A Preliminary Evaluation of Locally Used Plant Coagulants for Household Water Treatment

Abstract

Conventional chemical water treatment systems which involve a series of steps are not feasible in rural areas, where a dispersed population is found. Moreover, it is extremely costly for investment in developing countries. Hence, improving drinking water quality at a household level is believed to be effective in fighting waterborne diseases. For this purpose, we investigated the performance of indigenous plant species locally used for turbid water treatment in Ethiopia. Batch coagulation and microbial reduction experiments were carried out on surface river waters found in Ethiopia having initial turbidities of 20, 45, 46, 80, and 195 nephelometric turbidity unit (NTU) with the flocculent dosages of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mg/l. Tubers of Maerua subcordata (Gilg.) DeWolf and seeds of Moringa stenopetala (Baker f.) Cufod. were used for this study, and they were able to achieve appreciable removal efficiency (up to 98 %) of turbidity at an optimum dose range of 20 to 80 mg/l in 6 h of settling time. About 99.9 % of microbial load removal were observed for both M. subcordata and M. stenopetala, which is comparable with chlorine disinfection. The experimental result revealed that these plant coagulants were able to meet World Health Organization (WHO) standards of drinking water quality (<5 NTU). This implies that with further optimization, M. subcordata and M. stenopetala can be used as an alternative to household-level water treatment in low-income countries.

Coupling Extracts of Plant Coagulants With Solar Disinfection Showed a Complete Inactivation of Faecal Coliforms

“…The plant extracts showed microbial removal efficiency up to 80% on different turbidity levels of well water in Malawi. A similar study conducted by Megersa et al reported efficient reduction (99.9%) of faecal coliforms from turbid river.…”

“…For instance, seeds of Vigna unguiculata and Parkinsonia aculeata are used by local people of Tanzania, whereas indigenous people of Venezuela use seeds of Cactus latifaria and Prosopis juliflora for turbid water treatment . It has been reported in various studies that some plant species may have the ability to kill microorganisms beyond their coagulation ability . For instance, Pritchard et al tested the coagulation and disinfection ability of Jatropha curcas on shallow well water.…”

“…Like other countries, people living in rural areas in Ethiopia use many plant species in water treatment. Among these, the tubers of Maerua subcordata and seeds of Moringa stenopetala are proven to be used as natural coagulants and disinfectants . M. subcordata is a shrub, which can reach a height of 2 m. The roots of M. subcordata are swollen.…”

“…[23] It has been reported in various studies that some plant species may have the ability to kill microorganisms beyond their coagulation ability. [21,22,24] For instance, Pritchard et al [21] tested the coagulation and disinfection ability of Jatropha curcas on shallow well water. The plant extracts showed microbial removal efficiency up to 80% on different turbidity levels of well water in Malawi.…”

Moringa oleifera as coagulant used in water purification process for consumption

“…Sasikala & Muthuraman [13] mentioned in their study that Moringa oleifera coagulation efficiency is particularly good at pH acidic which is at less than 6 and also pH that is greater than 11 dues to the influence of positive charges on the amino acids that builds up the protein molecule. Both coagulants trend of reduction was seen to increased and decreased constantly due to the hydrolysis where the hydrogen ions are balancing out the hydroxide ions for both of the coagulants [9]. But nevertheless, the most important finding is aluminum sulphate usage was seen to lower the pH of the groundwater sample to acidic, while for the usage of Moringa oleifera as caogulant is that they do not cause water to turn acidic as compared to when aluminium sulphate was used.…”