The assessment of water quality in river Molo water basin, Kenya

Abstract

The monitoring of water quality for both domestic and commercial use is absolutely essential for policy formulation that affects both public and environmental health. This study investigates the quality of water of river Molo system which lies in the Kenyan Rift Valley. The river is considered a vital source of water for the residents and industrial activities in Nakuru and Baringo Counties. Six water samples were collected during the dry season of December 2017. Various physicochemical parameters were determined in situ by use of a portable pH meter. These parameters included pH, temperature, electrical conductivity and total dissolved solids (TDS). Anions such as fluorides, sulfates, phosphates, nitrates, chlorides, carbonates and bicarbonates were determined using conventional methods such as titrimetry and (ultra-violet visible) UV–Vis techniques. The cations including sodium, potassium, calcium and magnesium were determined using flame photometry. The results showed that the water had pH values ranging from 7.90 to 9.66 units, temperature ranged from 14.02 to 31.5 °C, while electrical conductivity ranged from 181 to 1637 μS/cm, TDS (69–823 mg/L), F (2.76–3.28 mg/L), sulfates (4.97–85.66 mg/L), phosphates (0.13–11.06 mg/L), nitrates (1.73–6.16 mg/L), chlorides (38.5–69.4 mg/L), carbonates (18–148 mg/L), bicarbonates (54–384 mg/L), sodium (19–1800 mg/L), potassium (8.9–121 mg/L), magnesium (4.8–106.8 mg/L) and calcium (13.4–77.4 mg/L). The pH, temperature, fluorides and sodium were above the World Health Organization permissible limits for drinking water in S4 and S5. All the water samples fall under bicarbonate or freshwater zone. The sampling points can be classified into five water types: Na–Mg–Ca–HCO3, Na–HCO3, Na–Ca–Mg–HCO3–CO3, Na and Na–Ca–HCO3–CO3. Chemical indices such as sodium adsorption ratio, magnesium hazard, percent sodium and permeability index are reported. Accordingly, the findings from this work indicate that the river Molo water in general is good for irrigation.