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This study investigated the bioreactor performance, production of extracellular polymeric substance (EPS), and microbial activity of a granulated sequencing batch reactor (SBR) by increasing the graphene oxide nanoparticle (GO NP) concentration stepwise. The GO NPs reduced the removal of chemical oxygen demand (COD), ammonia, and phosphorus, wherea...
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... the whole experiment, nitrite-and nitrate-nitrogen concentrations in the effluent remained stable (0.04 ± 0.01 and 0.5 ± 0.15 mg/L). Previous AGS studies reported similar observations, that is, the denitrification processes remained unaffected by adding CuO and Ag nanoparticles even at high amount [26,27]. Fig. 2. illustrates the effluent COD, NH 4 -N, and TP contents, and the removal efficiency of these nutrients. Ammonia-nitrogen removal remained comparatively stable during the experiment. In the first phase, the removal efficiency of ammonia-nitrogen was 99%, and it declined to 88.5% at 115 mg/L GO, suggesting that the GO NPs did not cause ...
Citations
... These findings highlight the potential negative impacts of nanoparticle exposure on wastewater treatment processes. Further research is needed to understand the underlying mechanisms and develop strategies to mitigate these effects [19]. ...
Background
The increasing use of nanoparticles (NPs) necessitates investigation of their impact on wastewater treatment processes, particularly anammox, a critical biological nitrogen removal pathway. This study explored the effects of short-term exposure to TiO2, ZnO, and Ag-NPs on anammox activity in enriched cultures derived from River Nile sediments.
Materials and methods
Anammox bacteria were identified and enriched, with activity confirmed through 16S rRNA and hydrazine oxidoreductase (hzo) gene amplification and sequencing. Activity assays demonstrated efficient ammonium removal by the enriched culture. Subsequently, the impact of different sized and concentrated NPs on anammox activity was assessed.
Results
XRD analysis confirmed NP behavior within the microcosms: TiO2 transformed, ZnO partially dissolved, and Ag remained ionic. hzo gene expression served as a biomarker for anammox bacterial activity. Interestingly, 100 nm TiO2-NPs up-regulated hzo expression, potentially indicating a non-inhibitory transformed phase. Conversely, ZnO and Ag-NPs across all sizes and concentrations significantly down-regulated hzo expression, suggesting detrimental effects. Ag-NPs amended microcosms showed a significant reduction (79%) in hzo gene expression and a detrimental effect on bacterial populations. Overall, anammox activity mirrored hzo expression patterns, with TiO2 (21 and 25 nm, respectively) exhibiting the least inhibition, followed by ZnO and Ag-NPs.
Conclusion
This study highlights the differential effects of NPs on anammox, with the order of impact being Ag > ZnO > TiO2. These findings provide valuable insights into the potential environmental risks of NPs on anammox-mediated nitrogen cycling in freshwater ecosystems.
... The microorganisms employed in this process are highly sensitive to various pollutants in wastewater [36], which necessitates the development of new technologies. Aerobic granular sludge (AGS) and algal-bacterial aerobic granular sludge (AB-AGS) technologies represent novel and emerging biological processes for wastewater treatment [37,38]. Both AGS and AB-AGS achieve the simultaneous removal of carbon, nitrogen, phosphorus, and other pollutants within a single sludge system [39]. ...
... Extracellular polymeric substances (EPSs) play a vital role in granulation, facilitating faster attachment of microorganisms to each other. Furthermore, microorganisms and algae are embedded in the polymer matrix, providing a shield against harmful substances [37,38]. These innovative technologies have already demonstrated their capability of treat landfill leachate [41,43], pharmaceuticals [44,45], and textile dyes [46,47]. ...
... The bioreactor operated at 21 ± 3 • C in 4-h cycles, consisting of filling (5 min), aeration (225 min), settling (5 min), and withdrawal (5 min) periods. Peristaltic pumps controlled the filling and withdrawal of wastewater at specified flow rates [37]. Synthetic wastewater (SWW) fed into the reactors consisted of the following components per liter of deionized water: 1200 mg COD as glucose, 110 mg NH 4 -N as NH 4 ...
Currently, the increasing use of nickel metal-organic frameworks (Ni-MOF) and nickel oxide nanoparticles (NiO NPs) has raised concerns regarding their potential environmental impact on wastewater treatment systems. Herein, the responses of aerobic granular sludge (AGS) and algal-bacterial aerobic granular sludge (AB-AGS) to Ni-MOF and NiO NPs were investigated. The results showed that Ni-MOF concentrations of 50, 100, and 200 mg/L significantly reduced nutrient removal in both systems, particularly affecting ammonia, nitrite, and phosphorus removal, while denitrification processes remained stable. AB-AGS exhibited greater tolerance to nickel than AGS, likely due to its higher content of extracellular polymeric substances (EPSs), in which the algae were embedded, indicating a robust bacterial-algal symbiotic system. Conversely, NiO NPs had no adverse effects on bioreactor performance, likely due to their insolubility and integration into the sludge matrix. This research provides valuable insights into the potential future applications of AGS and AB-AGS technologies for treating wastewater contaminated with nickel and other heavy metals, highlighting the superior resilience of AB-AGS to nickel exposure.
... The formation of biofilms is a phenomenon that could lead to fouling in membranes. Studied as a critical issue, these biofilms become the nutrient source for the bacteria and hence become a roadblock in several industrial applications like biorefineries, osmosis (Valladares Linares et al., 2014), and water treatment (Kedves et al., 2021). Membrane bioreactors (Malaeb et al., 2013) are used for their sustainability advantage and because of their elimination of the secondary treatment processes with a compact size and high water quality obtained. ...
... Graphene-family NPs are widely used in almost all industrial regions owing to their unique physicochemical properties. GO-NPs serving as the most popular carbon-based nanomaterial with excellent electrochemical properties are synthesised by chemical oxidation of graphite [100]. Nonetheless, they are toxic to Pseudomonas putida, rhizobacteria, phytopathogenic bacteria, and marine organisms. ...
The presence of xenobiotic compounds in biological wastewater treatment processes with activated sludge may reduce microbial communities, disrupt microbial diversity, and diminish system performance. Shock loads and unusual operating events in these biological systems have negative impacts on their efficiency and reliability for pollutant degradation, thereby posing high risk to microorganisms and water quality of receiving treated water bodies. The severity and characteristics of the occurring damage are determined by the toxic contaminant's degree, nature and mode of application. This review highlights the effects of metabolic uncouplers, heavy metals, carbon nanotubes, pharmaceuticals and personal care products, nanoparticles, and phenolic compounds stress on microbial biomass in activated sludge systems. The synergistic, antagonistic, and shock load toxic effects of hybrid substances exposure in an activated sludge sequential batch reactor (SBR) system on organic and nutrient removal, system efficiency, and toxicants biodegradation are discussed. The findings can be used to provide a theoretical foundation and professional assistance for optimizing the shock impacts of these toxic substances on biological wastewater treatment systems, which will help to reduce their negative effects on treatment system efficiency.
... On extensive stage, AGS is currently being used in wastewater treatment due to the number of advantages like excellent settling ability and being rich in microbial compositions . There are some recent studies in which GO has been employed to form granular consortia for the wastewater treatment (Liu et al., 2017;Guo et al., 2018;Kedves et al., 2021). Nevertheless, AGS is unexplored in terms of biohydrogen production till date. ...
... It has been documented in recent studies that the low amounts of GO (0.01-1 %) can significantly improve the associated processes (Chuah et al., 2014;Wang et al., 2016;Qin et al., 2017). Moreover, in the investigation of Kedves et al. (2021), authors have reported 55 mg/L of GO for the effective treatment of wastewater. Further, improvement in stability of the microbial enzymes in presence of GO might be a reason for higher H 2 production which is easily affected in case of normal H 2 production process performed in the absence of GO. ...
Biohydrogen production using renewable sources has been regarded as one of the most sustainable ways to develop low-cost and green production technology. In order to achieve this objective, herein biohydrogen production has been conducted using the combination of untreated secondary sewage sludge (Sss), algal biomass hydrolyzate (Abh), graphene oxide (GO) and bacterial consortia that forms a granular system. Thus, naturally formed granular system produced cumulative H2 of 1520 mL/L in 168 h with the maximum production rate of 13.4 mL/L/h in 96 h at initial pH 7.0, and optimum temperature of 37 oC. It is noticed that the combination of Abh, Sss and GO governed medium showed 42.05% higher cumulative H2 production along with 22.71% higher production rate as compared to Abh and Sss based H2 production medium. The strategy presented herein may find potential applications for the low-cost biohydrogen production using waste biomasses including Sss and Abh.
... [38][39][40] The interaction between GBMs and microbial communities in anaerobic digesters was also investigated in reactors fed with swine manure, 41,42 cattle manure 43 or synthetic wastewater. 44,45 Communities in aerobic granular sludges [46][47][48][49] (strong compact structures embedding microbial cells) were also exposed to GBMs. In addition to the aforementioned bioprocesses that are designed to remove organic matter (and recover energy through methane production in the case of anaerobic digestion), anammox reactors carrying out anaerobic ammonium oxidation were also investigated. ...
... 33 In the same way, in aerobic granular sludges, after 7 days of exposure to GO ranging from 35 to 95 mg L −1 , the COD (Chemical Oxygen Demand) removal was highly decreased in a dose dependent manner (up to 73.7% decrease). 46 A decrease of the COD removal was also found in aerobic granular sludge exposed to 115 mg L −1 of GO 47 and in sequential batch reactors exposed to 3,64 and 5.26 g L −1 of GO for 8 days. 36 On the contrary the COD removal increased in the presence of 10 mg L −1 of GO in anaerobic digesters. ...
... The protein content of EPS was also increased in an annamox reactor exposed to 10 mg L −1 of graphene 52 and in aerobic granular sludge exposed to 35 and 50 mg L −1 . 47 On the contrary, it was observed in aerobic granular sludge, after an increase of the protein content at day 5, a decrease of the protein content and total EPS production after 30 days of exposure to 150 and 200 mg L −1 of GO. 48 This showed the capacity of graphene-based materials to modify not only the quantity but also the quality of EPS. ...
This review discusses the interactions between graphene-based nanomaterials and microbial communities in different environmental compartments reconstituted in microcosms, from soil and freshwater to bioprocesses treating waste.
... Additionally, graphite oxide nanoparticles (GO NPs) promoted the rapid generation of granular sludge and produced abundant EPS content. The cultivated sludge had a compact structure with a particle size between 300 and 500 μm [39]. ...
Recently, hydrocyclone separator is introduced into the field of aerobic granular sludge (AGS), and applied in wastewater treatment plant to recover the dense sludge. However, the function of hydrocyclone separator for AGS cultivation is still unclear. Thus, the granulating and granular separation efficiencies of hydrocyclone separator were investigated from perspectives of experiment and hydrodynamic modelling. By comparing traditional sequencing batch reactor, the introduction of hydrocyclone separator greatly decreased the mixed liquid suspended sludge by maximum 61%, although it could improve the sludge settling performance and reduce SVI, no matter operational time of separator high or low. The reason might be attributed to strong shear force and centrifugal force provided by hydrocyclone separator. Therefore, the inlet water velocity, a factor of shear stress, was studied. The medium water velocity of 0.3 m/s contributed to appropriate tangential velocity and static pressure, reaching the optimal granular separation efficiency that was larger than 97% for the particle diameter over 400 μm. Besides, carrier particles in previous studies were summarized and found to enhance AGS formation in short time (15 to 54 days). When they were combined with hydrocyclone separator for continuous AGS cultivation, the carrier particles with large particle size (GAC, ceramsite, etc) were proposed to be used, instead of biochar or graphite oxide nanoparticle. This study explored the feasibility of hydrocyclone separator to culture AGS, which is helpful to realize the continuous AGS cultivation.
... Finally, the samples were dried (3 h, 30 • C) and coated with gold for microscopic examination. Electron microscopy images were taken with a 10 kV accelerating voltage Hitachi S-4700 Type II FE-SEM microscope, observing secondary electrons with magnitudes of 150×, 250×, 600×, and 2000× [68]. ...
Citation: Kedves, O.; Kocsubé, S.; Bata, T.; Andersson, M.A.; Salo, J.M.; Mikkola, R.; Salonen, H.; Szűcs, A.; Kedves, A.; Kónya, Z.; et al. Chaetomium and Chaetomium-like Species from European Indoor Environments Include Dichotomopilus finlandicus sp. nov. Pathogens 2021, 10,
... Recently, the application of aerobic granular sludge (AGS) attracted much attention because of its high biomass retention, good settle ability, excellent pollutant removal capability and strong tolerance to toxicity and high organic loading rate when comparing with conventional activated sludge [23,24,4,54,60,61]. Owing to these advantages, AGS can simultaneously remove high concentration of carbon, nitrogen, phosphorus, and other pollutants [41]. ...
Piggery wastewater with high concentration of carbon and nitrogen could be effectively treated by aerobic granular sludge (AGS). However, the underlying mechanisms responsible for simultaneous nitrogen and carbon removal have not been well revealed. Here we conducted a combined analysis of microbial community, denitrification genes and mathematical model calculation to illuminate the metabolic process of this AGS. The relative abundances of the dominant microorganisms were Comamonadaceae (accounting for 24.79%, including Comamonadaceae-un, Ideonella, Comamonas and Variovorax), Saccharibacteria-un (6.07%), Ideonella (5.51%), Luteimonas (4.81%), Bacteroidales (4.09%), Niabella (3.95%), Fillimonas (3.53%), Thauera (3.51%) and Pseudoxanthomonas (3.44%). The dominant microorganisms in the AGS mainly had the potentials of heterotrophic nitrification, aerobic denitrification, organic macromolecule degradation, organics storage and granule stability maintaining. Interestingly, only 0.145% of the communities were found as autotrophic nitrifiers. Moreover, the quantitative analysis of denitrification genes showed the abundance of napA gene was significantly higher than that of narG gene, suggesting that aerobic and anoxic denitrification process coexisted in the AGS, and the former was dominant. Furthermore, the calculations based on mathematical model were used to deduce the nitrification, denitrification and organic matter utilization process in one running cycle of the AGS. The results also indicated that the rapid organic substrates storage in the feast phase might resist the impact of high strength wastewater, and provide carbon and energy sources in the famine phase. Together, our study elucidated the nitrogen and carbon removal process of the AGS treating piggery wastewater with high concentrations.
... Recently, the application of aerobic granular sludge (AGS) attracted much attention because of its high biomass retention, good settle ability, excellent pollutant removal capability and strong tolerance to toxicity and high organic loading rate when comparing with conventional activated sludge [23,24,4,54,60,61]. Owing to these advantages, AGS can simultaneously remove high concentration of carbon, nitrogen, phosphorus, and other pollutants [41]. ...
Piggery wastewater with high concentration of carbon and nitrogen could be effectively treated by aerobic granular sludge (AGS). However, the underlying mechanisms responsible for simultaneous nitrogen and carbon removal have not been well revealed. Here we conducted a combined analysis of microbial community, denitrification genes and mathematical model calculation to illuminate the metabolic process of this AGS. The relative abundances of the dominant microorganisms were Comamonadaceae (accounting for 24.79%, including Comamonadaceae-un, Ideonella, Comamonas and Variovorax), Saccharibacteria-un (6.07%), Ideonella (5.51%), Luteimonas (4.81%), Bacteroidales (4.09%), Niabella (3.95%), Fillimonas (3.53%), Thauera (3.51%) and Pseudoxanthomonas (3.44%). The dominant microorganisms in the AGS mainly had the potentials of heterotrophic nitrification, aerobic denitrification, organic macromolecule degradation, organics storage and granule stability maintaining. Interestingly, only 0.145% of the communities were found as autotrophic nitrifiers. Moreover, the quantitative analysis of denitrification genes showed the abundance of napA gene was significantly higher than that of narG gene, suggesting that aerobic and anoxic denitrification process coexisted in the AGS, and the former was dominant. Furthermore, the calculations based on mathematical model were used to deduce the nitrification, denitrification and organic matter utilization process in one running cycle of the AGS. The results also indicated that the rapid organic substrates storage in the feast phase might resist the impact of high strength wastewater, and provide carbon and energy sources in the famine phase. Together, our study elucidated the nitrogen and carbon removal process of the AGS treating piggery wastewater with high concentrations.
