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Accumulating Organisms (accumulating + organism)
Selected AbstractsWhich are the polyphosphate accumulating organisms in full-scale activated sludge enhanced biological phosphate removal systems in Australia?JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006M. Beer Abstract Aims:, To see if the compositions of the microbial communities in full scale enhanced biological phosphorus removal activated sludge systems were the same as those from laboratory scale sequencing batch reactors fed a synthetic sewage. Methods:, Biomass samples taken from nine full scale enhanced biological phosphate removal (EBPR) activated sludge plants in the eastern states of Australia were analysed for their populations of polyphosphate (polyP)-accumulating organisms (PAO) using semi-quantitative fluorescence in situ hybridization (FISH) in combination with DAPI (4,-6-diamidino-2-phenylindole) staining for polyP. Results:, Very few betaproteobacterial Rhodocyclus related organisms could be detected by FISH in most of the plants examined, and even where present, not all these cells even within a single cluster, stained positively for polyP with DAPI. In some plants in samples from aerobic reactors the Actinobacteria dominated populations containing polyP. Conclusions:, The PAO populations in full-scale EBPR systems often differ to those seen in laboratory scale reactors fed artificial sewage, and Rhodocyclus related organisms, dominating these latter communities may not be as important in full-scale systems. Instead Actinobacteria may be the major PAO. Significance and Impact of the Study:, These findings illustrate how little is still known about the microbial ecology of EBPR processes and that more emphasis should now be placed on analysis of full-scale plants if microbiological methods are to be applied to monitoring their performances. [source] Dynamic peroxide method for kLaO2 estimationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2009Marcos Marcelino Abstract BACKGROUND: A reliable kLaO2 estimation methodology in bioreactors is a recurrent topic in the literature owing to the significance of this value, particularly in respirometric measurements. The most common methodologies for kLaO2 estimation consist of modeling the profile of dissolved oxygen (DO) obtained after a perturbation of the system aeration. Among them, the dynamic peroxide method (DPM), which consists of a small addition of peroxide hydrogen for a sudden increase in the DO level, is a promising methodology. RESULTS: This work studies the reliability of kLaO2 estimates using DPM. Different experiments were performed with sludge cultures enriched with heterotrophs, nitrifiers and polyphosphate accumulating organisms (PAO). The influence of several operational conditions (i.e. air flow, sludge concentration, H2O2 volume addition) on kLaO2 estimates was studied and the reliability of DPM was compared with the widely used reaeration methodology. An application of DPM in the assessment of oxygen surface transfer in a mechanically stirred bioreactor is described. CONCLUSION: DPM is a reliable methodology for kLaO2 estimation that can be successfully applied to heterotrophs, nitrifiers and PAO without observing any inhibitory effect ([H2O2] , 6 mg L,1). Copyright © 2009 Society of Chemical Industry [source] The beneficial role of intermediate clarification in a novel MBR based process for biological nitrogen and phosphorus removalJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009MinGu Kim Abstract BACKGROUND: A novel membrane bioreactor (MBR) is described, employing an intermediate clarifier. Unlike the established function of a final clarifier in a conventional biological nutrient removal system, the role of an intermediate clarifier has rarely been studied. Thus, this work focused on explaining the fate of nutrients in the intermediate clarifier, as influenced by the hydraulic retention time (HRT) of the preceding anaerobic bioreactor. RESULTS: The system was tested with two different anaerobic/anoxic/aerobic biomass fractions of 0.25/0.25/0.5 (run 1) and 0.15/0.35/0.45 (run 2) using synthetic wastewater. The major findings of the study were that phosphorus (P) removal was affected by the role of the intermediate clarifier. In run 1, P was removed at a rate 0.16 g d,1 in the intermediate clarifier while in run 2, additional P was released at 0.49 g d,1. The nitrogen (N) removal efficiencies were 74 and 75% for runs 1 and 2 respectively, while P removal was 91 and 96%. P uptake by denitrifying phosphate accumulating organisms (DPAOs) accounted for 41,52% of the total uptake in the MBR. CONCLUSIONS: This study found that the intermediate clarifier assisted chemical oxygen demand (COD), N, and P removal. With respect to the fate of P, the intermediate clarifier functioned as an extended anaerobic zone when the HRT of the preceding anaerobic zone was insufficient for P release, and as a pre-anoxic zone when the anaerobic HRT was adequate for P release. Copyright © 2008 Society of Chemical Industry [source] Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full-scale WWTPAICHE JOURNAL, Issue 6 2010Bing-Jie Ni Abstract In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio-P model with an incorporation of the two-step nitrification,denitrification, the anoxic P uptake, and the associated two-step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full-scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH -N, NO -N, NO -N, PO -P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full-scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The utilization of glycogen accumulating organisms for mixed culture production of polyhydroxyalkanoatesBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009*Article first published online: 15 JUN 200, Simon Bengtsson Abstract Production of polyhydroxyalkanoates (PHAs) by an open mixed culture enriched in glycogen accumulating organisms (GAOs) under alternating anaerobic,aerobic conditions with acetate as carbon source was investigated. The culture exhibited a stable enrichment performance over the 450-day operating period with regards to phenotypic behavior and microbial community structure. Candidatus Competibacter phosphatis dominated the culture at between 54% and 70% of the bacterial biomass throughout the study, as determined by fluorescence in situ hybridization. In batch experiments under anaerobic conditions, PHA containing 3-hydroxybutyrate (3HB) and 27,mol-% 3-hydroxyvalerate (3HV) was accumulated up to 49% of cell dry weight utilizing the glycogen pool stored in the SBR cycle. Under aerobic and ammonia limited conditions, PHA comprising only 3HB was accumulated to 60% of cell dry weight. Glycogen was consumed during aerobic PHA accumulation as well as under anaerobic conditions, but with different stoichiometry. Under aerobic conditions 0.31 C-mol glycogen was consumed per consumed C-mol acetate compared to 0.99 under anaerobic conditions. Both the PHA biomass content and the specific PHA production rate obtained were similar to what is typically obtained using the more commonly applied aerobic dynamic feeding strategy. Biotechnol. Bioeng. 2009; 104: 698,708 © 2009 Wiley Periodicals, Inc. [source] | |||||||||||||