The 2-Minute Rule for chemical oxygen demand test
The 2-Minute Rule for chemical oxygen demand test
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COD measurement concentrations Commonly take all around 2 hours both in the laboratory or with an internet analyser, so can be a more rapidly test than the usual BOD measurement which will take all over five days.
The COD test can be a useful measure of effluent top quality of the wastewater therapy plant. It offers A fast, approximate evaluate of all chemically oxidizable substances and can be utilized to identify performance difficulties in cure facilities.
Do có nồng độ cao trong phần lớn các loại nước thải nên chloride thông thường là nguồn quan trọng nhất trong việc gây nhiễu. Phản ứng của nó với dicromat kali như sau:
Digestion is carried out over the samples with a established quantity of the oxidant, sulfuric acid, and heat (one hundred fifty°C). Metal salts usually are bundled to suppress any interferences and to catalyze the digestion. This digestion ordinarily requires two several hours to execute.
A single vial is marked to be a “blank,” and a few or 4 vials are marked with identified conventional concentrations. Two vials are then marked for the wastewater sample to produce a reproduction run. Take note: If many wastewater samples are being run, not less than 10% of samples are duplicated.
A different problem is The shortcoming of the standard COD methods to differentiate in between biologically readily available and inert natural matter. This can result in overestimation of the quantity of oxygen demanded for Organic treatment method processes.
Electrodes: Electrodes are necessary factors of electrochemical measurements. They are usually fabricated from conductive supplies, which include metals or steel oxides, and so are designed to communicate with the analyte of desire.
Aquatic organisms begin to suffocate and die. The measurement of COD is actually a more rapidly measurement than The everyday five-day test required for BOD, so is much more valuable for serious time checking.
Discharge restrictions vary from plant to plant according read more to the characteristics of your obtaining water, effects on aquatic lifestyle, leisure utilizes together with other factors.
Divide the COD concentration with the BOD focus for each sample and average the outcome. One example is, below would be the COD:BOD ratio developed applying a few wastewater samples from the meals processor:
It might be defined as the level of oxygen demanded by organic and natural issue inside a click here sample of drinking water for its oxidation by a strong oxidizing agent and is particularly expressed as ppm of oxygen taken from a solution of K2Cr2O7 in two sorts.
In several situations, there is a constructive correlation between TOC and COD. Which means given that the TOC concentration will increase, the COD worth also tends to raise. This correlation happens for the reason that nearly all organic and natural compounds contribute to both equally the TOC and COD values.