| Webster's Online Dictionary |
| Expressions | Definition | ||
| Biochemical oxygen demand | In ecology, biochemical (biological) oxygen demand (BOD) is an indicator for the concentration of biodegradable organic matter present in a sample of water. It can be used to infer the general quality of the water and its degree of pollution. BOD measures the rate of uptake of oxygen by micro-organisms in the sample of water at a fixed temperature and over a given period of time. 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. All samples being tested in any one batch are inoculated with an equal volume of seed including the sample control of de-ionised water saturated with oxygen. The BOD in the UK is carried out by diluting the sample with de-ionised water saturated with oxygen then sealing the sample (to prevent further oxygen dissolving in), and placing it in the dark (to prevent photosynthesis and thereby the addition of oxygen). This sample is kept at 20 °C in the dark and tested for dissolved oxygen (DO) after five days. The apparent BOD for the control is subtracted from the test result to provide the corrected value. 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 allyl thiurea 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 US. 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. (references) | ||
Source: compiled by the editor from various references; see credits. | Top | ||
| Expressions | Domain | Definition | |
| Biochemical oxygen demand | Agriculture | A measure of the amount of oxygen consumed by natural, biological processes that break down organic matter, such as those that take place when manure or sawdust is put in water. High levels of oxygen-demanding wastes in waters deplete dissolved oxygen (DO) thereby endangering aquatic life. Sometimes referred to as "biological oxygen demand. Chemical oxygen demand (COD) is a measure of the oxygen consumed when organic matter is broken down chemically rather than biologically. COD can be determined much more quickly than BOD and more accurately reflects the amount of organic matter in a water sample. BOD is a standard measure of water quality. (BOD). (references) | |
| Biochemical oxygen demand | Biology & Biotechnology | Consumption of oxygen by biochemical oxidation of a substance in water under certain conditions; indicated in mg 02/1; Amount of dissolved oxygen consumed by a microbiological action when a sample is incubated, usually for 5 days at 20 degrees C and in the presence of a nitrification inhibitor, usually allyl thiourea; Demand: the amount of oxygen used by microorganisms to break down organic waste. -Handbook of Solid Waste Management (Bi) 'biochemical oxygen demand'. Source: European Union. (references) | |
| Biochemical oxygen demand | Energy | The weight of oxygen taken up mainly as a result of the oxidation of the constituents of a sample of water by biological action; expressed as the number of parts per million of oxygen taken up by the sample from water originally saturated with air, usually over a period of five days at 20 degrees centigrade. A standard means of estimating the degree of contamination of water. (references) | |
| Biochemical oxygen demand | Geology | The amount of oxygen aerobic organisms need to carry out oxidative metabolism in water containing organic matter, such as sewage. (references) | |
| Biochemical oxygen demand (BOD) | Administration | (1) A measure of the quantity of dissolved oxygen, in milligrams per liter, necessary for the decomposition of organic matter by microorganisms, such as bacteria. (2) A measure of the amount of oxygen removed from aquatic environments by aerobic micro-organisms for their metabolic requirements. Measurement of BOD is used to determine the level of organic pollution of a stream or lake. The greater the BOD, the greater the degree of water pollution. Also referred to as Biological Oxygen Demand (BOD). (references) | |
| Biochemical oxygen demand (BOD) | Aerospace | Amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. (references) | |
| Biochemical oxygen demand (BOD) | Geology | The amount of oxygen, measured in milligrams per liter, that is removed from aquatic environments by the life processes of microorganisms. (references) | |
| Biochemical oxygen demand (BOD) | Technology | The amount of oxygen consumed by micro-organisms (mainly bacteria) and by chemical reactions in the biodegradation of organic matter. (references) | |
| Biochemical Oxygen Demand (BOD) Loading | Administration | (Water Quality) The BOD content, commonly expressed in pounds/day, of wastewater passing into a waste treatment system or a body of water. The greater the BOD content, the greater the degree of pollution. (references) | |
| Carbonaceous Biochemical Oxygen Demand | Administration | The incubation of a sample of water or wastewater for a relatively short period of time in order to determine the Biochemical Oxygen Demand (BOD). The short incubation, usually 5 days, is sufficient to detect only the microbial utilization of carbon compounds. A longer incubation (15 to 20 days) would also detect the oxidation of inorganic nitrogenous compounds (ammonia and nitrite) and the subsequent demand for molecular oxygen by chemoautotrophic bacteria. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
