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Chloraminated Drinking Water Distribution System Nitrification: Batch and Biofilm Inactivation Studies, Model Nitrifying Biofilm Investigations, and Evaluation of Operational Responses to Nitrification Episodes
Citation:
LATHAM, M. AND J. G. PRESSMAN. Chloraminated Drinking Water Distribution System Nitrification: Batch and Biofilm Inactivation Studies, Model Nitrifying Biofilm Investigations, and Evaluation of Operational Responses to Nitrification Episodes. U.S. Environmental Protection Agency, Washington, DC, EPA/600/F-10/009, 2010.
Impact/Purpose:
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Description:
Studies are currently underway to help fill knowledge gaps that exist in the general understanding of nitrification episodes. One of these gaps includes the need for growth and inactivation kinetic parameters for nitrifiers representative of those inhabiting distribution systems to be used in modeling nitrification processes. In order to fill this gap, new molecular genetics techniques are being used to study both the growth and inactivation kinetics of pure and mixed culture nitrifiers. Another major gap in our understanding of nitrification events is the relative contribution from suspended culture nitrifiers compared with nitrifiers growing in biofilm. Nitrifying biofilm research is ongoing with new microelectrodes capable of probing the full depth of a model distribution system biofilm, determining the profile of the relevant water quality parameters and enabling calculations of the relative contribution of biofilm nitrification. For development and application of the microelectrodes, EPA’s National Risk Management Research Laboratory researchers are collaborating with The University of Cincinnati to develop, validate, and utilize a total chlorine microelectrode to measure disinfectant profiles within a nitrifying biofilm. In addition to the microelectrode investigations, biofilm annular reactors enriched for AOB biofilm growth are being used to assess the temporal changes to nitrifying biofilm community structure after receiving periodic increases in chloramines. The results of these annular reactor experiments may help elucidate which AOB species are most resistant to chloramines. In the future, current operational responses to nitrification episodes will be evaluated with respect to their effect on the biofilm.
URLs/Downloads:
CHLORAMIN DW DIST SYS NITRIFICATION: BATCH & BIOFILM INACT STUDIES, MODEL NITRIFY BIOFILM INVEST, & EVAL OF OPER RESPONSES TO NITRIFICATION EPISODESFact Sheet (PDF, NA pp, 188 KB, about PDF)