How is chemical oxygen demand measured?

COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.

How long does a COD test take?

This is usually done by titration, using an indicator solution. COD is expressed in mg/L, which indicates the mass of oxygen consumed per liter of solution. The COD test only requires 2-3 hours, while the Biochemical (or Biological) Oxygen Demand (BOD) test requires 5 days.

What is the value of COD?

The COD value indicates the amount of oxygen which is needed for the oxidation of all organic substances in water in mg/l or g/m3. The COD (Chemical Oxygen Demand) is closely related to the laboratory standard method named Dichromate-Method.

How is COD measured in the lab?

To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples. Divide the COD concentration by the BOD concentration for each sample and average the results.

What is COD and how it measure?

COD is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, which in SI units is milligrams per liter (mg/L). A COD test can be used to easily quantify the amount of organics in water.

What is COD parameter?

When discussing package sewage treatment one parameter that we neglected to cover is that of COD which means Chemical Oxygen Demand. It is a test of the amount of oxygen required to oxidise organic matter in a sewage sample by chemical oxidation with a powerful oxidising agent such Potassium Dichromate.

How is COD measured in water sample?

The COD is often measured using a strong oxidant (e.g. potassium dichromate, potassium iodate, potassium permanganate) under acidic conditions. A known excess amount of the oxidant is added to the sample.

What is high COD?

Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels. A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.

What is good COD level?

Influent COD in normal domestic sewage is therefore generally 600 – 900 mg/l and it is then treated to at least 75 -100 mg/l before discharge to minimise pollution potential.

What is COD level?

Chemical oxygen demand (COD) is the amount of dissolved oxygen that must be present in water to oxidize chemical organic materials, like petroleum. COD is used to gauge the short-term impact wastewater effluents will have on the oxygen levels of receiving waters.

What is COD BOD and Tod?

The most popular sum parameter in waste water analysis are the BOD (biochemical oxygen demand), COD (chemical oxygen demand), TOD (total oxygen demand) and TOC (total organic carbon). The TOC reflects the organic pollution on the basis of a direct carbon determination.

What is BOD COD and TDS?

The most popular sum parameter in waste water analysis are the BOD (biochemical oxygen demand), COD (chemical oxygen demand), TOD or Total Oxygen Demand and TOC or Total Organic Carbon. The TOC reflects the organic pollution on the basis of a direct carbon determination. [ 1] But why does the BOD, COD, TOC, TDS etc.

Is Tod greater than COD?

∴ TOD > COD > BOD Other Important points: COD is also known as Di-chromate demand. With hundreds of Questions based on Quality and Characteristics of Sewage, we help you gain expertise on Environmental Engineering.

Why do we measure TSS?

TSS is the most visible indicator of water quality. It is considered that clear water is usually considered healthy water. It is especially cause for concern if the water becomes murky in a previously clear body of water.

What is TDS and TSS?

The particles that are large enough to be held back by the filter are called total suspended solids (TSS), while the particles that pass through the filter are called total dissolved solids (TDS).