Toward Understanding the Efficacy and Mechanism of Opuntia spp. as a Natural Coagulant for Potential Application in Water Treatment

Abstract

Historically, there is evidence to suggest that communities in the developing world have used plant-based materials as one strategy for purifying drinking water. In this study, the coagulant properties of Opuntia spp., a species of cactus, are quantitatively evaluated for the first time. Opuntia spp. was evaluated for turbidity removal from synthetic water samples, and steps were made toward elucidating the underlying coagulation mechanism. In model turbid water using kaolin clay particles at pH 10, Opuntia spp. reduced turbidity by 98% for a range of initial turbidities. This is similar to the observed coagulation activities previously described for Moringa oleifera, a widely studied natural coagulant. Although it has been reported that Moringa oleifera predominantly operates through charge neutralization, comparison of zeta potential measurements and transmission electron microscopy images of flocs formed by Opuntia spp. suggest that these natural coagulants operate through different mechanisms. It is suggested that Opuntia spp. operates predominantly through a bridging coagulation mechanism. Once optimized, application of these readily available plants as a part of point-of-use water treatment technology may offer a practical, inexpensive, and appropriate solution for producing potable water in some developing communities.

Applications of Natural Coagulants to Treat Wastewater − A Review

“…Mucilage in cactus opuntia has fiber such as l-rhamanosei, l-arabinose, d-galactose, d-xyloose, and galacturonic acid, predominantly during a bridging coagulation method solution particulates carry out indirectly contact from the cactus genus [24]. The most capable coagulation and active element is galacturonic acid, it is wellknown 50% of turbidity removal [25].…”

“…To shrink cyanogenic & phytate substance to maintain their natural value, altered methods are adopted in sinking cyanogenic glycoside like sun-drying, ensiling, and soaking + sun-drying. Peels are chopped to obtain good quality 2 cm for easy compression, and sagging for two days to decrease moisture substance from 70-75% to about 40% [25]. After 21 days cassava peel silage was observe as light brown in appearance, with satisfying odour.…”

Post-treatment sludge analyses and purification of paint effluent by coag-flocculation method

“…However, these traditional coagulants have several disadvantages, which include: large volume of sludge [7]; dissolution of metals/constituents into after treatment sludge, under performance and corrosiveness at lower pH and pKa (dissociation constant of a solution) [8]. In addition, Miller et al [9] and Crapper et al [10], reported that these alum-based chemical coagulants can cause pre-senile dementia in human.…”

Treatment of landfill leachate by using lateritic soil as a natural coagulant

“…This coagulant, under optimal conditions, can achieve between 90 % and 99 % efficiency on removing microorganisms [4]. However, it has drawbacks, such as the fact that the residual aluminum resulted from the process of coagulationflocculation has a high eco-toxicological and economic impact when is discarded into the environment through the treated sludge, and the high cost for communities involved in its import and transport [5].…”