INVESTIGATING THE ABILITY OF WATER TREATMENT RESIDUALS TO FILTER CONTAMINANTS**

Surface water and groundwater resources are easily impacted by contamination from agriculture (both plant and livestock farming). When surface water runs off farms, receiving bodies of water may become impaired due to the presence high nutrient concentrations (that possibly cause algal blooms) and pathogens. Algae can produce toxins and algal blooms can reduce available oxygen in the water impacting water quality. Pathogens in the water also contribute to waterborne illnesses in animals and humans. Alum is a coagulant used to assist in the drinking water treatment process for removing suspended clay particles, resulting in water treatment residuals (WTRs). Treatment plants have a surplus of WTRs and there are currently no national regulations regarding their disposal or viable alternative uses for them. Due to the aluminum applied in the treatment process, WTRs are inclined to adsorb anionic particles. It is already established that WTRs can successfully adsorb phosphorus from water, so the current study aims to investigate whether nitrate and bacteria can also be removed from water using WTRs. Vertical and slanted column experiments were performed to evaluate the adsorption and filtration capacity. Varying concentrations of standard solutions of nitrate and bacteria were run through the columns and the concentrations measured at the outlet. A field trial will also be conducted to test the ability of a WTR filter to readily remove phosphorus, nitrate, and microbes from surface water. Preliminary results showed a nitrate reduction of 10-20% when the initial standard concentrations were between 23 mg/L and 90 mg/L. No reduction was present for the 10 mg/L concentration. This study also showed a slight reduction in bacteria concentrations. These preliminary results indicate potential of WTRs to be used as a filter for farm runoff to protect water quality