Lindsay Peddle, B.Sc.
600 Main St., Tonawanda, NY
The Rapid Measurement of Chemical Oxygen Demand in a
Variety of Sample Matrices Utilizing a New Green Technology
An alternative means to standard COD methods based on photoelectrochemical oxidation in a microcell
INTRODUCTION
Objectives
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Background
Importance of Measuring OD
Regulatory Uses
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CJPEFHSBEBCMFGSBDUJPOBOE$0%UIFUPUBMPSHBOJDQPMMVUJPOMPBEPGXBUFSTDPOUBNJOBUFECZSFEVDUJWFQPMMVUBOUT
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Non-regulatory Uses
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The Measurement of COD & BOD
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Step 1 - Oxidation of organic matter
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Step 2 - Measurement of extent of oxidation
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Dichromate Method (conventional) for COD Analysis
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PeCOD COD Analysis
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TFOTPS
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PeCOD Sensor Technology COD vs. Theoretical Oxygen Demand
(ThOD)
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PeCOD Sensor Technology
1
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APPLICATIONS
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BOD Screening:
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JFOPIB[BSEPVTDIFNJDBMTOFFEFE
900
800
700
600
500
400
300
200
100
0
Dichromate COD
PeCOD COD
BOD
1
2
3
4
5
6
7
8
9
COD/BOD Value (mg/L)
COD/BOD value (mg/L)
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1200
1000
800
600
Dichromate COD
400
PeCOD COD
BOD
200
0
1
10
2
3
4
5
6
7
8
9
10
Sample
Sample
Plot of Dichromate COD, PeCOD COD and BOD for influent sample. A similar pattern should be
observed for each trend line, which is apparent for PeCOD COD and BOD, while Dichromate COD
results are more variable.
Plot of Dichromate COD, PeCOD COD and BOD for an effluent sample. PeCOD COD
demonstrates a much stronger correlation to BOD than Dichromate COD values and in fact are
almost equal.
80
60
50
40
Dichromate COD
30
PeCOD COD*0.6
20
BOD
10
COD/BOD Value (mg/L)
COD/BOD Value (mg/L)
70
70
60
50
Dichromate COD
40
30
PeCOD COD
20
BOD
10
0
0
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
Sample
Sample
Plot of BOD, Dichromate COD and PeCOD COD with a factor of 0.6 applied to PeCOD values for a
secondary combined sample. This factor was applied to COD values as it provides very close
estimations of BOD for most of the samples. As noted by the enduser, 2 small outliers may be
observed in this data set because of extremely dark and turbid samples which makes
representative sampling more difficult.
Plot of Dichromate COD, PeCOD COD and BOD for a final sample. A good correlation is observed
between all trends, with PeCOD COD and BOD showing an excellent correlation.
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WWT Plant Protection & Optimization:
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Wastewater Treatment Plant Inuent Stream
600
COD / [mg/L O2]
500
Online PeCOD COD
400
300
200
100
0
0
Online monitoring of COD in 15 minute cycles in the primary clarifier effluent at a WWTP.
Major fluctuations in COD would be hard to see without continuous monitoring.
100
200
300
Sample
400
500
600
Online Monitoring of COD in 15 minute cycles over 6 days at the secondary stage influent of a
WWTP. The expected regular diurnal variations are apparent, however it started high and then
declined which was the result of someone illegally dumping high COD industrial waste into a public
drain
2
APPLICATIONS
Manufacturing Plant Performance Optimization:
–
–
–
Real-time analysis of COD on the efﬂuent of an industrial plant will provide the operational feedback necessary to optimize production processes and cleaning practices.
Spot-check COD at various locations throughout the process to identify any problem streams. Quick point-of-origin notiﬁcation provides the information
needed to optimize treatment processes.
The lowering of discharge levels of COD will reduce the consumption of raw materials and reduce sewer discharge costs or internal wastewater treatment plant costs.
Online PeCOD COD, Jan 2007
14000
0.61 × (PeCOD COD)
0.61 × (Dichromate COD)
BOD5
7000
1-hour Avg COD
BOD5 & Esmated BOD5 / (mg/L)
COD / [mg/L O2]
8000
PeCOD COD
12000
10000
8000
6000
4000
2000
6000
5000
4000
3000
2000
1000
0
30-Jan
29-Jan
28-Jan
27-Jan
26-Jan
0
0
5
10
15
20
25
30
Day
Daily monitoring of COD & BOD in Brewery wastewater effluent
Online monitoring of COD in 15 minute cycles of a brewery effluent stream
6000
6000
5000
5000
PeCOD Results
Dichromate COD Results
4000
4000
ppm COD
ppm COD
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–
Treatment utilizes high COD waste to create energy
–
A spike in COD could create an over-production of methane gas, which would then need to be ﬂared off
–
Also ensures ﬁnal efﬂuent is within discharge limitations
3000
2000
3000
2000
PeCOD Results
1000
1000
Dichromate COD Results
0
0
#101 #102 #114 #115 #116 #117 #118 #130 #131 #132 #146
24Mar
24Mar
25Mar
25Mar
25Mar
25Mar
25Mar
26Mar
26Mar
26Mar
31Mar
Date/Sample
#89
#94
#95 #105 #106 #121 #122 #123 #124 #138 #139
23Mar
23Mar
23Mar
24Mar
24Mar
25Mar
25Mar
25Mar
25Mar
29Mar
29Mar
Sample
Plot of Dichromate COD and PeCOD COD for a brewery anaerobic influent sample
Plot of Dichromate COD and PeCOD COD for a brewery anaerobic digester effluent sample
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–
PeCOD provides soluble COD information
–
The dichromate test is unable to differentiate between soluble and total COD (in this study, dichromate results were obtained by pre-ﬁltering samples)
–
PeCOD is providing another valuable result that wasn’t available before
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Plant Organic Source Monitor & Control:
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monitoring of conditions is essential.
Manufacturing Plant Water Feedstock Monitor
o
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Plant Efﬂuent Discharge Monitor:
–
–
–
–
Cooling tower monitoring
High COD in outﬂow means loss of product for reﬁnery and potential environmental breach penalties
Real-time COD monitoring enables corrective action to be taken by the plant
Avoid potential for bad publicity that could have a direct negative impact on perceived company value in the share market
14
BOD(5)
12
PeCOD Est. BOD(5)
BOD5 / [mg/L O2]
10
8
6
BOD5 = 0.55 × COD
4
2
16:00
15:00
14:00
13:00
12:00
11:00
10:00
0
Time of Day
Online Monitoring of COD/Estimation of BOD in a Sugarcane Mill Effluent
Stream
Potable Water Monitor:
–
–
Similar to monitoring water feed stocks, TOC has been used for monitoring drinking water as the standard COD method is unable to provide real-time information
and lacks sensitivity.
TOC analysis is widely used in applications where the analysis of carbon levels is sufﬁcient but it lacks important information about the environmental effects of the
organic matter that COD would provide.
e.g. TOC is the same for methanol and formic acid solutions given the single carbon in each compound. COD values however are different because of the different redox state of
carbon in methanol compared to formic acid
SUMMARY
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3