Title: Bacterial removal efficiency of Moringa stenopetala and Cadaba farinosa from surface water: Laboratory-based cross-sectional study

Abstract

Background: Consumption of polluted surface waters are leading to waterborne diseases, especially in developing countries, which results in the deaths of millions of people annually around the world. Ethiopia, like the rest of developing countries, suffers a lot of water-associated health problems. Chemical disinfectants are in use to disinfect water with some drawbacks like expensiveness, unavailability, and detrimental effect on human health. Researchers are on the search for non expensive and locally available methods, and natural plants are the ones in the study. Thus, this study is designed to test Escherichia coli (E. coli) removal efficiency of Moringa stenopetala (M. stenopetala) and Cadaba farinosa (C. farinosa) from surface water. Methods: A cross-sectional study was conducted from June to July 2021. A 14L water sample was collected from Lake Hawassa. A 30, 60 and 100 mg weights of the leaf and seed powder dosages of M. stenopetala and C. farinosa at contaminant settling times of 30, 60 and 90 minutes were used. Each one liter water sample was treated with each of the dosages. E.coli count, temperature, pH and turbidity were measured using standard methods for water and wastewater analysis. Statistical package for social sciences (SPSS) version.23 was used for analysis. Treatment differences between plant parts and association between variables were also tested. Result: The result indicated that raw water samples having 18 initial E. coli colonies per 100mL of water showed zero E. coli colonies per 100mL of water after treatment with 30mg dosage of M. stenopetala seed, 30mg dosage of C. farinosa seed and 60mg dosage of M. stenopetala leaf after 90 minutes of settling time, but C. farinosa leaf was unable to reduce E. coli colonies to zero per 100mL of water. M. stenopetala leaf showed the highest turbidity reduction of 83.3% at 60mg dosage. A pH of 7.30 and 8.50 and a temperature of 20°C-23.5°C were recorded. There was a significant difference in E. coli removal between C. farinosa seed and leaf. Turbidity was identified as a factor that positively affects E. coli removal during M. stenopetala seed and leaf. Dosage and settling time were also identified as predictors of E. coli removal. Conclusion: M. stenopetala and C. farinosa have antimicrobial properties against E. coli, but only M. stenopetala showed E. coli, turbidity, and pH values within the recommended World Health Organization standards. So, we suggest M. stenopetala as a promising natural disinfectant that needs attention from organizations working on the water.