Adsorption of the cyanobacterial hepatotoxin microcystin-LR by a low-cost activated carbon from the seed husks of the pan-tropical tree, Moringa oleifera

Anti-cyanobacterial activity of Moringa oleifera seeds

“…Such cyanobacterial intoxication of humans may occur not only through consumption of cyanotoxin-contaminated drinking water but also through food and dietary supplements; through recreational and occupational contact, and by hemodialysis (e.g., Carmichael et al 2001; Dittmann and Wiegand 2006; Stewart et al 2006). It has been demonstrated that 10 mg L −1 Moringa could remove 93% to 98% of the cyanotoxin microcystin-LR (20 µg L −1 ) from the aqueous phase, while 50 mg L −1 removed the toxin to levels below the practical detection limit (<0.08 µg L −1 ) of the HPLC-DAD procedure (Warhurst et al 1997b). In microcystin-contaminated drinking water, the absorbed material should be removed from the water by coagulation, sedimentation, or filtering prior to consumption, whereas in reservoirs, ponds and irrigation impoundments natural sedimentation might yield sufficient removal.…”

“…M. oleifera pods are efficient in absorbing organic pollutants and pesticides (Akhtar et al 2007a, b). High-quality activated carbon can be prepared from the waste husks of M. oleifera (Pollard et al 1995; Warhurst et al 1997a), which could effectively remove up to 98% of the cyanobacterial microcystin-LR (Warhurst et al 1997b). In addition to the strong water-clarifying properties, Moringa seeds have also been reported removing more than 90% of cercariae from the water phase (Olsen 1987).…”

Experimental studies on removal of microcystin-LR by peat

“…Adsorption seems to be an effective and cheaper technology, comparatively. Some researchers have reported the possibility of using activated carbon for removal of MCLR and related toxins [18][19][20][21]. Even though activated carbon adsorption poses to be an attractive and cheaper technology available, the need to replenish the column with fresh carbon after its saturation makes it still economically not feasible.…”

Cyanobacterial (blue-green algae) toxins

“…Due to the role of oxidative stress, antioxidants such as vitamin E, selenium, and green tea polyphenols also appear to be beneficial prophylactically (Gehringer et al, 2003a,b;Jayaraj et al, 2007;Xu et al, 2007). Although the adsorption of microcystins by activated charcoal was used successfully to decontaminate drinking water (Warhurst et al, 1997), this decontamination procedure was not protective in mice dosed with microcystins (Mereish and Solow, 1989); no data are available for other species.…”