Search results for "aerobic granular sludge"
showing 10 items of 21 documents
Simultaneous nitrogen and organic carbon removal in aerobic granular sludge reactors operated with high dissolved oxygen concentration
2013
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 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 eval- uate 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 sig- …
Study of aerobic granular sludge stability in a continuous-flow membrane bioreactor.
2015
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…
Fate of aerobic granular sludge in the long-term: The role of EPSs on the clogging of granular sludge porosity
2016
This work aims to investigate the stability of aerobic granular sludge in the long term, focusing on the clogging of the granular sludge porosity exerted by the extracellular polymeric substances (EPSs). The effects of different cycle lengths (short and long-term cycle) on the granular sludge stability were investigated. Results obtained outlined that during the short duration cycle, the formation and breakage of the aerobic granules were continuously observed. During this period, the excess of EPS production contributed to the clogging of the granules porosity, causing their breakage in the long run. During the long-duration cycle, the extended famine period entailed a greater EPSs consump…
Treatment of high strength industrial wastewater with membrane bioreactors for water reuse: Effect of pre-treatment with aerobic granular sludge on s…
2019
Abstract In this study, the treatment of citrus wastewater with membrane bioreactors (MBRs) under different configurations was investigated for water reuse. In particular, one MBR and one aerobic granular sludge MBR (AGS + MBR) bench scale plants were operated for 60 days. The experimental campaign was divided into two periods. In Phase I, a conventional hollow fiber MBR was employed for the treatment of the raw high strength wastewater, whereas in Phase II a combination of in-series reactors (AGS + MBR) was adopted for the treatment of the high strength citrus wastewater The results demonstrated that both plant configurations enabled very high COD removal, with average values close to 99%.…
Physical properties and Extracellular Polymeric Substances pattern of aerobic granular sludge treating hypersaline wastewater.
2017
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 compos…
Comparison between kinetics of autochthonous marine bacteria in activated sludge and granular sludge systems at different salinity and SRTs.
2019
Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L−1), from 30 gNaCl L−1 up to 50 gNaCl L−1 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L−1). The organic carbon was remove…
Simultaneous nitritation-denitritation for the treatment of high-strength nitrogen in hypersaline wastewater by aerobic granular sludge
2015
Abstract Fish processing industries produce wastewater containing high amounts of salt, organic matter and nitrogen. Biological treatment of such wastewaters could be problematic due to inhibitory effects exerted by high salinity levels. In detail, high salt concentrations lead to the accumulation of nitrite due to the inhibition of nitrite-oxidizing bacteria. The feasibility of performing simultaneous nitritation and denitritation in the treatment of fish canning wastewater by aerobic granular sludge was evaluated, and simultaneous nitritation–denitritation was successfully sustained at salinities up to 50 gNaCl L −1 , with a yield of over 90%. The total nitrogen concentration in the efflu…
Aerobic granular sludge: State of the art, applications, and new perspectives.
2018
The aerobic granular sludge (AGS) process has attracted significant interest over the last decade and is one of the most promising wastewater treatment technologies. AGS offers several advantages over conventional activated sludge (CAS) including excellent settling, and higher volumetric loading capacity. Because of porosity, concentration gradients develop and stratified aerobic, anoxic, and anaerobic layers develop throughout granule depth. This is the reason for simultaneous nutrient removal in a single tank. Aerobic granulation is influenced by many parameters including wastewater characteristics and operating conditions. Among these, the anaerobic upflow feeding strategy and a properly…
The role of extracellular polymeric substances (EPS) on aerobic granules formation: comparison between a case of synthetic wastewater supply and anot…
2015
The paper focused on the evolution of extracellular polymeric substances (EPSs) content during the granulation process in two Granular Sequencing Batch Airlift Reactors (GSBAR) (3,5 L) fed with synthetic and industrial wastewater. Results showed that EPSs, in particular proteins (PN) were mainly produced during the feast phase because of high substrate availability, especially under conditions of metabolic stress. Than EPSs content reduced during the famine period. More in detail, during the granulation process, a greater polysaccharides (PS) consumption occurred in both reactors, while PN content reduced significantly only in R2. As a result PN/PS ratio increased significantly during granu…
Influence of ferric iron dosing on aerobic granular sludge: granule formation, nutrient removal and microbial community
2021
BACKGROUND: Three lab-scale sequencing batch reactors were used to investigate the effects of Fe3+ on aerobic granular sludge (AGS) formation, nutrient removal, and microbial community. RESULTS: The addition of 6 and 12 mg Fe3+ L−1 could not shorten the granulation time. However, compared to the reactor without Fe3+ addition (average sludge volume index at 30 min (SVI30) 70.8 mL g−1; stable average particle size 548 μm), the addition of 12 mg Fe3+ L−1 helped improve the physical properties of AGS (average SVI30 57.0 mL g−1; stable average particle size 1067 μm). Furthermore, with 12 mg Fe3+ L−1 addition (Fe3+ to PO43−-P molar ratio = 1.33), effective removal of NH4+-N (≤0.5 mg L−1) and PO43…