Feasibility of biological ion exchange in removal of organic carbon from drinking water at different temperatures

Removing organic carbon (OC) from drinking water effectively while utilizing technologies that are both low cost and easy to operate poses challenges. Current available technologies are either very complex, expensive and/ or cannot achieve high removal efficiencies. Conventional biological filtration has long been used to remove OC from water however it has not done so effectively and therefore cannot be used as a standalone technology. Biological ion exchange (BIEX) is a new technology that promises to address the limitations of existing technologies. Initial studies have indicated that this technology is effective at reducing OC in water, further studies are needed to optimize the design parameters under a variety of environmental conditions. Previous studies on conventional (BAC) biofilters have indicated that empty bed contact time (EBCT) and operating temperature influences the efficacy of OC removal. The objective of the present study is to determine the EBCT needed in BIEX biofilters to effectively remove NOM at different temperatures. To determine the impact of EBCT on OC removal biofilters at three different EBCT (7.5, 15 and 30-minutes) and three different temperatures (4, 10 and 20°C) were operated for 150 days. Results from the present research indicate that BIEX biofilters more effectively remove OC from water than BAC biofilters. BIEX biofilters remove 46.5-77.5% OC while BAC biofilters remove 4.6-31.3% OC depending on the experimental conditions (temperature and EBCT). Statistical analysis indicated that both temperature and EBCT significantly impact OC removal in both BIEX and BAC biofilters. The temperature activity coefficients were calculated to be 1.044 and 1.066 for BIEX and BAC biofilters respectively indicating that temperature has a greater impact on OC removal for BAC biofilters than for BIEX biofilters. The rate constant for removal of OC was calculated for both BIEX and BAC biofilters and ranged from 0.156 to 0.312 min⁻¹ and 0.034 to 0.108 min⁻¹ respectively. These results indicate that BIEX biofilters can also remove OC at a higher rate than BAC biofilters. To ensure adequate removal of OC at all temperatures that were tested (90% removal of OC) BIEX and BAC biofilters require an EBCT of 55-minutes and 90-minutes respectively.Applied Science, Faculty ofCivil Engineering, Department ofGraduat