Four Pilot-scale Moving Bed Biofilm Reactors (MBBRs) were operated for the treatment of real, saline, bilge wastewater. The MBBRs were connected in pairs to create two system configurations with ...different filling ratios (20%, 40%) and were operated in parallel. The inflow organic loading rate (OLR) varied from 3.6 ± 0.2 to 7.8 ± 0.6 g COD L
−1
d
−1
, salinity was >15 ppt and three hydraulic residence times (HRTs) were tested 48, 30 and 24 h. In both systems, the first-stage bioreactors (R1 and R3) eliminated the higher part of the organic load (57%-65%). The second-stage bioreactors (R2 and R4) removed an additional fraction (18%-31%) of the organic load received by the effluent of R1 and R3, respectively. The microbial communities of the influent wastewater, suspended, and attached biomass were determined using 16S rRNA gene amplicon sequencing analysis. The evolution of the microbial communities was investigated and compared over the different operational phases. The microbial communities of the biofilm presented higher diversity and greater stability in composition over time, while the suspended biomass exhibited intense and rapid changes in the dominance of genera. Proteobacteria, Bacteroidetes and Firmicutes were highly present in the biofilm. The genera Celeribacter, Novispirillum, Roseovarius (class: Alphaproteobacteria) and Formosa (class: Flavobacteriia) were highly present during all operational phases. Principal Component Analysis (PCA) was used to identify similarities between samples, exhibiting high relation of samples according to the series of the bioreactor (1st, 2nd).
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•All target compounds were biodegradable in both activated sludge and MBBR systems.•Operation of MBBR at low organic loading enhanced micropollutants removal.•Attached biomass ...exhibited greater ability to remove micropollutants.•Biodegradation potential in biofilm differed in each bioreactor of MBBR system.•Biodegradation of micropollutants occurs due to co-metabolic phenomena.
Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic.
Bilge wastewater is a high strength, typically saline wastewater, originating from operation of ships. In this study, the treatment of real bilge wastewater was tested using pure isolated aerobic ...strains and mixed cultures (aerobic and anaerobic). The Chemical Oxygen Demand (COD) and ecotoxicity decrease were monitored over time, while the microbial dynamics alterations in mixed cultures were also recorded. The isolated strains
Pseudodonghicola xiamenensis
,
Halomonas alkaliphila
and
Vibrio antiquaries
were shown to significantly biodegrade bilge wastewater. Reasonable COD removal rates were achieved by aerobic mixed cultures (59%, 9 days), while anaerobic mixed cultures showed lower performance (34%, 51 days). The genus
Pseudodonghicola
was identified as dominant under aerobic conditions both in the mixed cultures and in the control sample (raw wastewater), after exposure to bilge wastewater, demonstrating natural proliferation of the genus and potential contribution to COD reduction. Biodegradation rates were higher when initial organic load was high, while the toxicity of raw wastewater partially decreased after treatment.
Two labscale aerobic moving bed biofilm reactor (MBBR) systems, with a different type of biocarrier in each (K3 and Mutag BioChip), were operated in parallel for the treatment of real saline bilge ...water. During the operation, different stress conditions were applied in order to evaluate the performance of the systems: organic/hydraulic load shock (chemical oxygen demand (COD): 9 g L−1; hydraulic retention time (HRT): 48–72 h) and salinity shock (salinity: 40 ppt). At the same time, the microbiome in the biofilm and suspended biomass was monitored through 16S rRNA gene analysis in order to describe the changes in the microbial community. The dominant classes were Alphaproteobacteria (families Rhodospirillaceae and Rhodobacteraceae) and Bacteroidia (family Lentimicrobiaceae), being recorded at high relative abundance in all MBBRs. The structure of the biofilm was examined and visualized with scanning electron microscopy (SEM) analysis. Both systems exhibited competent performance, reaching up to 86% removal of COD under high organic loading conditions (COD: 9 g L−1). In the system in which K3 biocarriers were used, the attached and suspended biomass demonstrated a similar trend regarding the changes observed in the microbial communities. In the bioreactor filled with K3 biocarriers, higher concentration of biomass was observed. Biofilm developed on Mutag BioChip biocarriers presented lower biodiversity, while the few species identified in the raw wastewater were not dominant in the bioreactors. Through energy-dispersive X-ray (EDX) analysis of the biofilm, the presence of calcium carbonate was discovered, indicating that biomineralization occurred.
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•All target compounds were partially removed in hybrid Moving Bed Biofilm Reactor.•5 compounds were removed mainly in 1st stage, critical role of 2nd stage for 4TTR.•AS and ...biocarriers contribute to different extent to micropollutants biodegradation.•HMBBR and low loaded MBBR are the most efficient systems for studied compounds.•22 biotransformation products were tentatively identified.
A laboratory scale Hybrid Moving Bed Biofilm Reactor (HMBBR) was used to study the removal of five benzotriazoles and one benzothiazole from municipal wastewater. The HMBBR system consisted of two serially connected fully aerated bioreactors that contained activated sludge (AS) and K3-biocarriers and a settling tank. The average removal of target compounds ranged between 41% (4-methyl-1H-benzotriazole; 4TTR) and 88% (2-hydroxybenzothiazole; OHBTH). Except for 4TTR, degradation mainly occurred in the first bioreactor. Calculation of biodegradation constants in batch experiments and application of a model for describing micropollutants removal in the examined system showed that AS is mainly involved in biodegradation of OHBTH, 1H-benzotriazole (BTR) and xylytriazole (XTR), carriers contribute significantly on 4TTR biodegradation, while both types of biomass participate on elimination of 5-chlorobenzotriazole (CBTR) and 5-methyl-1H-benzotriazole (5TTR). Comparison of the HMBBR system with MBBR or AS systems from literature showed that the HMBBR system was more efficient for the biodegradation of the investigated chemicals. Biotransformation products of target compounds were identified using ultra high-performance liquid chromatography, coupled with a quadrupole-time-of-flight high-resolution mass spectrometer (UHPLC-QToF-MS). Twenty two biotransformation products were tentatively identified, while retention time denoted the formation of more polar transformation products than the parent compounds.
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•The sorption and biodegradation of selected BTRs and OHBTH was studied.•Anoxic, aerobic conditions, SRT and organic substrate were investigated.•BTR, CBTR, XTR and OHBTH were ...biodegraded under aerobic, anoxic conditions.•With one exception, Sludge Retention Time did not affect biodegradation kinetics.•Partial removal of investigated compounds expected in STPs, mainly by biodegradation.
Biodegradation of benzotriazole (BTR), 5-chlorobenzotriazole (CBTR), xylytriazole (XTR), 4-methyl-1H-benzotriazole (4TTR), 5-methy-1H-lbenzotriazole (5TTR) and 2-hydroxybenzothiazole (OHBTH) was studied in activated sludge batch experiments under aerobic and anoxic conditions, presence of organic substrate and different sludge residence times (SRTs). Their sludge-water distribution coefficients were also calculated in sorption experiments and ranged between 87 and 220Lkg−1. Significant biodegradation of BTR, CBTR, XTR and OHBTH was observed in all biotic experiments. Half-life values ranged between 23 and 45h (BTR), 18 and 47h (CBTR), 14 and 26h (XTR), 6.5 and 24h (OHBTH). The addition of substrate did not suppress biodegradation kinetics; whereas in some cases accelerated biodegradation of microcontaminants. Except for CBTR, no effect of SRT on biodegradation constants was observed. Prediction of micropollutants removal in Sewage Treatment Plants (STPs) indicated that they will be partially removed, mainly due to aerobic biodegradation. Higher removal is expected at STPs operating at higher SRT and higher suspended solids concentrations.
The diagnosis of pediatric community-acquired pneumonia (CAP) is based on clinical criteria. Even though chest x-ray (CXR) is only recommended in severe cases, it is often requested from physicians ...in mild cases, thus increasing radiation exposure. Lung ultrasound (LUS) is not included in the diagnostic workup. The objective of this study was to evaluate the diagnostic performance of LUS against CXR.
Children who presented to the emergency department with clinical signs suggesting CAP and had already been evaluated with a CXR were included in the study. Availability of a pediatric sonographer expert in LUS was also considered a criterion for participation. Chest x-ray and LUS were considered positive for CAP in cases of alveolar or interstitial pattern of disease. The diagnostic criterion standard was the ex post diagnosis of pneumonia, made by an independent senior expert pediatrician, after evaluation of the complete medical chart.
Sixty-nine children were enrolled in the study, with 66 of 69 positive for CAP. Receiver operating characteristic curve analysis results for CXR were 95.5% sensitivity and 100% specificity, whereas for LUS, sensitivity was reported 92.42% and specificity 100%. Comparison of the 2 receiver operating characteristic curves revealed no difference in the diagnostic value of the 2 methods for the diagnosis of pneumonia (P = 0.658). However, LUS classified more cases as alveolar disease compared with CXR.
Lung ultrasound plays a significant role in the detection of CAP, not inferior to CXR. The aim of this study was to encourage the use of ultrasound as a first-line examination for CAP in children.
Water quality modeling is a key element for the support of environmental protection and policymaking. The aim of this work is to describe the application of a far-field water quality model for the ...simulation of marine pollution occurring from heavy metals (cadmium, lead, nickel, copper, and zinc). The highly stressed marine area of the Saronikos Gulf (Aegean Sea, Eastern Mediterranean) was chosen for investigation. Major pollution sources were identified, loads were estimated, and the model was parameterized to reproduce the local seawater conditions. The distribution of the pollutants between the dissolved and particulate phases was examined. The performance of the model set-up was evaluated using field concentration measurements. The described implementation succeeded in reproducing the observed levels of pollution and therefore can be used as a baseline configuration to examine the cumulative impact of future pollution sources; for example, accidental pollution events.
Hybrid Moving Bed Biofilm Reactor for the biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater Mazioti, Aikaterini A; Athanasios S. StasinakisauthorDepartment of Environment, University of the Aegean, 81100 Mytilene, GreeceDepartment of Environmental Engineering, Technical University of Denmark, Miljvej, B 113, 2800 Kgs. Lyngby, Denmark; Aikaterini K. PsomaauthorDepartment of Chemistry, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771 Athens, Greece ...
2015
Journal Article
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