[Show abstract][Hide abstract] ABSTRACT: The anammox-based process ELAN® was started-up in two different sequencing batch reactors (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors worked at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1 granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed by granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions.
[Show abstract][Hide abstract] ABSTRACT: Los procesos biológicos empleados para el tratamiento de las aguas residuales se pueden llevar a cabo tanto en sistemas de biomasa en suspensión como adherida. Cuando la biomasa se desarrolla de forma adherida crece en muchos casos sobre un material de soporte, formando una biopelícula que contiene una elevada concentración de biomasa, cuyas propiedades físicas (espesor, porosidad, distribución de zonas con presencia o ausencia de cada sustrato, densidad, etc.) dependen de las condiciones de operación del sistema en el que se desarrollan. En general, la operación con material de soporte implica un mayor grado de complejidad del sistema y mayores costes de operación, ya que es necesario mantener este material confinado dentro de la unidad de operación (reemplazando periódicamente el que se haya podido perder) y aportar la energía necesaria para garantizar una buena mezcla, y por lo tanto una buena transferencia de materia. La principal ventaja, por otra parte, reside en su capacidad de retener grandes cantidades de biomasa en su interior, por lo que estos sistemas están recomendados en el caso de procesos en los que la biomasa tiene velocidades de crecimiento lentas.
Como alternativa a estos sistemas se puede aprovechar la capacidad de la biomasa de autoagregarse formando gránulos, que es un caso especial de biopelícula donde no se requiere de un material de soporte. La transferencia de sustratos y productos desde la zona externa hacia el interior del gránulo provoca la existencia de zonas internas con diferentes ambientes, así como condiciones heterogéneas dentro de los reactores biológicos. Así, en un único reactor biológico pueden tener lugar de forma simultánea diferentes procesos como la eliminación de materia orgánica, nitrógeno y fósforo (de Kreuk et al. 2005). Dentro de los procesos de eliminación de nitrógeno, está despertando un gran interés en la actualidad la operación de sistemas con biomasa granular para la eliminación autótrofa mediante nitrificación parcial combinada con el proceso anammox (ANaerobic AMMonia OXidation), debido a las diversas ventajas que presenta frente a los procesos biológicos convencionales de nitrificación-desnitrificación (Vázquez-Padín et al. 2014; Morales et al. 2015a): reducción en los requerimientos de aireación (42%), ahorro de un 100% en materia orgánica para desnitrificar, reducción en la producción de lodos (94%) y reducción en las emisiones de gases de efecto invernadero (7% de CO2, 22% de N2O).
[Show abstract][Hide abstract] ABSTRACT: INTRODUCTION—POTENTIAL AND CHALLENGES
Shortcut nitrogen removal processes provide a superior alternative to conventional processes used in municipal wastewater treatment (i.e. nitrification-denitrification) since they significantly reduce oxygen demand and external carbon requirements for nitrogen removed (Vlaeminck et al., 2012). Deammonification processes have already been implemented and controlled successfully for sidestream treatment (i.e. nitrogen-rich warm streams) and the operational savings have been reported in the literature (Wett, 2007). In contrast, the potential operational savings using shortcut nitrogen removal processes can be significantly higher for mainstream applications with 40% savings for the nitritation/denitritation process and 84% saving for the deammonificaiton process compared to conventional nitrification/denitrification (De Clippeleir, 2012). Although the tremendous savings on energy and carbon source are possible, the challenges of mainstream deammonification should not be underestimated. One of the main challenges of mainstream deammonification is NOB out-selection to avoid nitrite oxidation to nitrate. The strategies of suppressing NOB in the mainstream process are very important, since maximizing the nitrite availability for AnAOB bacteria is crucial for successful operation. Due to lower biomass activity and diluted influent, retention of AnAOB bacteria should also be considered as a key parameter, especially in suspended growth systems. Moreover, if the influent COD is high, insufficient nitrite levels may occur due to rapid growth of heterotrophic bacteria. Temperature and flow variation could also be a challenge depending on the location.
Shortcut Nitrogen Removal—Nitrite Shunt and Deammonification, 06/2015: chapter Chapter 6: Mainstream Deammonification: pages 107-128; Water Environment Federation., ISBN: 978-1-57278-313-3
[Show abstract][Hide abstract] ABSTRACT: The ELAN® technology, based on the partial nitrification/anammox processes in a single stage with granular sludge, was tested for the treatment of fish canning effluents. The good results in the laboratory tests, despite the high salinity of the industrial wastewater, lead to the implementation of the ELAN reactor in an industrial WWTP for the treatment of 270 m3/d. Compared to the actual conventional nitrification-denitrification (N-DN) process used, the ELAN technology presents several advantages, reducing: a) the volume necessary for the reactor implementation, b) the production of sludge, c) the energy necessary to perform the ammonia oxidation and d) the organic matter necessary to denitrify. Since anammox bacteria do not require organic matter to denitrifiy, the organic load can be used to recover energy in the previous anaerobic digestion improving the efficiency and sustainability of the treatment. The OPEX of the ELAN® system is expected to be lower than 20% compared to the one of the conventional N-DN existing unit.
12th IWA Leading Edge Conference on Water and Wastewater Technologies. LET 2015, Hong Kong; 06/2015
[Show abstract][Hide abstract] ABSTRACT: The denitrification process was studied in two granular biomass denitrifying reactors (USB1 and USB2). In USB1 large quantities of biomass were accumulated (9.5 g VSS L−1) allowing for the treatment of high nitrogen loads ( ). As the biomass granulation process is not immediate the effects of different upflow velocities (0.12–5.5 m h−1) and calcium contents (5–200 mg Ca2+ L−1) were studied in order to speed up the process. Obtained results indicate that the optimum values for these parameters, which allow for the stable operation of USB1, are of 0.19 m h−1 and 60 mg Ca2+ L−1. Then these optimum conditions were applied to USB2 where the effects of concentrations from 335 to were tested. In these conditions nitrate concentrations of are required for denitrifying granular biomass formation. Summarizing denitrifying granules can be formed at low upflow velocities and in hard or extremely hard water composition conditions if sufficient high nitrogen loads are treated.
[Show abstract][Hide abstract] ABSTRACT: Up to now the main goal of wastewater treatment plants (WWTPs) was to remove pollutants content in order to protect downstream users. For this reason most efforts done to improve WWTPs design have been traditionally focused on achieving the disposal requirements in terms of solids, organic matter and nutrients content. Recently, new challenges are under consideration, oriented to assure the sustainability of WWTPs in terms of their technical reliability, economic feasibility and environmental impact. Energy consumption and greenhouse gases emissions are among the aspects that should become key-factors concerning the overall performance of the WWTPs.
With regards to energy consumption, the potential energy available in the raw wastewater influent exceeds the electricity requirements of the treatment process. However, in actual WWTPs only a low fraction of this energy is recovered through methane production during anaerobic sludge digestion while a large fraction of this energy is dissipated in the secondary biological reactors to remove nitrogenous compounds by nitrification-denitrification processes. In order to improve the recovery of energy from the raw wastewater, the application of partial nitrification and Anammox (Anaerobic Ammonia Oxidation) processes, which take place without organic matter requirement, is one of the most interesting options. These processes would allow increasing the amount of organic matter converted into methane and decreasing the oxygen needed to remove nitrogenous compounds. They are already applied at full scale to treat the supernatants of the anaerobic sludge digesters, the total electrical consumption of the WWTPs being reduced by 40-50%. If these processes are also applied in the main stream the energy savings could be increased and the WWTPs could change from energy consumers to energy source systems.
The application of partial nitrification and Anammox processes would also allow decreasing the greenhouse gases emissions of the WWTPs due to the reduction of energy requirements and to the lower production of N2O compared to that of the nitrification-denitrification processes.
Water Week Latinoamerica 2015, VIÑA DEL MAR, CHILE; 03/2015
[Show abstract][Hide abstract] ABSTRACT: Filamentous bacteria are associated to biomass settling problems in wastewater treatment plants. In systems based on aerobic granular biomass they have been proposed to contribute to the initial biomass aggregation process. However, their development on mature aerobic granular systems has not been sufficiently studied. In the present research work, filamentous bacteria were studied for the first time after long-term operation (up to 300 days) of aerobic granular systems. Chloroflexi and Sphaerotilus
natans have been observed in a reactor fed with synthetic wastewater. These filamentous bacteria could only come from the inoculated sludge. Thiothrix and Chloroflexi bacteria were observed in aerobic granular biomass treating wastewater from a fish canning industry. Meganema perideroedes was detected in a reactor treating wastewater from a plant processing marine products. As a conclusion, the source of filamentous bacteria in these mature aerobic granular systems fed with industrial effluents was the incoming wastewater.
[Show abstract][Hide abstract] ABSTRACT: e l vertido de aguas residuales con exceso de nutrientes, como nitrógeno y fósforo, en los ecosistemas provoca el crecimiento y proliferación de determinadas plantas, algas y organismos, que consumen una gran cantidad del oxígeno disuelto del medio. Esto provoca una disminución del oxígeno disponible para otras especies y, consecuentemente, se reduce la diversidad del ecosistema y da lugar al problema
de la eutrofización. El tratamiento de estas aguas residuales, que se generan como consecuencia de la actividad humana (doméstica, agrícola e industrial), está regulado desde la Comunidad Europea (Directiva 91/271/). El sistema más ampliamente utilizado en las estaciones depuradoras de aguas residuales (EDARs) es el denominado de “lodos activos”, donde se tiene una biomasa de microorganismos en suspensión que llevan a cabo una serie de reacciones biológicas encaminadas a eliminar la materia orgánica y nutrientes que contaminan el agua residual. La eliminación convencional de nitrógeno en este sistema de lodos activos está basada en el proceso biológico de nitrificación-desnitrificación. En este proceso el nitrógeno, que está presente fundamentalmente en forma de amonio, es convertido por medio de reacciones biológicas a nitrógeno gas. En el proceso de nitrificación el nitrógeno amoniacal es oxidado a nitrito y posteriormente éste es oxidado a nitrato, mediante la intervención de bacterias oxidantes de amonio (BOA) y oxidantes de nitrito (BON), respectivamente. A continuación, en el proceso de desnitrificación, el nitrato formado durante la nitrificación es reducido a nitrógeno gas en condiciones anóxicas, consumiéndose materia orgánica. Aunque el sistema de lodos activos ya ha cumplido 100 años y sigue siendo el más utilizado en las EDARs, en los últimos años se han investigado y desarrollado nuevas tecnologías que permitirán en el futuro un tratamiento más eficaz de las aguas residuales a menor coste. Así, como alternativa a los procesos de nitrificación-desnitrificación, se plantea el denominado proceso anammox (ANaerobic AMMonia OXidation). En este proceso la oxidación de amonio a nitrógeno gas se realiza utilizando nitrito como aceptor de electrones. En este caso no es necesario añadir materia orgánica ni oxígeno, lo cual permite ahorrar los costes de operación asociados en la eliminación de nitrógeno en las aguas residuales.
[Show abstract][Hide abstract] ABSTRACT: The ELAN® process is an anammox based process carried out with granular biomass in one single reactor. The operation of this ELAN® process was evaluated at low ammonia concentrations of 50 mg N/L and relatively low temperature of 15 ºC in order to simulate the conditions of the water line of a municipal WWTP. Two different laboratory scale sequencing batch reactors (SBR) were used, with height to diameter ratios of 3.4 (SBR-1) and 1.4 (SBR-2) respectively. In the former breakage of the granules occurred followed by biomass wash-out and operation failure. In the latter, up to 80% of nitrogen removal was registered at a nitrogen loading rate of 0.1 g N/(L d); however, the operational strategy still needs further improvement in order to avoid nitrite oxidation at long term.
IWA World Water Congress and Exhibition, Lisboa, Portugal; 09/2014
[Show abstract][Hide abstract] ABSTRACT: The activated sludge process (AS) is still nowadays the most applied one in wastewater treatment plants (WWTP). This technology evolved throughout this last century into multiple configurations to achieve organic matter (COD, BOD5, etc.) and nutrients (nitrogen and phosphorous) removal. However, the severe increases of energy and sludge management costs registered in the last decades are boosting the research in the quest for more sustainable and efficient processes. The energetic demand of the AS, when nitrogen removal is required, varies typically in the range from 0.5 to 1.4 kWh/m3 of treated water (Lazarova et al., 2012). The AS is based on aeration to catalyse biological processes and it does not take advantage of the potential energy contained in the organic matter present in the wastewater. The energetic potential of every kilogram of organic matter oxidized (as COD) is about 4 kWh (Garrido et al., 2013).
Considering 250 litres of wastewater and 60 g of organic matter (as BOD5) per inhabitant
equivalent and day, about 1 kWh/m3 of wastewater could potentially be produced.
In order to profit from this potential energy production the future of the wastewater treatment should be focused on anaerobic processes, for both organic matter and nitrogen removal. These processes present higher efficiency and sustainability in terms of biomass growth (the yields are at least one order of magnitude lower) and energy requirements compared to aerobic ones. The energy will be produced by anaerobic digestion of the organic matter. For the nitrogen removal the discovery of anammox bacteria in the nineties opened the possibility to shortcut the nitrogen cycle which involved the decrease of oxygen requirements due to the partial nitrification of half of the ammonium to nitrite while organic matter is not required for denitrification. The company
aqualia GIA with the know-how of the University of Santiago de Compostela (USC) developed the so called ELAN® process which performs autotrophic nitrogen removal in a single granular biomass sequencing batch reactor (SBR) (Vazquez-Padin et al, in press).
Around 20% of the nitrogen load in municipal WWTP comes from the supernatant of the
anaerobic sludge digester. Nitrogen removal rates of 0.5 – 1.0 kg N/(m3 d) are achieved when the ELAN® process (Figure 1a) is applied for the treatment of the digester supernatant. The introduction of the ELAN® process in the sludge line is already a mature technology that brings WWTP closer to energy autarky (Siegrist et al., 2008). The next step and challenge will be the direct application of the anaerobic digestion process in the mainstream followed by the ELAN® process (Figure 1b). This treatment strategy will switch the paradigm and transform municipal and industrial WWTP from energy consumers to energy producers. Laboratory and pilot scale reactors are being run in the USC and in Guillarei WWTP respectively, to study the applicability of the autotrophic nitrogen removal ELAN® process (Figure 2) to mainstream conditions, i.e., low temperature and low ammonia concentration.
Activated Sludge – 100 Years and Counting!, Essen, Germany; 06/2014
[Show abstract][Hide abstract] ABSTRACT: El vertido de aguas residuales con exceso de nutrientes, como nitrógeno y fósforo, en los ecosistemas provoca el crecimiento y proliferación de determinadas plantas, algas y organismos, que consumen una gran cantidad del oxígeno disuelto del medio. Esto provoca una disminución del oxígeno disponible para otras especies y, consecuentemente, se reduce la diversidad del ecosistema y da lugar al problema de la eutrofización. El tratamiento de estas aguas residuales, que se generan como consecuencia de la actividad humana (doméstica, agrícola e industrial), está regulado desde la Comunidad Europea (Directiva 91/271/CEE). El sistema más ampliamente utilizado en las estaciones depuradoras de aguas residuales (EDARs) es el denominado "lodos activos", donde se tiene una biomasa compuesta por microorganismos en suspensión que llevan a cabo una serie de reacciones biológicas encaminadas a eliminar la materia orgánica y nutrientes que contaminan el agua residual. La eliminación convencional de nitrógeno en este sistema de lodos activos está basada en el proceso biológico de nitrificación-desnitrificación (N-DN). En este proceso el nitrógeno, que está presente fundamentalmente en forma de amonio, es convertido por medio de reacciones biológicas a nitrógeno gas. Aunque el sistema de lodos activos ya ha cumplido 100
años y sigue siendo el más utilizado en las EDARs, en los últimos años se han investigado y desarrollado
nuevas tecnologías que permitirán en el futuro un tratamiento más eficaz y a menor coste de las aguas residuales. Así, como alternativa a los procesos de nitrificación-desnitrificación, se plantea el denominado proceso anammox (ANaerobic AMMonia OXidation). En este proceso la oxidación de amonio a nitrógeno gas se realiza utilizando nitrito como aceptor de electrones. En este caso no es necesario añadir materia orgánica ni oxígeno, lo cual permite ahorrar los costes de operación asociados a la eliminación de nitrógeno en las aguas residuales. El proceso anammox se conoce desde mediados de los años 90 (Figura 1). Sin embargo, ya en 1977, Broda predice, basándose en cálculos termodinámicos, la
existencia de una bacteria autótrofa que sería capaz de oxidar el amonio empleando el nitrato como aceptor
de electrones1. Posteriormente, se comprobó que en lugar de nitrato empleaba el nitrito.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND
Management of the sludge generated in the wastewater treatment plants accounts for more than 50% of their operational costs. To minimise these costs, technologies capable of reducing the production of sludge in the plant need to be developed, such as aerobic granular systems. The aggregation state of aerobic granular sludge (AGS) could be a limiting factor for its further anaerobic digestion. Therefore in this work the feasibility of anaerobic digestion of AGS has been studied under three conditions: (1) raw AGS, (2) thermal pre-treated AGS and (3) a mixture of thermal pre-treated AGS with primary sludge.
The values obtained for anaerobic biodegradability and reduction of solids in the case of raw AGS were 44% and 32%, respectively. Thermal pre-treatment of AGS at 133 °C enhanced the anaerobic digester performance, in terms of solids reduction, by approximately 47%. The mixture of thermal pre-treated AGS with primary sludge provided better results for solids removal than in the case with only thermal pre-treated AGS.
Anaerobic digestion of AGS has a similar performance as that reported for waste activated sludge, which indicates that the aggregation of the biomass into granules does not seem to limit the anaerobic process.
Journal of Chemical Technology & Biotechnology 05/2014; DOI:10.1002/jctb.4171 · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Poster: Application of aerobic granular pilot scale SBR plant to treat swine slurry wastewaters.
Conference: EcoTechnologies for Wastewater Treatment. ECO STP. Santiago de Compostela June, 2012.
[Show abstract][Hide abstract] ABSTRACT: The presence of salts in wastewaters is common in coastal areas, where leakages of salty water occur into the sewage systems, but also when the industrial process involves the use of salts or seawater. Aerobic granular systems can be suitable to treat brackish wastewaters as an alternative to activated sludge ones since the high biomass concentrations make up for the decrease of the activity due to salt presence. These granular systems have also as advantage the lower amount of sludge generated in comparison with the activated sludge ones but, in both cases, the excess of sludge produced needs to be post-treated. Anaerobic digestion is normally used to reduce the concentration of solids and to produce biogas. To the present, the effect of saline conditions in anaerobic digestion was preferentially studied in systems treating wastewaters but scarcely revised when treating sewage sludge. The aim of this work is to determine the feasibility, under brackish conditions, of the anaerobic biodegradability of the aerobic granular sludge (AGS) and to compare the results with the anaerobic digestion of flocculent activated sludge (FLAS). The results showed that the biodegradabilities of AGS (32%) and FLAS (27%) were similar, which indicates that the aggregation state of the substrate did not limit the process. Brackish conditions led to a concentration of sodium and free sulphide (FS) inside the reactor in the range of 2.1-5.2 g L-1 and 38-93 mg L-1 respectively, that are within the inhibitory levels reported for the anaerobic treatment of wastewaters. However, the biomethane potential and biodegradability obtained in this work indicated that neither sodium nor free sulphide had an inhibitory effect at these concentrations. The content of H2S in the biogas was relevant (1.5-3.8%) and its pre-treatment is needed if the biogas is going to have any further use, i.e., in energy production.
The Chemical Engineering Journal 09/2013; 231:449-454. DOI:10.1016/j.cej.2013.07.052 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A pilot-scale Sequencing Batch Reactor was operated during 307 days in order to treat swine slurry characterized by its high variable composition: organic and nitrogen applied loading rates and C/N ratio were 1.4–6.3 kg CODs/(m3 d), 0.5–2.5 kg N/(m3 d) and 1.9–9.4 g CODs/(g N), respectively. Aerobic granules successfully developed in the reactor and their physical properties remained rather stable despite the feeding composition variability. Organic and ammonia removal efficiency reached 61–73% and 56–77%, respectively, however ammonia was mainly oxidized to nitrite. The reactor had a good biomass retention capacity to select for granular biomass. However, its efficiency to retain the solids present in the feeding was low. Aerobic granulation in SBR systems appears as an interesting alternative to treat slurry in small livestock facilities where the implementation of anaerobic digestion systems is not a feasible option or the removal of nitrogenous compounds is required.
PROCESS BIOCHEMISTRY 08/2013; DOI:10.1016/j.procbio.2013.06.004 · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nowadays, Anammox based processes have been successfully applied to high temperature and ammonia loaded streams. However, the application of such processes to the main stream of WWTPs opens the possibility of removing the nitrogenous compounds with less energy and chemicals requirements.
Furthermore more organic matter is available for methane production. In this work the long-term performance and stability of a CANON system operated at 20 and 15 ºC was researched. When the system was fed with a medium containing 200 mg NH4+-N/L, nitrogen removal rates of 0.45 and 0.33 g N/L•d were achieved at 20 and 15 ºC, respectively, and the operation was stable. However, when the inlet ammonia concentration was decreased to 70 mg NH4+-N/L (15 ºC), the nitrogen removal rate was of only 0.05 g N/L•d limited by the low dissolved oxygen level maintained in the bulk liquid in order to avoid nitrite oxidation.
13th World Congress on Anaerobic Digestion, Santiago de Compostela; 06/2013
[Show abstract][Hide abstract] ABSTRACT: The aerobic granular systems are mainly sequencing batch reactors where the biomass is submitted to feast-famine regimes to promote its aggregation in the form of granules. In these systems, different cycle distributions can be applied for the simultaneous removal of organic matter, nitrogen and phosphorus. In this work two strategies were followed in order to evaluate the effects of the cycle distribution. In the first experiment, the length of the operational cycle was decreased in order to maximize the treatment capacity and consequently the famine/feast ratio was also decreased. In the second experiment, an initial anoxic phase was implemented to improve nitrogen removal efficiency. The results obtained showed that to reduce the famine/feast ratio from 10 to 5 was possible by increasing the treated organic and nitrogen loading rates in the system to 33%, without affecting the removal efficiencies of organic matter (97%) and nitrogen (64%) and producing a slight detriment of the granules characteristics. On the other hand, the implementation of an anoxic phase of 30 min previous to the aerobic one with a pulse-fed mode increased the nitrogen removal of pig manure from 20 to 60%, while the cycle configuration comprising a continuous feeding simultaneous with an anoxic phase of 60 min did not enhance the nitrogen removal and even worsen the ammonia oxidation.
[Show abstract][Hide abstract] ABSTRACT: Aerobic granular sludge is presented as an alternative technology to conventional activated sludge processes for the treatment of low-strength wastewaters. Results obtained with granular aerobic reactors at laboratory scale are promising but, there are few studies carried out at pilot scale. Therefore, more information about the stability of granules and their performance at larger scale is needed to establish if aerobic granulation could be a feasible treatment. With this aim, a 100 L granular sequencing batch reactor (GSBR) operating at high loading rate and treating low-strength wastewater for simultaneous carbon, nitrogen and phosphorus removal was operated for 11 months. Mature granules prevailed in the GSBR during a period of 5 months (from days 150 to 330), with a SVI30 of 13 ± 6 mL g−1 TSS, a granule density around 114 ± 5 g TSS L−1 and an average particle size of 2.4 mm. The biological nitrogen removal with mature granules was mainly performed via nitrite, probably due to the large granule size achieved. Nitrification efficiency was higher than 75% and occurred simultaneously with denitrification during the aerobic phase of the GSBR. A progressive accumulation of P-salts (probably apatite), was found from days 150 to 300, which could enhance the destabilization of granules at the end of the experimental period.
The Chemical Engineering Journal 08/2012; 198-199:163-170. DOI:10.1016/j.cej.2012.05.066 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The first studies about granular biomass developed in aerobic conditions are dated in the early 90’s. Mishima and Nakamura (1991) developed aerobic granules in a UASB type reactor using pure oxygen. This work was not really appreciated at that moment and it was in the late 90’s when extensive research was performed in this field. In these systems the simultaneous removal of organic matter, nitrogen and phosphorus compounds from wastewater can be developed (de Kreuk et al., 2005a). From the carried out research it has been found that aerobic granular systems present several advantages compared to conventional activated sludge such as excellent settling properties of the biomass, large biomass retention, the ability to withstand shock and toxic loadings, the presence of aerobic and anoxic zones inside the granules to perform different biological processes, etc. (Morgenroth et al., 1997; Dangcong et al., 1999; Beun et al. 1999; Peng et al. 1999; Tay et al. 2001a; Lin et al. 2003; Liu et al., 2003; Yang et al., 2003; Arrojo et al., 2004; Campos et al., 2009).
Innovative Technologies for Urban Wastewater Treatment Plants (2nd Edition)., 2nd edited by Francisco Omil, Sonia Suárez, 07/2012: chapter Aerobic granulation technology .: pages 39-62; Lápices 4., ISBN: 13-978-84-695-3514-1