A comparison between Moringa oleifera and chemical coagulants in the purification of drinking water - An alternative sustainable solution for developing countries

A research project was commissioned to investigate the performance of Moringa oleifera compared with that of aluminium sulphate (Al2(SO4)3) and ferric sulphate (Fe2(SO4)3), termed alum and ferric respectively. A series of jar tests was undertaken using model water, different raw water sources and hybrid water containing a mixture of both of these types of water. The model water consisted of deionised water spiked with Escherichia coli (E. coli) at 104 per 100ml and turbidity (146NTU) artificially created by kaolin. Results showed that M. oleifera removed 84% turbidity and 88% E. coli, whereas alum removed greater than 99% turbidity and E. coli. Low turbidity river water (<5NTU), with an E. coli count of 605 colony forming units (cfu)/100ml was treated with M. oleifera and ferric. Results showed an 82% and 94% reduction in E. coli for M. oleifera and ferric respectively. Tests on turbid river water of 45NTU, with an E. coli count of 2650cfu/100ml, showed a removal of turbidity of 76% and E. coli reduction of 93% with M. oleifera. The equivalent reductions for alum were 91% and 98% respectively. Highly coloured reservoir water was also spiked with E. coli (104cfu/100ml) and turbidity (160NTU) artificially created by kaolin; termed hybrid water. Under these conditions M. oleifera removed 83% colour, 97% turbidity and reduced E. coli by 66%. Corresponding removal values for alum were 88% colour, 99% turbidity and 89% E. coli, and for ferric were 93% colour, 98% turbidity and 86% E. coli. Tests on model water, using a secondary treatment stage sand filter showed maximum turbidity removal of 97% and maximum E. coli reduction of 98% using M. oleifera, compared with 100% turbidity and 97% E. coli for alum. Although not as effective as alum or ferric, M. oleifera showed sufficient removal capability to encourage its use for treatment of turbid waters in developing countries. © 2010 Elsevier Ltd.