Overcoming the drawbacks of natural coagulants for drinking water treatment

Abstract

A number of natural coagulants from plants or animal origin can be effectively used for the treatment of drinking water. Some are used at household levels in traditional systems using crude (non-purified) extract. In the crude extract form, natural coagulants release organic and nutrient loads to the water resulting in poor treated water quality. In such cases it becomes necessary to purify the coagulant component from the crude extract before using it for water treatment. This paper discusses an effective and simple purification of the coagulant from Moringa oleifera seed using an ion exchange method that would overcome the drawbacks of natural coagulants. The impact of the purification process on reducing organic and nutrient release was studied. Adsorption and elution parameters of the ion exchange process were optimised. The study indicated that the purified protein has effective coagulation activity and it did not release organic and nutrient loads to the water. Compared to other purification methods used in previous studies, this is simple and of comparatively lower cost. This purification method can be readily scaled up and applied even in remote parts of developing countries. This work suggests that the concerns of natural coagulants can be overcome by simple purification and this is believed to promote their use in drinking water treatment.

Reduction of Turbidity of Water Using Locally Available Natural Coagulants

“…More than six million people die because of diarrhea which is caused by polluted water. Developing countries pay a high cost to import chemicals for water treatment [1]. This problem is critical in Bangladesh.…”

Utilization of plant-based natural coagulants as future alternatives towards sustainable water clarification

“…Crude extracts contained various inorganic and organic biomolecules such as lipids which do not participate in active coagulation (Ghebremichael, 2007). Increased levels of organic matters in treated water would have serious implications on the subsequent disinfection process using chlorine.…”

“…These organic matters can act as precursors to the formation of trihalomethanes (THMs) in which many are carcinogenic (Duan and Gregory, 2003) and might also increase the required chlorine demand for adequate disinfection (Anastasakis et al, 2009). The use of purified active agents could tackle this undesirable and problematic issue (Ghebremichael, 2007;Sathiyabama, 2012). Protein purification via ion exchange has successfully eliminated the additional nutrient and organic loading introduced by the seeds of M. oleifera (Ghebremichael, 2007).…”

“…The use of purified active agents could tackle this undesirable and problematic issue (Ghebremichael, 2007;Sathiyabama, 2012). Protein purification via ion exchange has successfully eliminated the additional nutrient and organic loading introduced by the seeds of M. oleifera (Ghebremichael, 2007). Partial purification of active agents in legume; Phaseolus vulgaris has also been rewarding as the organic loading content has been reduced by at least 16 times in contrast to the use of crude extracts (Antov et al, 2010).…”

A review on common vegetables and legumes as promising plant-based natural coagulants in water clarification

“…This additional pretreatment step is highly important to lower the introduction of organic loadings (Ghebremichael 2007) which is a common issue when using natural coagulants and to reduce the dosage of coagulant in achieving similar coagulation activities. The molecular weight of the trimer coagulant protein subunit is approximately 50 kDa which is larger than that in M. oleifera.…”