AWWA WQTC71509

This study investigated the possibility of mineral (biotite, bentonite, fuller's earth) amendment to Fe(0)-based treatment system in the groundwater for enhancing nitrate reduction. It was expected that amendment of mineral surfaces enhances nitrate reduction by providing surfaces to form green rusts or reaction precipitates to prevent passivation of Fe(0) surfaces, as well as to adsorb produced ammonium. Batch tests for kinetics experiments were conducted by adding 20 mL solutions to 25 mL plastic vials containing 0.5 g of Fe(0) and 0.5 g of minerals. Other experiments were carried out by changing the amount of bentonite, fuller's earth, and biotite (0.01-0.5 g) in vials containing 0.5 g of Fe(0) with GW solutions. The reduction experiments were performed at room temperature (25±0.2ºC) for 64 h. The adsorption experiments were performed with bentonite and fuller's earth by batch method for 24 h. All the samples were shaken by a shaking incubator (shaking water bath, BS-31) with 150 rpm, filtered through 0.45 µm PVDF filter (Whatman) and diluted for NO₃^-, NH₄ ⁺ analysis. Nitrate, sulfate, and chloride concentrations were measured by ion chromatography (Dionex CX-120). Ammonium was measured using Nessler method with UV/VIS spectrophotometer (DR4000/HACH). The solution pH in batch experiments was measured using a pH meter (Horiba, Ltd. Kyoto, Japan). The concentrations of cations in groundwater were measured by inductively coupled plasma-optical emission spectrometer (ICP-OES, Ultima 2C, Horiba). Includes 34 references, tables, figures.