The Basic Principles Of chemical oxygen demand test
The Basic Principles Of chemical oxygen demand test
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There are plenty of approaches for measuring COD, Every single with its advantages and disadvantages. The most typical solutions incorporate the dichromate method, the permanganate system, and also the shut reflux system.
Drinking water Quality Assessment: COD measurement is usually a precious Resource for assessing the overall air pollution amount and natural and organic content material of water. Substantial COD values point out the existence of major quantities of organic pollutants, which include wastewater, industrial effluents, or organic and natural chemicals. Checking COD aids in assessing the water high quality and pinpointing sources of air pollution.
You can quantify the amount of trivalent chromium within a sample after digestion by measuring the absorbance in the sample at a wavelength of 600 nm in a photometer or spectrophotometer.
The level of potassium dichromate Employed in the response is equivalent to the level of oxygen (O2) required to oxidise the wastewater’s organic and natural content material.
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:
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Influent waters coming into wastewater plants are significant in organics and also the wastewater plant ought to decrease the “natural and organic loading” prior to discharging drinking read more water to the receiving human body.
Should the wastewater sample is tested at comprehensive strength, then 2 ml is added for the corresponding vial. If dilution is needed, then serial dilutions are carried out and 2 ml in the diluted sample are additional for the corresponding vial.
The COD test makes use of a chemical (potassium dichromate inside of a 50% sulfuric acid Option) that “oxidizes” each organic and natural (predominate) and inorganic substances inside a wastewater sample, which ends up in an increased COD focus get more info than BOD concentration for a similar wastewater sample given that only organic and natural compounds are eaten during BOD testing.
Choose these vials Should your perform calls for you to report COD success to your regulatory agency demanding EPA methodologies.
System Summary – An aliquot in the sample is digested for 2 hrs at a hundred and fifty°C from the presence of dichromate and sulfuric acid. The ensuing Resolution is titrated to a coloured endpoint with ferroin indicator or Read more a spectrophotometer at an suitable wavelength.
Make certain all caps are secured tightly, then invert Just about every vial quite a few situations. Remember that scorching vials may perhaps shatter if dropped or cooled fast.
Entire Carbon Oxidation: The superior temperatures Employed in the combustion course of action be certain the whole oxidation of carbon compounds, providing accurate and responsible measurements.
BOD benefit approximates the amount of oxidizable organic make any difference. As a result, it can be used like a evaluate of the diploma of drinking water pollution and waste toughness.