The Use of a Full-Scale Fluidized Bed Bioreactor System for the Treatment of Perchlorate in Groundwater to Drinking Water Standards
Shaw Environmental, Inc, in collaboration with the City of Rialto and the Environmental Security Technology Certification Program (ESTCP), has conducted a demonstration study to treat perchlorate laden groundwater to drinking water standards using a fluidized bed biological reactor
treatment train (FBR). This study focused on demonstrating: (1) the bioremediation of nitrate and perchlorate contaminated groundwater to current method reporting limits through a fluidized bed bioreactor with an added electron donor; (2) the short- and long-term performance effects in self-inoculating
the system with the incoming groundwater; (3) the resulting short-term performance effects in the simulation of both a feed pump failure and an electrical shutdown; (4) the use of on-line, nitrate and perchlorate analyzers to continuously monitor the system treatment performance and to provide
feed-forward control of the electron donor addition; (5) the use of a post aeration vessel, multimedia filter, and liquid granular activated carbon (LGAC) to produce a potable-like effluent water stream; and (6) the disinfection effects via chlorination and ultraviolet light on the system
For the study, all of the objectives were met or successfully demonstrated. Using only the groundwater to microbiologically seed the system, the FBR treatment plant removed all of the nitrate and perchlorate at the design loading conditions to meet the State of California Public
Health Goal standards. In addition, the downstream equipment was operated to produce an effluent water of potable quality, meeting all State of California primary and secondary MCL requirements established under Title 22. The restart of the plant after the artificially induced system interruptions
was rapid and required less than 24 hours to achieve acceptable treatment performance. The use of on-line instrumentation for rapid analysis of system performance proved effective and reliable. Such instrumentation was able to effectively control the feed rate of acetic acid, the chosen electron
donor, to meet all performance objectives. Finally, chlorination disinfection studies indicated that E.Coli was not formed within the system, disinfection byproduct formation potential did not exceed State of California water standards, and microbial effluent concentrations could be
effectively controlled using a CT value of 4.
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