Determination of Biochemical Oxygen Demand

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Determination of Biochemical Oxygen Demand Powered By Docstoc



                                       GROUP MEMBERS:

                                      MUHAMMAD AIZAT

                                   AHMAD AIZAT B SAMAD

                                MUHAMMAD AIZAT B KATTNI

                               MUHAMMAD RUZAIDI B ISMADI

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    •   To determine DO and BOD in wastewater.


Experiment Sample


Distilled water


    •   Pipette 25 mm

    •   Test tube

    •   Beaker

    •   class A

    •   wide bore

    •   dropper

    •   filter funnel

    •   volumetric. Flask

    •   syringe

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    •    bulb

    •    spectrophometer


The value for DO and BOD before and after 5 days.

                                       Table 1: The DO and BOD value

                           Initial (mg/L)           Final (mg/L)               BOD
Sample                     9.03                     0.58                       7.3
Blank                      9.01                     7.63                       0.04


        Based on the result, it shown microorganisms activity happen in the wastewater. The dissolve
oxygen decreased after 5 days. The low value of BOD contain in the wastewater show that the water is
clean. The result is an increase in microbial populations, higher levels of BOD, and the increased oxygen
demand from the photosynthetic organisms during the dark hours. This result in a reduction in dissolved
oxygen concentrations, especially during the early morning hours. The difference in initial DO readings
(prior in incubation) and final DO readings (after 5 days of incubation) is used to determine the initial
BOD concentration of the sample. This is referred to as a BOD5 measurement. The dissolve oxygen
contain in the bottle was measure by using the pH DO probe. The initial reading for the sample bottle is
9.03mg/L moving on towards the final reading is 0.58 mg/L. The reading of DO is decrease after 5 days
of incubation. The blank bottle was duplicated in order to get the result, and the blank bottle for the initial
reading is 9.01 mg/L, and the blank final reading is 7.63mg/L, which is also decrease.

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From the experiment, Biochemical oxygen demand (BOD) is usually defined as the amount of oxygen
required by bacteria while stabilizing decomposable organic matter under aerobic conditions. The BOD
test widely used to determine the pollution strength of domestic and industrial wastes in terms of oxygen
that they will require if discharged into natural watercourses in which aerobic conditions exist. We also
know how to conduct the experiment and understand the procedure on determining the DO and BOD.
Terms “decomposable” may be interpreted as meaning that the organic matter can serve as food for the
bacteria, and energy is derived from its oxidation.


      •   Hammer, M.J., and Hammer, J.M.JR., ‘Water and Wastewater Technology’, 3rd edition,
          Prentice Hall International Editions, 1996.
      •   Clesceri, L.S., Greeberg, A.E and Trussel, R.R.(1992) ’Standard Method for the Examination
          of Water and Wastewater ‘, 18th ed. American Public Health Association (APHA).
      •   Metcalf & Eddy: Wastewater Engineering ; Treatment,Disposal Reuse, Mc Graw-Hill, 1979.

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