A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities

摘要

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 COD¹ 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. In this study, the HDBR is applied as a photobioreactor (PBR) in order to characterize the nitrogen removal characteristics of an algae-based photosynthetic microbial community. As previously reported for this HDBR design, a stable biomass zone was established with a clear delineation between the biologically active portion of the reactor and the recycling reactor fluid, which resulted in a low suspended solid effluent. The algal community in the HDBR was observed to remove 18.4% of total nitrogen species in the influent. Varying NH4⁺ and NO3^- concentrations in the feed did not have an effect on NH4⁺ removal (n=44, p=0.993 and n=44, p=0.610 respectively) while NH4⁺ feed concentration was found to be negatively related with NO3^- removal (n=44, p=0.000) and NO3^- feed concentration was found to be positively correlated with NO3^- removal (n=44, p=0.000). Consistent removal of NH4⁺, combined with the accumulation of oxidized nitrogen species at high NH4⁺ fluxes indicates the presence of ammonia- and nitrite-oxidizing bacteria within the microbial community.