Measurement of Biochemical Oxygen Demand (Bod)

Title Laboratory 2 Measurement of Biochemical Oxygen consume ( strain) Objective To suss out the tote up of oxygen necessary for biologic oxidation of ravagewater effluent and determine the amount of oxygen selectd by bacteria while stabilise decomposable organic issuing. Methodology Apparatus Biochemical Oxygen Demand ( frame of reference) meter, Dissolved Oxygen bottle (DO bottle), pipette, Teflon tape, dilution water, incubator machine. Procedure leave 300 ml deoxidize water then stop DO exercise immediately Closed properly and keep into the incubator (200C).Take reading for the next 5 days Add 3 ml dilute water and fill up with dilute water until 300ml then take DO reading immediately Figure 1 Precaution take ins for material body analysis may change greatly during handling and storage. Testing should be started as quickly as possible. To reduce the changes in those consumes which must be held, keep the leavens at or below 4C. Do non allow warnings to freeze. Samples may be kept for no more than 48 bits before beginning the human body test. Students assign to close out interference from atomic number 17. Because atomic number 17 is such a strong oxidizing agent, it will inhibit the growth of surviving bacteria in the BOD test.Any samples containing residual chlorine must be pretreated to remove chlorine before the test is run. This is done by adding sodium sulfite to the sample. Samples with extreme pH values and samples containing disinfectants such as residual chlorine must be treated prior to testing. Caustic alkalinity or sour can prevent bacteria from growing during the course of the BOD test. To prevent this, samples which have pH values lavishlyer than pH 8. 0 or lower than pH 6. 0 must be neutralized to pH 7. 0 before the test is performed. Result 1) 3 ml sampleGroup Sample Result First day ( first) Fifth day (5th) DO temporary worker DO Temp (mg/l) (0C) (mg/l) (0C) 1 booby 1st 9. 20 25. 8 9. 26 20. 3 second 9. 16 25. 8 9. 30 20. 4 tertiary 9. 13 25. 8 9. 31 20. 5 Mean 25. 8 20. 4 Waste Water 1st 9. 24 26. 2 8. 73 20. 5 2nd 9. 12 26. 2 8. 77 20. 6 3rd 9. 10 26. 2 8. 79 20. 7 Mean 26. 2 20. 6 4 Blank 1st 9. 14 25. 9 9. 04 20. 5 2nd 9. 16 26 9. 02 20. 5 3rd 9. 15 26 9. 01 20. 5 Mean 25. 97 20. 5 Waste Water 1st 9. 08 26. 2 8. 31 20. 2nd 9. 05 26. 3 8. 34 20. 7 3rd 9. 02 26. 4 8. 35 20. 8 Mean 26. 3 20. 73 5 Blank 1st 9. 10 25 8. 86 20. 5 2nd 9. 11 25 8. 88 20. 5 3rd 9. 10 25 8. 86 20. 5 Mean 25 20. 5 Waste Water 1st 9. 10 25 7. 82 20. 5 2nd 9. 11 25 7. 82 20. 5 3rd 9. 11 25 7. 84 20. 5 Mean 25 20. 5 The BOD of the sample can be calculates using the equations provided in the following First Equation is provided by the regulation method BOD5= mgL= D1 D2P Second Equation is BOD5= mgL= D1 D2 -B1 B2 P WhereD1 DO of the diluted sample immediately after preparation, mg/L D2 DO of the diluted sample after 5-day incubation at 200c, mg/L B1 DO of the beneathwrite before incubation B2 DO of the control after incubation P fraction of the wastewater sample record book to total combined volume Group Sample First day (1st) Fifth day (5th) BOD5 BOD5 DO Temp DO Temp (mg/l) (mg/l) (mg/l) (0C) (mg/l) (0C) (1st Equation) (2ndEquation) 1 Blank 9. 16 25. 8 9. 29 20. 4 52 Waste Water 9. 15 26. 2 8. 76 20. 6 39 4 Blank 9. 15 25. 97 9. 02 20. 5 59 Waste Water 9. 05 26. 3 8. 33 20. 73 72 Blank 9. 1 25 8. 87 20. 5 one hundred five Waste Water 9. 11 25 7. 83 20. 5 128 password From the equation, the result atomic number 18 totally different, it is because second (2nd) equation actually are specialist for seeded sample. Since that, it does not suitable and cant be used to calculate the BOD aim. BOD test is a biological test dependent on the actions of the microorganisms found in the wastewater and, as such, is subject to a number of variations. These variations can be caused by a number of factors, including changes in t emperature, weather, composition of incoming sewage, in plant operations, and take points.Results can vary widely from day to day, or even hour to hour. . Form the result we found that the the BOD level in root word 5 is 128mg/L, Group 4 72mg/L is quiet higher kinda than Group 1 39mg/L. When BOD levels are high, dissolved oxygen (DO) levels descend because the oxygen that is available in the water is being consumed by the bacteria. Since slight dissolved oxygen is available in the water, fish and other aquatic organisms may not survive. If referred to the IWK website, BOD5 at 200C is 20mg/L for standard A and 50mg/L for standard B.Its symbolize only sample from group 1 is under control and can be entitled as clean. High level of result from group 4 and 5 may resulted by the commentary of nitrates and phosphate. Nitrates and phosphates in a body of water can contribute to high BOD levels. Nitrates and phosphates are plant nutrients and can cause plant action 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. One of the major disadvantages of the BOD test is the time lag between the collection of samples and the final calculation of results.This makes the BOD test a poor test for determining whether or not operational changes are needed. In addition, the rate and degree that organic matter in wastewater is decomposed (or oxidized) by the normal bacteria present in a sample is largely dependent on the characteristics of the organic matter. For example, more or less organic matter (like sugars or starches) are oxidized very soft and rapidly, and will almost always result in measurable BOD. Other organic matter, however, is sometimes resistant to biological oxidation, and may require special acclimated bacteria to oxidize the material and to show a BOD.Although this is what actually happens in nature, it causes significant variation in BOD res ults from sample to sample. Conclusion, high level of BOD reflects to the DO which it will be decrease. Which is mean the water quality if poor. References Unknown. (n. d. ). Indah Water. Retrieved from http//www. iwk. com. my/v/knowledge-arena/effluent-standards Unknown, A. (n. d. ). Biological Oxygen Demand (BOD) Overview. 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