Ceramic Water Filters for the Filtration of Bacteria and Chemical Contaminants

Abstract

Of recent, individuals, community and government across the globe are embracing the ceramic water filters technology as a means of screening out chemicals and pathogens from water. This is to help reduce water related diseases to a great level. Ceramic Water Filter (CWF) is gaining prominence because its major raw material is clay which is readily available. Doping materials used and the filter‘s flow rate are of great importance in the production. This work gives account of empirical studies on fluoride removal ability of HA - doped ceramic water filter and that of bovine (cow) Bone - doped ceramic water filter. The sintering temperatures used are 850oC, 900oC and 950oC for making the ceramic water filters. Equally, a study on the effect of sintering temperature on the flow rate and bacteria removal of disc-shaped ceramic water filter was conducted. Also study was done on mechanical properties of the CWFs. The purpose of the first study was to maximize fluoride and bacteria removal from contaminated water from groundwater sources with very high fluoride contents, such as boreholes and wells, to make them safe for drinking. The CWFs were manufactured from clay, sieved sawdust and either HA or Bone in a 30:50:20 volume proportion. Firing of the mixtures at temperature of 850oC and 900oC resulted in the pyrolysis of the sawdust and sintering of the clay matrix and HA or Bone particles to produce micro - and nano-porous structures. The CWFs doped with HA and Bone has similar flow rates, which were dependent on sintering temperature. Fluoride removal efficiency decreased with increasing temperature but was higher for the Bone - doped than for the HA - doped CWFs. Fluoride adsorption was modeled using the Freundlich isotherm equation, which revealed that adsorption was spontaneous but heterogeneous. E. coli removal efficiency was also higher for the Bone - doped than for the HA - doped CWFs. Taken together, Bone - doped CWFs sintered at 850oC maximized both the fluoride and bacteria removal efficiencies. The implications of these outcomes are discussed for the design of point-of-use CWFs for the filtration of fluoride and microbial pathogens from groundwater sources. The second study was designed to optimize the bacteria removal efficiency of the CWFs for potential application as point-of-use filters to produce potable water from contaminated water. The CWFs were made from a mixture of clay (ceramic matrix) and sieved sawdust (porogen) in a 50:50 volume proportion. The mixtures were heated at temperatures of 850oC, 900oC and 950oC resulting in the pyrolysis of the mixture. The porosities and pore sizes of the CWFs depended on their sintering temperatures. The flow rates were influenced by the porosity and pore sizes of the CWFs and were large for high sintering temperatures. The E. coli removal efficiency was inversely related to the sintering temperature, through the porosity and flow rate, as manifested in the log removal values (LRV) of 4.89, 4.59 and 4.46 obtained for CWFs sintered at 850oC, 900oC and 950oC, respectively.