An experimental study on aerobic denitrification with polyvinyl alcohol as a carbon source in biofilms

Abstract

Aerobic denitrification occuring in the biofilms attached to a partially submerged RBC, was investigated. Denitrification using polyvinyl alcohol (PVA) as a organic carbon source, was well proceeded by aerobic RBC systems at 25 °C. At an influent C/N ratio of around 1.2, the maximum net-denitrification efficiency was about 78% at a TOC loading of 2g/m2/d. In a chemostat experiment, aerobic denitrification was well proceeded under the dissolved oxygen concentration of 3 to 6 mg/L. The PVA-decomposing bacteria, nitrifiers, and denitrifiers co-existed in the biofilm, but the population of PVA-decomposing bacteria and denitrifiers in the surface layer was 1 to 2 orders of magnitude higher than those in the middle and bottom layers. It may indicate that the surface layer had a higher denitrifying activity. The nitrogen mass balance obtained using the experimental data clearly indicates a reasoning for aerobic denitrification.

Denitrification and nitric oxide reduction in an aerobic toluene-treating biofilter

“…Apparent CBND is often ascribed to aerobic conditions outside a biomass floc or soil aggregate with anaerobic or anoxic conditions prevailing in the interior. Bang et al (1995), however, presented evidence that CBND did indeed occur, even in the absence of spatial complexity, such as aggregation, and thus anoxic microsites. The experimental approach in this study was to determine: (1) whether denitrification would occur within a superficially aerobic toluene-treating biofilter; and (2) whether such a system could be utilized for NO reduction.…”

Denitrification in a closed rotating biological contactor: effect of disk submergence

“…These authors also consider that extensive process design information with respect to disk submergence is still not available in the literature. Several studies have employed rotating biological contactors for nitrogen removal [4][5][6][7][8]. However, partially submerged disks are used for nitrification, while completely submerged disks are used for denitrification.…”