BOD measuring instruments mainly include BOD rapid measuring meter, pressure method BOD meter, and dissolved oxygen BOD meter based on the principle of bio-sensor method.
I. BOD rapid measuring meter
The water sample containing saturated dissolved oxygen enters the measuring tank and contacts the bio-sensor, generating a constant current. When there are biodegradable organic matter in the water sample, a constant current is generated. The difference between the two constant currents has a quantitative relationship with the concentration of biodegradable organic matter in the water sample. Therefore, the current signal is amplified and analyzed by a computer to directly display the BOD detection result.
II. Pressure method BOD meter
In a closed system, the microorganisms in the sample consume oxygen and generate carbon dioxide at the same time. The carbon dioxide generated is absorbed by the NaOH pill, and the air pressure changes. A pressure sensor is used to detect the pressure change and converts it into a BOD value.
III. Dissolved oxygen BOD meter
It is based on the quenching principle of specific substances to active fluorescence. The blue light irradiates the fluorescent material to excite the fluorescent material and emit red light. Since oxygen molecules can take away energy (quenching effect), the time and intensity of the excited red light are inversely proportional to the concentration of oxygen molecules. By measuring the phase difference between the excited red light and the reference light, and comparing it with the internal calibration value, the concentration of oxygen molecules can be calculated.
BOD meter is widely used in materials, chemical, pharmaceutical, fine ceramics, paper-making, cosmetics, metallurgy and other industries, for laboratory analysis and quality control in industrial production with particulate matter as raw materials or intermediates.
