The effects of organic carbon ammoniacalnitrogen

Authors: Timothy M LaPara Alina C Cole John W Shanahan Michael J Semmens

Publish Date: 2005/11/15

Volume: 33, Issue: 4, Pages: 315-323

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Abstract

The purpose of this study was to examine the effects of different nutrient carbon nitrogen oxygen concentrations on the microbial activity and community structure in membraneaerated biofilms MABs MABs were grown under welldefined conditions of fluid flow substrate concentration and membrane oxygen partial pressure Biofilms were then removed and thinsliced using a cryostat/microtome parallel to the membrane Individual slices were analyzed for changes with depth in biomass density respiratory activity and the population densities of ammoniaoxidizing and denitrifying bacteria populations Oxygensensing microelectrodes were used to determine the depth of oxygen penetration into each biofilm Our results demonstrated that ammoniaoxidizing bacteria grow near the membrane while denitrifying bacteria grow a substantial distance from the membrane However nitrifying and denitrifying bacteria did not grow simultaneously when organic concentrations became too high or ammonia concentrations became too low In conclusion membraneaerated biofilms exhibit substantial stratification with respect to community structure and activity A fundamental understanding of the factors that control this stratification will help optimize the performance of fullscale membraneaerated biofilm reactors for wastewater treatmentThis research was funded by National Science Foundation grant BES 0123394 Water Environment Research Foundation grant WERF/00CTS11 and a Graduate Assistantship in Areas of National Need GAANN fellowship to ACC from the US Department of Education

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