Assessing the efficacy of Elephantorrhiza goetzei (Ndorani) seed extracts for household water treatment in Zimbabwe

Abstract

Poor access to clean and safe water is one of the major problems being encountered the world over. There has been considerable attention in recent times towards the use of natural coagu-lants. The study seeks to investigate the efficacy of Elephantorrhiza goetzei (E.goetzei) seed extracts as natural coagulants for synthetic water treatment. The methodology consisted of the proximate analysis to investigate the active ingredient(s) responsible for coagulation. Standard methods were used for experiments in this study. Coag-ulant dosages ranging from 0 to 300 mg/L with a rapid mixing speed of 120 rpm for 1-minute, slow mixing speed of 30 rpm for 15 minutes and settling time of 15 minutes were used for the jar test. IBM SPSS Version 20 was used for data analysis. The results obtained from the proximate analysis of E. goetzei seed extracts show that values of 5.25%, 21.40%, 8.23%, 32.99%, 2.20%, and 29.93% were obtained for moisture, crude pro-tein, crude fibre, fat, ash, and carbohydrate content, respectively. Moreover, seed extracts of E.goetzei achieved removal efficiencies up to 94.8%, 50.1%, 90.0%, and 53.9% for turbidity, fluoride, iron and manganese in water, respectively. The COD increased from 55.3 mg/L to 419.3mg/L as the coagulant dosage increased from 0 to 100 mg/L. The total nitrogen and phos-phorus obtained in the sludge at 100 mg/L were 0.343 μg/kg and 0.194 μg/kg. Coagulant dos-age had a significant effect (p< 0.05) on pH, TDS, turbidity, fluoride, iron, manganese and COD of the treated water and on the nitrogen and phosphorus in the sludge. In conclusion, the study proved that E.goetzei seed extracts contain proteins, carbohydrates, fat, and fibre as potential active coagulation ingredients. E.goetzei seed extracts coagulant has potential to achieve the desired World Health Organisation (WHO) drinking water standard at higher dosages for fluoride, iron, and manganese. It can also be concluded that there is a con-sistent pattern of higher COD levels in the treated water as the dosage of coagulant increases. The significantly lower nitrogen and phosphorus content in the sludge following water treat-ment, in comparison to compost and organic fertilizer, restricts the potential use of sludge as a fertilizer. As a recommendation, further work needs to be done on the use of E.goetzei seed extracts for raw water sources within households. The impact of operational parameters such as pH on treatment efficiency should be investigated. Finding solutions to address the increase in resid-ual organic matter with higher coagulant dosages is also crucial for improving water quality.