ORCID Profile
0000-0002-3862-2636
Current Organisations
Universidade Nova de Lisboa Faculdade de Ciências e Tecnologia
,
Universidade Nova de Lisboa
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 08-2018
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.
Publisher: IWA Publishing
Date: 28-03-2014
DOI: 10.2166/WST.2014.146
Abstract: A rapid methodology for intracellular storage polyphosphate (poly-P) identification and monitoring in enhanced biological phosphorus removal (EBPR) systems is proposed based on quantitative image analysis (QIA). In EBPR systems, 4′,6-diamidino-2-phenylindole (DAPI) is usually combined with fluorescence in situ hybridization to evaluate the microbial community. The proposed monitoring technique is based on a QIA procedure specifically developed for determining poly-P inclusions within a biomass suspension using solely DAPI by epifluorescence microscopy. Due to contradictory literature regarding DAPI concentrations used for poly-P detection, the present work assessed the optimal DAPI concentration for s les acquired at the end of the EBPR aerobic stage when the accumulation occurred. Digital images were then acquired and processed by means of image processing and analysis. A correlation was found between average poly-P intensity values and the analytical determination. The proposed methodology can be seen as a promising alternative procedure for quantifying intracellular poly-P accumulation in a faster and less labour-intensive way.
Publisher: Elsevier BV
Date: 11-2013
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.
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.WATRES.2019.115373
Abstract: This study demonstrates that META-ASM, a new integrated metabolic activated sludge model, provides an overall platform to describe the activity of the key organisms and processes relevant to biological nutrient removal (BNR) systems with a robust single-set of default parameters. This model overcomes various shortcomings of existing enhanced biological phosphorous removal (EBPR) models studied over the last twenty years. The model has been tested against 34 data sets from enriched lab polyphosphate accumulating organism (PAO)-glycogen accumulating organism (GAO) cultures and experiments with full-scale sludge from five water resource recovery facilities (WRRFs) with two different process configurations: three stage Phoredox (A2/O) and adapted Biodenitro™ combined with a return sludge sidestream hydrolysis tank (RSS). Special attention is given to the operational conditions affecting the competition between PAOs and GAOs, capability of PAOs and GAOs to denitrify, metabolic shifts as a function of storage polymer concentrations, as well as the role of these polymers in endogenous processes and fermentation. The overall good correlations obtained between the predicted versus measured EBPR profiles from different data sets support that this new model, which is based on in-depth understanding of EBPR, reduces calibration efforts. On the other hand, the performance comparison between META-ASM and literature models demonstrates that existing literature models require extensive parameter changes and have limited predictive power, especially in the prediction of long-term EBPR performance. The development of such a model able to describe in detail the microbial and chemical transformations of BNR systems with minimal adjustment to parameters suggests that the META-ASM model is a powerful tool to predict and mitigate EBPR upsets, optimise EBPR performance and to evaluate new process designs.
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.
Location: Portugal
Location: Portugal
Location: No location found
No related grants have been discovered for Mónica Carvalheira.