Removal of Sediment and Bacteria from Water Using Green Chemistry

Abstract

Although nearly all newly derived water purification methods have improved the water quality in developing countries, few have been accepted and maintained for long-term use. Field studies indicate that the most beneficial methods use indigenous resources, as they are both accessible and accepted by communities they help. In an effort to implement a material that will meet community needs, two fractions of mucilage gum were extracted from the Opuntia ficus-indica cactus and tested as flocculation agents against sediment and bacterial contamination. As diatomic ions are known to affect both mucilage and promote cell aggregation, CaCl(2) was studied in conjunction and compared with mucilage as a bacteria removal method. To evaluate performance, ion-rich waters that mimic natural water bodies were prepared. Column tests containing suspensions of the sediment kaolin exhibited particle flocculation and settling rates up to 13.2 cm/min with mucilage versus control settling rates of 0.5 cm/min. Bacillus cereus tests displayed flocculation and improved settling times with mucilage concentrations lower than 5 ppm and removal rates between 97 and 98% were observed for high bacteria concentration tests (>10(8) cells/ml). This natural material not only displays water purification abilities, but it is also affordable, renewable and readily available.

Harvesting Microalgae Grown on Wastewater

“…cactus acted as an efficient coagulant for bacteria and kaolin particles (Buttice et al, 2010), no significant algae recovery was observed with cactus mucilage in this study. Good harvesting efficiency (85%) was observed using Moringa Oleifera seed powder, although the dosage needed (4,670 mg/L) was much higher than the dose required for other coagulants (Table 2).…”

“…It is important to note that natural coagulant tests were done using crude extracts from both cactus and moringa with no pH amendment. Buttice et al (2010) used a solvent extraction procedure to produce both gelling and non-gelling extracts of the cactus mucilage rather than the crude preparation used in this study, which is more typical of what is done in developing countries. Sánchez-Martín et al (2010) found that flocculation performance of moringa could be improved by modifying the purification processes.…”

“…Moringa oleifera seed flour has been used traditionally for drinking water treatment in parts of Asia and Africa and was recently investigated by Teixeira et al (2012) for harvesting C. vulgaris. Although not previously investigated for algae harvesting applications, mucilage extracted from Opuntia ficusindica cactus was shown to increase sedimentation rates for clay particles and bacteria (Buttice et al, 2010) and to transport arsenic to an air water interface (Fox et al, 2012).…”

“…These materials can be produced in a more sustainable way than synthetic organic polymers (Buttice et al, 2010) and have the potential to generate an algae product that is free from undesirable and potentially toxic contaminants (Ahmad et al, 2011;Teixeira et al, 2012). Chitosan is produced from chitin, a structural element in the exoskeletons of crabs and shrimp.…”

Improvement of electrocoagulation–electroflotation treatment of effluent by addition of Opuntia ficus indica pad juice

“…A large number and variety of natural substances, extracted from plant, have been examined for their coagulation properties [10]. Several authors reported the efficiency of Opuntia ficus indica mucilage for antimicrobial activity [11], for metals reduction (As, Cd, Cu and Fe) [12,13] as well as for turbidity removal [10,11,[14][15][16], in the treatment of synthetic and real wastewaters by standard jar tests. Even if some authors consider that Opuntia ficus indica mucilage has potential to replace Fe or Al in the coagulation-flocculation process [15], and hence it can be used as coagulant-flocculant instead of using Fe or Al or other synthetic polymers.…”