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The use, overuse, and improper use of antibiotics have resulted in higher levels of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs), which have profoundly disturbed the equilibrium of the environment. Furthermore, once antibiotic agents are excreted in urine and feces, these substances often can reach wastewater treatment plants (WWTPs), in which improper treatments have been highlighted as the main reason for stronger dissemination of antibiotics, ARB, and ARGs to the receiving bodies. Hence, achieving better antibiotic removal capacities in WWTPs is proposed as an adequate approach to limit the spread of antibiotics, ARB, and ARGs into the environment. In this review, we highlight hospital wastewater (WW) as a critical hotspot for the dissemination of antibiotic resistance due to its high level of antibiotics and pathogens. Hence, monitoring the composition and structure of the bacterial communities related to hospital WW is a key factor in controlling the spread of ARGs. In addition, we discuss the advantages and drawbacks of the current biological WW treatments regarding the antibiotic-resistance phenomenon. Widely used conventional activated sludge technology has proved to be ineffective in mitigating the dissemination of ARB and ARGs to the environment. However, aerobic granular sludge (AGS) technology is a promising technology—with broad adaptability and excellent performance—that could successfully reduce antibiotics, ARB, and ARGs in the generated effluents. We also outline the main operational parameters involved in mitigating antibiotics, ARB, and ARGs in WWTPs. In this regard, WW operation under long hydraulic and solid retention times allows better removal of antibiotics, ARB, and ARGs independently of the WW technology employed. Finally, we address the current knowledge of the adsorption and degradation of antibiotics and their importance in removing ARB and ARGs. Notably, AGS can enhance the removal of antibiotics, ARB, and ARGs due to the complex microbial metabolism within the granular biomass. [Display omitted] • Antibiotics are usually discharged into sewers, worsening the antibiotic-resistance. • Hospital WWs are crucial reservoirs of ARGs, acting as hotspots of ARB dissemination. • Hospital effluent requires specific treatments to shrink the dissemination of ARGs. • CAS technology cannot completely remove high levels of antibiotics, ARB, and ARGs. • AGS-SBR is a promising technology with excellent performance in antibiotic removal. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge reactors usually operate in sequential batch mode, although this configuration limits the treatment of large volumes of wastewater, and they require a storage system. To implement this technology at full-scale, it would be necessary to design a simple and compact continuous-flow bioreactor able to treat larger volumes of wastewater. In this study, four aerobic granular sludge single-chamber continuous-flow reactors (R1, R2, R3 and R4) were designed and operated at the lab scale to evaluate and select a bioreactor configuration that achieves high organic matter removal performance while maintaining a stable granulation for long-term operation, promoting the washout of filamentous microorganisms. Results confirmed that the bioreactor including a lateral decanter (R1), was able to work in a steady state without loss of granular biomass and reached 95% of organic matter removal performance. Its granules had excellent compaction, with settling velocity values above 100 m·h−1. The R1 bioreactor also allowed rapid biomass adaptation and therefore a fast start-up (11 days). Results of this preliminary study at the lab scale suggested that the new and simple bioreactor design could be promising for its implementation at full scale. For that, future research is required to optimise the current model and to determine the most suitable operational parameters to treat domestic wastewater at full scale. [Display omitted] • A novel continuous-flow reactor maintains stable granules for long-term. • Granular biomass achieves an organic matter removal performance above 95%. • Granular biomass presents a microbial community with high functional diversity. • The results obtained in the R1 reactor suggest its future application on a full scale. [ABSTRACT FROM AUTHOR]

Aerobic Granular Biomass (AGB) technology is widely used for urban and industrial wastewater treatment, however, its application in groundwater remediation, is practically unknown. A mixture of carbendazim, simazine, and diuron were amended to the nitrate-polluted synthetic groundwater at increasing concentrations to validate the ability of technology to remove both kind of pollutants, pesticides and nitrate which are commonly found in the water resources. The nitrate removal was a success with values below 0.010 g·L-1. The increased concentration of pesticides in the influent did not distort the pattern observed for pesticide removal. Carbendazim was almost completely eliminated, followed by simazine elimination, while diuron showed adsorption-desorption patterns during experimentation. The addition of pesticides had a drastic effect on the basal community conducted by proliferation of Hyphomicrobium and Dokdonella. The pesticide compounds had a negative effect on number of copies for fungal population, while archaeal population was unharmed, according to qPCR results. Denitrifying bacteria need 70 days as acclimatization period for achieving activity values as initial inoculum. The results obtained have shown for the first time the capacity of AGB system to treat groundwater polluted with nitrate and pesticide using low carbon load. Therefore, the results suggested the potential application of AGB technology for the purification of groundwater polluted with both nitrates and pesticides. [Display omitted] • AGB is an efficient technology to treat nitrate and pesticides polluted-groundwater. • Carbendazim and simazine were successfully removed even at high concentrations. • Granular biomass revealed bioadsorption-desorption process with diuron. • Fungal and archaeal populations interchanged roles in presence of pesticides. • Hyphomicrobium was the most dominant phylotype in granules. [ABSTRACT FROM AUTHOR]

Next-generation sequencing and metatranscriptomic analysis were used to study the diversity and characterize the gene machinery in a cold bioreactor treating urban wastewater located near the Polar Artic Circle. The bacterial population was dominated by the family Comamonadaceae ; archaeal population was highly represented by Methanococcales clones while class Sacharomycetes was the most abundant Fungi. Metatranscriptomic analysis demonstrated several cold adaptation mechanisms such as the expression of cold-shock protein (CspA),trigger factor (TF), antitermination protein NusA and polyribonucleoide nucleotidytransferase (PNP). Genes coding for transcriptional regulator WhiB and peptide deformylase (def) , described as targets of novel antibiotics were detected as well as multidrug resistance proteins (MdtC , MdtD) and genes encoding resistance to arsenicals (arsr) and cobalt-zinc-cadmium (czcc). Moreover, genes that encode UV radiation resistance (uvrA) and expression of catalase and superoxide dismutase to protect against reactive oxygen species (ROS) were identified. Prokaryotic metabolism was mainly related to energy metabolism pathways, while eukaryote metabolism was related to protein metabolism. The most annotated reads belonged to viral particles, specifically RNA-1 polyprotein was the dominant which is involved in viral replication, suggesting wastewater may be an important reservoir of viruses in cold environments. Despite low-temperature, microbial community identified by massive parallel sequencing in the activated sludge demonstrated high diversity and evenness in comparison with others WWTPs. In addition, metatranscriptomics analysis revealed high functional diversity with mechanisms against cold-shock, as well as multidrug and heavy metals resistant genes, widely detected in WWTPs worldwide. [Display omitted] • Cold-shock response was detected through expression of CspA, NusA, TF and PNP. • The low nitrogen removal ratio was linked with the low abundance of amoA β- subunit. • Several multidrug resistance proteins were found (MdtC and MdtD). • Viral particles were the most annotated reads, following by the Eukarya. • Activated sludge could be a reservoir for viruses in bioprocess at ultra-low temperature. [ABSTRACT FROM AUTHOR]

An aerobic granular biofilm process was operated in a sequential batch reactor for treating nitrate-pollute groundwater at 6 ºC, which was fed with a progressively reduced carbon concentration to understand the nitrate removal efficacy in cold regions by denitrifying microorganisms. The evaluation of the performance reflected a quick granulation promoted by hydraulic stress and a high organic loading rate (OLR). The granules were dense and compact and kept stable conformation until the end of operation, despite the low temperature. Nitrate removal in the stage with high OLR was close to 100%, while the stage with the lowest OLR reached efficiencies higher than 87% in steady-state, suppose a successful advantage against other biological processes for treating drinking water. The bacterial community in the mature granules were colonized by cold-adapted microorganisms such as Holophagaceae and Candidatus Microthrix. Methanospirillum and Bathyarchaeota were the most abundant archaeal phylotypes, which showed a more stable consortium and Nectriaceae and Trichosporonaceae were the most dominant fungal phylotypes for all stages. The qPCR revealed that the crucial role was played by Fungi and Bacteria , while Archaea lost abundance in granular biomass, despite extreme conditions. Aerobic granular sludge is a robust biological technology able to remove nitrate in oligotrophic waters bodies. • Aerobic granular biomass was used to treat nitrate-polluted groundwater. • Nitrate removal ratio was success under low ORL at low temperature. • Holophagaceae and Candidatus Microthrix proliferated in granular biomass. • qPCR revealed the key role of Fungi and Bacteria in denitrification and granulation. [ABSTRACT FROM AUTHOR]

A pilot-scale anammox biofilter was set up and operated using reject water in order to investigate its nitrogen removal performance and the microbial community present at different stages of operation of this technology. A novel material "Filtralite" was used a support in order to achieve shorter start-up periods and obtain higher nitrogen load removal than other anammox technologies. Physico-chemical analysis demonstrated that nitrogen removal efficiency was higher than 70% from operational Day 100, reaching steady-stable total nitrogen removal and NH 4 +-N of 82% and 91%, respectively, this results suggest the robustness and adaptability of the technology to withstand changing nitrogen loads in the influent. Molecular analysis showed the presence of Nitrosomonas and Candidatus Brocadiales with relative abundance on different key days at around 2.5% of total relative abundance, although other phylotypes involved in the nitrogen cycle were also found. RT-PCR analysis showed that the pre-seed Filtralite used promoted the occurrence of anammox bacteria and other ammonia-oxidizing bacteria. The eukaryotic community oscillated greatly during operation and did not show any clear pattern. Both Prokarya and Eukarya showed high diversity and evenness, attributes which were very stable during operation. The biofilter performed robustly, despite changes in influent and nitrogen load, validating its suitability for treating industrial or urban effluent with high nitrogen loading in order to avoid damages in the environment in the save-cost way. [Display omitted] • Filtralite Biofilter reactor was implemented at pilot scale treating reject water. • The bioreactor achieved high nitrogen performance in short period. • The ammonium removal efficiency was higher than 70% in steady-stable. • Candidatus Brocadiales was the most representative anammox bacteria. • Hypotrichia and Tetramitia were the dominant eukaryotic phylotypes. [ABSTRACT FROM AUTHOR]

Biofouling significantly reduces the performance efficiency of membrane bioreactors due to the colonization and accumulation of a matrix of microorganisms. In order to investigate the effect of ultrasonic frequency on biofilm formation and bacterial ecology at different frequencies, four microfiltration membrane modules were subjected at 0, 20, 30 and 40 kHz in pilot-scales. The results of massive parallel sequencing showed that the application of ultrasonic frequency significantly affected the bacterial population in biofouling and modifies the species richness even at low frequency. This research reveals that the application of ultrasonic frequencies avoids the colonization of Acinetobacter genus, which is considered an initial colonizer of biofouling and clogging in the submerged membrane reactor, fact that caused problems in full-scale wastewater treatment plant. The promotion of Gordonia genus was observed during the application of any ultrasounds frequencies (20,30 and 40 Hz). The compositional statistics data exposed the similarity of bacterial communities under medium-high ultrasonic frequency, while those great distances were found in both low and no-ultrasounds frequencies apply. These results suggest that the application of ultrasounds in membrane bioreactor for treating wastewater could be effective in the potential reduction of biofouling formation in order to improve the to improve the useful life of this system with short periods of application of ultrasound. • Biofouling on membrane treatment using ultrasonic frequency. • The ultrasonic applied to membrane affects to microbial population in biofilm. • Acinetobacter genus was the dominant phylotype in the biofouling. • Gordonia genus showed high resistance against high ultrasonic frequency. [ABSTRACT FROM AUTHOR]

Abstract A lab-scale partial nitritation SBR was operated at 11 °C for 300 days used for the treatment of high-ammonium wastewater, which was inoculated with activated sludge from Rovaniemi WWTP (located in Polar Arctic Circle) in order to evaluate the influence the temperature on the performance, stability and dynamics of its microbial community. The partial nitritation achieved steady-state long-term operation and granulation process was not affected despite the low temperature and high ammonia concentration. The steady conditions were reached after 60 days of operation where the granular biomass was fully-formed and the 50%–50% of ammonium-nitrite effluent was successful achieved. Inoculation with cold adapted inoculum showed to yield bigger, denser granules with faster start-up without necessity of low temperature adaptation period. Next-generation sequences techniques showed that Trichosporonaceae and Xanthomonadaceae were the dominant OTUs in the mature granules. Our study could be useful in the implementation of full-scale partial nitritation reactors in cold regions such as Nordic countries for treating wastewater with high concentration of ammonium. Highlights • A partial-nitritation system was started-up with Polar Arctic Circle inoculum at 11 °C. • Ratio of ammonia oxidation was achieved for long-term operation at low temperature. • Trichosporon and Xanthomonadaceae family were related to granule formation. • A0839 bacterial clone and an unclassified archaeon were linked to ammonium oxidation. • Oligotypes distribution for dominant OTUs changed during the granulation process. [ABSTRACT FROM AUTHOR]

Highlights • Two microbial fuel cells were started-up with cold-adapted inoculum. • COD removal and voltage were similar at different operational temperatures. • Fungi disappeared from the microbial fuel cell at high operational temperature. • Methanogenic archaea proliferated under both temperature conditions. • Blastocatella was the strongest-related phylotype to voltage generation. Abstract Two microbial fuel cells were inoculated with activated sludge from Finland and operated under moderate (25 °C) and low (8 °C) temperatures. Operation under real urban wastewater showed similarities in chemical oxygen demand removal and voltage generated, although moderate temperature supported higher ammonium oxidation. Fungi disappeared in the microbial fuel cell operated at temperature of 25 °C. Archaea domain was dominated by methanogenic archaea at both temperature scenarios. Important differences were observed in bacterial communities between both temperatures, however generating similar voltage. The results supported that the implementation of microbial fuel cells in Nordic countries operating under real conditions could be successful, as well as suggested the flexibility of cold-adapted inoculum for starting-up microbial fuel cells, regardless of the operating temperature of the system, obtaining higher COD removal and voltage generation performances at low temperature than at moderate temperature. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the performance and microbial community structure of a polar Arctic Circle aerobic granular sludge (AGS) system operating at low temperature. Thus, an AGS bioreactor was operated at 7, 5 and 3 °C of temperature using a cold-adapted sludge from Lapland. At 5 °C, it yielded acceptable conversion rates, in terms of nitrogen, phosphorous, and organic matter. However, under 3 °C a negligible nitrogen and phosphorous removal performance was observed. Below 5 °C, scanning electron microscopy studies showed a wispy, non-dense and irregular granular structure with a strong outgrowth of filamentous. Moreover, Illumina next-generation sequencing showed a heterogeneous microbial population where SM1K20 ( Archaea ), Trichosporon domesticum ( Fungus ), and Zooglea , Arcobacte r and Acinetobacte r ( Bacteria ) were the dominant phylotypes. Our study suggests that AGS technologies inoculated with North Pole sludge could be operated, in cold regions for a period longer than 3 months (winter season) under 5 °C of water temperature. [ABSTRACT FROM AUTHOR]

An autotrophic nitrogen removal bioreactor with granular biomass was exposed to high antibiotics concentration in order to evaluate its impact over the performance and the biomass of this bioprocess. A mixture of azithromycin, norfloxacin, trimethoprim and sulfamethoxazole caused loss of autotrophic nitrogen removal performance, coupled to a deep change in the bacterial community diversity and structure of the granular biomass. Azithromycin, norfloxacin and trimethoprim were efficiently removed in the CANON bioreactor, reducing its concentration 77.9 ± 11.2%, 51.7 ± 10.7% and 57.8 ± 8.1%, respectively. The granular biomass changed significantly with the addition of the antibiotics, decreasing in settling velocity but increasing in compactness, losing its inner porous structure but developing a protective outer layer build of cell material. Prolonged operation under the antibiotics loading promoted the adaptation of multi-drug resistant fungus Scedosporium boydii fungal species and of Acidovorax ebreus TPSY , Alcaligenes aquatilis , Paracoccus versutus or Ochrobactrum antropii , which have been identified as human, animal and/or plant pathogens. [ABSTRACT FROM AUTHOR]

An aerobic granular sludge system has been started-up and operated at 7 °C temperature using cold-adapted activated sludge as inoculum. The system could form granular biomass due to batch operation allowing for just 5–3 min of biomass sedimentation. Scanning electron microscopy showed that fungi helped in the granular biomass formation in the early stages of the granule formation. The removal performance of the system was of 92–95% in BOD5, 75–80% in COD, 70–76% in total nitrogen and 50–60% in total phosphorous. The bacterial community structure from cold-adapted activated sludge changed during the operational time, leading to a final configuration dominated by Microbacteriaceae members Microbacterium and Leucobacter, which were strongly correlated to biomass settling velocity and bioreactor performance, as suggested by multivariate redundancy analyses. This experiment showed that aerobic granular sludge systems could be successfully started-up and operated, with high performance, under low operational temperatures when using cold-adapted biomass as inoculum. [ABSTRACT FROM AUTHOR]

Abstract: Nineteen bacterial isolates were grown in shaken cultures in media containing chitin as carbon source and different additional nitrogen sources such as yeast nitrogen base (YNB), yeast extract (YE), corn steep liquor (CSL) and ammonium sulfate. Strain BM17 showed the highest activity (200U/l) in medium containing Chitin (1%) and YNB (0.5%). Molecular analysis of the 16S rRNA gene showed that strain BM17 belongs to the species Paenibacillus pabuli (99.72% homology). The enzyme activity started after 12–24h; exponential enzyme production was recorded from the 24thh and lasted till the 96thh of incubation when activity peaked to decrease thereafter. Medium optimisation was carried out by Response Surface Methodology (RSM) considering the effects of chitin, corn steep liquor and yeast extract. BM17 chitinolytic activity was induced by chitin but the increase of its concentration did not have significant effects on the enzyme activity. By contrast, the nitrogen source, particularly YE, strongly affected the enzyme production. [Copyright &y& Elsevier]

• Granular sludge bioreactors were inoculated with cold-adapted activated. • The system at 8 °C achieved the higher removal ratios and faster granulation. • At day 150, the performances were similar in all bioreactor. • The prokaryotic communities were strongly dependent on temperature. • Greenhouse gases emission related to biomass were lower at cold temperature. Three bioreactors were inoculated with Polar Arctic Circle-activated sludge, started-up and operated for 150 days at 8, 15 and 26 °C. Removal performances and granular conformation were similar at steady-state, but higher stability from start-up was found when operating at 8 °C. Important changes in the eukaryotic and prokaryotic populations caused by operational temperature were observed, being fungi dominant at 8 °C and 15 °C, while that ciliated organisms were found at 26 °C. The qPCR results showed higher copies of bacteria, and nitrifiers and denitrifying bacteria at cold temperature. The emission of nitrous oxide was linked directly with temperature and the involved microorganisms. This study represents a proof of concept in performance, greenhouse gas emission, granular formation and the role of the Polar Arctic Circle microbial population in AGS technology under different temperatures with the aim to understand the effect of seasonal o daily changes for implementation of AGS at full-scale. [ABSTRACT FROM AUTHOR]

The communities of Bacteria , Archaea and Fungi in a full-scale moving bed biofilm reactor in Rukatunturi (Ruka, Finland, in the Polar Arctic Circle) were analyzed in order to observe their ecological role in the operation of this system at low temperature. The bioreactor achieved efficient removal performances organic matter (>96%) and for ammonium (>95%), however a modest removal for total nitrogen (>63–75%). Bacteria dominant phylotypes changed in relation to the different functions: Trichococcus and Polaromonas for denitrification, Trichococcus and Simplicispira for organic matter removal, and Devosia and Thermomonas for nitrification. Bacteria predicted metagenome related to nitrification confirmed ammonium oxidation in nitrification chamber, and reduction of nitrate and nitrite in the denitrification and organic matter removal chambers. Dynamics of Fungi , dominated by Trichosporonaceae and Ascomycota clones, were linked to aeration conditions but not to substrate concentrations. Archaea communities, dominated by Methanobrevibacter genus and Thermoplasmatales -related clones, were not affected by aeration or substrate concentrations. The results obtained offer a valuable insight into the ecological role of microbial communities in full-scale moving bed biofilm reactor operating under extremely low temperatures. • Bacteria communities were sensitive to aeration and substrate concentrations. • Fungi communities were sensitive to aeration conditions. • Archaea communities were not affected by aeration and substrate concentrations. • NH 4 + and NO 3 − removal occurred in the nitrification and denitrification chambers. • Top contribution of nosZ and nirK occurred in the organic matter removal chamber. [ABSTRACT FROM AUTHOR]