Nitrifying bacterial communities and its activities in aerobic biofilm reactors under different temperature conditions

Abstract

Tests were performed to investigate nitrifying bacterial communities and activities in aerobic biofilm reactors with different temperature conditions, denaturing gradient gel electrophoresis (DGGE) based on polymerase chain reaction targeting 16S rRNA and amoA gene, fluorescence in situ hybridization (FISH) and dehydrogenase activity (DHA). T1, T2 and T3 reactors operated at different temperatures (5, 10 and 30 o C, respectively) were set up in the thermostat and acclimated. Nitrification was considerably limited in T1 and T2 reactors. DGGE revealed specific genera of ammonium-oxidizing bacteria (AOB) and some Nitrosomonas genera endured at the low temperatures. FISH revealed a decreased distribution ratio between AOB and nitrate-oxidizing bacteria at 5 o C, and showed that the decrease of AOB also affected the nitrification failure in the aerobic biofilm reactor. The mean attached biomass of the T1, T2 and T3 reactors was 69.6, 80.6 and 112.9 mg/L, respectively, and the 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride dehydrogenase activity of the respective reactors was 73.6, 87.4 and 134.2 mgO 2 * /g VSS/day. The results demonstrate that a low temperature condition in an aerobic biofilm reactor decreases the attached biomass, distribution ratio and activity of nitrifying bacteria, and produces a change in the composition of the AOB species, which results in the failure of nitrification.

Ammonia oxidizing bacterial community composition and process performance in wastewater treatment plants under low temperature conditions

“…These results suggest a seasonal shift in the ammonia oxidizing community at Vasterâs between December and February resulting in increased diversity. Park et al (2009) highlighted the relevance of temperature in terms of AOB community diversity and variations in the AOB community composition were reported as one of the reasons for nitrification failure (Park et al 2008). However, at Vasterâs the nitrification rates remained constant even though the AOB community changed.…”

Evaluating the performance of activated sludge ammonia oxidizing bacteria in a lab-scale alternating hypoxic/oxic membrane bioreactor

“…Stable and complete nitrification in H/O MBR results from the adaptive response [10] of activated sludge AOB to alternating hypoxic/oxic condition rather than from the selection mechanism [11,12,29] by low DO condition. This finding can be supported by some direct and indirect evidence from the results of alternating hypoxic/oxic batch assay and subsequent molecular microbiological analyses.…”

Laboratory assessment of biofilm process and its microbial characteristics for treating nonpoint source pollution

“…4(a), a reaction time of at least 15 h was required to accomplish stable COD removal at 10 o C. The nitrification efficiencies after 24 hs for interevent periods of 0, 5, 10 and 15 d were 96.1, 96.9, 56.3 and 4.8%, respectively. These results indicate that a low temperature has a greater influence on nitrification than on COD removal; nitrification is considerably limited with interevent periods above 10 d. Park et al [26] reported that a low temperature in an aerobic biofilm reactor causes decreases in attached biomass, distribution ratio and activity of nitrifying bacteria, as well as facilitating an altered ammonia-oxidizing bacteria (AOB) species composition. In this study, it also became clear that the nitrifying bacteria were more sensitive to temperature than were heterotrophic bacteria.…”