Quality Assessment of Irrigation Water from theVicinity of a Hospital Liquid Waste Treatment Plant

摘要

The quality assessment of surface water used for irrigation within the vicinity of a Hospital liquid waste treatment plant in Zaria, Nigeria was conducted. A total of thirty-three (33) water samples were collected from four sampling sites in the study area. These samples were examined for heavy metal content using Atomic Absorption Spectrophotometer. Major physicochemical water quality indicators were determined by standard methods. At 95% confidence level, the average levels in mg/l of Chromium, Lead, Cadmium, Iron Manganese, Nickel and Cobalt were 0.39±0.11, 1.52±0.8, 0.09±0.01, 6.93±0.62, 0.36±0.09, 0.37±0.04, 0.70±0.32 respectively. These values were above the World Health Organization permissible limit for these heavy metals in surface water. The mean value of 1.16±0.07 mg/l dissolved oxygen in the samples was lower than the World Health Organization standard of 5 mg/l. The mean turbidity value of 5.93±0.06 mg/l exceeded the permissible levels set by World Health Organization. All other physicochemical parameters (pH, electrical conductivity, sulphate, nitrate, phosphate, Biochemical Oxygen Demand, Chemical Oxygen Demand and temperature) were below World Health Organization permissible limits. In view of elevated heavy metal concentrations, depleted oxygen and high turbidity, the study have shown that effluents from the hospital liquid waste treatment plant contaminate the receiving irrigation surface water system which may in turn have deleterious impact on crops and other organisms in the study area. To reduce the pollution of the liquid wastewater on the receiving environment complete overhauled or replacement of the treatment plant is recommended.