19 results on '"TORREGROSSA, M"'
Search Results
2. Pilot scale experiment with MBR operated in intermittent aeration condition: Analysis of biological performance
- Author
-
Capodici, M., Di Bella, G., Di Trapani, D., and Torregrossa, M.
- Published
- 2015
- Full Text
- View/download PDF
3. Effect of chemical and biological surfactants on activated sludge of MBR system: Microscopic analysis and foam test
- Author
-
Marco Capodici, Salvatore Nicosia, Gaetano Di Bella, Michele Torregrossa, Capodici, M, Di Bella, G, Nicosia, S, and Torregrossa, M
- Subjects
Environmental Engineering ,Segmented filamentous bacteria ,chemistry.chemical_element ,Bioengineering ,Fraction (chemistry) ,MBR ,Surface-Active Agents ,Ink test ,Biopolymers ,Bioreactors ,Pulmonary surfactant ,Foam test ,Surfactant ,Waste Management and Disposal ,Biological Oxygen Demand Analysis ,Microscopy ,Chromatography ,Bacteria ,Sewage ,Settore ICAR/03 - Ingegneria Sanitaria-Ambientale ,Viscosity ,Renewable Energy, Sustainability and the Environment ,Membranes, Artificial ,General Medicine ,Activated sludge ,Wastewater ,chemistry ,Chemical engineering ,Carbon ,Foaming - Abstract
A bench-scale MBR unit was operated, under stressing condition, with the aim of stimulating the onset of foaming in the activated sludge. Possible synergies between synthetic surfactants in the wastewater and biological surfactants (Extra-Cellular Polymeric Substances, EPSs) were investigated by changing C/N ratio. The growth of filamentous bacteria was also discussed. The MBR unit provided satisfactory overall carbon removal overall efficiencies: in particular, synthetic surfactants were removed with efficiency higher than 90% and 95% for non-ionic and ionic surfactants, respectively. Lab investigation suggested also the importance to reduce synthetic surfactants presence entering into mixed liquor: otherwise, their presence can significantly worsen the natural foaming caused by biological surfactants (EPSs) produced by bacteria. Finally, a new analytic method based on “ink test” has been proposed as a useful tool to achieve a valuation of EPSs bound fraction.
- Published
- 2015
4. Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: Influence of wastewater salinity variation
- Author
-
Daniele Di Trapani, Michele Torregrossa, Gaetano Di Bella, Gaspare Viviani, Giorgio Mannina, Di Trapani, D, Di Bella, G, Mannina, G, Torregrossa, M, and Viviani, G
- Subjects
Salinity ,Environmental Engineering ,Biofouling ,Pilot Projects ,Bioengineering ,Wastewater ,Membrane bioreactor ,Waste Disposal, Fluid ,chemistry.chemical_compound ,Biopolymers ,Bioreactors ,Ammonium Compounds ,Electric Impedance ,Ammonium ,Biomass ,Waste Management and Disposal ,Biological Oxygen Demand Analysis ,Settore ICAR/03 - Ingegneria Sanitaria-Ambientale ,Fouling ,Renewable Energy, Sustainability and the Environment ,Membrane fouling ,Environmental engineering ,Membranes, Artificial ,General Medicine ,Membrane fouling Saline wastewater MB-MBR Respirometry ,Pulp and paper industry ,Kinetics ,Pilot plant ,Membrane ,chemistry ,Biofilms ,Extracellular Space ,Filtration - Abstract
Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the pore fouling tendency in the membrane module of MB-MBR system. On the contrary, the MBR pilot, even showing a lower irreversible cake deposition, was characterized by a higher pore fouling tendency.
- Published
- 2014
5. Physical properties and Extracellular Polymeric Substances pattern of aerobic granular sludge treating hypersaline wastewater
- Author
-
Gaspare Viviani, Santo Fabio Corsino, Michele Torregrossa, Marco Capodici, Corsino Santo Fabio, Capodici, M., Torregrossa, M., and Viviani, G.
- Subjects
Salinity ,Environmental Engineering ,0208 environmental biotechnology ,Bioengineering ,02 engineering and technology ,010501 environmental sciences ,Sodium Chloride ,Wastewater ,01 natural sciences ,Waste Disposal, Fluid ,Protein content ,Extracellular polymeric substance ,Biopolymers ,Bioreactors ,Food-Processing Industry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Settore ICAR/03 - Ingegneria Sanitaria-Ambientale ,Sewage ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Granule (cell biology) ,General Medicine ,Aerobiosis ,020801 environmental engineering ,Chemical engineering ,Aerobic granular sludge EPS Industrial wastewater Fish-canning wastewater Hypersaline wastewater ,Gradual increase ,Hydrophobic and Hydrophilic Interactions - Abstract
The modification of the physical properties of aerobic granular sludge treating fish-canning wastewater is discussed in this paper. The structure and composition of the Extracellular Polymeric Substances (EPSs) were analyzed at different salinity levels and related to granules stability. Results outlined that the total EPSs content increased with salinity, despite the EPSs increment was not proportional to the salt concentration. Moreover, the EPSs structure was significantly modified by salinity, leading to a gradual increase of the not-bound EPSs fraction, which was close to the 50% of the total EPSs content at 75 g NaCl L-1. The increasing salt concentration modified also the EPSs composition, causing the gradual reduction of protein content resulting in a decrease of granule hydrophobicity. The results pointed out that the granules stability significantly reduced above 50 g NaCl L-1, suggesting the existence of a salinity threshold above which granules stability is compromised.
- Published
- 2016
6. Study of aerobic granular sludge stability in a continuous-flow membrane bioreactor
- Author
-
Gaspare Viviani, Santo Fabio Corsino, Michele Torregrossa, Riccardo Campo, G. Di Bella, Corsino, S., Campo, R., Di Bella, G., Torregrossa, M., and Viviani, G.
- Subjects
Flocculation ,Environmental Engineering ,Aerobic granular sludge (AGS) ,Segmented filamentous bacteria ,0208 environmental biotechnology ,Microbial Consortia ,Biomass ,Bioengineering ,02 engineering and technology ,010501 environmental sciences ,Membrane bioreactor ,01 natural sciences ,Waste Disposal, Fluid ,Bioreactors ,Breakage ,Bioreactor ,Pressure ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Continuous-flow reactor ,Settore ICAR/03 - Ingegneria Sanitaria-Ambientale ,Bacteria ,Sewage ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Continuous flow ,Feast/famine condition ,Membrane ,Environmental engineering ,Washout ,General Medicine ,Equipment Design ,Pulp and paper industry ,Aerobiosis ,020801 environmental engineering ,Hydraulic selection pressure ,Feast/famine conditions - Abstract
A granular continuous-flow membrane bioreactor with a novel hydrodynamic configuration was developed to evaluate the stability of aerobic granular sludge (AGS). Under continuous-flow operation (Period I), AGS rapidly lost their structural integrity resulting in loose and fluffy microbial aggregates in which filamentous bacteria were dominant. The intermittent feeding (Period II) allowed obtaining the succession of feast and famine conditions that favored the increase in AGS stability. Although no further breakage occurred, the formation of new granules was very limited, owing to the absence of the hydraulic selection pressure. These results noted the necessity to ensure, on the one hand the succession of feast/famine conditions, and on the other, the hydraulic selection pressure that allows flocculent sludge washout. This preliminary study shows that the proposed configuration could meet the first aspect; in contrast, biomass selection needs to be improved.
- Published
- 2015
7. Effect of C/N shock variation on the performances of a moving bed membrane bioreactor
- Author
-
Gaspare Viviani, Gaetano Di Bella, Michele Torregrossa, Daniele Di Trapani, Giorgio Mannina, Di Trapani, D., Di Bella, G., Mannina, G., Torregrossa, M., and Viviani, G.
- Subjects
Moving bed membrane bioreactor ,Environmental Engineering ,Biofouling ,Nitrogen ,OLR ,Bioengineering ,Pilot Projects ,C/N ratio ,Nitrification ,Waste Management and Disposal ,Membrane bioreactor ,Waste Disposal, Fluid ,Ammonia ,chemistry.chemical_compound ,Extracellular polymeric substance ,Biopolymers ,Bioreactors ,Bioreactor ,Biomass ,Biological Oxygen Demand Analysis ,Chromatography ,Fouling ,Bacteria ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Membranes, Artificial ,General Medicine ,Carbon ,Membrane ,Chemical engineering ,Biofilms ,Oxidation-Reduction ,Particle deposition - Abstract
The effect of a sharp variation of C/N ratio in a moving bed membrane bioreactor (MB-MBR) pilot plant treating high strength wastewater has been investigated. The experimental campaign was divided into two periods, each characterized by a different C/N ratio (namely, 2.5 and 15, Period 1 and Period 2, respectively). The MB-MBR system was analyzed in terms of organic carbon removal, nitrification efficiency, biokinetic activity and fouling behavior. The results showed that the nitrification process was severely affected by lower C/N value and by high concentration of ammonia. It was noticed an extensive stress effect on the autotrophic bacteria. Furthermore, it was observed an increase of the resistance related to particle deposition into membrane pores, likely due to a worsening of the cake layer features, with a reduction of the “pre-filter” effect, also related to the increase of the total Extracellular Polymeric Substances production with the C/N ratio.
- Published
- 2015
8. Pilot scale experiment with MBR operated in intermittent aeration condition: analysis of biological performance
- Author
-
G. Di Bella, Daniele Di Trapani, Marco Capodici, Michele Torregrossa, Capodici, M, Di Bella, G, DI Trapani D, and Torregrossa, M
- Subjects
Environmental Engineering ,Nitrogen ,Bioengineering ,Pilot Projects ,MBR systems ,Wastewater ,law.invention ,Extracellular polymeric substance ,Biopolymers ,Bioreactors ,law ,Bioreactor ,Waste Management and Disposal ,Filtration ,Biological Oxygen Demand Analysis ,Fouling ,Settore ICAR/03 - Ingegneria Sanitaria-Ambientale ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Environmental engineering ,General Medicine ,Anoxic waters ,Nitrification ,Aerobiosis ,Carbon ,Intermittent aeration ,Activated sludge ,Pilot plant ,Biodegradation, Environmental ,Denitrification ,Aeration ,Volatilization ,Biological treatment ,Biotechnology - Abstract
The effect of intermittent aeration (IA) on a MBR system was investigated. The study was aimed at ana- lyzing different working conditions and the influence of different IA cycles on the biological performance of the MBR pilot plant, in terms of organic carbon and ammonium removal as well as extracellular poly- meric substances (EPSs) production. The membrane modules were placed in a separate compartment, continuously aerated. This configuration allowed to disconnect from the filtration stage the biological phenomena occurring into the IA bioreactor. The observed results highlighted good efficiencies, in terms of organic carbon and ammonium removal. It was noticed a significant soluble microbial products (SMPs) release, likely related to the higher metabolic stress that anoxic conditions exerted on the biomass. How- ever, the proposed configuration, with the membranes in a separate compartment, allowed to reduce the EPSs in the membrane tank even during the non-aerated phase, thus lowering fouling development.
- Published
- 2014
9. Combination of the OSA process with thermal treatment at moderate temperature for excess sludge minimization.
- Author
-
Corsino SF, Capodici M, Di Trapani D, Torregrossa M, and Viviani G
- Subjects
- Anaerobiosis, Biomass, Bioreactors, Temperature, Sewage, Waste Disposal, Fluid
- Abstract
This study investigated the chance to couple the conventional Oxic Settling Anaerobic (OSA) process with a thermic treatment at moderate temperature (35 °C). The maximum excess sludge reduction rate (80%) was achieved when the plant was operated under 3 h of hydraulic retention time (HRT). Compared with the conventional OSA system, the thermic treatment enabled a further improvement in excess sludge minimization of 35%. The observed yield coefficient decreased from 0.25 gTSS gCOD
-1 to 0.10 gTSS gCOD-1 when the temperature in the anaerobic reactor was increased to 35 °C, despite the lower HRT (3 h vs 6 h). Moreover, the thermic treatment enabled the decrease of filamentous bacteria, thereby improving the sludge settling properties. The thermic treatment enhanced the destruction of extracellular polymeric substances and the increase of endogenous decay rate (from 0.64 d-1 to 1.16 d-1 ) that reduced the biomass active fraction (from 22% to 4%)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)- Published
- 2020
- Full Text
- View/download PDF
10. Biological minimization of excess sludge in a membrane bioreactor: Effect of plant configuration on sludge production, nutrient removal efficiency and membrane fouling tendency.
- Author
-
de Oliveira TS, Corsino SF, Di Trapani D, Torregrossa M, and Viviani G
- Subjects
- Biomass, Denitrification, Nitrogen, Sewage, Waste Disposal, Fluid, Bioreactors
- Abstract
Excess sludge minimization was studied in a MBR with pre-denitrification scheme. Sludge minimization, nitrogen removal performance and membrane fouling tendency were investigated in two configurations, characterized by a different position of the sludge retention reactor (SRR). In particular, the SRR was placed: i) in the return activated sludge line (Anaerobic Side-Stream Reactor - ASSR configuration) and ii) in the mainstream between the anoxic and aerobic reactor (Anaerobic Main-Stream Reactor - AMSR configuration). The achieved results demonstrated that the ASSR enabled a higher excess sludge reduction (74% vs 32%), while achieving lower biological nitrogen removal (BNR) (TN = 63% vs 78%) and membrane fouling tendency (FR = 2.1 · 10
12 m-1 d-1 vs 4.0 · 1011 m-1 d-1 ) than the AMSR. It was found that metabolism uncoupling, destruction of EPS and endogenous decay simultaneously occurred in the ASSR. Conversely, selective enrichment of bacteria population with low biomass yield was found the main mechanism affecting sludge minimization in the AMSR., (Copyright © 2018 Elsevier Ltd. All rights reserved.)- Published
- 2018
- Full Text
- View/download PDF
11. Physical properties and Extracellular Polymeric Substances pattern of aerobic granular sludge treating hypersaline wastewater.
- Author
-
Corsino SF, Capodici M, Torregrossa M, and Viviani G
- Subjects
- Aerobiosis, Bioreactors, Food-Processing Industry, Hydrophobic and Hydrophilic Interactions, Salinity, Sodium Chloride chemistry, Waste Disposal, Fluid instrumentation, Biopolymers chemistry, Sewage chemistry, Waste Disposal, Fluid methods, Wastewater chemistry
- Abstract
The modification of the physical properties of aerobic granular sludge treating fish-canning wastewater is discussed in this paper. The structure and composition of the Extracellular Polymeric Substances (EPSs) were analyzed at different salinity levels and related to granules stability. Results outlined that the total EPSs content increased with salinity, despite the EPSs increment was not proportional to the salt concentration. Moreover, the EPSs structure was significantly modified by salinity, leading to a gradual increase of the not-bound EPSs fraction, which was close to the 50% of the total EPSs content at 75gNaClL
-1 . The increasing salt concentration modified also the EPSs composition, causing the gradual reduction of protein content resulting in a decrease of granule hydrophobicity. The results pointed out that the granules stability significantly reduced above 50gNaClL-1 , suggesting the existence of a salinity threshold above which granules stability is compromised., (Copyright © 2017 Elsevier Ltd. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
12. Effect of extended famine conditions on aerobic granular sludge stability in the treatment of brewery wastewater.
- Author
-
Corsino SF, di Biase A, Devlin TR, Munz G, Torregrossa M, and Oleszkiewicz JA
- Subjects
- Aerobiosis, Bacteria metabolism, Biological Oxygen Demand Analysis, Bioreactors microbiology, Carbon metabolism, Food Industry, Waste Disposal, Fluid instrumentation, Wastewater chemistry, Sewage chemistry, Sewage microbiology, Waste Disposal, Fluid methods
- Abstract
Results obtained from three aerobic granular sludge reactors treating brewery wastewater are presented. Reactors were operated for 60d days in each of the two periods under different cycle duration: (Period I) short 6h cycle, and (Period II) long 12h cycle. Organic loading rates (OLR) varying from 0.7kgCODm
-3 d-1 to 4.1kgCODm-3 d-1 were tested. During Period I, granules successfully developed in all reactors, however, results revealed that the feast and famine periods were not balanced and the granular structure deteriorated and became irregular. During Period II at decreased 12h cycle time, granules were observed to develop again with superior structural stability compared to the short 6h cycle time, suggesting that a longer starvation phase enhanced production of proteinaceous EPS. Overall, the extended famine conditions encouraged granule stability, likely because long starvation period favours bacteria capable of storage of energy compounds., (Copyright © 2016 Elsevier Ltd. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
13. Effect of C/N shock variation on the performances of a moving bed membrane bioreactor.
- Author
-
Di Trapani D, Di Bella G, Mannina G, Torregrossa M, and Viviani G
- Subjects
- Ammonia metabolism, Bacteria metabolism, Biofilms, Biofouling, Biological Oxygen Demand Analysis, Biomass, Biopolymers metabolism, Oxidation-Reduction, Pilot Projects, Waste Disposal, Fluid, Bioreactors, Carbon analysis, Membranes, Artificial, Nitrogen analysis
- Abstract
The effect of a sharp variation of C/N ratio in a moving bed membrane bioreactor (MB-MBR) pilot plant treating high strength wastewater has been investigated. The experimental campaign was divided into two periods, each characterized by a different C/N ratio (namely, 2.5 and 15, Period 1 and Period 2, respectively). The MB-MBR system was analyzed in terms of organic carbon removal, nitrification efficiency, biokinetic activity and fouling behavior. The results showed that the nitrification process was severely affected by lower C/N value and by high concentration of ammonia. It was noticed an extensive stress effect on the autotrophic bacteria. Furthermore, it was observed an increase of the resistance related to particle deposition into membrane pores, likely due to a worsening of the cake layer features, with a reduction of the "pre-filter" effect, also related to the increase of the total Extracellular Polymeric Substances production with the C/N ratio., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
14. Effect of chemical and biological surfactants on activated sludge of MBR system: microscopic analysis and foam test.
- Author
-
Capodici M, Di Bella G, Nicosia S, and Torregrossa M
- Subjects
- Bacteria drug effects, Bacteria metabolism, Biological Oxygen Demand Analysis, Biopolymers chemistry, Microscopy, Viscosity, Bioreactors, Membranes, Artificial, Sewage chemistry, Surface-Active Agents pharmacology
- Abstract
A bench-scale MBR unit was operated, under stressing condition, with the aim of stimulating the onset of foaming in the activated sludge. Possible synergies between synthetic surfactants in the wastewater and biological surfactants (Extra-Cellular Polymeric Substances, EPSs) were investigated by changing C/N ratio. The growth of filamentous bacteria was also discussed. The MBR unit provided satisfactory overall carbon removal overall efficiencies: in particular, synthetic surfactants were removed with efficiency higher than 90% and 95% for non-ionic and ionic surfactants, respectively. Lab investigation suggested also the importance to reduce synthetic surfactants presence entering into mixed liquor: otherwise, their presence can significantly worsen the natural foaming caused by biological surfactants (EPSs) produced by bacteria. Finally, a new analytic method based on "ink test" has been proposed as a useful tool to achieve a valuation of EPSs bound fraction., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
15. Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: influence of wastewater salinity variation.
- Author
-
Di Trapani D, Di Bella G, Mannina G, Torregrossa M, and Viviani G
- Subjects
- Ammonium Compounds isolation & purification, Biofilms growth & development, Biofouling, Biological Oxygen Demand Analysis, Biomass, Biopolymers analysis, Electric Impedance, Extracellular Space chemistry, Filtration, Kinetics, Pilot Projects, Waste Disposal, Fluid, Bioreactors, Membranes, Artificial, Salinity, Wastewater chemistry
- Abstract
Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the pore fouling tendency in the membrane module of MB-MBR system. On the contrary, the MBR pilot, even showing a lower irreversible cake deposition, was characterized by a higher pore fouling tendency., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
16. Performance of a MBR pilot plant treating high strength wastewater subject to salinity increase: analysis of biomass activity and fouling behaviour.
- Author
-
Di Bella G, Di Trapani D, Torregrossa M, and Viviani G
- Subjects
- Biomass, Pilot Projects, Salinity, Wastewater chemistry
- Abstract
Membrane bioreactors produce high quality effluents that could be suitable for reuse. However, when treating high strength wastewater subject to a salinity increase, a modification of biomass characteristics may occur. This circumstance is of importance, since it can have a significant impact in terms of biokinetic as well as fouling behaviour. The aim of the study was to evaluate the performance of a pilot plant MBR, in terms of biomass activity and membrane fouling, fed with high strength synthetic wastewater, when subject to a salinity increase. With normal salinity, the pilot plant showed high removal efficiencies and high biomass respiratory activity. On the other hand, the salinity increase significantly affected the removal efficiency as well as the SMP production. Furthermore, the salinity increase showed a strong effect on biomass activity, reducing in particular the respiration rates of autotrophic populations., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
17. The role of EPS in fouling and foaming phenomena for a membrane bioreactor.
- Author
-
Cosenza A, Di Bella G, Mannina G, and Torregrossa M
- Subjects
- Bioreactors, Membranes, Artificial, Polymers chemistry
- Abstract
In contraposition to conventional activated sludge processes, the foaming phenomenon in membrane bioreactor (MBR) is still in its infancy. On the other hand, although several studies have been carried out for better understanding the fouling phenomenon in MBR there are still some gaps in the up-to-date knowledge. The extracellular polymeric substances (EPSs) may have a primary role in fouling and foaming phenomena which in turn can be crucial for MBRs. The aim of this study is to detect a possible relationship that EPSs may have with fouling and foaming in an MBR for wastewater treatment. Foaming phenomenon is monitored by performing specific foam-tests: Foam Power, Scum Index, Foam Rating and filamentous abundance. Results show a high correlation between fouling vs EPS and foaming vs bound EPSs. A relationship between foaming and fouling was also found: in general, when foaming occurred the fouling rate decreases because the EPS bound remained trapped in the floating scum., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
18. Simultaneous nitrogen and organic carbon removal in aerobic granular sludge reactors operated with high dissolved oxygen concentration.
- Author
-
Di Bella G and Torregrossa M
- Subjects
- Aerobiosis, Pilot Projects, Solubility, Bioreactors, Carbon isolation & purification, Nitrogen isolation & purification, Oxygen analysis, Sewage
- Abstract
Simultaneous nitrification and denitrification (SND) together with organic removal in granules is usually carried out without Dissolved Oxygen (DO) concentration control, at "low DO" (with a DO<30-50% of the saturation value, about 3-4 mg/L) to promote anoxic conditions within the aggregates. These conditions can sometimes be in detrimental of the stability of the granules itself due to a lack of shear force. In this work, the authors achieved SND without oxygen control with big sized granules. More specifically, the paper presents a experimentation focused on the analysis of two Sequencing Batch Reactors (SBRs), in bench scale, working with different aerobic sludge granules, in terms of granule size, and high DO concentration, (with concentration varying from anoxic conditions, about DO ∼0 mg/L, to values close to those of saturation, >7-8 mg/L, during feast and famine conditions respectively). In particular, different strategies of cultivation and several organic and nitrogen loading rate have been applied, in order to evaluate the efficiencies in SND process without dissolved oxygen control. The results show that, even under conditions of high DO concentration, nitrogen and organic matter can be simultaneously removed, with efficiency >90%. Nevertheless, the biological conditions in the inner layer of the granule may change significantly between small and big granules, during the feast and famine periods. From point of view of granule stability, it is also interesting that with a particle size greater than 1.5mm, after the cultivation start-up, the granules are presented stable for a long period (about 100 days) and, despite the variations of operational conditions, the granules breaking was always negligible., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
19. The role of EPS concentration in MBR foaming: analysis of a submerged pilot plant.
- Author
-
Di Bella G, Torregrossa M, and Viviani G
- Subjects
- Biofouling, Pilot Projects, Sewage microbiology, Surface Properties, Biopolymers analysis, Bioreactors microbiology, Extracellular Space chemistry, Membranes, Artificial, Water Purification instrumentation
- Abstract
Foaming in Membrane BioReactor (MBR) is a frequently discussed topic. Some authors reported that the phenomenon is due to filamentous organisms, like at Conventional Activated Sludge (CAS) plants. However, in recent years, other authors reported that the Extra-cellular Polymer Substances (EPSs) concentration is an important factor for controlling foam as well. Nevertheless, even if a number of MBR plants are affected by foaming, presently there are no suitable methods to evaluate the phenomenon. To facilitate the study of this controversial phenomenon in an MBR system, certain foam tests proposed in the past for CASPs were investigated. The results of the tests were able to adequately measure quantity, stability and quality of the foam. In particular, the Scum Index increased proportionally with the EPS concentration and mixed liquor viscosity; Foam Power was mainly correlated with the protein concentration of in the EPS; Foam Rating was also correlated with the EPS concentration., (Copyright © 2010 Elsevier Ltd. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
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