Development of an Iron-Oxide Coated Ceramic Filter for Removal of As(III) and As(V) in Developing Nations

Abstract

Over 4,000 children die each day due to diarrheal diseases which are often related to drinking unsafe water, and are often preventable with proper water treatment. Many regions of the world also suffer from high levels of arsenic due to natural and/or anthropogenic sources. Chronic arsenic poisoning leads to many maladies including skin, bladder and lung cancer, as well as non-carcinogenic arsenicosis symptoms including hyperpigmentation of skin, thickening hands and feet, and skin lesions. A new point-of-use (POU) technology using conventional ceramic filters coated with a ferric-iron coating to achieve simultaneous arsenic (III) and (V) removal along with filtrative disinfection has been developed in the research for this thesis. The Iron-Oxide Coated Ceramic Filter (IOCCF) is produced using the standard ceramic filter methods (see www.pottersforpeace.org) leading to a porous clay pot that will filter out most pathogens. The iron was shown to bond strongly with the ceramic filter such that no iron leaching occurs. Experiments were conducted on ceramic micro-columns prepared to have the exact thickness and properties of a full-scale ceramic filter. While no significant arsenic removal is achieved in a traditional ceramic filter, the IOCCF was shown to be capable of filtering arsenic for long periods of time with essentially no As breakthrough. For example, As concentrations in source water can be easily reduced from 250 µg/L to less than the 10 µg/L WHO and EPA guideline for arsenic for over 365 effective filter runs. As(V) was sorbed more effectively at lower pH values while sorption of As(III) was not as sensitive to pH. However, there was not a large difference in As(V) or As(III) removal performance over a pH range of 6 to 9. Filtration of lake water containing NOM reduced performance of As(III) and As(V) removal, but the IOCCF still removed both As species from natural water for a significant number of filter runs. As(III) and As(V) remain strongly adsorbed at normal pH levels, however more research is needed on this topic. Results also showed that the IOCCF retained the bacterial removal capabilities of the Potters for Peace Filter.