This section provides an overview for cod meters as well as their applications and principles. Also, please take a look at the list of 10 cod meter manufacturers and their company rankings.
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A COD meter is a machine used to measure chemical oxygen demand (COD) in water.
*COD: An indicator used to measure organic pollution in a water sample. The higher the COD value (the higher the oxygen demand of the sample), the more polluted the water is.
Similar to COD, biochemical oxygen demand (BOD) is also used as an indicator of water quality.
*BOD: An indicator of the amount of oxygen required by microorganisms to decompose organic matter in water, and is used as a reference item for rivers.
COD measures the amount of oxygen consumed when organic matter is decomposed by an oxidizing agent (potassium permanganate is often used). The more organic matter there is, the more oxygen is required when the oxidizer is added, and thus the higher the COD.
Standard and target values for COD are generally set by government environmental agencies and serve as criteria for environmental assessment and wastewater treatment. These standard values vary depending on the type of water body and the intended use of the water, such as for seaweed cultivation and industrial water. COD is expressed in mg/L, but it is important to note that the value varies depending on the measurement method.
The following methods are used as measurement methods for COD meters.
The acidic method accounts for the largest share of automatic COD analyzers.
This method automates the entire process from adding reagents to the sample to heating and potassium permanganate measurement.
The following methods are employed in simple COD meters. It can be easily measured in the field or on site.
An electrode is placed in the sample and electrolyzed to produce an oxidant for titration. The COD concentration is determined based on the amount of electricity used in the titration.
The residual amount of potassium permanganate, an oxidant, is determined by irradiating the sample with a certain wavelength and determining the absorbance. Based on this, COD is calculated. Note that the absorbance measurement may be affected by turbidity of the reagent or suspended matter in the sample. A simpler method, the colorimetric method using a pack test, also exists.
Other methods of measurement by manual analysis are also available, but will be omitted from this article in order to focus on COD meters.
*Including some distributors, etc.
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Endress+Hauser Group is based in Switzerland and has over 15,000 employees worldwide. Endress+Hauser manufactures measurement instrumentation and provides services for industrial process engineering. Endress+Hauser’s customers come from various industries including chemical, life sciences, energy, and water. Endress+Hauser’s products include those for level measurement, pressure measurement, software, industrial communication technologies, and liquid analysis. Endress+Hauser also offers services including project and commissioning, support and education, maintenance, and performance optimization. The company has an assortment of online tools to assist customers in services such as product selection.
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