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Which one is better BOD or COD?

By: Todd RuhlUpdated: March 18, 2021

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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. There is a strong correlation between COD and BOD, however COD analysis is a much faster and more accurate method.

Likewise, what is COD and BOD in ETP water?

BOD reduction is used as a gauge of the effectiveness of wastewater treatment plants. BOD analysis is similar in function to chemical oxygen demand (COD) analysis, in that both measure the amount of organic compounds in water.

Beside above, why do we measure BOD and COD?

BOD measures the amount of oxygen required by the aerobic organisms to decompose organic matter and COD measures the oxygen required to decompose organic and inorganic constituents present in the wastewater by chemical reaction. Hence, the value of COD is greater than BOD.

Why is COD higher than BOD?

COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.

What is BOD COD and do?

COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized. TOC or Total Organic Carbon is the measurement of organic carbons. BOD- Biochemical Oxygen Demand is supposed to measure the amount of food (or organic carbons) that bacteria can oxidize.

Related

What happen 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.

How is cod calculated?

The COD test involves a blank, which is a sample made by adding the reagents of acid and an oxidizing agent to distilled water. There is a formula for calculating COD. Consider the formula for COD calculation: (a - b) X C X 8,000 / the volume of the sample in mL.

What is BOD formula?

BOD = biochemical oxygen demand, mg/L. When seed is added, seed control tests must be done to determine the amount of oxygen depleted by the seed. Calculation of BOD includes a correction factor for seed as expressed by Equation 2.

What is COD in wastewater?

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. The most common application of COD is in quantifying the amount of oxidizable pollutants found in surface water (e.g. lakes and rivers) or wastewater.

How do you calculate BOD and COD?

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 a good BOD level?

A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean.

Why is bod done for 5 days?

While calculating the oxygen demand, the carbonaceous stage is taken into account. This stage is almost completed in 5 days, which means that most of the organic content of the sewage is oxidized under aerobic conditions in 5 days. Hence, BOD for 5 days is calculated.

What is BOD of drinking water?

A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean. At BOD levels of 100 ppm or greater, the water supply is considered very polluted with organic waste.

Is BOD higher than cod?

BOD can be higher than COD determined by dichromate oxidation in a few cases. The most common is a sample with very degradable organic matter and high organic nitrogen or ammonium such as wastewater from fish processing.

Can COD be lower than bod?

COD express the total organic load that can be decomposed chemically (thus more drastically). Based on that, it derives that always BOD is less or equal to COD. (b) water from the shower, due to the presence of detergents, is expected to have a BOD value less than the value of COD.

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 BOD ETP?

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed (i.e. demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.

What is BOD value?

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.

How do you calculate wastewater COD?

The COD test involves a blank, which is a sample made by adding the reagents of acid and an oxidizing agent to distilled water. There is a formula for calculating COD. Consider the formula for COD calculation: (a - b) X C X 8,000 / the volume of the sample in mL.