Waterborne diseases pose major challenges in developing countries. The World Health Organization estimates that 90.0% of the 2.3 million people who die annually due to waterborne diseases come from developing countries. At the same time fluorosis occurrence in the world’s geological fluoride belts has left many people maimed due to drinking highly fluoridated water. This work is in two parts. The first part reports on the fabrication of diatomaceous earth (DE)-based water filter membranes whose mechanical strength was altered through the application of organic binders, and filtration characteristics using charcoal and carbon activated with molasses to improve the efficiency of the filters. The effect of the use of a static magnetic field in water purification was the second part investigated in this
work. The ceramic membranes were fabricated from DE-powder and plant-based organic binders (Abelmoschus esculentus, Basella alba, Corchorus olitoris, and Aloe vera) in a ratio of 2:1 by mass. The dried samples were fired at 700.0 to 1150.0 °C and cooled at room temperature. A third of the fabricated membranes were soaked in molasses for 24.0 hours and heat-treated anaerobically for 2.0 hours at 600.0 °C then cooled to room temperature for 24.0 hours. The elemental analysis was carried out on binders, DE powder, molasses, and membranes using an x-ray fluorescence spectrometer. The x-ray diffraction pattern of DE powder and membrane was also determined. The three-point test was done using Universal Testing Instrument (Model EN 77065 7108CCN) 60000 N and the bulk density and the porosity were determined by the Archimedes’ immersion technique. The fabricated membranes were then made to filter water contaminated with Escherichia coli, Rotavirus, and sodium fluoride. The second part reports on the efficiency of water purification using a 0.8 T static magnetic field from permanent magnets in defluoridation of sodium fluoride and purification of E. coli and Rotavirus. The water being purified was circulated at varying fluxes of 2.0 ml/s to 0.1 ml/s and ambient temperatures of 16.0 °C to 40.0 °C for 0.5 hours to 9.0 hours.
The results show that the DE had high content silica: DE-A had 87.5% silica content, DE-B had 89.6%, and waste had 79.0%. Other metallic oxides were in traces acceptable for the fabrication of membranes. The potter's clay comprised 50.0% silica,28.8% AL2O3, and 7.0% total flux content. The XRD of DE-A, DE-B, and DE-waste powder and membrane showed crystalline structures matching cristobalite, quartz, and wollastonite. The viscous binders were mostly characterized by metallic ions, carbohydrates proteins, and fats. All binders improved the MOR of the membranes ranging from 33% to 175.0% increase. Basella alba was found to form membranes with the highest MOR, with a percentage increase of 175.1%, compared to the effect of the other binder. The diatomaceous membranes were stronger than the Potter’s clay membranes. Carbon activating the membranes improved the mechanical strength but
reduced their flow rates significantly. All the fabricated membranes passed the Escherichia coli test by recording >99.9% efficacy. The result of the Rotavirus in the Enzyme-linked immunoassay ELISA test showed that the membranes fabricated showed an efficiency of
more than 88.5% of defluoridation and Rotavirus removal. The activated carbon had a bulk density of 450.0 kg/m3 and it improved the decontamination of water by around 10.0%. The activated carbon improved the modulus of rupture (MOR) of the DE-waste membrane by 47.8% and the average pore size of the active DE-waste membrane was 18.4 nm. The filtration process was found to be dependent on the contaminant’s size, concentration, and pressure applied to the water during the filtration process. The use of normal pressure only yielded 88.7% and 48.5% in filtering Rotavirus, and NaF respectively. Carbon-activating the membranes improved the efficiency of removing Rotavirus and defluoridation by 9.7% and 8.6% respectively while applying a pressure of 50.0kPa reduced the efficiency of the carbon activated membranes by 4.3% and 5.5% in NaF and Rotavirus respectively. The filtration results of the DE-based membranes fitted best the Complete Blocking and Standard Blocking Filtration models than the Cake and Intermediate blocking models.
It was further found that when ionized water was circulated under the static magnetic field for nine hours, its pH was lowered by 9.7% and that the flux of water in circulation did not affect the purification efficiency. The static magnetic field lowered the replication of Escherichia. Coli and Rotavirus by 9.8% and 7.1% respectively and 14.1% of defluoridation of water was also achieved. Thus, DE-waste together with molasses is good material in fabricating water membranes. The use of the magnetic field in water purification should be complemented by other methods for it to be effective.