Online Chemical Oxygen Demand COD Probe for Sewage

The COD concentration of the inlet water of the sewage treatment plant refers to the COD concentration of the water inlet of the sewage treatment plant. It is an indicator of the amount of reducing substances in the water at the water inlet. If sewage with low COD content enters the sewage plant for treatment, it will not only increase the operational burden of the sewage plant but also destroy the sludge activity and affect the operating efficiency of the sewage biological treatment system. These phenomena should be paid full attention to, and effective measures should be taken for rectification and management. There is no upper limit for sewage inflow, but there is a lower limit. Those below 100mg/L do not need to be treated.

There are two ways to detect COD at the water inlet. The traditional laboratory measurement method is simple and technically mature, but the disadvantage is that the detection time is long, at least a few hours. Therefore, if you want to continuously monitor the COD value in real time, online COD sensors are now commonly used.

The online sensor COD351 developed and produced by Daruifuno is a digital sensor that uses the ultraviolet absorption method to measure the COD value in water. The measurement range has low-range and high-range options. This Chemical Oxygen Demand Sensor requires no reagents, is pollution-free, and can continuously monitor the COD value of water quality. It automatically compensates for turbidity interference, includes a self-cleaning wiper, and has a long maintenance cycle.

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Specification

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Monitoring COD Concentration Ranges

In the process of domestic sewage treatment, the monitoring concentration of water quality COD can be roughly divided into four ranges:

• Higher concentration raw water, COD is about 1000mg/L;
• The COD of the treated medium concentration effluent is about 500mg/L;
• The COD of the treated low-concentration effluent is about 150mg/L;
• After treatment, the effluent that basically reaches the standard has a COD of about 30mg/L.

Reasons for Sewage COD Exceeding the Standard

• Water quality reasons: Wastewater from industries like food factories, chemical plants, electroplating plants, printing and dyeing plants, and paper mills have unique water quality characteristics.
• Water treatment process reasons: Low water temperature during biochemical treatment reduces microbial activity. Low dissolved oxygen levels or high nitrogen and phosphorus concentrations can also reduce efficiency and cause toxicity to bacteria in the water.

The main factors that affect the COD treatment effect are nutrients (e.g., nitrogen, phosphorus), pH changes, high grease content, and temperature fluctuations that impact the activated sludge process.

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About Us

Delfino specializes in the R&D and production of water quality analysis instruments. Our measurement parameters include pH, ORP, conductivity, TDS, salinity, dissolved oxygen, COD, ammonia nitrogen, turbidity, chlorophyll, blue-green algae, residual chlorine, and chlorine dioxide. Our main products include pH ORP analyzers, conductivity analyzers, turbidity analyzers, COD analyzers, dissolved oxygen analyzers, ammonium analyzers, and chlorine analyzers. For more information, please contact us.