What causes biochemical oxygen demand to increase?
High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth.
What is BOD and how is it increased?
Biochemical oxygen demand (BOD) is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. The increasing oxygen consumed in the decomposition process robs other aquatic organisms of the oxygen they need to live.
What affects biochemical oxygen demand?
Biological oxygen demand directly affects the amount of dissolved oxygen in rivers and streams. The rate of oxygen consumption is affected by a number of variables: temperature, pH, the presence of certain kinds of microorganisms, and the type of organic and inorganic material in the water.
What is biological oxygen demand PDF?
Biological oxygen demand (BOD), also known as biochemical oxygen demand, is a bioassay procedure that measures the dissolved oxygen (DO) consumed by bacteria from the decomposition of organic matter.
Why is BOD done for 5 days?
The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD5). The BOD5 value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).
Why is Biochemical Oxygen Demand important?
The BOD is an important parameter for assessing water quality. It deals with the amount of oxygen consumption (mg O2 L− 1) by aerobic biological organisms to oxidize organic compounds. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.
What is biochemical oxygen demand and why is it important?
The biochemical oxygen demand (BOD) of water determines the impact of decaying matter on species in a specific ecosystem. Sampling for BOD tests how much oxygen is needed by bacteria to break down the organic matter.
Why is BOD important in wastewater treatment?
BOD has traditionally been used to measure of the strength of effluent released from conventional sewage treatment plants to surface waters or streams. This is because sewage high in BOD can deplete oxygen in receiving waters, causing fish kills and ecosystem changes.
What do you mean by biochemical oxygen demand?
Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature. The decay of organic matter in water is measured as biochemical or chemical oxygen demand.
How do you calculate biological oxygen demand?
How to calculate biological oxygen demand ( BOD ) The biochemical oxygen demand (BOD) is the capacity of organic and biological matter in natural water to consume oxygen. It is determined experimentally by measuring the oxygen concentration in a sealed sample before and after a 5-day incubation period.
What does high biochemical oxygen demand indicate?
High biological oxygen demand ( BOD ) means that a lot of oxygen is being used up, typically by bacteria breaking down organic material. As well as potentially high bacterial loads, a strong possibility that the BOD is associated with other pollutants as well,…
Why is there a demand for chemical oxygen?
Chemical Oxygen Demand is an important water quality parameter because, similar to BOD, it provides an index to assess the effect discharged wastewater will have on the receiving environment. Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen (DO) levels.
How is the biological oxygen demand determined?
Determination of the Biochemical Oxygen Demand (BOD) in polluted waste water as a pollution indicator by incubating the BOD bottles for five days at 20 degree C.. The amount of oxygen , taken up by the microorganisms that decompose the organic waste matter in wastewater is known as biological oxygen demand or biochemical oxygen demand.