Oxygen demand

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1. WEST BENGAL UNIVERSITY OF ANIMAL AND FISHERY SCIENCES FACULTY OF FISHERY SCIENCES A SEMINAR ON: ADVERSE EFFECT OF OXYGEN DEMANDING WASTE SUBMITTED BY: Chhoto Kisku AEM-327

2. INTRODUCTION Any material which cannot be used in the form in which it is produced is called a Waste. It is no longer needed by us because it has lost its value. If it is thrown around, it can cause soil, air or water pollution. It also poses a serious threat to normal life, plants, animals and human beings.

3. Definition…. The amount of oxygen absorbed by a sample of sewage during a specific period, generally 5 days at a specific temperature, generally 20° C for the aerobic destruction of the organic matter by living organisms. Total BOD is of more significance to food webs than to water quality. Oil spill: An oil spill is the release of a liquid petroleum hydrocarbons into the environment due to human activity. And it is a form of pollution

4. Cont…. Nitrates and phosphates in a body of water can contribute to high BOD levels. Nitrates and phosphates are plant nutrients and can cause plant life and algae to grow quickly. When plants grow quickly, they also die quickly. This contributes to the organic waste in the water, which is then decomposed by bacteria resulting in a high BOD level.

5. Environmental significance Principle test for biodegradability of any sample and strength of the waste so measures the amount of pollution. Important parameter to assess the pollution of surface and ground waters where contamination occurred due to disposal of domestic and industrial effluents. Allows calculation of the effect of the discharges on the oxygen resources of the receiving water. Measurement of BOD in raw (influent) and treated (effluent) wastewaters is a standard practice to evaluate treatment facility performance. Data from BOD tests used for the development of engineering criteria for the design of wastewater treatment plants.

6. Cont…. Used in studies to measure the self-purification capacity of streams Serves regulatory authorities as a means of checking on the quality of effluents discharged to stream waters. One of the most important method in sanitary analysis to determine the polluting power, or strength of sewage, industrial wastes or polluted water. It serves as a measure of the amount of clean diluting water required for the successful disposal of sewage by dilution.

7. Factors affecting BOD… Temperature Elevated temperature decreases the level of DO of water harming aquatic organisms like fish, amphibians and others Increases the metabolic rate of aquatic animals and enzyme activity, resulting in consumption of more food in a shorter time High temperature limits oxygen dispersion into deeper waters, contributing to anaerobic conditions. This can lead to increased bacterial levels when there is ample food supply. Higher water temperature increases plant growth rates This results in a shorter lifespan and species overpopulation causing an ”algae bloom” which reduces oxygen levels.

8. Eutrophication

9. Eutrophication occurs due to oversupply of nutrients, which causes explosive growth of plants and algae. when such organisms die, consume the oxygen in the body of water, thereby creating the state of hypoxia. The primary limiting factor is phosphorus which promotes excessive plant growth and decay, favouring simple algae and plankton, and causes a severe reduction in water quality. Phosphate adheres tightly to soil, so it is mainly transported by erosion. Once into the lakes, phosphate is extracted into water is slow, hence the difficulty of reversing the effects of eutrophication The source of this excess phosphate are detergents, industrial/domestic run-off, and fertilizers. CONT……

10. At higher levels of BOD…. At high BOD levels, organisms such as macro invertebrates that are more tolerant of lower dissolved oxygen (i.e. leeches and sludge worms) may appear and become numerous. Organisms needing higher oxygen levels (i.e. caddisfly larvae and mayfly nymphs) will NOT survive.

11. It is produced when oxygen dissolved in water reacts with pyritic materials found in association with most coal deposits. AMD degrades the water quality of stream and supplies often to the point of eliminating all biological activity within the stream contaminated with AMD.

12. Physical effects of oil in water: Reduction in dissolved oxygen – oil films are able to retard significantly the rate of oxygen uptake by water. Reduction in light penetration – oil slick decreases the light intensity up to 90% Smothering – Smothering coats of oil have killed lichens and algae along the shore line.

13. Garbage waste need oxygen for decomposing It is very harmful to our environment because of the way it is currently being disposed It possess dangerous risk to our land, water and air Landfill disposal if leaked, will contaminate surface and ground water which in turn will travel to the nearest ocean or lake and poison the wildlife there. Incinerating trash has bad effect on the environment as it contributes to air pollution which causes global warming.

14. Conclusion : Disposing of  waste  has huge  environmental impacts  and can cause serious problems. ... Some  waste  will eventually rot, but not all, and in the process it may smell or generate methane gas, which is explosive and contributes to the greenhouse  effect . Leachate produced as  waste  decomposes may cause pollution.

15. Thank you