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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., This work was supported by the Programa operativo FEDER de Andalucía 2014–2020 (Junta de Andalucía y Union ´ Europea) with reference B-RNM-137-UGR18., This work was supported by the Programa operativo FEDER de Andalucía 2014–2020 (Junta de Andalucía y Unión Europea) with reference B-RNM-137-UGR18.

The aim of this work was to study the operational performance and the microbial community dynamics during the start-up of ANITATMMox technology implemented at full-scale wastewater treatment plant in Finland to treat reject water from anaerobic digesters. The average ammonium removal in the studied setup reached around 90%, withstanding ammonium loads up to 0.13 g N m-2h-1. The nitrite concentration in the effluent did not exceed 10 mg L-1, and there was a slight accumulation of NO3--N during the operation which was controlled. Thus, the result showed a robust success to high ammonium loading in presence of organic matter. The sequencing showed a heterogeneous microbial population where Methanosaeta, WCHA1-57 genus, Sphingobacteriia, Chlorobia and diverse unknown fungi were found as dominant phylotypes. Moreover, members of the Brocadiaceae family were dominant in the adhered biomass, mostly represented by Candidatus Scalindua, rarely reported in WWTPs. Overall, the results demonstrated a drastic effect of region-specific operational conditions on carrier biofilm microbial communities as it was demonstrated by the microbial studies.

Four granular sequencing batch reactors (GSBRs) were inoculated with four denitrifying Pseudomonas strains carrying nosZ to study the process of granule formation, the operational conditions of the bioreactors, and the carbon concentration needed for nitrate removal. The selected Pseudomonas strains were P. stutzeri I1, P. fluorescens 376, P. denitrificans Z1, and P. fluorescens PSC26, previously reported as denitrifying microorganisms carrying the nosZ gene. Pseudomonas denitrificans Z1 produced fluffy, low-density granules, with a decantation speed below 10 m h−1 . However, P. fluorescens PSC26, P. stutzeri I1, and P. fluorescens 376 formed stable granules, with mean size from 7 to 15 mm, related to the strain and carbon concentration. P. stutzeri I1 and P. fluorescens 376 removed nitrate efficiently with a ratio in the range of 96%, depending on the source and concentration of organic matter. Therefore, the findings suggest that the inoculation of GSBR systems with denitrifying strains of Pseudomonas spp. containing the nosZ gene enables the formation of stable granules, the efficient removal of nitrate, and the transformation of nitrate into nitrogen gas, a result of considerable environmental interest to avoid the generation of nitrous oxide., LIFE16 ENV/ES/000196 project

The authors would like to acknowledge the support given by the Institute of Water Research of University of Granada and the disposition of Municipal Water Company of Granada (EMASAGRA S.A.) for financial support to carry out the research., In wastewater treatment plants, most microbial characterization has focused on bacterial, archaeal, and fungal populations. Due to the difficult isolation, quantification, and identification of viruses, only a limited number of virome studies associated with wastewater treatment plants have been carried out. However, the virus populations play an important role in the microbial dynamics in wastewater treatment systems and the biosafety of effluents. In this work, the viral members present in influent wastewater, mixed liquor (aerobic bioreactor), excess sludge, and effluent water of a conventional activated sludge system for the treatment of urban wastewater were identified. Viral members were observed by transmission electron microscopy and studied through next-generation sequencing studies. The results showed the dominance of bacteriophages in the viral community in all samples, with the dominant viral phylotype classified as Escherichia coli O157 typing phage 7. Moreover, different human viruses, such as Cynomolgus cytomegalovirus and Gammaherpesvirus, were also detected., Institute of Water Research of University of Granada

Three lab-scale sequential batch reactors were operated under aerobic granular sludge technology for 150 days. The reactors were inoculated with mild temperature-adapted activated sludge from Granada wastewater treatment plant (WWTP) in order to evaluate the microbial dynamics, the granulation process and the performance of the systems under low, mid and high temperature. The faster start-up was achieved at mid temperature at operational day 6, followed by warm temperature at day 10, with nitrogen and organic matter removal ratio higher than 90%. Conversely, the reactor under cold temperature produced granular biomass but the nitrogen and carbon removal ratios did not achieve good performance, close to 80%. The dynamics of Prokarya communities showed that Corynebacterium phylotype was present in all bioreactor despite temperature, although the microbial diversity at mid and warm temperature was higher than at cold temperature. The Eukarya communities in mature granules were represented by Pezizomycotina fungi and Oligohymenophorea ciliate.

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.

In this study, a lab-scale CANON bioreactor was operated for 260 days, decreasing operational temperature from 35 °C to 15 °C and from 466 to 100 mg-N L−1 ammonium. This was done in order to check the feasibility of the acclimation of CANON biomass treating anaerobic digestion supernatant to B-stage influent wastewater operational conditions. Results showed that decrease in temperature posed an impact over the performance of the CANON bioreactor as well as over its bacterial assemblage. Nitrogen removal efficiency showed a moderate decrease when the system was acclimated from 35 °C to 25 °C, but it decreased dramatically in the acclimation from 25 °C to 15 °C. The decrease in temperature and influent ammonium concentration posed an impact over the bacterial community structure of the system. Ammonium oxidizing bacteria changed from Nitrosomonas, Nitrosospira or Nitrosovibrio genera at high temperature and influent ammonium to Prosthecobacter at low temperature and low ammonium. As well, dominant anammox bacteria genus changed from Candidatus Brocadia to Candidatus Anammoxoglobus during acclimation. Proliferation of nitrite oxidizing bacteria only occurred under low temperature and influent ammonium conditions with growth of Rhodanobacter genus.

Partial-nitritation processes are used for the biological treatment of high nitrogen-low organic carbon effluents, such as anaerobic digestion reject water. The release of certain products generated during the anaerobic digestion process, such as amino acids, could potentially reduce the performance of these partial-nitritation bioprocesses. To investigate this, four partial-nitritation biofilters were subjected to continuous addition of 0, 150, 300, and 500 mg L-1 cysteine amino acid in their influents. The addition of the amino acid had an impact over the performance of the partial-nitritation process and the bacterial community dynamics of the systems analyzed. Ammonium oxidation efficiency decreased with the addition of the amino acid, and a net nitrogen elimination occurred in presence of cysteine through the operation period. Bacterial community dynamics showed a decrease of Nitrosomonas species and a proliferation of putative heterotrophs with nitrification capacity, such as Pseudomonas, or denitrification capacity, such as Denitrobacter or Alicycliphilus. The addition of cysteine irreversible affected the bioreactors, which could not achieve the performance obtained before the addition of the amino acid. A mathematical predictive equation of the process performance depending on cysteine concentration added and operational time under such concentration was developed. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1254-1263, 2016.

A partial-nitritation biofilter was tested in order to investigate the effect of organic matter loading over its performance and bacterial community structure. Analyses were done after each of a two-step organic loading of 45 days each. Without organic matter addition, the partial-nitritation biofilter performed in nearly ideal conditions in terms of ammonium oxidation to nitrite. Under these conditions its bacterial community structure was dominated by Nitrosomonas bacteria. The first loading of organic matter caused a decrease in ammonium oxidation as well as decrease in relative abundance of Nitrosomonas . The COD and BOD 5 removal increased with the operation time up to 85% and 81%. For the second loading of organic matter the partial-nitritation biofilter achieved 91% and 97% in COD and BOD 5 removal at the end of the experimental period but ammonium oxidation efficiency was still inefficient. The changes in the bacterial community structure of the biofilter were more pronounced at the first organic loading step as suggested by α- and β-diversity analyses. In this way, the partial-nitritation biofilter could not achieve the desired coupled ammonium oxidation and organic matter removal efficiency.

Seven full-scale biological wastewater treatment systems located in the Polar Arctic Circle region in Finland were investigated to determine their Archaea, Bacteria and Fungi community structure, and their relationship with the operational conditions of the bioreactors by the means of quantitative PCR, massive parallel sequencing and multivariate redundancy analysis. The results showed dominance of Archaea and Bacteria members in the bioreactors. The activated sludge systems showed strong selection of Bacteria but not for Archaea and Fungi, as suggested by diversity analyses. Core OTUs in influent and bioreactors were classified as Methanobrevibacter, Methanosarcina, Terrestrial Group Thaumarchaeota and unclassified Euryarchaeota member for Archaea; Trichococcus, Leptotrichiaceae and Comamonadaceae family, and Methylorosula for Bacteria and Trichosporonaceae family for Fungi. All influents shared core OTUs in all domains, but in bioreactors this did not occur for Bacteria. Oligotype structure of core OTUs showed several ubiquitous Fungi oligotypes as dominant in sewage and bioreactors. Multivariate redundancy analyses showed that the majority of core OTUs were related to organic matter and nutrients removal. Also, there was evidence of competition among Archaea and Fungi core OTUs, while all Bacteria OTUs were positively correlated among them. The results obtained highlighted interesting features of extremely cold temperature bioreactors.

Two pilot-scale hybrid moving bed biofilm reactor-membrane bioreactors were operated in parallel for the treatment of salinity-amended urban wastewater under 6 hours of hydraulic retention time and 2500 mg L&minus, 1 total solids concentration. Two salinity conditions were tested: the constant salinity of 6.5 mS cm&minus, 1 electric conductivity (3.6 g L&minus, 1 NaCl) and the tidal-like variable salinity with maximum 6.5 mS cm&minus, 1 electric conductivity. An investigation was developed on the biofouling produced on the ultrafiltration membrane surface evaluating its bacterial community structure and its potential function in the fouling processes. The results showed that biofouling was clearly affected by salinity scenarios in terms of &alpha, diversity and &beta, diversity and bacterial community structure, which confirms lower bacterial diversity under variable salinity conditions with Rhodanobacter and Dyella as dominant phylotypes. Microorganisms identified as bio-mineral formers belonged to genera Bacillus, Citrobacter, and Brevibacterium. These findings will be of help for the prevention and control of biofouling in saline wastewater treatment systems.