Abstract:
The characterisation of industrial effluents
revealed that the nature and volume of the pollution load
were dependent on the type of industry. The values of BOD 5
showed that the industries which use organic raw materials,
for example, the beer breweries, the vegetable oil
industries, and the textile mills , showed the highest
pollution loads. The bottling companies which use
"concentrates" as their raw materials generally showed
intermediate values whereas the paint industries using
inorganic raw materials showed the lowest BOD 5 values.
Estimation of the heavy metals revealed that Cd, Co,
X i , and C r were below detection level; Cu and Zn were
within the WHO limits ; Mn and Fe exceeded WHO maximum
but fell below the maximum permissible level; while Pb was
excessive (0.03 mg/dm 3 ) being above the highest desirable
level. While Pb and Mn showed higher levels i n the dry
season than i n the rainy ,season, Fe showed higher level
in the wet season. The order of bioaccumulation of the
metal ions i n the predominant fish species: Synodontis
membranaceus (catfish) and Oreochromis -zilli (tilapia) in
the study area was found t o be Mn > Pb > Zn > Cu > Fe ,
indicating that both species of f i s h can be used t o
monitor Mn and Pb in water. Sgnodontis membranaceus was
found t o be a better indicator for Mn while Oreochromis zilli was found to be better for Pb. The concentration
levels for these metals are not such as t o give cause
for alarm since they are comparable t o and sometimes,
even lower than the levels i n the mackerel fish samples
(common in Nigerian diets) .
Presently, there is paucity of baseline data for
many Nigerian rivers. It is hoped that the analytical
data herein assembled would add t o the growing Nigerian
data bank.
