Use of Moringa oleifera seed extracts to polish effluents from natural systems treating faecal sludge

ABSTRACT

The removal of pathogens in irrigation water is of great importance in developing countries. Indeed, wastewater generally reused for agriculture in countries such as Cameroon is associated with health and environmental concerns. Recent studies have shown a strong disinfectant action of the natural coagulant from the seeds of Moringa oleifera. These findings have raised the question whether or not they can be used to polish effluents from natural systems treating faecal sludge. This paper deals with trials carried out to investigate the effect of these extracts in reducing faecal indicators from initially treated faecal sludge leachate. Bacteriological and physico-chemical parameters were used to determine the optimum conditions and assess treatment efficacy. Settling time of 3 h at a concentration of extracts between 267 and 333 mg/L permitted to reduce Escherichia coli and faecal coliforms from 4.85 to 3.92 ulog (86.74%) and from 5.75 to 4.87 ulog (86.39%) respectively with 1 ulog equal to 90%. For the same settling time and at a concentration of 333 mg/L, faecal streptococci were removed from 6.40 to 5.67 ulog (81.33%). This level of removal suggests that this natural coagulant cannot be used alone for disinfection of heavily loaded effluent. Further investigations are therefore still needed to fulfil the Cameroon and WHO guidelines for safe reuse in agriculture.

KEYWORDS:

• Moringa oleifera
• wastewater treatment
• faecal sludge
• developing country
• water reuse

Acknowledgements

The authors would like to thank the research team of the wastewater research unit of the University of Yaoundé I and Oloyede Oyedibu Oyebayo from Ecology and Environmental Biology Unit of the University of Ibadan, Nigeria for their support during this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge support from the Central Africa and the Great Lakes Regional Office of the Agence Universitaire de la Francophonie (AUF) Bureau Afrique Centrale et Grands Lacs, Small grant 2016 for its financial support.