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Alaro
River is receiving industrial effluent as a point source. The water
quality of the river upstream and downstream after the point of
effluent discharge was assessed with the view of determining the
effect of industrial effluent on the water quality of the river. The
water samples were analyzed for dissolved oxygen (DO), pH,
alkalinity, electrical conductivity, total solid (TS), chloride,
sulphate, phosphate and heavy metals (Pb, Mn, Ni, Cd, Cr and Cu).
The average levels of the parameters upstream were: pH (7.8 ±
0.5); DO (7.0 ±
1.3 mg/L); alkalinity (405 ±
103 mg CaCO3/L); TS (328.8 ±
106.7 mg/L); chloride (474.8 ±
154.1 mg/L); sulphate (2.3 ±
0.7 mg/L); phosphate (0.175 ±
0.026 mg/L); Pb (0.023 ±
0.001mg/L); Mn (0.169 ±
0.009 mg/L); Ni (0.011 ±
0.003 mg/L); Cd (0.004 ±
0.002 mg/L); Cr (0.003 ±
0.001 mg/L) and Cu (0.005 ±
0.001 mg/L). Much higher average levels of alkalinity (744 ±
80 mg CaCO3/L); total solids (1379 ±
389 mg/L); chloride (1126 ±
83 mg/L); sulphate (16.4 ±
13.9 mg/L); phosphate (4.62 ±
2.07 mg/L); Pb (0.14 ±
0.03 mg/L); Mn (0.456 ±
0.190 mg/L); Ni (0.03 ±
0.03 mg/L); Cd (0.01 ±
0.001 mg/L); Cr (0.021 ±
0.007 mg/L); Cu (0.0923 ±
0.035 mg/L) and lower average levels of pH (6.5 ±
0.5) and DO (0.63 ±
0.93 mg/L) were obtained downstream. The levels of most parameters
in the effluent exceeded the effluent guideline for discharge into
surface water. River’s recovery capacities for the water quality
parameters were fairly good and ranged between 36 and 90 %.
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