Evaluation of moringa oleifera cationic protein functionalized rice husk ash as point-of-use water treatment for water disinifection

• Main Author: Barajas, John Raymond B.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5210
• Institution: De La Salle University

The recurring incidences of diarrhea worldwide calls for the implementation of low-cost point-of-use water treatment technologies (POU) in many low-income regions. To address this concern, this study explored the possibility of developing a potential and readily available point-of-use water treatment based on Moringa oleifera (MO) seeds. MO seeds are composed of natural flocculating proteins which can be used as antimicrobial agents to produce potable water but unwanted soluble organics which increase total organic carbon (TOC) in the treated water are also co-extracted during treatment. This observed increase in TOC results to regrowth of pathogens and shortens the shelf-life of the treated water. To eliminate this risk, this study immobilized MO proteins onto rice husk ash (RHA) and evaluated its performance in bacterial disinfection. Saturation of RHA and its equilibrium time for sorption were observed to be 31.5 mg MO protein/g and 60 min, respectively. MO protein adsorption onto the surface of RHA was found to be well defined by Dubinin-Radushkevich and intra-particle diffusion models. Further examination through confocal imaging confirmed that MO proteins were tightly bound to the RHA surface. TOC of the MO functionalized RHA was observed (1.03 0.06 mg/L) to be below the threshold limit of 2.0 mg/L. Red fluorescence observed after confocal imaging confirmed the capacity of immobilized MO proteins to disrupt live bacterial cells and this well-defined by Homs disinfection model. Furthermore, adsorbent dosage, initial adsorbate concentration, and contact time were found to significantly affect MO protein adsorption and the relative performance of MO functionalized RHA in disinfection. As a final step, MO functionalized RHA was also evaluated in a biofilter assembly. Results revealed that preparation of MO functionalized RHA required at least 48.6 MO seeds in order to achieve an equivalent dose of 1.4 MO seeds needed to purify the same volume of water. Nevertheless, these results demonstrate the potential of MO functionalized RHA to be implemented as a low-cost POU in regions where access to safe drinking water is limited.