Evaluation of the Effectiveness of Some Local Plants in Purification of Water Samples from Selected Sources

This study evaluates the effectiveness of local plants such as banana peel, watermelon seed, neem leaf and orange peel in treating borehole and well water around Kontagora in Nigeria. Chemical coagulants such as alums present hazard and economic shortcomings in water treatment. They reduce water pH due to their acidic nature, against the pH 6.5 – 8.5 standard recommended for potable water. It is therefore, desirable to replace these chemical coagulants with plant-based ones, which are economic and environmental friendly. This study analysed some physicochemical parameters such as temperature, conductivity, and others, and heavy metals such as Cu, Fe and Pb before and after treatment with plant-based coagulants and alum. From the results, irrespective of water sample type and coagulant, the conductivities measurement before treatment was 28.8 – 30.6 µs/cm, and increased to 34.8 – 48.0 µs/cm for alum. The range was 37.6 – 48.8 µs/cm for plant-based. Turbidity before treatment ranged 0.96 – 6.50 NTU and decreased to the range 0.1 – 0.36 NTU for alum and 0.05 – 0.09 for plant-based. Total Dissolved Solid (TDS) before treatment ranged 4.00 – 7.00 mg/L and reduced to 2.15 – 4.00 mg/L for alum, 1.00 – 4.32 mg/L for plant-based. Total Hardness (TH) before treatment showed 28.00 – 32.00 mg/L range, which reduced to 28.00 – 30.00 mg/L for alum, 19.00 – 28.50 mg/L for plant-based. Most parameters, including alkalinity, acidity, BOD, DO, chloride, sulphate, colour and TSS showed improved performance with plant-based coagulants better than alum with values within the WHO standards for drinking water. Heavy metals analysed recorded varied concentrations: Fe in raw borehole water was 0.85 mg/L and reduced to 0.10 mg/L with alum, and 0.1 – 0.27 mg/L range with plant-based coagulants. Fe concentration in well water increased with all treatments, including alum. Cu, Fe and Pb concentrations in raw well water were 0.30 mg/L, 0.05 mg/L and 0.2 mg/L respectively, where Pb concentration was higher than the WHO limit of 0.01 mg/L set for drinking water. Pb was found below detection limit in borehole water. While alum reduced the levels of Cu to 0.07 mg/L, all the plant-based treatments increased its concentration within 0.1 – 0.87 mg/L range, which were below the 1.0 mg/L, WHO limits for Cu in drinking water. From these findings, in no particular order, the plant-based coagulants of banana peel, watermelon leaf and orange peel displayed greater potency for water treatment than neem leaf. Conclusively, all plant-based coagulants used in this study showcased better alternatives than alum.