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BOD and COD Measurem ent

What is the correlation?

November 15, 2011

Derek Walker, Applications Development ManagerMick Dollenmayer, Regional Sales Manager

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Agenda

1. pp cat ons or an measurement

2. COD and BOD: What are we really measuring?

.

4. Understanding plant baselines and trends

5. Correlation between COD and BOD measurement

6. Question and Answer Session

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Why m easure BOD and COD?

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Why m easure BOD and COD?

Evaluate the efficiency of treatment process and removal

Effluent impact to receiving waters low oxygen demand

For rocess control:

Activated sludge process: do we have enough O2?

Food / Biomass ratios vance rea men processes

Any other reasons?

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What are w e m easur ing w i t h BOD and COD?

BOD (biochemical oxygen demand): a measureof oxygen demand occurring when bacteria

Oxygen depleted by microorganisms (bugs)found in a water sample

reng o e was e s ream

demand of a sample that is susceptible to oxidation by astrong chemical oxidant

xygen ep e e y c em ca ox a on

Organics: carbohydrates (sugars/cellulose), proteins, hydrocarbons

5from waste streams

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How do w e Measure Organ ics?

SAC (UV254)

Mineral Oils

BODCOD TOC

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Are Al l Met hods Equal?

T e Definition Accurac *

BODBio-available organics and other compounds that can be

oxidized through consumption of dissolved oxygen15%

-

CBOD

prevent nitrogen oxidation through consumption ofdissolved oxygen 15%

Chemical ox en demand, measurin the reduction of

COD (Cr) chromium: Cr2O72- (orange-colored) Cr3+ (green-

colored)

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Biggest Issues w i t h Organic Measur ing

BOD: Is there anything that is good about it?

Comparing BOD, TOC, UV, COD: can this be done?

Can it be used to tune the food to microorganism ratio

(F/M)?

Waiting 2 hours or 5 days doesnt allow me to see what is

com ng n o my p an r g now, ow o now ave alarge organic slug?

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BOD & c BOD

Average number of hours/week a typical WW facilityspends on BOD? 15 hours

Average number of bottles set per week for BOD? 21 bottles

Average number of times per week BOD is run? 2 sets

Percent of BOD tests that FAIL to meet StandardMethods Guidelines?

5-10%

Industrial waste streams or slugs can also beproblematic for the BOD test!

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Issues and Root Causes

Failure Key Root Cause(s)

Blank depletion Organic contamination indilution water or bottles

Effluent fails to achieve 2

ppm depletion

Insufficient nutrient or seed

Toxicity

Fail G/GA referenceInaccurate G/GAToxicity

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Tim et he Ac hi l les Heel o f

=

COD = 2-3 Hour Procedure

COD not affected by industrial/toxicsamp es

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Chem ic a l Ox ygen Dem and

COD is a measure of the oxygen demand of asamp e a s suscep e o ox a on y a s rongchemical oxidant

Digestion required: 2 hours @ 150 C

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Com m on Uses o f COD

How do ou use COD??

Food estimate?

Tracking industrial dischargers?

An one char in industrialdischarges based on COD insteadof BOD?

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COD Met hods

Dichromate micro digestion (0.7 15,000 mg/L COD)

Dichromate = strong oxidizer; good digestion

Interference from chlorides occurs > 2,000 mg/L

Mercury waste must be disposed of properly and recycled

Manganese III micro digestion (25 1,000 mg/L COD) ercury ree reagen eas er o spose o

Mn III is not as strong of an organic oxidizer

Chlorides can be removed via precipitation with silver salts,filtered, or centrifuged

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Plant Basel ines, Trends, andCorre la t ions

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Organic s Trend = Load Equal izat ion

400

Inlet of plant

Equalisation to

aeration

200

300

(UV)[m

g/l]

0

100BO

Target: Steady loading to the aeration basin

time [h]

->optimal denitrification and biological phosphorus removal

Solution: - Bypass the primary clarifier during low loading

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Can w e mak e cor re la t ions?

True or False? There is NO general correlation

However:

Correlations can be made on samples with consistent

composition can e use o es ma e eve s

Useful relationships can be made for some samples

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pudljumper1@comcast.net

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What c or rela t ions are useful?

Standards

Some influent streams, if consistent! Is our influent consistent?

COD: Use to estimate BOD to calculate

required dilutions

,results, and proficiencies

Recommended by Standard Methods!20

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BOD:COD Ex am ple

New Belgium Brewery

BOD removal before dischargingto municipality

Uses COD for daily processcontrol

COD:BOD ratio usually 100:1 for influent, 10:1 effluent

COD #1 parameter used to give operators the big picture

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COD for Rapid Organic Est im at es

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Tak e Hom e Messages

BOD and COD evaluate the efficiency of treatment

COD can be a time saver and is not affected b toxicit

Correlations can be made on samples with consistentcomposition for process control

: ra os can e a grea way o assess resu s oBOD test and proficiency samples!

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An i n ?

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Produc t s for BOD

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LDO fo r BOD

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LDO Met hod Approval

Green: Approved - No data needed

Blue: Approved with Performance Data* - Est. total time 2-8 Lab hrs/ 30-90 days

Orange: Tier 1 Submission

28http://www.hach.com/hqdguide-do

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The COD Prob lem Wast e

EZ COD recycling

Heritage Environmental will pickup and recycle

Mercury Free CODTNTplus packaging

Not EPA approved

Only for low-chloride waters

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Produc t s for COD

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Com parison be t w een

G a n g l in i e n v e r g l e i c h d e r G e r t e T O C T A X u n d U V A S p l u s

a m A b l a u f e i n e r V o r k l r u n g

1 6 0

uv]

m g / l T O C ( T O C T A X ) m g / l D O C u v ( U V A S p lu s )

G a n g l in i e n v e r g l e i c h d e r G e r t e T O C T A X u n d U V A S p l u s

a m A b l a u f e i n e r V o r k l r u n g

1 6 0

uv]

m g / l T O C ( T O C T A X ) m g / l D O C u v ( U V A S p lu s )

6 0

8 0

1 0 0

1 2 0

1 4 0

on[mg/lTOCbzw

.mg/lDOC

6 0

8 0

1 0 0

1 2 0

1 4 0

on[mg/lTOCbzw

.mg/lDOC

SAC / TOC

Primary Effluent

0

2 0

4 0

2 8 . S e p 2 9 . S e p 3 0 . S e p 1 . O k t 2 . O k t 3 . O k t 4 . O k t

Konzentrati

0

2 0

4 0

2 8 . S e p 2 9 . S e p 3 0 . S e p 1 . O k t 2 . O k t 3 . O k t 4 . O k t

Konzentrati

300

400

500

30

40

50

CSB [mg/l] SAK [1/m]

300

400

500

30

40

50

CSB [mg/l] SAK [1/m]

SAC / CODRaw Influent

particulate COD

0

100

200

0 24 48 72 96 120

0

10

20

t [h]0

100

200

0 24 48 72 96 120

0

10

20

t [h]

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