What is COD test?

By: James AlvarezUpdated: March 21, 2021


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    June 26, 2022
In environmental chemistry, the chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. A COD test can be used to easily quantify the amount of organics in water.

Accordingly, how COD is measured?

COD. The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in liquid waste. It is expressed in milligrams/grams per liter, which indicates the mass of oxygen consumed per liter of solution. Older references may express the units as parts per million (ppm).

Furthermore, what is the difference between COD and BOD?

COD is the amount of oxygen required to chemically breakdown the pollutants whereas BOD is the amount of oxygen required to do this biologically through micro-organisms. Low levels of organic waste and fewer bacteria present mean the BOD will be lower and the dissolved oxygen levels higher.

What causes high COD in wastewater?

High COD/BOD levels in stormwater runoff are cause by the residual food and beverage waste from cans/bottles, antifreeze, and emulsified oils from industrial food processing and agricultural activities. As most forms of COD are water soluble, this pollutant spreads easily via stormwater to waterways.

Is high COD good or bad?

It is bad. COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized. The limit of COD for drinking water as set by WHO and ICMR is 10 ppm. Beyond that it is not drinkable but everyday, millions drink bad water with very high COD levels.


What happens if cod is high?

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 COD value?

COD, Chemical Oxygen Demand, is a measure of the total quantity of oxygen required to oxidize all organic material into carbon dioxide and water. COD values are always greater than BOD values, but COD measurements can be made in a few hours while BOD measurements take five days.

What is the COD of drinking water?

The COD is the amount of oxygen consumed to chemically oxidize organic water contaminants to inorganic end products. The COD is often measured using a strong oxidant (e.g. potassium dichromate, potassium iodate, potassium permanganate) under acidic conditions.

What is cod used for?

Cod is popular as a food with a mild flavour and a dense, flaky, white flesh. Cod livers are processed to make cod liver oil, an important source of vitamin A, vitamin D, vitamin E, and omega-3 fatty acids (EPA and DHA). Young Atlantic cod or haddock prepared in strips for cooking is called scrod.

Why is cod so important?

The chemical oxygen demand (COD) is a measure of water and wastewater quality. The COD test is often used to monitor water treatment plant efficiency. The COD is the amount of oxygen consumed to chemically oxidize organic water contaminants to inorganic end products.

What is COD method?

COD Chemical Oxygen Demand. 1.0 Scope and Application. 1.1 The Chemical Oxygen Demand (COD) method determines the quantity of oxygen required to oxidize the organic matter in a waste sample, under specific conditions of oxidizing agent, temperature, and time.

How do you reduce COD in wastewater?

Coagulation and flocculation processes are some of the best options to treat pulping wastewater using aluminium, ferric chloride, lime, ferrous sulfate and polyaluminium chloride and can be considered as an efficient treatment method to reduce COD, total suspended solids (TSS) and colour of pulping effluent (Rahbar et

What is cod medical?

Dual diagnosis. Dual diagnosis (also called co-occurring disorders, COD, or dual pathology) is the condition of suffering from a mental illness and a comorbid substance abuse problem.

How do you make COD reagent?

Prepare by dissolving 85 mg of dried (120 °C, overnight) potassium acid phthalate (KHP) in 1 liter of deionized water. Use 2.0 mL as the sample volume. The expected result will be 100 mg/L COD. As an alternative, dilute 10 mL of 1000-mg/L COD Standard Solution to 100 mL to make a 100-mg/L standard.

What is a high dissolved oxygen level?

Dissolved oxygen refers to the level of free, non-compound oxygen present in water or other liquids. In limnology (the study of lakes), dissolved oxygen is an essential factor second only to water itself ¹. A dissolved oxygen level that is too high or too low can harm aquatic life and affect water quality.

How do you find theoretical Cod?

We can calculate by following steps:
  1. Write balanced reaction for the carbonaceous oxygen demand. CH2(NH2)COOH + 1.5O2 → NH3 + 2CO2 + H2O.
  2. Write balanced reactions for the nitrogenous oxygen demand. NH3 + 1.5O2 → HNO2 + H2O. HNO2 + 0.5O2 → HNO3
  3. Determine the ThOD. ThOD = (1.5 + 2) mol O2/mol glycine.

What is BOD in wastewater?

The decay of organic matter in water is measured as biochemical or chemical oxygen demand. Oxygen demand is a measure of the amount of oxidizable substances in a water sample that can lower DO concentrations. BOD is used, often in wastewater-treatment plants, as an index of the degree of organic pollution in water.

What is cod anaerobic digestion?

Anaerobic digestion is a biological process which utilises bacteria that operate without the need for a constant supply of oxygen. These bacteria convert COD to methane and carbon dioxide thus reducing the trade effluent charge for the effluent treatment.