A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities.

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD(1) and nitrogen species(2-4) by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sedimentation processes while still yielding effluent containing low suspended solids.

Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment.

The occurrence of autotrophic denitrification and nitrification activities by ammonia-oxidising bacteria and nitrite-oxidising bacteria is studied in a bioreactor system operable at low-dissolved oxygen (DO) and at variable oxygen influx rates. At a loading of 3.6 mg NH4(+)-N/h into the bioreactor, simultaneous autotrophic denitrification and nitrification contributed to NH4(+)-N removal over oxygen influxes of 2-14 mg O2/h and DO <0.

Analysis of an upflow bioreactor system for nitrogen removal via autotrophic nitrification and denitrification.

The upflow bioreactor system without biomass-liquid separation unit was evaluated for its efficacy in sustaining autotrophic nitrification and denitrification (AND). The bioreactor system was capable of sustaining AND by means of carefully controlled oxygenation to achieve the maximum NH(4)(+)-N removal rate of 0.054 g N gVSS(-1) day(-1) (38% removal efficiency) at the oxygen influx and nitrogen loading rate of 3.

Performance of an aerobic/anaerobic hybrid bioreactor under the nitrogen deficient and low F/M conditions.

A bioreactor system without a biomass-liquid separation unit is evaluated for its chemical oxygen demand (COD) removal and biomass retention capabilities under the nitrogen deficient and low F/M conditions that are known to produce bulking biomass. A fully oxygenated stream recycled from an external oxygenator delivers the oxygen to an upflow bioreactor in which a biomass zone is formed and maintained in the absence of gas effervescence. COD is removed with up to 90% efficiency by means of aerobic and anaerobic bacterial activities occurring in the biomass zone.

Impulse responses of a monoethylamine-fed fluidized bed reactor.

The responses of a steady-state, continuous-flow, completely-mixed fluidized bed reactor (FBR) to a range of monoethylamine (MEA) impulses are analyzed in terms of its combined carbon oxidation and nitrification efficiencies. Immobilized cells are cultivated at a mean cell residence time (MCRT) that exceeds 75 days. Responses due to bacterial activities and physical flows are separately estimated using a methodology based on mass balance calculations.