Biochemical Oxygen Demand is an analytical parameter indicating how much dissolved oxygen is consumed under specific conditions by aerobic bacteria and by other microorganisms present in a water sample (e.g waste water, surface water). Bacteria take the oxygen from the water when they oxidise organic matter. Biochemical Oxygen Demand 5 (BOD5) is a testing method which determines the oxygen consumption during 5-days at 20°C ±1°C.f

The test uses a BOD unit which is a closed system comprising of test flasks and BOD sensors. The bacteria present in water consume the oxygen dissolved in the sample over the course of the BOD measurement and is replaced by air oxygen while carbon dioxide is simultaneously produced and chemically bound by the potassium hydroxide in seal cup. As a result, a pressure drop occurs in the system, which is measured by the BOD sensor and shown in the display as a BOD value in mg/L O₂. 

• Good water quality means low BOD (mg/O₂) values;
• Poor water quality means high BOD (mg/O₂) values;

• You have a sewage treatment plant or a distillery;
• Want to ensure the water leaving the plant can safely be released in rivers/environment which is typically 20 mg/L;
• By comparing the BOD of the incoming sewage and the BOD of the effluent water leaving the plant, the efficiency and effectiveness of the sewage treatment plant can be judged;

If this is a test suitable to your needs please do get in touch for more information.