The Removal of Nitrate from Solution by Floc‐forming Bacteria on Decomposing Cellulose Particles

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Abstract
Summary: Cellulose particles in aerated liquid medium inoculated with activated sludge quickly became enveloped in floccular microbial growth (cellulose floc) able to assimilate nitrate rapidly from solution. Sedimenting the floc removed assimilated nitrogen, excess cellulose and biomass. At 18 and 22°, nitrate was removed from solution at 1·76 and 1·83 μg of nitrate‐N/ml/h, respectively. Similar results were found with floc formed by a cellulose decomposing isolate and some noncellulolytic floc‐forming bacterial contaminants. Washed preformed cellulose floc removed nitrate from dilute solution at 0·89 μg of nitrate‐N/ml/h at pH 7·1–8·6. The C : N ratio of the supernatant fluid changed rapidly as nitrate became exhausted; the significance of this is considered in relation to complete removal of C and N by further biological oxidation.