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The phenomenon of nitrogen and phosphorus removal in aerated biological reactors where no formal anoxic or anaerobic zones are present is referred to as simultaneous biological nutrient removal (SBNR). One possible mechanism for SBNR is the development of anoxic/anaerobic zones within floc particles (designated the floc microenvironment). A better understanding of the mechanisms of SBNR can provide a basis for the rational design of dispersed growth systems optimized for SBNR. In this research, a bench-scale CSTR was used to simulate an activated sludge system and maintain typical conditions observed at treatment plants for in situ microprobe measurements of floc particles. Microprobes were used to obtain pH and dissolved oxygen (DO) profiles through floc particles. The results show that anoxic zones exist within floc particles of sufficient diameter. Profiles of pH were also taken and found to remain relatively constant through a floc particle. Initial results suggest that time of floc growth and floc sizes have direct effects on the size of the intraparticle anoxic zone. Shearing of the floc, or reducing the floc size, is believed to be detrimental to the presence of intraparticle anoxic zones.

Document Type: Research Article


Publication date: 2000-01-01

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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