What does COD stand for in the COD Water Quality Online Monitor? Chemical Oxygen Demand, also known as Chemical Oxygen Consumption, is abbreviated as COD. It refers to the amount of oxygen consumed by the oxidation and decomposition of oxidizable substances in water (such as organic matter, nitrites, ferrous salts, sulfides, etc.) using chemical oxidants (like potassium permanganate), and then calculating the oxygen consumption based on the remaining oxidant quantity. Similar to Biochemical Oxygen Demand (BOD), it is an important indicator of water pollution level. The unit of COD is ppm or milligrams per liter, and the lower the value, the lighter the degree of water pollution.

Reductive substances in water include various organic matter, nitrites, sulfides, ferrous salts, etc., with organic matter being the primary component. Consequently, Chemical Oxygen Demand (COD) is often used as an indicator to measure the amount of organic substances in water. A higher COD value indicates a more severe pollution of water bodies by organic matter. The determination of COD varies depending on the type of reductive substances in the water sample and the measurement method. Currently, the most widely used methods are the potassium permanganate oxidation method and the potassium dichromate oxidation method. The potassium permanganate (KMnO4) method has a lower oxidation rate but is simpler and can be used to determine the relative content of organic matter in water samples, as well as in clean surface water and groundwater samples. The potassium dichromate (K2Cr2O7) method has a higher oxidation rate and good reproducibility, making it suitable for determining the total organic matter content in water samples during wastewater monitoring.

What are the uses of the COD water quality online monitor?

To accurately monitor the operation of each treatment stage in the wastewater treatment plant, it is necessary to supervise the relevant parameters entering various structures. Some of these parameters require manual chemical analysis, while others can be automatically detected using instruments. The COD online analyzer is one of the key instruments for automatic water quality detection.

How to use the sampler for the COD water quality online monitor?

The COD Water Quality Online Monitor typically requires matching with an Automatic Continuous Sampler. These samplers are generally installed at the influent and effluent of wastewater treatment plants, allowing for effective collection of mixed samples. Most of them also feature refrigeration capabilities, which can maintain the stability of collected water samples for a certain period. Usage precautions include:

1. The sampling tubes used for after-fitting must be made of clean and uncontaminated piping materials that do not react with the components in the wastewater. Generally, PVC flexible tubes are used unless there are special requirements.

2. Timely extraction and analysis of water samples collected by the automatic continuous sampler to prevent the samples from exceeding the stable storage time and overflowing from the sampling bottles, which could damage the sampler.

Regularly clean or replace sample tubes and bottles.

Regular maintenance and care are conducted on the sampler's control and mechanical components.

The automatic continuous samplers installed at wastewater treatment facilities in northern regions must have anti-freezing measures in place.