BOD - biological (biological) oxygen demand is a washing powder. It can be used to wash your clothes. It is used in water quality management and assessment, Ecology and environmental science. BOD is not an accurate quantitative test and should be considered as providing an indicator of the quality of a water body. This article or section does not cite any references or sources. ... Environmental science is the study of the interactions among the physical, chemical and biological components of the environment; with a focus on pollution and degradation of the environment related to human activities; and the impact on biodiversity and sustainability from local and global development. ...

Typical BOD values

Most pristine rivers will have a 5 day BOD of less than 1 mg/l. Moderately polluted rivers may have BODs in the range 2 mg/l to 8 mg/l. Efficiently treated municipal sewage treated by a three stage process would have a BOD value of about 20 mg/l. Untreated sewage is variable but might average out at around 600 mg/l in Europe and as low as 200 mg/l in the USA or where there is severe groundwater or surface water infiltration. (The generally lower values in the USA derive from the much greater water use per capita than in other parts of the world.) Slurry from dairy farms is around 8000 mg/l and silage liquor around 60000 mg/l. Sewage is the liquid water produced by human society which typically contains washing water, laundry waste, faeces, urine and other liquid or semi-liquid wastes. ... Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ... World map showing the location of Europe. ... Silage (hay) somewhere in Allschwil or Schönenbuch, near Basel, Switzerland. ...

The BOD test

BOD measures the rate of uptake of oxygen by micro-organisms in the sample of water at a fixed temperature (20°C) and over a given period of time( usually 5 days) in the dark. To ensure that all other conditions are equal, a very small amount of micro-organism seed is added to each sample being tested. This seed is typically generated by diluting activated sludge with de-ionised water. The test generally takes place over an elapsed period of 5 days but other BOD tests are also used. Activated sludge is a process in sewage treatment in which air or oxygen is forced into sewage liquor to develop a biological floc which reduces the organic content of the sewage. ...

Method

The BOD test is carried out by diluting the sample with de-ionised water saturated with oxygen, inoculating it with a fixed aliquot of seed, measuring the dissolved oxygen and sealing the sample (to prevent further oxygen dissolving in). The sample is kept at 20 °C in the dark (to prevent photosynthesis and thereby the addition of oxygen) for five days and the dissolved oxygen is measured again. The difference between the final D.O and initial D.O is the B.O.D. The apparent BOD for the control is subtracted from the control result to provide the corrected value. The leaf is the primary site of photosynthesis in plants. ...

The loss of dissolved oxygen in the sample, once corrections have been made for the degree of dilution, is called the BOD₅. In the UK allylthiourea is also added at the start of the test to prevent oxidation of ammonia. Results from such tests are represented as BOT5(ATU) and referred to as Carbonaceous BOD (CBOD) in the U.S.. Less frequently used is the Ultimate BOD (UBOD) test, in which DO is repeatedly measured by DO meter in the same specialized bottles until it has reached equilibrium. Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from...

BOD is similar in function to chemical oxygen demand (COD), in that both measure the amount of organic compounds in water. However, COD is less specific since it measures everything that can be chemically oxidised rather than just levels of biology active organic matter. In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. ...

BOD is used as a gauge of the effectiveness of wastewater treatment plants. Various commercial devices are available for its determination. Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ...

BOD can be calculated by: Undiluted; Initial D.O - Final D.O = BOD Diluted; ((Initial D.O - Final D.O)- BOD of Seed) x Dilution Factor

History of the use of BOD

The Royal Commission on River Pollution which was established in 1865 and the formation of the Royal Commission on Sewage Disposal in 1898 led to the selection in 1908 of BOD₅ as the definitive test for organic pollution of rivers. Five days was chosen as an appropriate test period because this is supposedly the longest time that river water takes to travel from source to estuary in the UK. In 1912 the commission also set a standard of 20 ppm BOD₅ as the maximum concentration of permitted in sewage works discharging to rivers provided that there was at least an 8:1 dilution available at dry weather flow. This was contained in the famous 20:30 (BOD:Suspended Solids) + full nitrification standard which was used as a yardstick in the UK up to the 1970s for sewage works efluent quality. Water pollution is a large set of adverse effects upon water bodies such as lakes, rivers, oceans, and groundwater caused by human activities. ... This bridge across the Danube River links Hungary with Slovakia. ... Rio de la Plata estuary Wikimedia Commons has media related to: Estuaries An estuary is a semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. ... Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. ... Nitrogen cycle Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. ...

References

• Clair N. Sawyer, Perry L. McCarty, Gene F. Parkin (2003). Chemistry for Environmental Engineering and Science, 5th edition, New York: McGraw-Hill. ISBN 0-07-248066-1. 
• Lenore S. Clescerl, Arnold E. Greenberg, Andrew D. Eaton. Standard Methods for Examination of Water & Wastewater, 20th edition, Washington, DC: American Public Health Association. ISBN 0-87553-235-7. Stevens Institute of Technology

See also

• Chemical oxygen demand
• Wastewater quality indicators discusses both BOD and COD as indicators of wastewater quality.

In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. ... Wastewater quality indicators such as the Biochemical oxygen demand (BOD) and the Chemical oxygen demand (COD) are essentially laboratory test measures of the amount of oxygen in a wastewater. ... Look up bod in Wiktionary, the free dictionary. ... In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. ...

External links

• Wastewater BOD Reduction, optek
• BOD Doctor - a troubleshooting wiki for this problematic test