Chemical Oxygen Demand (COD)

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Calculate the amount of oxygen required to chemically oxidize organic compounds in water.

Titration Data

Vol. FAS for Blank

Vol. FAS for Sample

Sample Parameters

Molarity of FAS

Original Sample Vol.

COD Results

Enter parameters to see results

About this calculator

Overview

Chemical Oxygen Demand (COD) is a critical water quality parameter that measures the total quantity of oxygen required to chemically oxidize all organic matter and some inorganic compounds in water. It provides an estimate of the oxygen depletion potential of wastewater and is widely used in environmental monitoring, wastewater treatment, and industrial process control. COD values are typically higher than BOD (Biochemical Oxygen Demand) because COD measures both biodegradable and non-biodegradable organic matter, including toxic substances that inhibit microbial activity.

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Pro Tips

Ensure all glassware is acid-washed to prevent contamination from organic residues.
Ferrous Ammonium Sulfate (FAS) is the standard titrant used in the back-titration process.
The blank titration is crucial for correcting any background oxidation from reagents.

Fun Facts

"COD testing takes only 2-3 hours compared to 5 days for BOD testing, making it invaluable for industries requiring rapid results."
"A high COD value indicates significant organic pollution; typical values range from <50 mg/L for clean water to >1000 mg/L for heavily polluted industrial wastewater."
"The potassium dichromate method (using K₂Cr₂O₇) is the most common chemical method for COD determination due to its reliability and broad applicability."
"COD measures both biodegradable and non-biodegradable organic matter, including toxic compounds like heavy metals, cyanides, and pesticides that BOD cannot detect."
"COD:BOD ratios help assess wastewater treatability - ratios >2 indicate significant non-biodegradable organic matter requiring advanced treatment."
"In 2026, automated online COD analyzers provide real-time monitoring in wastewater treatment plants, enabling immediate process adjustments."
"COD is used in regulatory compliance worldwide, with limits typically ranging from 50-250 mg/L depending on discharge standards."
"The COD test uses strong chemical oxidants under acidic conditions, capable of oxidizing compounds that bacteria cannot break down."
"The COD:BOD ratio is a key indicator of biodegradability: a ratio < 2 implies the water is easily biodegradable."
"Potassium dichromate is used as the oxidant because it is more robust than potassium permanganate, which was used in earlier 'Oxygen Consumed' tests."

Formula: COD (mg/L) = [(V_blank - V_sample) × M × 8000] / Sample_Vol

COD Level Comparison (mg/L)

Comparing your result against typical environmental standards.