Influence of growth manner on nitrifying bacterial communities and nitrification kinetics in three lab-scale bioreactors

Abstract

The effects of growth type, including attached growth, suspended growth, and combined growth, on the characteristics of communities of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were studied in three lab-scale Anaerobic/Anoxic(m)-Oxic(n) (AmOn) systems. These systems amplified activated sludge, biofilms, and a mixture of activated sludge and biofilm (AS-BF). Identical inocula were adopted to analyze the selective effects of mixed growth patterns on nitrifying bacteria. Fluctuations in the concentration of nitrifying bacteria over the 120 days of system operation were analyzed, as was the composition of nitrifying bacterial community in the stabilized stage. Analysis was conducted using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR. According to the DGGE patterns, the primary AOB lineages were Nitrosomonas europaea (six sequences), Nitrosomonas oligotropha (two sequences), and Nitrosospira (one sequence). The primary subclass of NOB community was Nitrospira, in which all identified sequences belonged to Nitrospira moscoviensis (14 sequences). Nitrobacter consisted of two lineages, namely Nitrobacter vulgaris (three sequences) and Nitrobacter alkalicus (two sequences). Under identical operating conditions, the composition of nitrifying bacterial communities in the AS-BF system demonstrated significant differences from those in the activated sludge system and those in the biofilm system. Major varieties included several new, dominant bacterial sequences in the AS-BF system, such as N. europaea and Nitrosospira and a higher concentration of AOB relative to the activated sludge system. However, no similar differences were discovered for the concentration of the NOB population. A kinetic study of nitrification demonstrated a higher maximum specific growth rate of mixed sludge and a lower half-saturation constant of mixed biofilm, indicating that the AS-BF system maintained relatively good nitrifying ability.

Treatment of Slaughter House Wastewater in a Sequencing Batch Reactor: Performance Evaluation and Biodegradation Kinetics

“…Biological treatment of wastewater containing organic carbon and nitrogen (COD and TKN) is also carried out in laboratory and pilot scale experiment by several researchers successfully [18–26]. Nutrients in piggery wastewater with high organic matter, nitrogen, and phosphorous content were biological removed by Obaja et al [27] in a sequencing batch reactor (SBR) with anaerobic, aerobic, and anoxic stages.…”

Effect of Methylisothiazolinone on Biological Treatment: Efficiency of SBRs and Bioindicative Studies

“…Although the system is too complex to attribute this effect to a single cause, MIT might play an important role in the inhibition of nitrification by autotrophic bacteria (Zanetti et al, 2012, Feng Wang et al, 2012, as other important operational parameters remained constant throughout the experiment (pH, temperature, dissolved oxygen concentration and alkalinity) and nitrite concentration in the effluent was systematically below 2 mg L -1 after the complete cycle. It is worth commenting that the low final values of nitrite could be attributed to the action of heterotrophic bacteria during the anoxic phase of the cycle.…”

Nitrogen removal in a moving bed membrane bioreactor for municipal sewage treatment: Community differentiation in attached biofilm and suspended biomass

“…In WWTPs, it is known that the stability of nitrification relies on several operating conditions, such as solids concentration, temperature, SRT, pH, HRT and COD concentration of the influent [29,30]. However, according to Wang et al [31], the relationships between operational conditions and the dynamics of nitrifying bacteria remain unresolved.…”