
◦ Stopped feeding ammonia, increased chlorine feed
 After 8 weeks, started adding ammonia
◦ Targets:
◦ Free ammonia <0.1
◦ Monochloramine = total chlorine
◦ All total chlorine residuals >1.5
 Very specific to each system
 No magic fix that will work for all
systems
 Must know what disinfection
practice you are using and where
you are on the curve!
 Minimum = 1.5 mg/L total Min = 0.3 mg/L free

From Bob Spon, OpFlow Article, June 2008

 Julie Sievers
712-262-4177
Julie.sievers@dnr.iowa.gov
Class Number: 23884
Sponsor: IRWA
Title: Ammonia & Disinfection in
Drinking Water - Flint Crisis & Lead in
Iowa
Date: February 28, 2018
Location: Ventura
CEU Hours: 6