How is BOD measured? 

Biochemical oxygen demand, or BOD, is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. So, how is BOD measured? It is not a precise quantitative test, although it is widely used as an indication of the organic quality of water. It is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days (BOD5) of incubation at 20°C and is often used as a robust surrogate of the degree of organic pollution of water.

What's effect of BOD value in water ?

Biological oxygen demand directly affects the amount of dissolved oxygen in rivers and streams. The rate of oxygen consumption is affected by a number of variables: temperature, pH, the presence of certain kinds of microorganisms, and the type of organic and inorganic material in the water. The greater the value, the more rapidly oxygen is depleted in the stream. This means less oxygen is available to higher forms of aquatic life. The consequences of high BOD are the same as those for low dissolved oxygen: aquatic organisms become stressed, suffocate, and die. Sources of biochemical oxygen demand include topsoil, leaves and woody debris; animal manure; effluents from pulp and paper mills, wastewater treatment plants, feedlots, and food-processing plants; failing septic systems; and urban stormwater runoff. Biolgoical oxygen demand is affected by the same factors that affect dissolved oxygen. Measuring biochemical oxygen demand requires taking two measurements. One is measured immediately for dissolved oxygen (initial), and the second is incubated in the lab for 5 days and then tested for the amount of dissolved oxygen remaining (final). This represents the amount of oxygen consumed by microorganisms to break down the organic matter present in the sample during the incubation period.

As above conclusion ,User can get the BOD value in 5 days in laboratory,so far laboratory measurement is the most accuracy and accuracy is ±10%,the model is Model: CY-5 Laboratory BOD5 Analyzer as below.

Below is relationship between BOD and COD for 8 different kinds of waste water.

1. Machinery wastewater : y=0.2732x + 1.80

2. Cooling wastewater : y=0.1285x + 0.11

3. Pharmaceutical Wastewater : y=0.3922x + 131.21

4. Textile printing and dyeing wastewater : y=0.4208x - 2.49

5. Food processing wastewater : y=..6126x +13.70

6. Food wastewater : y=0.5992x + 17.51

7. Hospital wastewater : y=0.3439x - 0.41

8. Domestic sewage : y=0.486x + 17.02
   

               

CY-5 Laboratory BOD5 Analyzer

BOD5 measurement Range: 0mg/L～1000mg/L(dilute if BOD5 value exceeds);BOD Sample Quantity:  8 at same time

               

CY-5-I BOD Biochemical Incubator

BOD biochemical incubator (BOD Incubator, the same below) is a BOD test equipment that integrates heating and cooling functions,Capacity is100L

About Online BOD Measurement,the value is all converted from COD,the accuracy is over 10%,so in most condition, users only need to know the change curve by BOD measurement.now here is two method.

               

CODS-3000-01 Online BOD COD Sensor

1)COD value will be converted to BOD on transmitter.

2)It’s online and continuous measurement.

3)User should calibrate it at local site and compare the value with Lab BOD Analyzer.

4)The calibration period is according to water quality at site, and recommend: 3~6 months

               

BODG-3063 online BOD analyzer

1)It's reagent type and will directly shows BOD.

2)The instrument should be installed at room with airconditioner.

3)It’s online measurement; measurement period is 45mins ~ 120mins(it can be adjusted by user).

4)We will provide calibration buffer and it don’t need to compare value with Lab BOD analyzer.

5)The calibration period is one month.