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BOD (Biochemical Oxygen Demand)

Biochemical oxygen demand or biochemical oxygen consumption is an environmental monitoring indicator. It is mainly used to monitor the pollution of organic matter in water. It is defined as the consumption of organic matter in unit volume of water by aerobic microorganisms under aerobic conditions. The amount of free oxygen, expressed in milligrams of oxygen

/

Rise

(O ₂

,

Mg/L)

. Generally, organic matter can be decomposed by microorganisms, but microorganisms need to consume oxygen when decomposing organic compounds in water. If the dissolved oxygen in the water is insufficient to supply microorganisms, the water body is in a state of pollution.

The degradation of organic matter by microorganisms is related to temperature, and the most suitable temperature is generally

15~30°C

, so in the determination of biochemical oxygen demand

20 ° C

As the standard temperature for the measurement.

20 ° C

At the time

BOD

Measuring condition

(

Oxygen is sufficient, does not stir

)

Under, general organic matter

20

Genius can basically complete the oxidative decomposition process in the first stage

(

Complete the process

99%)

, that is, to determine the biochemical oxygen demand in the first stage,

20

Days, this is difficult to do in actual work. For this purpose, a standard time is also specified, generally

5

Day as a measure

BOD

Standard time, hence the so-called five-day biochemical oxygen demand,

BOD5

Express it.

BOD5

About

BOD20

of

70%

about.

Announcement of the Ministry of Environmental Protection

2009

Year

54

The number clearly stated

HJ505-2009

Water quality

5th day BOD (

BOD5

Determination

Detailed measurement method for dilution and inoculation method. The principle is: usually the water sample is filled with a completely closed dissolved oxygen bottle, at (

20

±

1 ^o C

) cultivation in the dark

5 d

±4 h

or(

2+5

)

d

±4 h[

First in

0-4

o

C

Dark culture

2 d

And then at (

20

±

1 ^o C

Dark culture

5 d

Training

(

2+5

)

d

]

According to the iodometric method or the electrochemical probe method, the mass concentration of dissolved oxygen in the water sample before and after the culture is determined, and the dissolved oxygen content per liter of sample is calculated from the difference of the mass concentration of dissolved oxygen before and after the cultivation.

BOD5

Formal representation (non-dilution method):

ρ=ρ1-ρ2

In the formula:

Ρ-

5th day BOD mass concentration,

Mg/L;

Ρ1-

The dissolved oxygen concentration of the water sample before the culture,

Mg/L;

Ρ2-

The dissolved oxygen concentration of the water sample after cultivation,

Mg/L

.

Detection limit of the method

0.5 mg/L

, the lower limit of the method is

2 mg/L

The upper limit of the undiluted and non-dilute inoculation method is

6 mg/L/

.

The method requires a large number of reagents, wherein the propylene thiourea inhibitor is a toxic compound.

And the whole process is cumbersome.

(EN NF 1899-1)

,

5210 B

(

USA

)and

ISO

5815

,Correct

BOD5

The detection methods are basically the same. but

In the past few decades, as the public's awareness of the protection of natural resources has increased, the demand for the environmental analysis market has increased significantly. Therefore, in the face of increasing sample numbers, rapid batch analysis has become an urgent need for laboratories, and the five-day incubation time has greatly reduced the overall detection efficiency.

Based on bioanalytical techniques,

AMS Alliance

The group combines fluorescence detection with the world

96

The standard design of the microplate was developed and an innovative rapid analysis test kit was developed. The principle of the method is based on the application of biological reagents. During the aerobic respiration of microbial cells, the biological reagents are reduced, resulting in enhanced fluorescence signals and recording the fluorescence intensity and organic matter throughout the culture period.

(Biodegradable Organic Matter

,

BOM )

The proportional relationship of the amount of degradation, that is, the more the organic organism is degraded, the higher the fluorescence intensity (Fig.

1

).

and

BOD5

The measured value is the difference between the mass concentration of dissolved oxygen before and after culture, and is also positively correlated with the amount of organic matter to be degraded, so the fluorescence intensity of the detection kit can be quickly established.

BOD5

The linear relationship between the three is shown in the figure

2

But it is worth noting

AMS Alliiance

Group of fluorescent kits

Enverdi BOD

in

30 ^o C

Protected from light

2

day(

48 h

Detected

BOD5

Result and standard method

20 ^o C

Protected from light

5

The test results of the day are highly consistent.

Compared to the standard method,

Enverdi BOD

The kit also has the following advantages:

1,

Microporous design, lower cost and more economical;

2,

Can be cultured directly in the fluorescence detector, occupying less than the area

1m ²

;

3,

Easy and fast batch testing, one kit can be completed at most

80

(no repetition) or

40

(repeated)

BOD5

Sample analysis;

4,

ready

40

Repeated samples only need

45

Minutes, faster than regular methods

5-10

Times

5,

Fully automated data logging and management.

Figure

1 Enverdi BOD

Schematic diagram of kit detection principle