Research Publication Title

ASSESSING WATER TREATMENT RESIDUALS ABILITY TO FILTER PATHOGENS AT PH LEVELS AND IONIC STRENGTHS COMMONLY FOUND IN GEORGIA SOILS USING RHODAMINE-COATED MICROPARTICLES**

Presenter Information

Callum LeverFollow

Major

Environmental Science

Faculty Mentor(s)

Dr. Allison VandeVoort Dr. Samuel Mutiti

Keywords

Water Treatment Residuals, Pathogens, Water Contamination, Rhodamine, Filtration

Abstract

Water treatment residuals (WTRs), a byproduct of surface drinking water treatment, were studied for their ability to filter contaminants through column flow experiments. WTRs have strong potential as a filtration medium due to their high clay content, and high numbers of sorption sites. The WTRs used were sourced from the Sinclair Water Authority and were composed primarily of kaolinite clay. Quartz sand is widely used for filtration, and was used as a control. Rhodamine-coated microparticles (RMPs) were used as proxies for pathogens including large bacteria such as Salmonella enterica and small protozoa such as Cryptosporidium because they are of similar size, 4 μm. Column flow experiments were run to test WTR and sand filtration ability under varying solution chemistry at two pH levels (5 and 8) and two different ionic strengths (3 mM and 15 mM) representative of environmental conditions found in Georgia. The pH and ionic strength changes alter the surface charge and potentially sorption of RMPs onto WTRs and quartz sand. A chlorine tracer was used to asses the speed of water through the mediums. Preliminary data shows WTRs had a small retardant effect on the RMP compared to the normal flow of water through the column, but also had created preferential flow and moved RMPs through the column more quickly. The different combinations of pH and ionic strength did not have a significant difference on the retardation of the RMP. In the sand columns the RMP was filtered out almost immediately leaving a pink ring in the first 1 cm of the medium. This happened for all conditions tested. This shows sand is superior for filtering pathogens, but WTR have some ability to slow the pathogen movement.

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ASSESSING WATER TREATMENT RESIDUALS ABILITY TO FILTER PATHOGENS AT PH LEVELS AND IONIC STRENGTHS COMMONLY FOUND IN GEORGIA SOILS USING RHODAMINE-COATED MICROPARTICLES**

Water treatment residuals (WTRs), a byproduct of surface drinking water treatment, were studied for their ability to filter contaminants through column flow experiments. WTRs have strong potential as a filtration medium due to their high clay content, and high numbers of sorption sites. The WTRs used were sourced from the Sinclair Water Authority and were composed primarily of kaolinite clay. Quartz sand is widely used for filtration, and was used as a control. Rhodamine-coated microparticles (RMPs) were used as proxies for pathogens including large bacteria such as Salmonella enterica and small protozoa such as Cryptosporidium because they are of similar size, 4 μm. Column flow experiments were run to test WTR and sand filtration ability under varying solution chemistry at two pH levels (5 and 8) and two different ionic strengths (3 mM and 15 mM) representative of environmental conditions found in Georgia. The pH and ionic strength changes alter the surface charge and potentially sorption of RMPs onto WTRs and quartz sand. A chlorine tracer was used to asses the speed of water through the mediums. Preliminary data shows WTRs had a small retardant effect on the RMP compared to the normal flow of water through the column, but also had created preferential flow and moved RMPs through the column more quickly. The different combinations of pH and ionic strength did not have a significant difference on the retardation of the RMP. In the sand columns the RMP was filtered out almost immediately leaving a pink ring in the first 1 cm of the medium. This happened for all conditions tested. This shows sand is superior for filtering pathogens, but WTR have some ability to slow the pathogen movement.