Impact of periods of no inflow on dissolved organic carbon (DOC) removal by Biological Ion Exchange (BIEX) systems

Biological Ion Exchange (BIEX) offers effective removal of dissolved organic carbon (DOC) from surface waters without the need for frequent regeneration, making it suitable for small and remote communities. Traditional work hours, night routines, and system maintenances can impose conditions in small and remote communities, where inflow of water to be treated is highly variable, and possibly intermittent. The present study investigated the impact of periods of no inflow on DOC removal by BIEX systems. Various operating conditions were applied to the BIEX systems, to investigate if the extent of the potential impacts of periods of no inflow were influenced by the duration and/or frequencies of these periods. Effluent recirculation within the BIEX systems were also considered as a means to mitigate the extent of the potential impacts of periods of no inflow. The results of the present study indicated that three phases with distinct treatment mechanisms occurred in the BIEX systems: primary IEX, secondary IEX, and stunted secondary IEX (i.e., biodegradation). Considering these three phases of treatment, in general, operation of BIEX systems with periods of no inflow impacted DOC removal. The extent of the potential impacts of no inflow on DOC removal was also affected by the duration and/or frequency of the periods of no inflow. DOC removal in BIEX systems operated with a daily and short (~3h) period of no inflow and a weekly and long (~2d) period of no inflow were similar to continuous operations. However, a daily and long (~8h) period of no inflow resulted in a lower DOC removal than continuous operations. Also, in general, extent of the potential impacts of operation with periods of no inflow on DOC removal could not be mitigated by effluent recirculation within the BIEX systems. Overall, the study offered insight into operation of BIEX systems with periods of no inflow and the impact of the duration and/or frequency of periods of no inflow as well as effluent recirculation on the DOC removal performance. The results of the present study concluded BIEX systems can maintain water quality even under periods of no inflow.Applied Science, Faculty ofCivil Engineering, Department ofGraduat