Groundwater quality assessments around acassava processing mill on the sedimentary terrain of Ilaro, South-western Nigeria

Groundwater quality assessments were carried out around a cassava processing mill within the Ilaro metropolis, South-western Nigeria using a hydro-chemical approach. Nineteen samples were obtained from proximate water wells which serve as sources of water for drinking, domestic, and irrigation activities. Twenty physicochemical parameters were analyzed, and the results were compared with the permissible limits of world health organization (WHO) for drinking water. The pH values of the groundwater samples (4.60–7.65) were not within the limit and suggest the presence of contaminants in the water samples. The concentrations of electrical conductivity (EC), total dissolved solid (TDS) and total hardness (TH) in the groundwater samples were 100% compliance, while Hydrogen cyanide (HCN) concentrations in the groundwater samples were 0%with standard permissible limit by WHO. All the Anions (Cl−, HCO3−, NO3−, SO42−) in the groundwater samples were 100% compliance except CO32−which is 79% compliance and cations (Ca2+, Mg2+, Na+ and K+) concentrations were 100% compliance the standard permissible limits. The concentrations of Fe, Cd, Mn, Pb, Zn, Cu in the samples were 0%, 0%, 31%, 36%, 100%, 100% in compliance respectively with standard permissible limits. The groundwater quality index (GWQI) and contamination index (CI) of the groundwater samples ranges from 527.24 to 699.16 and 24.03 to 38.80 respectively. The values of GWQI and CI of the groundwater samples were 0% compliance with recommended standard permissible limit for drinking and domestic purposes. The samples also showed moderate to high tendencies of aggressively corroding metals. The samples were unsuitable for irrigation and the concentrations of HCO3− and CO32− influenced the suitability of the samples. Strong direct relations exist between carbonate and electrical conductivity indicating freshwater status.