Benefits of On-line Monitoring of Carbon, Nitrogen and Phosphorus

New Jersey Water Environment Association

Dan DavisShimadzu Scientific Instruments

Benefits of On-Line Monitoring

• Environment

• Consumers

• Treatment Facilities

Environmental Impact

Why Carbon, Nitrogen and Phosphorus?

Potomac River

• These elements are nutrients and can enrich aquatic systems

• The problem is when we over enrich: Eutrophication

Because of their environmental impact

Drinking Water: TOC

EPA established two drinking water Regulations:

• Stage 1 Disinfection Byproducts Rule (DBPR)1Protects customers from disinfectants and disinfectant byproducts (DBP)

• Enhanced Surface Water Treatment Rule (IESWTR)1Reduce microbial contamination in drinking water

Federal Register, December 16, 1998, Volume 63, Number 241, or 40 CFR Parts 9, 141, and142 http://www.epa.gov./OGWDW/mdbp/mdbp.html

Response by EPA: Nitrogen & Phosphorus

• States & EPA : issue permits to all wastewater treatment facilities that regulate pollutants such as nitrogen and phosphorus

• “Nutrient Criteria Technical Guidance Manual for ₋ Lakes & Reservoir” (EPA-822-B-00-001), released 5/2000₋ Rivers & Streams” (EPA-822-B-00-002), released 7/2000₋ Estuarines and Coastal Waters” (EPA-822-B-00-003), released 10/2001

• http://www.epa.gov/ost/criteria/nutrient/guidance/

Total Organic Carbon

Consists of:• Purgeable Organic Carbon (POC)• Non-purgeable Organic Carbon (NPOC)

i.e. TOC = POC + NPOC

Analysis: There are 2 methods, • Difference method : TOC = (TC – IC)• Direct method : TOC ≅ NPOC (if no POC)

TOC (Total Organic Carbon):

Organic carbon bonding with hydrogen or oxygen to form organic compounds

Measure the sample (dilute)

Decomposition : 680℃ with Pt catalyst

Inorganic Carbon Removal

Obtain the TOC Result

Hydrochloric Acid SolutionAgitate

Total Organic Carbon Measurement

Formation of CO2

Removal of CO2

Total Nitrogen

Organic Nitrogen (R-N)(Inorganic) Nitrate (NO3)(Inorganic) Nitrite (NO2)(Inorganic) Ammonia (NH3)

Does not include:

Nitrogen Gas (N2)Chemical unreactive and not very reactive biologically Not detected by TN Method

TN (Total Nitrogen):

Sum of Both Organic Nitrogen and Inorganic Nitrogen:

Measure the sample (dilute)

Decomposition : 720℃ with Pt catalyst

Ozone

Obtain the TN Result

O2

Electricity

Total Nitrogen Measurement

Formation of NO

Formation of NO2* , -> NO2, Photon Emission

Relaxation of NO2* to NO2 by emitting light

Total Phosphorous Measurement

Measure(dilute) the sample

Decomposition : 95℃ with UV irradiation and air

Sulfuric acid solution

Sodium hydroxide solution for pH control

Obtain the TP Result

L-ascorbic acid solutionSulfuric acid ammonium molybdate

Color the solution to blue

Measure 880nm absorbance of Phosphomolybdate blue

COD, BOD & TOC

• Permits are usually written on COD, BOD, or TOC

• TOC can be used in place of COD or BOD after conversion trends (correlation) have been made.

• Running COD or BOD and TOC in parallel

COD, BOD & TOC

All treatment plants are required to measure one of these three items as a measure of the pollution value water.

• COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized.

• BOD or Biological Oxygen Demand is supposed to measure the amount of food (or organic carbons) that bacteria can oxidize.

• TOC or Total Organic Carbon is the measurement of organic carbons.

What is the difference between BOD, COD or TOC? Why do I have to measure them?

COD, BOD & TOC

COD -COD is a chemically chelated/thermal oxidation reaction and can be measured in 2 hours.

False Lows and False HighsA COD test measures all organic carbon with the exception of certain aromatics (benzene, toluene, phenol, etc.) which are not completely oxidized in the reaction, other reduced substances such as sulfides, sulfites, and ferrous iron will also be oxidized and reported as COD.

NH3-N (ammonia) will NOT be oxidized as COD. • No indication for nitrogen loading

COD, BOD & TOC

BOD…

• Two Types C-BOD & BOD

BOD5 measures the oxidation of carbons and possibly nitrogenous compounds present in a water sample. CBOD only measures oxidation of carbons.

• 5-day test

• Need to do Both

Places where the nitrification of ammonia may not be complete (i.e., incomplete conversion of ammonia (NH3) to nitrate (NO3)) or where high levels of amines or ammonia are present, false BOD readings may occur. This can occur in municipal lagoons, wineries and general industry.

COD, BOD & TOC

BOD Uses and Limitations

• BOD testing has its widest application in measuring waste loadings of treatment plants, and in evaluating the efficiency of treatment processes.

• It is usually seeded with the type of bacteria found in municipal plants. The types of bacteria needed in wineries and general industry usually differ in species.

• The hard to degrade organics found in some of these systems also may take longer than five days to break down, so a BOD test will give an inaccurate measurement.

COD, BOD & TOC

What is Total Organic Carbon?

• Organic matter content is typically measured as total organic carbon and dissolved organic carbon, which components of the carbon cycle.

• The Total Organic Carbon test measures all organic carbon as CO2

• TOC does not differentiate between the source of organic carbon, which can be metabolized (assimilated).

• Total organic carbon is a more accurate indication of pollutants that cause problems with BOD testing.

Sampling Scheme

Collection

Sampling

Preserving

Storage

Analysis

Physical Treatment

Chemical Treatment

BatchMeasurement

Reporting

Report Generation

Review/React

Sampling Scheme

Collection

Sampling

Preserving

Storage

Analysis

Physical Treatment

Chemical Treatment

Measurement

Reporting

Report Generation

Review/React

On-Line Sampling Considerations

When selecting a sampling device Consider:

• Particulates– Are there a lot of particulates?– Do I need to include them in my reading?

• Concentration of Analyte– Are there special precautions based on level?– Do I need to consider environmental influences?

• Number of Sampling Points– Can I monitor all necessary points?

On-Line Sampling Considerations

Particulates can add to the complexities of collecting and analyzing samples.

• Do you have particulates?– If yes will they interfere with the analysis

• Do I need to consider them in my analysis?– Do they contribute to your analysis?

On-Line Sampling Considerations

Performing low level analysis can be influenced by environmental influences such as contact with air or water used in the process.

Concentration of Analyte– Are there special precautions based on level?– Do I need to consider environmental influences?

Multi-Stream Suspended Solids Unit

• Sample flows in the top and drains out the bottom

• Actuators move the sampling arm into the stream

• Sample flows down into the sampling chamber through the strainer removing larger particles

• Mixing blades homogenizes the sample

• System back flushes then washes

Movie

Multi-Stream Sample Switching Unit

• Sample flows in the bottom and out the top

• Some sample flows in lower chamber on the outside of the sample collection cup

• Actuators move the stream to the sample collection chamber.

• Reduces Sample-Air Contact

• Eliminates need for washing

Backwash Strainer Sampling Unit

• Sample flows in the bottom and out the top

• Air pressure prevents sample from entering inner chamber until sampling

• Air is turned off and sample is filtered as it enters chamber

• Sample flow dynamics self clean the sample mechanism

Movie

Field Application: Waste Water Facility

Wastewater Treatment Facility

A X

X

Points of Monitoring

(A) Currently (X) Future

Onsite Installation

Water Treatment Utility

WATER SOURCE

MANUAL TECHNIQUE

MONITORING

TECHNIQUE

CHEMICALS COST(per Analysis)

Labor(per Analysis)

Time(per Analysis)

TREATMENT

Frequency

AUTOMATIC TECHNIQUE

•AUTOMATIC ADDITION

•REDUCE ERROR

•LAST LONGER

Hourly/Weekly/ Monthly

Biweekly

Variability

Comparable Data

0

10

20

30

40

50

11/19/04 11/29/04 12/9/04 12/19/04 12/29/04 1/8/05

Aver

age

Tota

l Nitr

ogen

(m

g/L/

day)

Date

TKN vs TN TKN

TN

TN

0

5

10

15

20

25

30

35

40

12/9/04 12/19/04 12/29/04

Date

Ave

rage

Tot

al N

itrog

en

(mg/

L/da

y)TN

Manual vs AutomaticTotal Nitrogen

Manual vs AutomaticTotal Phosphorus

Comparable Data

TPK vs TP

0

1

2

3

4

5

6

7

11/19/04 11/29/04 12/9/04 12/19/04 12/29/04 1/8/05

Date

Ave

rage

Tot

al

Phos

phor

us (m

g/L/

day)

TP ManualTP

TP

0

1

2

3

4

5

12/9/04 12/19/04 12/29/04

Date

Ave

rage

Tot

al

Phos

phor

us (m

g/L/

day)

TP

MonitoringWhy Biweekly vs. Hourly ?

Manual:• To reduce cost• To reduce labor• To reduce time

Automatic:• Reduces labor• Reduces time• Reduces cost

HOURLY/DAILY/WEEKLY/ MONTHLY

REDUCES COST OF POST TREATMENT

FASTER RESPONSE

IMPROVE WATER QUALITY

BIWEEKLY

Manual vs AutomaticTotal Phosphorus

Hourly :

• More information

• Less labor

• Better quality

Relative TPK (mg/L) per day

0

1

2

3

4

5

6

7

10/4/04 11/3/04 12/3/04 1/2/05

Date

Rel

ativ

e TP

K (m

g/L)

TOC/TN/TP Relative mg/L/day

0

30

60

90

120

150

180

7:34 18:34 5:34

Time (hrs)

Rel

ativ

e C

once

ntra

tion

(mg/

L/da

y)

TOCTNTP

Biweekly

Hourly

Hourly vs Biweekly…..AllowsFASTER RESPONSE

0

1

2

3

4

5

6

7

10/4/2004 10/24/2004 11/13/2004 12/3/2004 12/23/2004

Relat

ive T

P (mg

/L)

Date

Biweekly Monitor

Hourly Monitor

0

1

2

3

4

5

6

8:32 19:32 6:32 19:32 6:32 18:32 16:32 14:32Time (Hrs)

Rela

tive

TP (m

g/L)

Sudden Changes

BiweeklyTPK

HourlyTP

Benefits of On-Line Monitoring

Achieve Maximum Efficiency

• Faster Response• Better Treatment• Cost Reduction

Reduce

• Labor• Time• Money

Flexibility of Sampling

• Hourly• Daily• Weekly• Monthly

Automatic• Sampling• Pretreatment• Digestion• Analysis• Report

Thank You!

Special Thanks to