ORCID Profile
0000-0002-3514-806X
Current Organisation
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Wastewater Treatment Processes | Chemical Engineering | Water Treatment Processes | Environmental Technologies | Water treatment processes | Chemical engineering | Environmental Science and Management | Environmental Chemistry (incl. Atmospheric Chemistry) | Environmental Engineering Modelling | Environmental Monitoring | Climate change impacts and adaptation not elsewhere classified | Public health not elsewhere classified
ANZSRC Socio-Economic Objective (SEO)
Urban and Industrial Water Management | Environmental Health | Land and Water Management of environments not elsewhere classified | Control of Pests, Diseases and Exotic Species in Urban and Industrial Environments | Physical and Chemical Conditions of Water for Urban and Industrial Use | Expanding Knowledge in the Environmental Sciences |
Related Links
Publications
Optimisation of glycogen quantification in mixed microbial cultures
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.BIORTECH.2012.05.087
Abstract: This study addressed the key factors affecting the extraction and quantification of glycogen from floccular and granular mixed microbial cultures collected from activated sludge, nutrient removal systems and photosynthetic consortiums: acid concentration, hydrolysis time and concentration of biomass in the hydrolysis. Response surface modelling indicated that 0.9 M HCl and a biomass concentration of 1 mg mL(-1) were optimal conditions for performing acid hydrolysis. Floccular s les only needed a 2-h hydrolysis time whereas granular s les required as much as 5 h. An intermediate 3 h yielded an error of 10% compared to the results obtained with the hydrolysis times specifically tailored to the type of biomass and can thus be recommended as a practical compromise.
Incorporating microbial ecology into the metabolic modelling of polyphosphate accumulating organisms and glycogen accumulating organisms
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.WATRES.2010.06.071
Abstract: In the enhanced biological phosphorus removal (EBPR) process, the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) has been studied intensively in recent years by both microbiologists and engineers, due to its important effects on phosphorus removal performance and efficiency. This study addresses the impact of microbial ecology on assessing the PAO-GAO competition through metabolic modelling, focussing on reviewing recent developments, discussion of how the results from molecular studies can impact the way we model the process, and offering perspectives for future research opportunities based on unanswered questions concerning PAO and GAO metabolism. Indeed, numerous findings that are seemingly contradictory could in fact be explained by the metabolic behaviour of different sub-groups of PAOs and/or GAOs exposed to different environmental and operational conditions. Some ex les include the glycolysis pathway (i.e. Embden-Meyerhof-Parnas (EMP) vs. Entner-Doudoroff (ED)), denitrification capacity, anaerobic tricarboxylic acid (TCA) cycle activity and PAOs' ability to adjust their metabolism to e.g. a GAO-like metabolism. Metabolic modelling may further yield far-reaching influences on practical applications as well, and serves as a bridge between molecular/biochemical research studies and the optimisation of wastewater treatment plant operation.
Effect of an azo dye on the performance of an aerobic granular sludge sequencing batch reactor treating a simulated textile wastewater
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.WATRES.2015.08.043
Abstract: This study analyzed the effect of an azo dye (Acid Red 14) on the performance of an aerobic granular sludge (AGS) sequencing batch reactor (SBR) system operated with 6-h anaerobic-aerobic cycles for the treatment of a synthetic textile wastewater. In this sense, two SBRs inoculated with AGS from a domestic wastewater treatment plant were run in parallel, being one supplied with the dye and the other used as a dye-free control. The AGS successfully adapted to the new hydrodynamic conditions forming smaller, denser granules in both reactors, with optimal sludge volume index values of 19 and 17 mL g(-1) after 5-min and 30-min settling, respectively. As a result, high biomass concentration levels and sludge age values were registered, up to 13 gTSS L(-1) and 40 days, respectively, when deliberate biomass wastage was limited to the s ling needs. Stable dye removal yields above 90% were attained during the anaerobic reaction phase, confirmed by the formation of one of the aromatic amines arising from azo bond reduction. The control of the sludge retention time (SRT) to 15 days triggered a 30% reduction in the biodecolorization yield. However, the increase of the SRT values back to levels above 25 days reverted this effect and also promoted the complete bioconversion of the identified aromatic amine during the aerobic reaction phase. The dye and its breakdown products did not negatively affect the treatment performance, as organic load removal yields higher than 80% were attained in both reactors, up to 77% occurring in the anaerobic phase. These high anaerobic organic removal levels were correlated to an increase of Defluviicoccus-related glycogen accumulating organisms in the biomass. Also, the capacity of the system to deal with shocks of high dye concentration and organic load was successfully demonstrated. Granule breakup after long-term operation only occurred in the dye-free control SBR, suggesting that the azo dye plays an important role in improving granule stability. Fluorescence in situ hybridization (FISH) analysis confirmed the compact structure of the dye-fed granules, microbial activity being apparently maintained in the granule core, as opposed to the dye-free control. These findings support the potential application of the AGS technology for textile wastewater treatment.
Patulibacter medicamentivorans sp. nov., isolated from activated sludge of a wastewater treatment plant
Publisher: Microbiology Society
Date: 07-2013
Abstract: A Gram-positive, aerobic, non-motile, non-endospore-forming rod-shaped bacterium with ibuprofen-degrading capacity, designated strain I11 T , was isolated from activated sludge from a wastewater treatment plant. The major respiratory quinone was demethylmenaquinone DMK-7, C 18 : 1 cis9 was the predominant fatty acid, phosphatidylglycerol was the predominant polar lipid, the cell wall contained meso -diaminopimelic acid as the diagnostic diamino acid and the G+C content of the genomic DNA was 74.1 mol%. On the basis of 16S rRNA gene sequence analysis, the closest phylogenetic neighbours of strain I11 T were Patulibacter ginsengiterrae CECT 7603 T (96.8 % similarity), Patulibacter minatonensis DSM 18081 T (96.6 %) and Patulibacter americanus DSM 16676 T (96.6 %). Phenotypic characterization supports the inclusion of strain I11 T within the genus Patulibacter (phylum Actinobacteria) . However, distinctive features and 16S rRNA gene sequence analysis suggest that is represents a novel species, for which the name Patulibacter medicamentivorans sp. nov. is proposed. The type strain is I11 T ( = DSM 25962 T = CECT 8141 T ).
Accumulibacter diversity at the sub-clade level impacts enhanced biological phosphorus removal performance
Publisher: Elsevier BV
Date: 07-2021
Biodegradation of clofibric acid and identification of its metabolites
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.JHAZMAT.2012.09.029
Abstract: Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration=2 mg L(-1)), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including α-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. α-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study.
Microbial population analysis of nutrient removal-related organisms in membrane bioreactors
Publisher: Springer Science and Business Media LLC
Date: 09-08-2011
DOI: 10.1007/S00253-011-3499-5
Abstract: Membrane bioreactors (MBR) are an important and increasingly implemented wastewater treatment technology, which are operated at low food to microorganism ratios (F/M) and retain slow-growing organisms. Enhanced biological phosphorus removal (EBPR)-related organisms grow slower than ordinary heterotrophs, but have never been studied in detail in MBRs. This study presents a comprehensive analysis of the microorganisms involved in EBPR in pilot- and full-scale MBRs, using fluorescence in situ hybridization (FISH), as well as an overall assessment of other relevant microbial groups. The results showed that polyphosphate accumulating organisms (PAOs) were present at similar levels in all studied MBRs (10% ± 6%), even those without a defined anaerobic zone. Glycogen accumulating organisms were also detected, although rarely. The FISH results correlated well with the observed P removal performance of each plant. The results from this study suggest that a defined anaerobic zone is not necessarily required for putative PAO growth in MBRs, since polyphosphate storage may provide a selective advantage in fulfilling cell maintenance requirements in substrate-limited conditions (low F/M).
Functional redundancy ensures performance robustness in 3-stage PHA-producing mixed cultures under variable feed operation
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.NBT.2017.08.007
Abstract: Polyhydroxyalkanoates (PHA) are biopolymers that can be produced by mixed microbial cultures using wastes or industrial by-products, which represent an economical and environmental advantage over pure culture processes. The use of alternate feedstocks enables using seasonal by-products, providing that the process is resilient to transient conditions. The mixed microbial communities of a 3-stage PHA producing system fed initially with molasses and then cheese whey were investigated through licon sequencing of the 16S rRNA gene. The transition in feedstock resulted in an adaptation of the acidogenic community, where Actinobacteria dominated with sugarcane molasses (up to 93% of the operational taxonomic units) and Firmicutes, with cheese whey (up to 97%). The resulting fermentation products profile also changed, with a higher fraction of HV precursors obtained with molasses than cheese whey (7.1±0.5 and 1.7±0.7 gCOD/L, respectively). As for the PHA storing culture, the genera Azoarcus, Thauera and Paracoccus were enriched with fermented molasses (average 89% of Bacteria). Later, fermented cheese whey fostered a higher ersity, including some less characterised PHA-storers such as the genera Paenibacillus and Lysinibacillus. Although the microbial community structure was significantly affected by the feedstock shift, the acidogenic and PHA storing performance of the 3-stage system was very similar once a pseudo steady state was attained, showing that a reliable level of functional redundancy was attained in both mixed cultures.
Modelling of activated sludge acclimisation to a non-ionic surfactant
Publisher: IWA Publishing
Date: 04-2001
Abstract: A model is proposed to describe activated sludge acclimatisation to a non-ionic surfactant. The model was calibrated automatically, using WEST, a specific software environment for wastewater treatment model building, simulation and parameter estimation. The assays have been performed in a sequencing-batch reactor (SBR), using a non-ionic surfactant as sole carbon source and non-acclimatised sludge. The best fitting model was based on the assumption of three sequentially degraded COD fractions, where the second fraction is a metabolite of the original molecule and the third fraction is a more slowly biodegradable metabolite resulting from the secondary degradation. For primary degradation, hydrolysis with no associated growth was assumed. The growth of microorganisms responsible for degradation of the second and third COD fractions was presumed to follow Haldane and first order kinetics, respectively. The model was able to fit four consecutive assays of the same acclimatisation process, using Brij 30 as carbon source, with different food/microorganism ratios. The parameters obtained showed that the (self-)inhibition of the growth on the second COD fraction decreased along acclimatisation.
Metabolic versatility in full-scale wastewater treatment plants performing enhanced biological phosphorus removal
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.WATRES.2013.08.042
Abstract: This study analysed the enhanced biological phosphorus removal (EBPR) microbial community and metabolic performance of five full-scale EBPR systems by using fluorescence in situ hybridisation combined with off-line batch tests fed with acetate under anaerobic-aerobic conditions. The phosphorus accumulating organisms (PAOs) in all systems were stable and showed little variability between each plant, while glycogen accumulating organisms (GAOs) were present in two of the plants. The metabolic activity of each sludge showed the frequent involvement of the anaerobic tricarboxylic acid cycle (TCA) in PAO metabolism for the anaerobic generation of reducing equivalents, in addition to the more frequently reported glycolysis pathway. Metabolic variability in the use of the two pathways was also observed, between different systems and in the same system over time. The metabolic dynamics was linked to the availability of glycogen, where a higher utilisation of the glycolysis pathway was observed in the two systems employing side-stream hydrolysis, and the TCA cycle was more active in the A(2)O systems. Full-scale plants that showed higher glycolysis activity also exhibited superior P removal performance, suggesting that promotion of the glycolysis pathway over the TCA cycle could be beneficial towards the optimisation of EBPR systems.
Impact of sludge retention time on the fine composition of the microbial community and extracellular polymeric substances in a membrane bioreactor
Publisher: Springer Science and Business Media LLC
Date: 06-06-2016
DOI: 10.1007/S00253-016-7617-2
Abstract: Membrane bioreactors (MBRs) are an advanced technology for wastewater treatment whose wide application has been hindered by rapid fouling of the membranes. MBRs can be operated with long sludge retention time (SRT), a crucial parameter impacting microbial selection in the reactor. This also affects filtration performance, since a major fouling agent are the extracellular polymeric substances (EPS). In this study, the impact of the SRT on the ecophysiology of the MBRs and, consequently, on membrane fouling was evaluated. A MBR was operated under a SRT of 60 days followed by a SRT of 20 days. A comprehensive analysis of the microbial community structure and EPS proteins and polysaccharide profiles of the mixed liquor and cake layer was carried out throughout both operation periods. The results of this study showed that the imposition of a shorter SRT led to a shift in the dominant bacterial populations. The mixed liquor and cake layer communities were very different, with Actinomycetales order standing out in the cake layer at SRT of 20 days. Overall, higher EPS concentrations (particularly proteins) were found at this SRT. Furthermore, EPS profiles were clearly affected by the SRT: it was possible to correlate a group of soluble EPS proteins with the SRT of 60 days, and a lower sludge age led to a lower ersity of polysaccharide sugar monomers, with an increase of glucose and galactose in the cake layer. This study improves our knowledge regarding the molecular reasons for fouling, which may contribute to improve MBR design and operation.
Colonization and beneficial effects on annual ryegrass by mixed inoculation with plant growth promoting bacteria
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.MICRES.2017.01.009
Abstract: Multi-strain inoculants have increased potential to accomplish a ersity of plant needs, mainly attributed to its multi-functionality. This work evaluated the ability of a mixture of three bacteria to colonize and induce a beneficial response on the pasture crop annual ryegrass. Pseudomonas G1Dc10 and Paenibacillus G3Ac9 were previously isolated from annual ryegrass and were selected for their ability to perform multiple functions related to plant growth promotion. Sphingomonas azotifigens DSMZ 18530
A review of the biotransformations of priority pharmaceuticals in biological wastewater treatment processes
Publisher: Elsevier BV
Date: 2021
Community profile governs substrate competition in polyhydroxyalkanoate (PHA)-producing mixed cultures
Publisher: Elsevier BV
Date: 09-2020
Impact of sludge retention time on MBR fouling: role of extracellular polymeric substances determined through membrane autopsy
Publisher: Informa UK Limited
Date: 04-07-2017
DOI: 10.1080/08927014.2017.1333112
Abstract: The impact of sludge retention time (SRT) on the biofouling of a membrane bioreactor (MBR) by extracellular polymeric substances (EPS) was investigated. The MBR was operated at 60 and 20 d SRT. The gel layer (recovered through optimized membrane autopsy methods) and the cake layer were analyzed for their content and profile of EPS proteins and polysaccharides. The change to a shorter SRT led to decreased membrane filterability, concomitant with a higher expression of EPS proteins in the cake layer, which were identified as being mainly related with biosynthesis and stress functions. The gel layer was more substantial in internal fibers, with polysaccharides being the major component in this layer. With the decrease in SRT (and filterability decrease), the overall polysaccharide content and sugar variety increased. In conclusion, SRT impacted not only on the quantity but also the composition of EPS molecules, and both were shown to be important in biofouling.
Optimal operation for timely adaptation of activated sludge plants to changes in the surfactant composition of wastewater
Publisher: IWA Publishing
Date: 02-2002
Abstract: The composition of a textile industry wastewater is highly variable, as the industrial process has to follow fashion and season trends. Surfactants represent one of the largest COD fractions in a typical textile wastewater. Therefore, it was the aim of this paper to model the acclimatisation behaviour of an activated sludge system when subjected to composition variations in the surfactant containing feed. The model was based on data obtained in SBR experiments in which a linear alkyl ethoxylate as sole carbon source in the feed was replaced by another with a longer ethoxylate chain. A previously developed model (Fractionated Degradation Model) was applied to each of the 21 SBR cycles carried out in this study. The resulting best-fit parameters were investigated and sub-models were further developed, to create an acclimatisation model, able to predict the sludge acclimatisation level. Using the information given by this model, it was possible to propose an optimal operation scheme to pre-acclimatise the sludge before a surfactant replacement is made in the textile process. A cost analysis was carried out to compare different scenarios, with and without the application of this operation scheme. It was concluded that the proposed pre-acclimatisation process may be cost effective as compared to other scenarios if a cheap surfactant-containing product was employed.
Metabolite identification of ibuprofen biodegradation by Patulibacter medicamentivorans under aerobic conditions
Publisher: Informa UK Limited
Date: 27-07-2018
DOI: 10.1080/09593330.2018.1502362
Abstract: Ibuprofen (IBU) is a non-steroidal anti-inflammatory drug that is becoming increasingly recognized as an important micropollutant to be monitored in wastewater treatment plants (WWTP), since it has been detected in effluents at the µg L
Segregated flux balance analysis constrained by population structure/function data: The case of PHA production by mixed microbial cultures
Publisher: Wiley
Date: 03-05-2013
DOI: 10.1002/BIT.24894
Abstract: In this study we developed a segregated flux balance analysis (FBA) method to calculate metabolic flux distributions of the in idual populations present in a mixed microbial culture (MMC). Population specific flux data constraints were derived from the raw data typically obtained by the fluorescence in situ hybridization (FISH) and microautoradiography (MAR)-FISH techniques. This method was applied to study the metabolic heterogeneity of a MMC that produces polyhydroxyalkanoates (PHA) from fermented sugar cane molasses. Three populations were identified by FISH, namely Paracoccus sp., Thauera sp., and Azoarcus sp. The segregated FBA method predicts a flux distribution for each of the identified populations. The method is shown to predict with high accuracy the average PHA storage flux and the respective monomeric composition for 16 independent experiments. Moreover, flux predictions by segregated FBA were slightly better than those obtained by nonsegregated FBA, and also highly concordant with metabolic flux analysis (MFA) estimated fluxes. The segregated FBA method can be of high value to assess metabolic heterogeneity in MMC systems and to derive more efficient eco-engineering strategies. For the case of PHA-producing MMC considered in this work, it becomes apparent that the PHA average monomeric composition might be controlled not only by the volatile fatty acids (VFA) feeding profile but also by the population composition present in the MMC.
Evaluation of continuous and intermittent trickling strategies for the removal of hydrogen sulfide in a biotrickling filter
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.CHEMOSPHERE.2021.132723
Abstract: Biotrickling filter (BTF) is a widely applied bioreactor for odour abatement in sewer networks. The trickling strategy is vital for maintaining a sound operation of BTF. This study employed a lab-scale BTF packed with granular activated carbon at a short empty bed residence time of 6 s and pH 1-2 to evaluate different trickling strategies, i.e., continuous trickling (different velocities) and intermittent trickling (different trickling intervals), in terms of the removal of hydrogen sulfide (H
Quantitative proteomic analysis of ibuprofen-degrading Patulibacter sp. strain I11
Publisher: Springer Science and Business Media LLC
Date: 02-12-2012
DOI: 10.1007/S10532-012-9610-5
Abstract: Ibuprofen is the third most consumed pharmaceutical drug in the world. Several isolates have been shown to degrade ibuprofen, but very little is known about the biochemistry of this process. This study investigates the degradation of ibuprofen by Patulibacter sp. strain I11 by quantitative proteomics using a metabolic labelling strategy. The whole-genome of Patulibacter sp. strain I11 was sequenced to provide a species-specific protein platform for optimal protein identification. The bacterial proteomes of actively ibuprofen-degrading cells and cells grown in the absence of ibuprofen was identified and quantified by gel based shotgun-proteomics. In total 251 unique proteins were quantitated using this approach. Biological process and pathway analysis indicated a number of proteins that were up-regulated in response to active degradation of ibuprofen, some of them are known to be involved in the degradation of aromatic compounds. Data analysis revealed that several of these proteins are likely involved in ibuprofen degradation by Patulibacter sp. strain I11.
Metabolic modelling of full-scale enhanced biological phosphorus removal sludge
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.WATRES.2014.08.036
Abstract: This study investigates, for the first time, the application of metabolic models incorporating polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) towards describing the biochemical transformations of full-scale enhanced biological phosphorus removal (EBPR) activated sludge from wastewater treatment plants (WWTPs). For this purpose, it was required to modify previous metabolic models applied to lab-scale systems by incorporating the anaerobic utilisation of the TCA cycle and the aerobic maintenance processes based on sequential utilisation of polyhydroxyalkanoates, followed by glycogen and polyphosphate. The abundance of the PAO and GAO populations quantified by fluorescence in situ hybridisation served as the initial conditions of each biomass fraction, whereby the models were able to describe accurately the experimental data. The kinetic rates were found to change among the four different WWTPs studied or even in the same plant during different seasons, either suggesting the presence of additional PAO or GAO organisms, or varying microbial activities for the same organisms. Nevertheless, these variations in kinetic rates were largely found to be proportional to the difference in acetate uptake rate, suggesting a viable means of calibrating the metabolic model. The application of the metabolic model to full-scale sludge also revealed that different Accumulibacter clades likely possess different acetate uptake mechanisms, as a correlation was observed between the energetic requirement for acetate transport across the cell membrane with the ersity of Accumulibacter present. Using the model as a predictive tool, it was shown that lower acetate concentrations in the feed as well as longer aerobic retention times favour the dominance of the TCA metabolism over glycolysis, which could explain why the anaerobic TCA pathway seems to be more relevant in full-scale WWTPs than in lab-scale systems.
Step-by-step strategy for protein enrichment and proteome characterisation of extracellular polymeric substances in wastewater treatment systems
Publisher: Springer Science and Business Media LLC
Date: 24-05-2012
DOI: 10.1007/S00253-012-4157-2
Abstract: Extracellular polymeric substances (EPS) are keys in biomass aggregation and settleability in wastewater treatment systems. In membrane bioreactors (MBR), EPS are an important factor as they are considered to be largely responsible for membrane fouling. Proteins were shown to be the major component of EPS produced by activated sludge and to be correlated with the properties of the sludge, like settling, hydrophobicity and cell aggregation. Previous EPS proteomic studies of activated sludge revealed several problems, like the interference of other EPS molecules in protein analysis. In this study, a successful strategy was outlined to identify the proteins from soluble and bound EPS extracted from activated sludge of a lab-scale MBR. EPS s les were first subjected to pre-concentration through lyophilisation, centrifugal ultrafiltration or concentration with a dialysis membrane coated by a highly absorbent powder of polyacrylate-polyalcohol, preceded or not by a dialysis step. The highest protein concentration factors were achieved with the highly absorbent powder method without previous dialysis step. Four protein precipitation methods were then tested: acetone, trichloroacetic acid (TCA), perchloric acid and a commercial kit. Protein profiles were compared in 4-12 % sodium dodecyl sulphate polyacrylamide gel electrophoresis gels. Both acetone and TCA should be applied for the highest coverage for soluble EPS proteins, whereas TCA was the best method for bound EPS proteins. All visible bands of selected profiles were subjected to mass spectrometry analysis. A high number of proteins (25-32 for soluble EPS and 17 for bound EPS) were identified. As a conclusion of this study, a workflow is proposed for the successful proteome characterisation of soluble and bound EPS from activated sludge s les.
Analysis of 65 pharmaceuticals and personal care products in 5 wastewater treatment plants in Portugal using a simplified analytical methodology
Publisher: IWA Publishing
Date: 12-2010
DOI: 10.2166/WST.2010.985
Abstract: Pharmaceuticals and personal care products (PPCPs) are becoming increasingly recognised as important micropollutants to be monitored in wastewater treatment plants (WWTPs), since WWTP effluents represent an important point source to natural aquatic systems. In this study, the abundance of 65 PPCPs was analysed in 5 Portuguese WWTPs during the spring and autumn. Due to the fact that analytical approaches normally used to quantify the abundance of these compounds are labour intensive and require various specific procedures, this study proposes a set of simplified analytical methods for the quantification of pharmaceutically active compounds (PhACs) and polycyclic musks in liquid and sludge s les. The analytical methods were validated using influent wastewater matrices, showing comparable limits of detection and quantification as literature values for most PPCPs, with the exception of the estrogenic compounds. The PhAC concentrations detected in the WWTP survey were in the range of 0.050–100 μg L−1 in the influent and up to 50 μg L−1 in the effluent, where the non-steroidal anti-inflammatory drugs (NSAIDs) were the most abundant and frequently detected group. Some musks were detected up to 11.5 μg L−1 in the influent and 0.9 μg L−1 in the effluent, and adsorbed in the sludge up to 22.6 μg g−1.
The link between the microbial ecology, gene expression, and biokinetics of denitrifying polyphosphate-accumulating systems under different electron acceptor combinations
Publisher: Springer Science and Business Media LLC
Date: 02-06-2018
DOI: 10.1007/S00253-018-9077-3
Abstract: The emission of the greenhouse gas nitrous oxide (N
Real-time monitoring of membrane bioreactors with 2D-fluorescence data and statistically based models
Publisher: IWA Publishing
Date: 04-2011
DOI: 10.2166/WST.2011.195
Abstract: The application of membrane bioreactors (MBR) for wastewater treatment is growing worldwide due to their compactness and high effluent quality. However, membrane fouling, mostly associated to biological products, can reduce MBR performance. Therefore, it is important to monitor MBRs as close to real-time as possible to accelerate control actions for maximal biological and membrane performance. 2D-fluorescence spectroscopy is a promising on-line tool to simultaneously monitor wastewater treatment efficiency and the formation of potential biological fouling agents. In this study, 2D-fluorescence data obtained from the wastewater and the permeate of a MBR was successfully modelled using projection to latent structures (PLS) to monitor variations in the influent and effluent total chemical oxygen demand (COD). Analysis of the results also indicated that humic acids and proteins highly contributed to the measured COD in both streams. Nevertheless, this approach was not valid for other performance parameters of the MBR system (such as influent and effluent ammonia and phosphorus), which is usually characterised through a high number of analytical and operating parameters. Principal component analysis (PCA) was thus used to find possible correlations between these parameters, in an attempt to reduce the analytical effort required for full MBR characterisation and to reduce the time frame necessary to obtain monitoring results. The 3 first principal components, capturing 57% of the variance, indicated and confirmed expected relationships between the assessed parameters. However, this approach alone could not provide robust enough correlations to enable the elimination of parameters for process description (PCA loadings ≤ 0.5). Nevertheless, it is possible that the information captured by 2D-fluorescence spectroscopy could replace some of the analytical and operating parameters, since this technique was able to successfully describe influent and effluent total COD. It is thus proposed that combined modelling of 2D-fluorescence data and selected performance/operating parameters should be further explored for efficient MBR monitoring aiming at rapid process control.
The impact of aeration on the competition between polyphosphate accumulating organisms and glycogen accumulating organisms
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.WATRES.2014.08.033
Abstract: In wastewater treatment plants (WWTPs), aeration is the major energetic cost, thus its minimisation will improve the cost-effectiveness of the process. This study shows that both the dissolved oxygen (DO) concentration and aerobic hydraulic retention time (HRT) affect the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). At low DO levels, Accumulibacter PAOs were shown to have an advantage over Competibacter GAOs, as PAOs had a higher oxygen affinity and thus largely maintained their aerobic activity at low DO levels, while GAO activity decreased. Bioreactor operation at low DO levels was found to increase the PAO fraction of the sludge. Furthermore, an increase in aerobic HRT (at a DO level of 2 mg O2/L), promoted the proliferation of GAOs over PAOs, decreasing the EBPR efficiency. Overall, this study shows that low aeration can be beneficial for EBPR performance through selecting for PAOs over GAOs, which should be incorporated into WWTP models in order to minimise energetic costs and improve WWTP sustainability.
Nitrous oxide emissions from a full-scale biological aerated filter (BAF) subject to seawater infiltration
Publisher: Springer Science and Business Media LLC
Date: 21-05-2019
DOI: 10.1007/S11356-019-05470-X
Abstract: The increase of salt concentrations in influent wastewaters will be a consequence of the sea level rises in coastal areas due to climate change and the future use of seawater to flush toilets as a cost-attractive option for alternative water resources. Yet, little is known about the salinity effect on full-scale wastewater treatment plants (WWTPs) performance and on greenhouse gas (GHG) emissions, such as nitrous oxide (N
Achieving combined biological short-cut nitrogen and phosphorus removal in a one sludge system with side-stream sludge treatment
Publisher: Elsevier BV
Date: 09-2021
Novel Bacteriophages Show Activity against Selected Australian Clinical Strains of Pseudomonas aeruginosa
Publisher: MDPI AG
Date: 19-01-2022
DOI: 10.3390/MICROORGANISMS10020210
Abstract: Multi-drug resistant (MDR) clinical strains of Pseudomonas aeruginosa are the most prevalent bacteria in the lungs of patients with cystic fibrosis (CF) and burn wounds and among the most common in immunocompromised hospital patients in Australia. There are currently no promising antibiotics in the pipeline being developed against these strains. Phage therapy, which uses viruses known as bacteriophages to infect and kill pathogenic bacteria, could be a possible alternative treatment. To this end, we isolated and characterised four novel phages against Australian clinical strains of P. aeruginosa isolated from patients with cystic fibrosis, from infected blood and joint aspirate in Southeast Queensland, Australia. Activated sludge was enriched for phages using the clinical strains, and four bacteriophages were isolated. The phages were able to cause lysis in a further three identified clinical isolates. Morphology showed that they were all tailed phages (of the order Caudovirales), two belonging to the family Myoviridae and the others assigned to the Podoviridae and Siphoviridae. Their genomes were sequenced to reveal a doubled stranded DNA topology with genome sizes ranging from 42 kb to 65 kb. In isolating and characterising these novel phages, we directed our efforts toward the development and use of these phages as candidates for phage therapy as an alternative strategy for the management or elimination of these pathogenic strains. Here we describe novel phage candidates for potential therapeutic treatment of MDR Australian clinical isolates of P. aeruginosa.
The effectiveness and role of phages in the disruption and inactivation of clinical P. aeruginosa biofilms
Publisher: Elsevier BV
Date: 10-2023
The effect of carbon source on the biological reduction of ionic mercury
Publisher: Elsevier BV
Date: 15-06-2009
DOI: 10.1016/J.JHAZMAT.2008.10.094
Abstract: Mercury (Hg) is the most highly toxic heavy metal, and must be removed from waterways to very low levels. Biologically mediated mercury removal is an emerging technology that has the potential to be robust, efficient and cost-effective. In this study, the impact of carbon source on the behaviour and microbial community composition of mixed microbial cultures was evaluated, and their performance was compared with a pure culture of Pseudomonas putida spi3. Glucose and acetate, two carbon sources that are commonly present in wastewaters, were chosen for this study. Distinct microbial populations were enriched with each carbon source. Glucose led to a more suitable microbial culture for Hg(2+) bioreduction that was able to reduce Hg(2+) at faster rates when compared to acetate. Furthermore, acetate consistently led to poorer process performance, irrespective of the microbial culture, possibly due to the formation of mercuric acetate complexes. It is proposed that glucose can be a more beneficial carbon source than acetate for the successful operation of Hg bioremediation systems.
Strategies for efficiently selecting PHA producing mixed microbial cultures using complex feedstocks: Feast and famine regime and uncoupled carbon and nitrogen availabilities
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.NBT.2016.10.008
Abstract: Production of polyhydroxyalkanoates (PHAs) by open mixed microbial cultures (MMCs) has been attracting increasing interest as an alternative technology to PHA production by pure cultures, due to the potential for lower costs associated with the use of open systems (eliminating the requirement for sterile conditions) and the utilisation of cheap feedstock (industrial and agricultural wastes). Such technology relies on the efficient selection of an MMC enriched in PHA-accumulating organisms. Fermented cheese whey, a protein-rich complex feedstock, has been used previously to produce PHA using the feast and famine regime for selection of PHA accumulating cultures. While this selection strategy was found efficient when operated at relatively low organic loading rate (OLR, 2g-CODL
Determination of the extraction kinetics for the quantification of polyhydroxyalkanoate monomers in mixed microbial systems
Publisher: Elsevier BV
Date: 11-2013
Application of dissolved oxygen (DO) level control for polyhydroxyalkanoate (PHA) accumulation with concurrent nitrification in surplus municipal activated sludge
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.NBT.2019.01.003
Abstract: Mixed microbial cultures are a viable means for polyhydroxyalkanoate (PHA) production, which can produce polymers of commercial quality with high yields. Various PHA co-polymer blends can be produced by surplus full-scale municipal activated sludge fed with fermented waste feedstocks. In biological nutrient removal, ammonia is converted to nitrate by ammonia and nitrite oxidizing bacteria (AOBs and NOBs) through nitrification and removed as nitrogen gas through denitrification. Activated sludge can be enriched with significant PHA storage potential alongside nitrogen removal by denitrifying heterotrophic and nitrifying autotrophic bacteria. The latter adds complexity and aeration demand during the aerobic side-stream PHA accumulation stage since fermented organic residuals often contain significant amounts of ammonia. In the present work, the influence of dissolved oxygen (DO) levels on both PHA accumulation and nitrification rates for a municipal activated sludge were evaluated. The objective was to identify potential for a DO control strategy for PHA accumulation, which would mitigate the unnecessary nitrification activity during PHA production. A much higher apparent Michaelis-Menten DO affinity for volatile fatty acid (VFA) consumption (K
Sludge retention time impacts on polyhydroxyalkanoate productivity in uncoupled storage/growth processes
Publisher: Elsevier BV
Date: 12-2021
Plant growth-promoting Burkholderia species isolated from annual ryegrass in Portuguese soils
Publisher: Oxford University Press (OUP)
Date: 09-02-2016
DOI: 10.1111/JAM.13025
Abstract: To search for culturable Burkholderia species associated with annual ryegrass in soils from natural pastures in Portugal, with plant growth-promoting effects. Annual ryegrass seedlings were used to trap Burkholderia from two different soils in laboratory conditions. A combined approach using genomic fingerprinting and sequencing of 16S rRNA and recA genes resulted in the identification of Burkholderia strains belonging to the species Burkholderia graminis, Burkholderia fungorum and the Burkholderia cepacia complex. Most strains were able to solubilize mineral phosphate and to synthesize indole acetic acid some of them could produce siderophores and antagonize the phytopathogenic oomycete, Phytophthora cinnamomi. A strain (G2Bd5) of B. graminis was selected for gnotobiotic plant inoculation experiments. The main effects were the stimulation of root growth and enhancement of leaf lipid synthesis and turnover. Fluorescence in situ hybridization and confocal laser microscopy evidenced that strain G2Bd5 is a rhizospheric and endophytic colonizer of annual ryegrass. This work revealed that annual ryegrass can naturally associate with members of the genus Burkholderia. A novel plant growth promoting strain of B. graminis was obtained. The novel strain belongs to the plant-associated Burkholderia cluster and is a promising candidate for exploitation as plant inoculant in field conditions.
The relationship between mixed microbial culture composition and PHA production performance from fermented molasses
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.NBT.2013.08.010
Abstract: Polyhydroxyalkanoates (PHAs) are polyesters that can be produced from industrial wastewater or surplus products by mixed microbial cultures (MMC). To optimise PHA production by MMCs, the link between the microbial structure and function of these enrichments must be better established. This study investigates, for the first time, the impact of operational changes on the microbial community and the associated process performance of PHA producing MMCs. It was found that a PHA producing community fed with fermented molasses was dominated by a combination of Azoarcus, Thauera and Paracoccus, where the former two groups were present in highest abundance. Dominance of either Thauera or Azoarcus seemed to be determined by the organic loading rate imposed in the selection reactor. While higher Azoarcus enrichments led to higher PHA production yields and lower biomass growth yields as compared to Thauera, the Thauera abundance was strongly linked to higher hydroxyvalerate (HV) fractions. Paracoccus abundance was correlated with a lower PHA production capacity as compared to Azoarcus, and produced lower HV fractions than Thauera and Azoarcus. The findings of this study suggest that MMCs targeting the enrichment of Azoarcus as the primary biomass fraction with Thauera as a minor fraction lead to optimal specific PHA production and polymers with high HV content, which is likely to improve their mechanical properties.
Activated sludge acclimatisation kinetics to non‐ionic surfactants
Publisher: Informa UK Limited
Date: 2003
DOI: 10.1080/09593330309385541
Abstract: The biodegradation of surfactants is a frequent and complex problem in domestic and industrial wastewater treatment processes. In addition to the resulting metabolites being sometimes refractory, the complete biodegradation of many of the most employed non-ionic surfactants requires long hydraulic retention times and the presence of specialised bacterial consortia. Preliminary acclimatisation tests highlighted the importance of the sludge acclimatisation state to a specific surfactant substrate for biotreatment efficiency. This paper reports on studies aimed at quantifying activated sludge acclimatisation and memory retention levels when subjected to changes in the type of surfactant included in the feed. Several transitions were tested, namely from an alkylphenol ethoxylate to a linear alkyl ethoxylate and the reverse, and between alkyl ethoxylates with different hydrophobic and hydrophilic molecular chain lengths. The kinetic results showed that sludge activation and memory loss were more dynamic for primary biodegradation It was found that the sludge was harder to adapt to alkylphenol ethoxylate than to alkyl ethoxylate. The former also apparently introduced an inhibitory effect, resulting in very slow degradation kinetics when imposed to alkyl ethoxylate acclimatised sludge. When replacing an alkyl ethoxylate with another surfactant of the same family, a longer ethoxylate chain reduced the degradation rates. This effect was further enhanced by simultaneously increasing the hydrophobic chain length of the substrate. The acclimatisation kinetic after the replacement of an alkyl ethoxylate by a longer counterpart was slower than the reverse case, and memory was also more easily lost.
Kinetics of nitrate and perchlorate removal and biofilm stratification in an ion exchange membrane bioreactor
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.WATRES.2012.05.045
Abstract: The biological degradation of nitrate and perchlorate was investigated in an ion exchange membrane bioreactor (IEMB) using a mixed anoxic microbial culture and ethanol as the carbon source. In this process, a membrane-supported biofilm reduces nitrate and perchlorate delivered through an anion exchange membrane from a polluted water stream, containing 60 mg/L of NO₃⁻ and 100 μg/L of ClO₄⁻. Under ammonia limiting conditions, the perchlorate reduction rate decreased by 10%, whereas the nitrate reduction rate was unaffected. Though nitrate and perchlorate accumulated in the bioreactor, their concentrations in the treated water (2.8 ± 0.5 mg/L of NO₃⁻ and 7.0 ± 0.8 μg/L of ClO₄⁻, respectively) were always below the drinking water regulatory levels, due to Donnan dialysis control of the ionic transport in the system. Kinetic parameters determined for the mixed microbial culture in suspension showed that the nitrate reduction rate was 35 times higher than the maximum perchlorate reduction rate. It was found that perchlorate reduction was inhibited by nitrate, since after nitrate depletion perchlorate reduction rate increased by 77%. The biofilm developed in the IEMB was cryosectioned and the microbial population was analyzed by fluorescence in situ hybridization (FISH). The results obtained seem to indicate that the kinetic advantage of nitrate reduction favored accumulation of denitrifiers near the membrane, whereas per(chlorate) reducing bacteria were mainly positioned at the biofilm outer surface, contacting the biomedium. As a consequence of the biofilm stratification, the reduction of perchlorate and nitrate occur sequentially in space allowing for the removal of both ions in the IEMB.
Bioaugmentation of membrane bioreactor with Achromobacter denitrificans strain PR1 for enhanced sulfamethoxazole removal in wastewater
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.SCITOTENV.2018.08.100
Abstract: Achromobacter denitrificans strain PR1, previously found to harbour specific degradation pathways with high sulfamethoxazole (SMX) degradation rates, was bioaugmented into laboratory-scale membrane bioreactors (MBRs) operated under aerobic conditions to treat SMX-containing real domestic wastewater. Different hydraulic retention times (HRTs), which is related to reaction time and loading rates, were considered and found to affect the SMX removal efficiency. The availability of primary substrates was important in both bioaugmented and non-bioaugmented activated sludge (AS) for cometabolism of SMX. High HRT (24 h) resulted in low food to microorganism ratio (F/M) and low SMX removal, due to substrate limitation. Decrease in HRT from 24 h to 12 h, 6 h and finally 4 h led to gradual increases in primary substrates availability, e.g. organic compounds and ammonia, resulted in increased SMX removal efficiency and degradation rate, and is more favorable for high-rate wastewater treatment processes. After inoculation into the MBRs, the bioaugmentation strain was sustained in the reactor for a maximum of 31 days even though a significant decrease in abundance was observed. The bioaugmented MBRs showed enhanced SMX removal, especially under SMX shock loads compared to the control MBRs. The results of this study indicate that re-inoculation is required regularly after a period of time to maintain the removal efficiency of the target compound.
Biotrickling filter for the removal of volatile sulfur compounds from sewers: A review
Publisher: Elsevier BV
Date: 08-2021
Ecotoxicity of ketoprofen, diclofenac, atenolol and their photolysis byproducts in zebrafish (Danio rerio)
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.SCITOTENV.2014.09.103
Abstract: The occurrence of pharmaceutical compounds in wastewater treatment plants and surface waters has been detected worldwide, constituting a potential risk for aquatic ecosystems. Adult zebrafish, of both sexes, were exposed to three common pharmaceutical compounds (atenolol, ketoprofen and diclofenac) and their UV photolysis by-products over seven days. The results show that diclofenac was removed to concentrations<LOD after 5 min of UV irradiation. The oxidative stress response of zebrafish to pharmaceuticals and their photolysis by-products was evaluated through oxidative stress enzymes (glutathione-S-transferase, catalase, superoxide dismutase) and lipid peroxidation. Results suggest that the photolysis by-products of diclofenac were more toxic than those from the other compounds tested, showing an increase in GST and CAT levels, which are also supported by higher MDA levels. Overall, the toxicity of waters containing atenolol and ketoprofen was reduced after the parent compounds were transformed by photolysis, whereas the toxicity increased significantly from the by-products generated through diclofenac photolysis. Therefore, diclofenac photolysis would possibly necessitate higher irradiation time to ensure that the associated by-products are completely degraded to harmless form(s).
A factorially‐designed study of physicochemical reactive dye colour removal from simulated cotton textile processing wastewaters
Publisher: Wiley
Date: 09-2002
Denitrification activity of polyphosphate accumulating organisms (PAOs) in full-scale wastewater treatment plants
Publisher: IWA Publishing
Date: 19-12-2018
DOI: 10.2166/WST.2018.517
Abstract: A comprehensive assessment of full-scale enhanced biological phosphorus removal (EBPR) plants (five plants, 19 independent tests) was undertaken to determine their effectiveness in terms of aerobic and anoxic P removal. By comparing parallel P uptake tests under only aerobic or under anoxic-aerobic conditions, results revealed that introducing an anoxic stage led to an overall P removal of on average 90% of the P removed under only aerobic conditions. This was achieved with negligible higher PHA and glycogen requirements, 30% lower overall oxygen consumption and with the simultaneous removal of nitrate, reducing up to an estimate of 70% of carbon requirements for simultaneous N and P removal. Varying fractions of denitrifying polyphosphate accumulating organisms (DPAOs), from an average of 25% to 84%, were found in different plants. No correlation was found between the DPAO fractions and EBPR configuration, season, or the concentration of any of the microbial groups measured via quantitative fluorescence in situ hybridisation. These included Type I and Type II Ca. Accumulibacter and glycogen accumulating organisms, suggesting that chemical batch tests are the best methodology for quantifying the potential of anoxic P removal in full-scale wastewater treatment plants.
Dynamic change of pH in acidogenic fermentation of cheese whey towards polyhydroxyalkanoates production: Impact on performance and microbial population
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.NBT.2016.07.001
Abstract: Polyhydroxyalkanoates (PHA) are a sustainable alternative to conventional plastics that can be obtained from industrial wastes/by-products using mixed microbial cultures (MMC). MMC PHA production is commonly carried out in a 3-stage process of acidogenesis, PHA culture selection and accumulation. This research focused on the possibility of tailoring PHA by controlling the acidogenic reactor operating conditions, namely pH, using cheese whey as model feedstock. The objective was to investigate the impact that dynamically varying the acidogenic pH, when targeting different PHA monomer profiles, had on the performance and microbial community profile of the anaerobic reactor. To accomplish this, an anaerobic reactor was continuously operated under dynamic pH changes, ranging from pH 4 to 7, turning to pH 6 after each change of pH. At pH 6, lactate and acetate were the dominant products (41-48% gCOD basis and 22-44% gCOD basis, respectively). At low pH, lactate production was higher while at high pH acetate production was favoured. Despite the dynamic change of pH, the fermentation product composition at pH 6 was always similar, showing the resilience of the process, i.e. when the same pH value was imposed, the culture produced the same metabolic products independently of the history of changes occurring in the system. The different fermentation product fractions led to PHAs of different compositions. The microbial community, analysed by high throughput sequencing of bacterial 16S rRNA gene fragments, was dominated by Lactobacillus, but varied markedly when subjected to the highest and lowest pH values of the tested range (4 and 7), with increase in the abundance of Lactococcus and a member of the Candidate Division TM7. Different bacterial profiles obtained at pH 6 during this dynamic operation were able to produce a consistent profile of fermentation products (and consequently a constant PHA composition), demonstrating the community's functional redundancy.
Simultaneous removal of micropollutants, antibiotic resistant bacteria, and antibiotic resistance genes using graphitic carbon nitride under simulated solar irradiation
Publisher: Elsevier BV
Date: 04-2022
Combined Strategies to Boost Polyhydroxyalkanoate Production from Fruit Waste in a Three-Stage Pilot Plant
Publisher: American Chemical Society (ACS)
Date: 09-06-2021
Robustness of sludge enriched with short SBR cycles for biological nutrient removal
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BIORTECH.2008.10.031
Abstract: In this study, it is proposed that short sequencing batch reactor (SBR) cycles select and maintain a robust and active biomass, able to cope with typical disturbances occurring in wastewater treatment plants. In order to test this hypothesis, an SBR system was subjected to COD, N and P shock loads. It was shown that the sludge enriched in the SBR operated with short cycles was able to rapidly recover from the tested disturbances. COD and N removal recovered within 1-2 days for shock loads of 10 times the standard concentration. The P removal took up to 2-3 sludge ages to fully recover from the COD spike, but the enhanced biological phosphorus removal (EBPR) performance was still able to be totally re-established after each of the tests, even in theoretically adverse conditions for the growth of polyphosphate accumulating organisms.
Assessment of the presence and dynamics of fungi in drinking water sources using cultural and molecular methods
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.WATRES.2010.07.018
Abstract: A comparison of different isolation techniques and culture media for detection of filamentous fungi and yeasts in the aquatic environment revealed that the use of membrane filtration with the media dichloran rose bengal chlor henicol (DRBC) optimized fungi detection in terms of abundance and variety in three untreated water sources with very different characteristics (surface water, spring water, and groundwater). The ersity of the fungi population captured by direct DNA extraction of fungi collected by membrane filtration was compared with the isolates obtained after selective growth using different culture media through lification of the internal transcribed spacer gene and denaturing gradient gel electrophoresis (DGGE). The Czapek-Dox agar, Sabouraud dextrose agar, and DRBC media showed closer similarities to those obtained by the uncultured biomass for the different water sources. Based on these data and the best enumeration results, DRBC is recommended for the assessment of fungi in water sources using culture-based methods. DGGE was also used to monitor temporal variations in the fungal population structure and showed that each water matrix possessed a distinct population profile as well as that changes in the fungal community can be expected in the different matrices throughout the year.
Fast method for the determination of short-chain-length polyhydroxyalkanoates (scl-PHAs) in bacterial samples by In Vial-Thermolysis (IVT)
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.NBT.2017.05.012
Abstract: A new method based on the GC-MS analysis of thermolysis products obtained by treating bacterial s les at a high temperature (above 270°C) has been developed. This method, here named "In-Vial-Thermolysis" (IVT), allowed for the simultaneous determination of short-chain-length polyhydroxyalkanoates (scl-PHA) content and composition. The method was applied to both single strains and microbial mixed cultures (MMC) fed with different carbon sources. The IVT procedure provided similar analytical performances compared to previous Py-GC-MS and Py-GC-FID methods, suggesting a similar application for PHA quantitation in bacterial cells. Results from the IVT procedure and the traditional methanolysis method were compared the correlation between the two datasets was fit for the purpose, giving a R
Two‐dimensional fluorescence as a fingerprinting tool for monitoring wastewater treatment systems
Publisher: Wiley
Date: 29-03-2011
DOI: 10.1002/JCTB.2613
Biofilms in RBC with Constant Ages and Thicknesses
Publisher: American Society of Civil Engineers (ASCE)
Date: 06-2019
Studies on activated sludge response to variations in the composition of a synthetic surfactant-containing feed effluent
Publisher: IWA Publishing
Date: 09-2000
Abstract: Laboratory batch and sequencing-batch reactors and closed respirometry techniques were used to study the response of activated sludge to non-ionic synthetic surfactants. Two laboratory-grade and three commercial surfactant mixtures used in the textile industry (alkyl- and alkylphenol-ethoxylate types) were tested. Respirometric profiles during degradation experiments were complemented with titrimetric surfactant measurements and TOC determinations, representing primary and ultimate biodegradation, respectively. Though non-acclimatized sludge was apparently not inhibited by the surfactant products, total degradation took at least 20 hours with S0/X0 values in the 0.24–0.86 range. Respiration rate profiles (respirograms) showed several peaks, suggesting stepwise primary-ultimate degradation of the surfactant molecules. Acclimatization shortened degradation times and produced repirograms with a single peak. Biomass adaptation, response to load increases and memory loss was faster for primary than for ultimate degradation. Alkyl ethoxylate-adapted biomass was apparently more capable of adaptation to alkylphenol ethoxylate than the inverse.
Polyhydroxyalkanoates production by a mixed photosynthetic consortium of bacteria and algae
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.BIORTECH.2013.01.050
Abstract: For the first time, a mixed photosynthetic culture (MPC) consisting of a consortium of bacteria and algae was investigated for its capacity to accumulate polyhydroxyalkanoates (PHA). The culture was subjected to a feast and famine regime in an illuminated environment without supplying oxygen or any other electron acceptor. The MPC accumulated PHA during the feast phase and consumed it in the famine phase, where the PHA consumption was made possible due to oxygen production by algae. The internal cycling of carbohydrates was also observed, which was likely linked to bacterial glycogen being used as an additional source of energy for acetate uptake during the feast phase, and restored in the famine phase via PHA degradation. The MPC reached a PHA content of 20%, with a PHA storage yield per acetate similar to aerobic systems, opening up the possibility of a new sunlight-driven PHA production process without the need for aeration.
Oryzisolibacter propanilivorax gen. nov., sp. nov., a propanil-degrading bacterium
Publisher: Microbiology Society
Date: 10-2017
Abstract: Strain EPL6
Microbial Characterization of Mercury-Reducing Mixed Cultures Enriched with Different Carbon Sources
Publisher: Japanese Society of Microbial Ecology
Date: 2011
Abstract: The use of mixed microbial cultures enriched for biological mercury removal is explored in this paper, focusing on the ecological shifts occurring throughout acclimatization to mercury and on the long-term stability of four microbial enrichments. The 16S rRNA genetic profiles obtained by denaturing gradient gel electrophoresis (DGGE) revealed that the glucose and ethanol cultures had similar profiles, whereas the acetate cultures erged into a totally dissimilar cluster. Quantification of the merA gene copies in each enrichment showed higher values for the glucose culture, followed by the ethanol and then the acetate cultures, which was consistent with the mercury removal performance throughout the study. Isolates were obtained from the four cultures and analyzed with respect to their genetic (16S rRNA) and functional (merA) phylogenies in order to identify mercury-resistant species enriched with different carbon sources. All mercury-resistant isolates obtained from the glucose and ethanol cultures belonged to the Gammaproteobacteria, whereas acetate cultures also contained members of other phyla, with differences in merA sequences. Higher phylogenetic than functional ersity of the isolates, together with increasing merA copies even after culture stabilisation, highlight the role of horizontal gene transfer in the acclimatization process.
Development of a hybrid model strategy for monitoring membrane bioreactors
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.JBIOTEC.2012.06.026
Abstract: In the present study, the performance of a membrane bioreactor (MBR) was modelled using a hybrid approach based on the activated sludge model number 3 (ASM3) combined with projection to latent structures (PLS) to predict the residuals of the ASM. The application of ASM to MBRs requires frequent re-calibration to adjust the model to variations in influent characteristics, determined through time-consuming analysis and batch tests. Considering this problem, the objective of this study was to improve ASM prediction ability with minimal additional monitoring effort. Hybrid models were developed to predict three MBR performance parameters: mixed liquor suspended solids (MLSS), COD in the permeate (CODp) and nitrite and nitrate concentration in the permeate (NOxp). For PLS modelling of ASM residuals three input strategies were used: (1) analytic and operating data (2) operating data plus 2D fluorescence spectroscopy (3) all the data. The first input strategy improved ASM prediction of the three selected outputs, and highlighted the lack of detailed and real-time information from wastewater and operating parameters in the ASM used in this study. In the second input strategy, the incorporation of updated data from 2D fluorescence spectroscopy resulted on better model fitting than in the first input strategy, for all the output parameters studied. Through the hybrid modelling approach it was possible to significantly improve the ASM predictions in real-time using 2D fluorescence measurements and other relevant parameters acquired on-line, without requiring further laboratory analysis. Furthermore, the third input strategy, incorporating all the collected data, did not significantly improve the prediction of the outputs beyond the second strategy. This shows that 2D fluorescence spectroscopy is a comprehensive monitoring tool, able to capture on-line the required information to complement, through hybrid modelling, the mechanistic information described by an ASM.
Production of single-cell proteins from organic matter and residual nitrogen
Publisher: Elsevier
Date: 2020
An integrated process for mixed culture production of 3-hydroxyhexanoate-rich polyhydroxyalkanoates from fruit waste
Publisher: Elsevier BV
Date: 2022
Multivariate statistically-based modelling of a membrane bioreactor for wastewater treatment using 2D fluorescence monitoring data
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.WATRES.2012.04.010
Abstract: This work presents the development of multivariate statistically-based models for monitoring several key performance parameters of membrane bioreactors (MBR) for wastewater treatment. This non-mechanistic approach enabled the deconvolution of 2D fluorescence spectroscopy data, a powerful technique that has previously been shown to capture important information regarding MBR performance. Projection to latent structure (PLS) modelling was used to integrate 2D fluorescence data, after compression through parallel factor analysis (PARAFAC), with operation and analytical data to describe an MBR fouling indicator (transmembrane pressure, TMP), five descriptors of the effluent quality (total COD, soluble COD, concentration of nitrite and nitrate, total nitrogen and total phosphorus in the permeate) and the biomass concentration in the bioreactor (MLSS). A multilinear correlation was successfully established for TMP, CODtp and CODsp, whereas the optimised models for the remaining outputs included quadratic and interaction terms of the compressed 2D fluorescence matrices. Additionally, the coefficients of the optimised models revealed important contributions of some of the input parameters to the modelled outputs. This work demonstrates the applicability of 2D fluorescence and statistically-based models to simultaneously monitor multiple key MBR performance parameters with minimal analytical effort. This is a promising approach to facilitate the implementation of MBR technology for wastewater treatment.
Diclofenac biotransformation in the enhanced biological phosphorus removal process
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.SCITOTENV.2021.151232
Abstract: Diclofenac is a pharmaceutical active compound frequently detected in wastewater and water bodies, and often reported to be persistent and difficult to biodegrade. While many previous studies have focussed on assessing diclofenac biodegradation in nitrification and denitrification processes, this study focusses on diclofenac biodegradation in the enhanced biological phosphorus removal (EBPR) process, where the efficiency of this process for diclofenac biodegradation as well as the metabolites generated are not well understood. An enrichment of Accumulibacter polyphosphate accumulating organisms (PAOs) was operated in an SBR for over 300 d, and acclimatized to 20 μg/L of diclofenac, which is in a similar range to that observed in domestic wastewater influents. The diclofenac biotransformation was monitored in four periods of stable operation and linked to the microbial community and metabolic behaviour in each period. Nitrification was observed in two of the four periods despite the addition of a nitrification inhibitor, and these periods were positively correlated with increased diclofenac biodegradation. Interestingly, in two periods with excellent phosphorus removal (>99%) and no nitrification, different levels of diclofenac biotransformation were observed. Period 2, enriched in Accumulibacter Type II achieved more significant diclofenac biotransformation (3.4 μg/gX), while period 4, enriched in Accumulibacter Type I achieved lower diclofenac biotransformation (0.4 μg/gX). In total, 23 transformation products were identified, with lower toxicity than the parent compound, enabling the elucidation of multiple metabolic pathways for diclofenac biotransformation. This study showed that PAOs can contribute to diclofenac biotransformation, yielding less toxic transformation products, and can complement the biodegradation carried out by other organisms in activated sludge, particularly nitrifiers.
Oerskovia paurometabola can efficiently decolorize azo dye Acid Red 14 and remove its recalcitrant metabolite
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.ECOENV.2019.110007
Abstract: The biodegradation of dyes remains one of the biggest challenges of textile wastewater. Azo dyes are one of the most commonly employed dye classes, and biological treatment processes tend to generate recalcitrant aromatic amines, which are more toxic than the parent dye molecule. This study aimed to isolate bacterial strains with the capacity to degrade both the azo dye and the resulting aromatic amines towards the development of a simple and reliable treatment approach for dye-laden wastewaters. A mixed bacterial enrichment was first developed in an anaerobic-aerobic lab-scale sequencing batch reactor (SBR) fed with a synthetic textile wastewater containing the model textile azo dye Acid Red 14 (AR14). Eighteen bacterial strains were isolated from the SBR, including members of the Acinetobacter, Pseudomonas and Oerskovia genera, Oerskovia paurometabola presenting the highest decolorization capacity (91% after 24 h in static anaerobic culture). Growth assays supported that this is a facultative bacterium, and decolorization batch tests with 20-100 mg AR14 L
Metabolic modeling of the substrate competition among multiple VFAs for PHA production by mixed microbial cultures
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.JBIOTEC.2018.06.342
Abstract: Mixed microbial cultures (MMCs) are an effective method for polyhydroxyalkanoates (PHA) production. There are several models established to describe the metabolism of this process. Substrate competition was commonly found in the uptake of multiple volatile fatty acids (VFAs), thus this behavior should be considered in process modeling. In this study, a metabolic model is developed to describe for the first time the substrate competition among four commonly used VFAs (acetate, propionate, butyrate and valerate) in PHA production by MMCs. An inhibition parameter was introduced to describe the inhibition of butyrate and valerate on the uptake of acetate and propionate. The modeled results showed good agreement with experimental data within 95% confidence interval. This model enhanced the understanding of the metabolism of substrate uptake in PHA production, providing a successful approach to predict PHA composition and optimize the process efficiency when four competing VFAs are supplied.
Denitrifying phosphorus removal: Linking the process performance with the microbial community structure
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.WATRES.2007.06.065
Abstract: This study investigated the link between the process performance of two denitrifying phosphorus (P) removal systems and their microbial community structure. Two sequencing batch reactors (SBRs) were operated with either acetate or propionate as the sole carbon source, and were gradually acclimatised from anaerobic-aerobic to anaerobic-anoxic conditions. It was found that the propionate SBR was able to sustain denitrifying P removal after acclimatisation, while the enhanced biological phosphorus removal (EBPR) activity in the acetate reactor collapsed after the aerobic phase was eliminated. The results suggested that the anoxic glycogen production rate in the acetate SBR was insufficient to support the anaerobic glycogen demand for acetate uptake. The chemical transformations in each SBR suggested that different types of polyphosphate-accumulating organisms (PAOs) were present in each system, possessing different affinities for nitrate. Microbial characterisation with fluorescence in situ hybridisation (FISH) revealed that Accumulibacter was the dominant organism in each reactor, although different cell morphotypes were observed. A coccus morphotype was predominant in the acetate SBR while the propionate SBR was enriched in a rod morphotype. It is hypothesised that the coccus morphotype corresponds to an Accumulibacter strain that is unable to use nitrate as electron acceptor but is able to use oxygen, and possibly nitrite. The rod morphotype is proposed to be a PAO able to use nitrate, nitrite and oxygen. This hypothesis is in agreement with literature studies focussed on the identity of denitrifying PAOs (DPAOs), as well as a recent metagenomic study on Accumulibacter.
The storage compounds associated with Tetrasphaera PAO metabolism and the relationship between diversity and P removal
Publisher: Elsevier BV
Date: 10-2021
Bioaugmentation of activated sludge with Achromobacter denitrificans PR1 for enhancing the biotransformation of sulfamethoxazole and its human conjugates in real wastewater: Kinetic tests and modellin
Publisher: Elsevier BV
Date: 11-2018
The link of feast-phase dissolved oxygen (DO) with substrate competition and microbial selection in PHA production
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.WATRES.2017.01.064
Abstract: Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polyesters with the potential to replace conventional plastics. Aeration requires large amounts of energy in PHA production by mixed microbial cultures (MMCs), particularly during the feast phase due to substrate uptake. The objective of this study was to investigate the impact of DO concentrations on microbial selection, substrate competition and PHA production performance by MMCs. This represents the first study investigating DO impact on PHA production while feeding the multiple volatile fatty acids (VFAs) typically encountered in real fermented feedstocks, as well as the substrate preferences at different DO levels. Efficient microbial cultures were enriched under both high (3.47 ± 1.12 mg/L) and low (0.86 ± 0.50 mg/L) DO conditions in the feast phase containing mostly the same populations but with different relative abundance. The most abundant microorganisms in the two MMCs were Plasticicumulans, Zoogloea, Paracoccus, and Flavobacterium. Butyrate and valerate were found to be the preferred substrates as compared to acetate and propionate regardless of DO concentrations. In the accumulation step, the PHA storage capacity and yield were less affected by the change of DO levels when applying the culture selected under low DO in the feast phase (PHA storage capacity >60% and yield > 0.9 Cmol PHA/Cmol VFA). A high DO level is required for maximal PHA accumulation rates with the four VFAs (acetate, propionate, butyrate and valerate) present, due to the lower specific uptake rates of acetate and propionate under low DO conditions. However, butyrate and valerate specific uptake rates were less impacted by DO levels and hence low DO for PHA accumulation may be effective when feed is composed of these substrates only.
Dynamics of Microbial Communities in Phototrophic Polyhydroxyalkanoate Accumulating Cultures.
Publisher: MDPI AG
Date: 03-02-2022
DOI: 10.3390/MICROORGANISMS10020351
Abstract: Phototrophic mixed cultures (PMC) are versatile systems which can be applied for waste streams, valorisation and production of added-value compounds, such as polyhydroxyalkanoates (PHA). This work evaluates the influence of different operational conditions on the bacterial communities reported in PMC systems with PHA production capabilities. Eleven PMCs, fed either with acetate or fermented wastewater, and selected under either feast and famine (FF) or permanent feast (PF) regimes, were evaluated. Overall, results identified Chromatiaceae members as the main phototrophic PHA producers, along with
Metabolic shift of polyphosphate-accumulating organisms with different levels of polyphosphate storage
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.WATRES.2012.01.003
Abstract: Previous studies have shown that polyphosphate-accumulating organisms (PAOs) are able to behave as glycogen-accumulating organisms (GAOs) under different conditions. In this study we investigated the behavior of a culture enriched with Accumulibacter at different levels of polyphosphate (poly-P) storage. The results of stoichiometric ratios Gly(degraded)/HAc(uptake), PHB(synthesized)/HAc(uptake), PHV(synthesized)/HAc(uptake) and P(release)/HAc(uptake) confirmed a metabolic shift from PAO metabolism to GAO metabolism: PAOs with high poly-P content used the poly-P to obtain adenosine tri-phosphate (ATP), and glycogen (Gly) to obtain nicotinamide adenine dinucleotide (NADH) and some ATP. In a test where poly-P depletion was imposed on the culture, all the acetate (HAc) added in each cycle was transformed into polyhydroxyalkanoate (PHA) despite the decrease of poly-P inside the cells. This led to an increase of the Gly(degraded)/HAc(uptake) ratio that resulted from a shift towards the glycolytic pathway in order to compensate for the lack of ATP formed from poly-P hydrolysis. The shift from PAO to GAO metabolism was also reflected in the change in the PHA composition as the poly-P availability decreased, suggesting that polyhydroxyvalerate (PHV) is obtained due to the consumption of excess reducing equivalents to balance the internal NADH, similarly to GAO metabolism. Fluorescence in situ hybridization analysis showed a significant PAO population change from Type I to Type II Accumulibacter as the poly-P availability decreased in short term experiments. This work suggests that poly-P storage levels and GAO-like metabolism are important factors affecting the competition between different PAO Types in enhanced biological phosphorus removal systems.
Survival strategies of polyphosphate accumulating organisms and glycogen accumulating organisms under conditions of low organic loading
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.BIORTECH.2014.09.059
Abstract: Enhanced biological phosphorus removal (EBPR) is usually limited by organic carbon availability in wastewater treatment plants (WWTPs). Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were operated under extended periods with low organic carbon loading in order to examine its impact on their activity and survival. The decrease in organic carbon load affected PAOs and GAOs in different ways, where the biomass decay rate of GAOs was approximately 4times higher than PAOs. PAOs tended to conserve a relatively high residual concentration of polyhydroxyalkanoates (PHAs) under aerobic conditions, while GAOs tended to deplete their available PHA more rapidly. This slower oxidation rate of PHA by PAOs at residual concentration levels enabled them to maintain an energy source for aerobic maintenance processes for longer than GAOs. This may provide PAOs with an advantage over GAOs in surviving the low organic loading conditions commonly found in full-scale wastewater treatment plants.
Eco-physiological characterization of fluorescence in situ hybridization probe-targeted denitrifiers in activated sludge using culture-independent methods
Publisher: Oxford University Press (OUP)
Date: 04-2007
The effect of substrate competition on the metabolism of polyphosphate accumulating organisms (PAOs)
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.WATRES.2014.07.004
Abstract: The type of carbon source present in the wastewater is one factor that affects the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) and therefore, the efficiency of the enhanced biological phosphorus removal (EBPR) process. This study investigated the impact of the carbon source composition on the anaerobic and aerobic kinetics of PAOs and the EBPR performance of an 85% PAO enrichment. When both acetate (HAc) and propionate (HPr) were present, propionate was depleted more quickly, with a constant uptake rate of 0.18 ± 0.02 C-mol/(C-mol biomass·h), while the acetate uptake rate decreased with an increase in propionate concentration, due to the substrate competition between acetate and propionate. The metabolic model for PAOs was modified to incorporate the anaerobic substrate competition effect. The aerobic rates for phosphorus (P) uptake, glycogen production and polyhydroxyalkanoates (PHA) degradation were within the same range for all tests, indicating that these rates are essentially independent of the acetate and propionate concentration, simplifying the calibration procedure for metabolic models. The metabolic model applied to describe the anaerobic and aerobic activity agreed well with the experimental data of HAc, HPr, P, PHA and biomass growth. The low glycogen consumption observed suggest that some reducing equivalents were generated anaerobically through the TCA cycle. The results of this work suggest that the propionate uptake kinetics by PAOs can provide them an advantage over GAOs in EBPR systems, even when the propionate fraction of the influent is relatively low.
The link between nitrous oxide emissions, microbial community profile and function from three full-scale WWTPs
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.SCITOTENV.2018.10.132
Abstract: Few attempts have been made in previous studies to link the microbial community structure and function with nitrous oxide (N
Impact of biogenic substrates on sulfamethoxazole biodegradation kinetics by Achromobacter denitrificans strain PR1
Publisher: Springer Science and Business Media LLC
Date: 11-03-2017
DOI: 10.1007/S10532-017-9789-6
Abstract: Pure cultures have been found to degrade pharmaceutical compounds. However, these cultures are rarely characterized kinetically at environmentally relevant concentrations. This study investigated the kinetics of sulfamethoxazole (SMX) degradation by Achromobacter denitrificans strain PR1 at a wide range of concentrations, from ng/L to mg/L, to assess the feasibility of using it for bioaugmentation purposes. Complete removal of SMX occurred for all concentrations tested, i.e., 150 mg/L, 500 µg/L, 20 µg/L, and 600 ng/L. The reaction rate coefficients (k
Performance of a two-stage anaerobic digestion system treating fruit pulp waste: The impact of substrate shift and operational conditions
Publisher: Elsevier BV
Date: 08-2018
Model development and application for surfactant biodegradation in an acclimatising activated sludge system
Publisher: Elsevier BV
Date: 03-2004
DOI: 10.1016/J.CHEMOSPHERE.2003.08.028
Abstract: A model for the biodegradation of non-ionic surfactants in an activated sludge system during acclimatisation was developed, based on respirometric and titrimetric experimental data. The data were obtained in a sequencing batch reactor (SBR) using a non-ionic surfactant as sole carbon source and sludge previously acclimatised to a different surfactant. The model was successfully applied to successive SBR-cycles of sludge acclimatisation processes subjected to two ethoxylated surfactants. The model was validated using the corresponding total organic carbon data. The evolution of the model parameters along the acclimatisation process was examined. An acclimatisation model was developed using the evolution of two of these parameters (affinity constant and inhibition constant), supported by two independently calculated acclimatisation indicators. This acclimatisation model was then applied to determine an optimal surfactant concentration sequence to feed non-acclimatised sludge during a period of 41 days, in order to induce pre-acclimatisation to this surfactant before it replaces another one in the wastewater. The model was also useful in the economical assessment of this and alternative procedures to cope with frequent changes in activated sludge feed composition.
Differential distribution of ammonia- and nitrite-oxidising bacteria in flocs and granules from a nitrifying/denitrifying sequencing batch reactor
Publisher: Elsevier BV
Date: 11-2006
Link between microbial composition and carbon substrate-uptake preferences in a PHA-storing community
Publisher: Springer Science and Business Media LLC
Date: 19-07-2012
Advances in enhanced biological phosphorus removal: From micro to macro scale
Publisher: Elsevier BV
Date: 06-2007
DOI: 10.1016/J.WATRES.2007.02.030
Abstract: The enhanced biological phosphorus removal (EBPR) process has been implemented in many wastewater treatment plants worldwide. While the EBPR process is indeed capable of efficient phosphorus (P) removal performance, disturbances and prolonged periods of insufficient P removal have been observed at full-scale plants on numerous occasions under conditions that are seemingly favourable for EBPR. Recent studies in this field have utilised a wide range of approaches to address this problem, from studying the microorganisms that are primarily responsible for or detrimental to this process, to determining their biochemical pathways and developing mathematical models that facilitate better prediction of process performance. The overall goal of each of these studies is to obtain a more detailed insight into how the EBPR process works, where the best way of achieving this objective is through linking together the information obtained using these different approaches. This review paper critically assesses the recent advances that have been achieved in this field, particularly relating to the areas of EBPR microbiology, biochemistry, process operation and process modelling. Potential areas for future research are also proposed. Although previous research in this field has undoubtedly improved our level of understanding, it is clear that much remains to be learned about the process, as many unanswered questions still remain. One of the challenges appears to be the integration of the existing and growing scientific knowledge base with the observations and applications in practice, which this paper hopes to partially achieve.
Assessment of Protein-Rich Cheese Whey Waste Stream as a Nutrients Source for Low-Cost Mixed Microbial PHA Production
Publisher: MDPI AG
Date: 03-10-2018
DOI: 10.3390/APP8101817
Abstract: The critical step in the mixed microbial cultures (MMC) polyhydroxyalkanoates (PHA) production process is the selection of an MMC enriched in an efficient PHA-accumulating organism, usually requiring growth-nutrients supplementation. This study aimed at assessing cheese whey (CW) proteins as a source of nitrogen for PHA-producing MMC, thus eliminating or reducing the need for nutrients supplementation. The selection reactor, operated with fermented CW, under a feast–famine regime, was initially supplemented with ammonia–nitrogen in a C/N ratio of 100/15 (Cmol/Nmmol), which was gradually reduced until eliminated, in order to select a culture capable of using CW proteins nitrogen. Decreasing nitrogen supplementation from a C/N ratio of 100/10 to 100/7.5 lead to significant microbial community changes, and reduced the MMC PHA-storing capacity, storage yield, and PHA productivity, decreasing by 30%, and over 45%, respectively. The PHA-storing capacity further deteriorated as nitrogen supplementation was reduced, despite increased protein-uptake. Results show that a culture enriched in PHA-accumulators capable of using proteins as sole nitrogen source could not be attained. In conclusion, this work reports for the first time that an easily bioavailable nitrogen source is required for efficiently selecting PHA-accumulating cultures. Based on the results obtained from this work, a pilot scale plant (two reactors of 100 L) fed with cheese whey for production of PHA is currently being successfully operated under the scope of the YPACK EU project, in which the selection reactor is supplemented with nitrogen (ammonia) from a total C/N ratio of 100/10.
Assessing the abundance and activity of denitrifying polyphosphate accumulating organisms through molecular and chemical techniques
Publisher: IWA Publishing
Date: 04-2010
DOI: 10.2166/WST.2010.976
Abstract: Biological nutrient removal (BNR) plants can reduce both carbon and oxygen requirements by increasing the fraction of phosphorus (P) removed by denitrifying polyphosphate accumulating organisms (DPAOs). Contrasting findings have been reported in literature concerning whether or not PAOs and DPAOs are different microorganisms. In this study, quantitative fluorescence in situ hybridisation (FISH) measurements from different EBPR sludges support the hypothesis that PAOs and DPAOs are phyogenetically different. This experimental evidence is discussed within the context of literature findings and suggestions for future research concerning the identity of PAOs and DPAOs are proposed. Further, this paper discusses the different methodologies available for assessing the DPAO fraction through chemical analytical techniques, where the relative fraction estimated is highly dependent on the methodology employed. Thus, we recommend an alteration to previously proposed methods in order to calculate the DPAO fraction through anaerobic-anoxic and anaerobic-aerobic batch tests. This information is expected to be valuable in studies focussed on optimising the amount of phosphorus removal achieved with simultaneous denitrification.
Modelling the population dynamics and metabolic diversity of organisms relevant in anaerobic/anoxic/aerobic enhanced biological phosphorus removal processes
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.WATRES.2010.06.017
Abstract: In this study, enhanced biological phosphorus removal (EBPR) metabolic models are expanded in order to incorporate the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) under sequential anaerobic/anoxic/aerobic conditions, which are representative of most full-scale EBPR plants. Since PAOs and GAOs display different denitrification tendencies, which is dependent on the phylogenetic identity of the organism, the model was separated into six distinct biomass groups, constituting Accumulibacter Types I and II, as well as denitrifying and non-denitrifying Competibacter and Defluviicoccus GAOs. Denitrification was modelled as a multi-step process, with nitrate (NO(3)), nitrite (NO(2)), nitrous oxide (N(2)O) and di-nitrogen gas (N(2)) being the primary components. The model was calibrated and validated using literature data from enriched cultures of PAOs and GAOs, obtaining a good description of the observed biochemical transformations. A strong correlation was observed between Accumulibacter Types I and II, and nitrate-reducing and non-nitrate-reducing PAOs, respectively, where the abundance of each PAO subgroup was well predicted by the model during an acclimatization period from anaerobic-aerobic to anaerobic-anoxic conditions. Interestingly, a strong interdependency was observed between the anaerobic, anoxic and aerobic kinetic parameters of PAOs and GAOs. This could be exploited when metabolic models are calibrated, since all of these parameters should be changed by an identical factor from their default value. Factors that influence these kinetic parameters include the fraction of active biomass, relative aerobic/anoxic fraction and the ratio of acetyl-CoA to propionyl-CoA. Employing a metabolic approach was found to be advantageous in describing the performance and population dynamics in such complex microbial ecosystems.
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