How is bod calculated? BOD is computed based on the difference between initial and final D.O. The test uses dilution water and a known amount of sample in a 250-300 ml incubation bottle. The initial D.O. is measured by probe and the bottle is stored at 20 °C. After five days, final D.O. is measured.
What is BOD and how is it determined? The test for biochemical oxygen demand (BOD) is a bioassay procedure that measures the oxygen consumed by bacteria from the decomposition of organic matter (Sawyer and McCarty, 1978). The change in DO concentration is measured over a given period of time in water samples at a specified temperature.
How do you calculate BOD in wastewater? For example: 1.0 mL of a full strength wastewater sample added to 9.0 mL of DI water results in a 0.1 dilution of the wastewater. The DO concentration (mg/L) reduction must then be multiplied by 10 to determine the final BOD concentration.
How do you calculate oxygen demand? We can calculate by following steps:
Write balanced reaction for the carbonaceous oxygen demand. CH2(NH2)COOH + 1.5O2 → NH3 + 2CO2 + H2O.
Write balanced reactions for the nitrogenous oxygen demand. NH3 + 1.5O2 → HNO2 + H2O. HNO2 + 0.5O2 → HNO3
Determine the ThOD. ThOD = (1.5 + 2) mol O2/mol glycine.
How is bod calculated? – Related Questions
What is a good BOD level?
A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean.
Why is COD higher than BOD?
COD is normally higher than BOD because more organic compounds can be chemically oxidised than biologically oxidised. This includes chemicals toxic to biological life, which can make COD tests very useful when testing industrial sewage as they will not be captured by BOD testing.
What is bod a measure of?
BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria (those bacteria that live only in an environment containing oxygen). BOD is used, often in wastewater-treatment plants, as an index of the degree of organic pollution in water.
What is BOD COD ratio?
BOD (Biochemical oxygen demand) is the pollution index of any water sample. BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6. The ultimate BOD (UBOD) was also performed by exceeding the 3-day dilution BOD test.
What is the principle of bod?
Principle BOD is expressed as weight of oxygen consumed per unit volume of water during 5 days at 20°C ; BOD is related to the amount of biodegradable organic matter in water sample ; during oxidative degradation of organic matter, aerobic micro-organisms which perform it, consume oxygen present in water as dissolved
How much oxygen is needed to survive?
Humans need oxygen to live, but not as much as you might think. The minimum oxygen concentration in the air required for human breathing is 19.5 percent. The human body takes the oxygen breathed in from the lungs and transports it to the other parts of the body via the body’s red blood cells.
Does BOD increase with time?
Both BOD and COD is increasing with time.
What happens if BOD is too high?
The greater the BOD, the more rapidly oxygen is depleted in the stream. This means less oxygen is available to higher forms of aquatic life. The consequences of high BOD are the same as those for low dissolved oxygen: aquatic organisms become stressed, suffocate, and die.
In which water bod is maximum?
Typical values. Most pristine rivers will have a 5-day carbonaceous BOD below 1 mg/L. Moderately polluted rivers may have a BOD value in the range of 2 to 8 mg/L. Rivers may be considered severely polluted when BOD values exceed 8 mg/L.
Is high BOD good or bad?
High BOD is harmful to ecosystems as fish and other aquatic life may suffocate in oxygen-depleted waters.
What is BOD COD and do?
BOD is the amount of oxygen that will be consumed by bacteria or other aerobic microorganisms while decomposing organic matter under aerobic conditions. COD measures the amount of oxygen that will be consumed by the chemical breakdown, or oxidation (degeneration) of organic pollutants in water.
What is the BOD of drinking water?
For drinking water BOD has to be less than 5 mg/L and for treated wastewater to be disposed of in the water bodies it is 30 mg/L, 100 mg/L if treated waste water is discharged into the sewerage system in India.
What causes high COD in wastewater?
High COD/BOD levels in stormwater runoff are cause by the residual food and beverage waste from cans/bottles, antifreeze, and emulsified oils from industrial food processing and agricultural activities. As most forms of COD are water soluble, this pollutant spreads easily via stormwater to waterways.
Why BOD is calculated for 5 days?
The BOD is an empirical test to determine the molecular oxygen used during a specified incubation period (usually five days), for the biochemical degradation of organic matter (carbonaceous demand) and the oxygen used to oxidise inorganic matter (e.g., sulphides and ferrous iron).
What does high BOD indicate?
Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower water quality. Inversely, low BOD means less oxygen is being removed from water, so water is generally purer.
What can the BOD test be used for?
The BOD test is used to measure waste loads to treatment plants, determine plant efficiency (in terms of BOD removal), and control plant processes. It is also used to determine the effects of discharges on receiving waters.
How do you reduce COD in wastewater?
The most important way to get rid of the sludge is to use coagulants and flocculants. The principle is to bind the sludge to one another so that a larger clumps of sludge and then be deposited in a sedimentation tank. Some chemicals commonly used as a coagulant, among others; PAC, FeCl3 (Ferric Chloride) and Alum.
