Evaluation of raw, treated and effluent water quality from selected water treatment plants: a case study of Lagos Water Corporation

Abstract

Abstract Water plays a significant role in maintaining human health and welfare. In this paper, eight selected water treatment plants (lshasi, Iju, Adiyan, Mosan Okunola, Ikorodu, Otta-ikosi, Alausa and Akilo) controlled by Lagos Water Corporation were studied to evaluate raw, treated and effluent water quality. Sixteen parameters (pH, Turbidity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Total Alkalinity (TA), Total Hardness (TH), Calcium (Ca2+), Magnesium (Mg2+), Chloride (Cl−), Sulphate (SO4 2−), Nitrate (NO3 −), Phosphate (PO4 3−), Total Coliform (TC), Copper (Cu2+), Cadmium (Cd2+) and Lead (Pb2+) were determined for a period of three months (July–September 2018) using standard methods. The results showed that Cd was not detected; the TC exceeded the World Health Organization (WHO) limit while all other parameters were within the (WHO) guideline for drinking purposes with the exception of turbidity. The values of water quality index (WQI) designated 70.83% as excellent water, 20.83% as good water and 8.33% as poor water in respect to drinking uses. The Principal Component Analysis (PCA) extracts five components with eigenvalue >1.0 and accounts for 78.22% of the total variance. The associated health risks were estimated for adults and children. The hazard quotients (HQ) were greater than one indicating an overall health risk for adults and children.