Why Is Biological Oxygen On Demand And Sewage Treatment Important For Aquatic Health March 12, 2022 by sewersmart The presence of a sufficient concentration of dissolved oxygen is critical to maintaining the aquatic life and aesthetic quality of streams and lakes.
Full Answer
How biochemical oxygen demand is used in sewage treatment?
Biochemical Oxygen Demand is used in secondary sewage treatment or biological sewage treatment. After the primary treatment in which the floating debris is removed by sequential filtration and sedimentation, the primary effluent is passed to aeration tanks where it is constantly agitated and the air is pumped into it.
How can the biological oxygen demand of water be reduced?
The biological oxygen demand of the water can be reduced by the following methods Advanced Oxidation Processes (AOP) by using H2O2/ UV, O3/UV, Fenton's reagent (H2O2+FeSO4), etc. Coagulation using alum or cationic polymers Flocculation (e.g. chitosan, isinglass, polyelectrolyte) and sedimentation.
What is biological oxygen demand?
Is this page helpful? Biochemical Oxygen Demand or alternatively termed as Biological Oxygen Demand (BOD) is the amount of oxygen needed or demanded by aerobic microorganisms to break down the organic matter present in a certain sample of water at a specific temperature and over a given time period.
What is the role of oxygen in water bodies?
Water bodies have a certain amount of oxygen dissolved in it on which the aquatic life is dependent for its respiratory needs. When there is organic matter present in the water body, aerobic microbes use the dissolved oxygen in the water to breakdown the organic substance thus reducing the oxygen available for the aquatic life.
Why is biological oxygen demand BOD important for the health of a body of water?
Higher BOD indicates more oxygen is required, signifying lower water quality. Low BOD means less oxygen is being removed from water, so the water is usually more pure. Since cold water retains oxygen better than warmer water, DO is usually lower in summer months.
Why is Biochemical Oxygen Demand important?
Biochemical oxygen demand / biological oxygen demand is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment.
Why is BOD important in water?
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 How is it related to water quality?
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.
What is biochemical oxygen demand as used in aquatic ecology?
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. When you look at water in a lake the one thing you don't see is oxygen.
Why is COD so important?
In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.
Why BOD treatment for domestic waste water is important?
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.
Why is it important to reduce BOD in the secondary treatment of sewage treatment plant what is the importance of Flocs?
Flocs are masses of bacteria associated with fungal filaments to form mesh like structure. Flocs digest most of the organic material from the sludge. Thus, floc helps in reducing the BOD (Biochemical Oxygen Demand) of the effluent. This helps in further treatment of sludge.
How does BOD affect aquatic life?
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.
How the biological oxygen demand gets affected with the increased presence of organic matter in water?
3. How the biological oxygen demand gets affected with the increased presence of organic matter in water? Explanation: With the increased presence of organic matter in water, the oxygen demand increases.
1. What are the sources of BOD?
The Sources of biological oxygen demand include woody and leaves debris, animal manure, dead animals and plants, wastewater treatment plants, efflu...
2. How is BOD used in wastewater treatment plants?
Industries that discharge wastewater into municipal sanitary waterways or sewage are facing strict regulations on levels of BOD. Solid materials in...
3. Is chlorine capable of reducing be BOD while treating wastewater?
Yes, chlorine is widely known as an excellent oxidant and is extensively used for a long time to purify water, oxidize chemicals in wastewater, des...
4. What pollutants can significantly increase biochemical oxygen demand?
Phosphates and nitrates in a water body can contribute to higher BOD levels, providing nutrients for algae and plants to grow quickly. This signifi...
5. Where can I find concept pages of my syllabus topics?
You can find concept pages of a syllabus topic on the official website of Vedantu and can also download the app from the Play store. The experts on...
6. What is BOD? What is its Significance?
BOD or Biochemical Oxygen Demand is the measure of the amount of oxygen utilized by aerobic microbes to degrade the organic waste present in water....
7. Why is it Important to Reduce the BOD of the Water Bodies?
It is extremely important to reduce the biochemical oxygen demand of water bodies or wastewater before discharging into water bodies because high B...
8. How is Biochemical Oxygen Demand Reduced?
The BOD of water can be reduced by reducing pollution. The lesser we contaminate the water bodies lesser is its biochemical oxygen demand levels. T...
9. How is BOD Related to Pollution?
Biochemical Oxygen Demand gives the level of pollution in a water body. It is used as an index for measuring the polluting potential of water bodie...
What is the effect of dissolved oxygen on marine animals?
Marine animals such as fish use dissolved oxygen for respiration. However, the balance of DO consumption is quite delicate. When a large number of organic compounds are present in water, microbial activity will proliferate, putting a strain on the aquatic ecosystem. Critical DO reduction will ultimately harm marine life.
What organisms need oxygen?
Both aquatic life and microorganisms require oxygen to survive. Microbes utilize dissolved O 2 in water to break down complex organic compounds present in the water such as sugars, cellulose, and other convertible synthetic substances. Marine animals such as fish use dissolved oxygen for respiration.
What is the maximum BOD level for wastewater disposal?
Clean Water Act. Typical maximum values range from 10 mg/L for direct environmental disposal and 300 mg/L for disposal to sewer systems .
How does wastewater clarification work?
Wastewater clarification removes organic solids (primary sludge) from the water by utilizing the force of gravity – in other words, the heavier particles settle to the bottom and are removed first. Wastewater clarification is often followed by a chemical separation process.
What is the name of the agglomerating agent that is added to wastewater to make it clumps
In coagulation, a non-toxic agglomerating agent such as Ferric Chloride (F e Cl) or alum is added to the wastewater causing the suspended particles to come together to form clumps which can easily be removed from the water by filtration.
What is the BOD test?
A BOD test is typically carried out over a standard 5-day incubation period at 20°C (68°F) for the most accurate results.
Why do municipalities use a BOD test?
Municipalities can use a BOD test to detect water contamination in their public supply to ensure that it is safe for human consumption. Industries need to know their BOD value to determine when treated wastewater is safe for reuse or disposal.
What is the biological oxygen demand?
Biochemical Oxygen Demand or alternatively termed as Biological Oxygen Demand (BOD) is the amount of oxygen needed or demanded by aerobic microorganisms to break down the organic matter present in a certain sample of water at a specific temperature and over a given time period. Water bodies have a certain amount of oxygen dissolved in it on which ...
Why is it important to reduce the biochemical oxygen demand of water bodies before discharging into water bodies?
It is extremely important to reduce the biochemical oxygen demand of water bodies or wastewater before discharging into water bodies because high BOD of water means more and more oxygen is utilized by the aerobic bacteria for breaking down the organic waste in the water. This significantly reduces the available oxygen for the respiration ...
What is the BOD of water?
Ans. BOD or Biochemical Oxygen Demand is the measure of the amount of oxygen utilized by aerobic microbes to degrade the organic waste present in water. It is calculated over five days at a specific temperature of 20°C.
What is the importance of BOD in sewage treatment?
These are -. BOD finds its primary importance in sewage treatment plants. It gives the respiration rate of sewage, sludge , soil, garbage. It determines the rate of respiration in living beings. Measuring BOD gives the COD or Chemical Oxygen Demand of inorganic substances. It indicates the polluting potential of water.
How does pollution affect the BOD of water?
Sources that increase Biological Oxygen Demand of water are both natural and man-made. Pollution is a major contributor to increasing the BOD of water bodies. A good lifestyle is associated with an ample usage of water on a regular basis which results in a lot of wastewater with organic content in it. With increasing industrialization, pollution is increasing manifold. Factories have enormous wastewater being generated. Few industries that have huge quantities of wastewater are paper mills, food processing plants, jute mills, etc. The environmental factors contributing to increasing BOD include surface runoff, floating debris, dead animal and plants, soil erosion, etc. There are few chemicals that affect the BOD of drinking water. One of these is phosphate, which when present in high amount increases the BOD of water.
How is oxygen demand measured in water?
Biochemical Oxygen Demand of a water sample is measured by a Bioassay procedure which measures the oxygen consumed by the bacteria from the decomposition of the organic matter over a period of five days at an incubation temperature of 20°C. BOD is expressed in milligrams per litre of sample water. Although this is not a precise quantitative test, it is widely used as an indication of the polluting potential of water. This test was given by Sawyer and McCarty in the year 1978.
How can the BOD of water be reduced?
The BOD of water can be reduced by reducing pollution. The lesser we contaminate the water bodies lesser is its biochemical oxygen demand levels. There are various treatments done to reduce BOD levels in various wastewaters.
Sewage Water Analysis BOD
The presence of free oxygen is necessary for the livelihood of organisms present in the sewage water The aerobic action continuous till the free oxygen is present. As the oxygen exhausts, the anaerobic action or putrification starts, when complex organic compounds split up. setting free gases like CO2, H2S NH3,CH4 etc.and foul smell starts coming.
BOD determination
The test is based upon determination of dissolved oxygen prior to and following a 5 day period at 20°C. A known volume of sample of sewage is diluted with a known volume of dilution water (water containing nutrients for bacterial growth), whose dissolved oxygen content is predetermined.
Importance of BOD
Biological Oxygen Demand test is the most important in sewage treatments as it is indicates the amount of decomposable organic matter in the sewage. Larger the concentration of decomposable organic matter. greater the BOD and consequently more the strength or nuisance potential.
Why is oxygen demand important in wastewater?
Oxygen demand is useful for measuring waste loadings, evaluating the efficiency of the treatment processes, and ensuring effluent compliance.
What is biological oxygen demand?
Biochemical oxygen demand, otherwise known as biological oxygen demand, is an important parameter in water treatment. When effluent wastewaters are discharged into the environment, they can introduce pollution in the form of organic content to receiving waters. High concentrations of organics can deplete dissolved oxygen levels in water, ...
What happens if the oxygen demand of effluent exceeds discharge limits?
If the oxygen demand of effluent exceeds discharge limits, regulatory agencies may impose fines. USEPA also allows the use of TOC when it is correlated with BOD or COD. When selecting a method for analyzing oxygen demand, it’s important to consider the following: Specific testing application. Oxidant that will be used.
What is the importance of BOD in water?
High concentrations of organics can deplete dissolved oxygen levels in water, leading to negative environmental and regulatory consequences. To help determine the impact and ultimately limit the amount of organic pollution in water , BOD is an essential measurement.
What is the purpose of BOD?
BOD is used to gauge the short-term impact wastewater effluents will have on the oxygen levels of receiving water.
What is the difference between COD and BOD?
COD describes the amount of oxygen required to chemically breakdown the pollutants, while BOD indicates the amount of oxygen required to breakdown the pollutants, biologically with microorganisms.
What is discharge limit?
Discharge limits vary from plant to plant depending on the characteristics of the receiving water, effects on aquatic life, recreational uses and other factors. Discharge permits may stipulate a specific maximum effluent concentration for BOD or COD, pounds loading, and/or a percent removal.
Why is BOD important in wastewater treatment?
The measurement in usually taken over the course of five days at 20ºC.1 BOD is an important parameter in wastewater treatment because high levels of organic matter should not be present during disinfection or in discharged effluent.
What happens when dissolved oxygen is high?
When BOD is high, microorganisms and bacteria will deplete the waterway of its DO and cause other species to suffocate.2.
What happens if you don't remove organic matter?
If treatment processes have not removed most of this organic matter, subsequent chlorination of the final effluent will result in high levels of harmful disinfection by-products , such as THM's, in receiving waters such as sensitive rivers and lakes.
What is the source of Bod?
Sources: BOD represents the amount of organic matter in a water supply; therefore, it increases when decaying plants, human or animal waste, and other organic compounds are added to water. Raw water sources, sewage, and industrial run-off may all be subject to high BOD levels; it is therefore important to monitor BOD levels ...
Is high BOD bad for the environment?
High BOD is harmful to ecosystems as fish and other aquatic life may suffocate in oxygen-depleted waters.4 Furthermore, it is important that wastewater treatment processes are designed to handle the high organic matter loading present in wastewaters.
What is the biochemical demand of oxygen?
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. Natural sources of organic matter include plant decay and leaf fall. However, plant growth and decay may be unnaturally accelerated when nutrients ...
How does urban runoff affect oxygen?
The increasing oxygen consumed in the decomposition process robs other aquatic organisms of the oxygen they need to live.
What happens to algae at the beginning of the cycle?
At beginning of the cycle, algae and other producers in the water take up inorganic nutrients and use them in the process of building up their organic tissues. Consumers like fish and other aquatic animals eat some of the producers, and the nutrients move up the food chain.
What organisms are more tolerant of low dissolved oxygen levels?
These organisms are part of decomposition cycle and they feed on dead algae and other dead organisms.
What fish will die from low oxygen?
All clean water species such as trout or salmon will die well above this level and even low oxygen fish such as catfish and carp will be at risk below 5 ppm. When abnormally high levels of aerobic bacterial activity take place, however, the level of dissolved oxygen can drop dramatically.
What happens to the nutrients in water when bacteria die?
When these organisms die, bacteria decompose the organic compounds and release into the water inorganic nutrients such as nitrate, phosphate, calcium, and others. Some of these nutrients end up at downstream or in sediments, but most of them recycle again and again.