Biochemical Oxygen Demand and Carbonaceous Oxygen Demand of the Covenant University Sewage Oxidation Pond

Ajayi A.A, Peter-Albert C.F., Ajojesu T.P., Bishop S.A., Olasehinde G.I., Siyanbola T.O.

Abstract


Biochemical  Oxygen  Demand  (BOD)  is  a  measure  of  the  dissolved  oxygen consumed  by  microorganisms  during  the  oxidation  of  reduced  substances  in  waters  and wastewaters.  It  is  often  used  ambiguously  in  relation  to  Carbonaceous  Oxygen  Demand CBOD) which is the oxygen consumed during the oxidation of carbonaceous compounds to carbon dioxide (CO2and other oxidized end product. BOD is actually the sum of CBOD and  NBOD  where  NBOD  is  the  Nitrogenous  Oxygen  Demand  which  is  the  oxygen consumed  during  the  oxidation  of  nitrogenous  compounds  (mainly  NH to  nitrates  with nitrites being an unstable intermediate. The major difference between CBOD and NBOD is that there are two classes of bacteria believed to be responsible for the oxidation of reduced nitrogen.  The  BOD value  of  Sewage  samples  collected  from  Covenant  University oxidation  pond  was  therefore  measured  and  the  samples  examined  for  the  presence  of Escherichia coli. The  sewage samples collected from  four points (starting point (A), two middle points (B, C), and end point (D) were inoculated on an Eosin Methylene Blue agar plates  and  the  presence  of  E.  coli  was  confirmed  by  the  appearance  of  greenish metallic sheen colonies on the agar plates and biochemical Tests. The  BOD of the effluent at the different  points  (A,  B,  C,  D)  respectively  showed  a  reduction  in  microbial  load.  The ultimate  CBOD  was  also  estimated  based  on  the  BOD5  value  which  is  based  upon  the exponential (first-order) nature of oxygen demand. This research describes the formulations of CBOD breakdown using simplified oxidation kinetics.

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