Physicochemical Characterization and the Effect of Flow-Distance on Correlation between Chemical and Biochemical Oxygen Demands of Industrial Wastewaters | Chapter 05 | Advances in Applied Science and Technology Vol. 3

This work was carried out to establish the effects of the activities of a cluster of industries in Jos-South Local Government Area of Plateau State, Nigeria, on the environmental quality of the industrial area. Some physicochemical parameters –temperature, pH, turbidity, suspended solids (SS), total solids (TS), total hardness, alkalinity, biological oxygen demand (BOD), chemical oxygen demand (COD), heavy  metals  (Cu²⁺,  Co²⁺,  Fe²⁺&  Zn²⁺),  phosphates,  nitrates,  sulphates  and  chlorides –of  the wastewaters  from  the  various  industries  were  investigated  using  standard  protocols.  Also,  the influence of flow-distance on the empirical correlation between biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the wastewaters was investigated. Wastewater samples were collected at point-sources and at 25, 50, 75 and 100m distances from the point-sources. Sampling was done twice a week for a full seasonal cycle at peak production period (morning and evening). The samples’ pH was adjusted to 7 using 0.5M acid for basic samples and 1.0M alkali for acidic samples, de-chlorinated using 0.0125M Na₂S₂O₃ and seeded when necessary and then diluted with de-ionized water. The ranges of the parameters were as follows: temperature: 22 –32°C, pH: 5.5 –10.4, SS: 0 –1,300  mg/L,  TS:  200 –1.400  mg/L,  sulphate:  0.37 –1.37  mg/L,  nitrites:  0.10 –1.09  mg/L  and phosphate: 14.80 –21.83 mg/L.  The phosphate values, especially, were in excess of the maximum contamination limit specified by Federal Environmental Protection Agency (FEPA) and World Health Organization  (WHO);  and  are  capable  of  triggering  eutrophication,which  will  in  turn  increase BOD/COD   values.  Concentrations  of  heavy  metals,  determined  by  Atomic   Absorption Spectrophotometry (AAS), ranged as follows: 0.07 –2.01 mg/L for Cu²⁺, 0.58 –3.27 mg/L for Fe²⁺, 0.01 –3.18 mg/L for Zn²⁺ and 0.11 –0.18 mg/L for Co²⁺ whose specified standard is not available. BOD₅ values ranged between 5.34 –25.88 mg/L while COD values ranged from 727.30 –8,308.66 mg/L.   Some BOD₅ values were in excess of the allowable limit while all COD values were observed to be very high. This implies an appreciable level of pollution exists here and recipient water bodies of these wastewaters are at  risk of being polluted. COD and BOD₅ of the wastewaters from different sources  highly  correlated  with  correlation  coefficients  ranging  0.9396-0.9985.  The  empirical correlation  between  COD  and  BOD₅ was  generally  maintained  despite  the  distance  of  flow  of  the wastewater  from  point-source  and  contributions  of  washings  from  farmlands  and  other  human activities  i.e.  the  correlation  between  COD  and  BOD₅ for  wastewaters  was  not  affected  by  flow distance. The correlation equations for the industries may, therefore, be used to deduce rapid effluent quality from chemical oxygen demand (COD) of sample from any point along the effluent flow path.

Author(s) Details

O. M. Myina

Department of Chemical Sciences, Bingham University, Karu, Nigeria.

A. O. Lawal

Department of Applied Science, Kaduna Polytechnic, Kaduna, Nigeria.

B. M. Ajiga

Jehovah Nissi Boutique and Accessories, Lagos, Nigeria.

A. Edah

Department of Chemistry, University of Jos, Jos, Nigeria.

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