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Scheme of the anaerobic sequencing batch reactor with external circulation of the liquid phase and immobilized biomass: 1) reactor containing immobilized biomass; 2) external reservoir; 3) circulation pump; 4) flow rate meter;
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An anaerobic sequencing batch bioreactor with external circulation of the liquid phase wherein the biomass was immobilized on a polyurethane foam matrix was analyzed, focussing on the influence of the liquid superficial velocity on the reactor's stability and efficiency. Eight-hour cycles were carried out at 30ºC treating glucose-based synthetic wa...
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... anaerobic bioreactor with external circulation of the liquid phase is shown in Figure 1. The reactor consists of a cylindrical flask with an external diameter of 60 mm, 460 mm of height and 3.5 mm of wall thickness, resulting approximately in a work volume of 1.0 L. The fixed-bed with 410 mm of height, composed of 5-mm cubic polyurethane foam matrices (apparent density of 23 kg/m 3 ) containing the immobilized biomass and confined between two punctured stainless steel disks, resulting in a bed porosity of 40% (Zaiat et al., 1997b). ...
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... The experimental conditions were compared based on the kinetic profiles of CHt consumption (considered as the primary fermentable substrate) during the incubation periods, CHt overall conversion, and the profiles of soluble metabolites measured at the end of Phases I, II, and III, except for the G/M ratio 1.67, characterized by only two phases (Phases I and II). The kinetic analysis was carried out considering only the data obtained for the last phase of each experimental condition (Phase III) and using a first-order kinetic model with residual as the mathematical approach [35]. The kinetic model (Equation (1)) was fitted to the experimental data using the software Origin 2020 (OriginLab Corporation, Northampton, MA, USA) with the aid of a nonlinear fitting tool by the Levenberg Marquardt iteration algorithm. ...
Melanoidins are heterogeneous polymers with a high molecular weight and brown color formed during the Maillard reaction by the combination of sugars and amino acids at high temperatures with the potential to inhibit the microbial activity in bioprocesses. This study assessed the impacts of melanoidins on the kinetic of substrate conversion and production of organic acids via dark fermentation using microbial consortia as inoculum. The investigations were carried out in fed-batch reactors using synthetic melanoidins following glucose-to-melanoidin ratios (G/M; g-glucose g−1 melanoidins) of 0.50, 1.50, 1.62, 1.67, and 5.00, also considering a melanoidin-free control reactor. The results showed that melanoidins negatively impacted the kinetics of glucose fermentation by decreasing the first-order decay constant (k1): when dosing equivalent initial concentrations of glucose (ca. 3 g L−1), the absence of melanoidins led to a k1 of 0.62 d−1, whilst dosing 2 g L−1 (G/M = 1.5) and 6.0 g L−1 (G/M = 0.5) of melanoidins produced k1 values of 0.37 d−1 and 0.27 d−1, respectively. The production of butyric and acetic acids was also negatively impacted by melanoidins, whilst the lactic activity was not impaired by the presence of these compounds. Lactate production reached ca. 1000 mg L−1 in G/M = 1.67, whilst no lactate was detected in the control reactor. The presence of melanoidins was demonstrated to be a selective metabolic driver, decreasing the microbial diversity compared to the control reactor and favoring the growth of Lactobacillus. These results highlight the importance of further understanding the impacts of melanoidins on melanoidin-rich organic wastewater bioconversion, such as sugarcane vinasse, which are abundantly available in biorefineries.
... The removal kinetics profile was evaluated by analysis of the samples collected along the bioreactor. Both organic matter (OM) and CAF followed first-order decay with residual, as described by Camargo et al. (2002). The HAIB bioreactor could be considered an ideal tubular system (plugflow), in agreement with behavior reported previously (de Nardi et al. 2007;Lunelli et al. 2016). ...
Anaerobic bioreactors are an efficient technology for the biodegradation of emerging contaminants in environmental matrices. In this work, a horizontal-flow anaerobic immobilized biomass (HAIB) bioreactor was used to remove caffeine (CAF), which is frequently found in various aqueous matrices. The acrylic bench top bioreactor, with dimensions of 100 × 5.00 cm, was operated with a hydraulic retention time (HRT) of 12 h, during 45 weeks, under mesophilic conditions. The operation was performed in 4 phases: without CAF addition (phase I); CAF spiked at 300 μg L⁻¹ (phase II); CAF at 600 μg L⁻¹ (phase III); and CAF at 900 μg L⁻¹ (phase IV). Samples of bioreactor influent and effluent were analyzed by liquid chromatography/tandem mass spectrometry (LC–MS/MS). The bioreactor removed organic matter (OM) and CAF with efficiencies of 88 and 93%, respectively. The first-order apparent removal constant (Kapp) values for OM and CAF were 0.419 and 0.304 h⁻¹, respectively. Five transformation products (TPs) were identified, with m/z 243, 227, 211, and 181 (two products). The HAIB bioreactor is a suitable system for the removal of CAF present in wastewater, even at a concentration level of µg L⁻¹.
... In Equation (6), COD HRT is the COD along the reaction bed for each HRT, COD 0 is the COD in the influent stream (HRT = 0), COD R is the COD residual in the reactor when the value of the reaction rate is null. The parameter k 1 stands for the apparent first-order kinetic coefficient, as it embodies the intrinsic kinetic constant as well as the internal and external mass transfer resistances (Camargo et al., 2002). Each sampling point represents a fraction of the total HRT of each reactorfrom 0 to 12 h in M 1 R, from 0 to 6 h in AcR and M 2 R. The VOA content was also assessed at each sampling point in order to elucidate the main metabolic pathways during the anaerobic digestion in each bioreactor. ...
The organic matter bioconversion into methane during anaerobic digestion (AD) comprises different steps, the acidogenic and methanogenic phases being clearly distinct in terms of metabolic activities. In this work, new configurations of anaerobic fixed bed biofilm reactors (AFBBR) were operated under conventional methanogenic conditions (single phase – SP-AFBBR, M1R), and in a sequential two-phase system, acidogenic reactor followed by methanogenic reactor (TP-AFBBR, AcR + M2R), in order to verify the impact of the AD phase separation on the overall system performance in operational, kinetics and microbiological aspects. The results indicated that feeding the methanogenic reactor with the acidogenic effluent stream provided a shorter operating start-up period (11 and 32 days for SP and TP-AFBBR, respectively), a greater alkalinity generation (0.14 and 0.41 g-CaCO3·g-CODremoved⁻¹ for M1R and M2R, respectively), and the optimization of biomethane production (methane yield of 95 and 154 N-mLCH4·g-CODremoved⁻¹ for M1R and M2R, respectively). The COD removal kinetics was also favored in the TP-AFBBR (k1-COD = 1.4 and 2.9 h⁻¹ for M1R and M2R, respectively), since the soluble fermentation products were readily bioavailable to the biomass in the reactor. Hydrogenotrophic methanogenesis was the predominant pathway in the M2R, while the Methanosaeta-driven acetoclastic pathway predominated in the M1R. The greater diversity of Bacteria and Archaea in M2R denotes a better balance between the species that degrade volatile organic acids from AcR (i.e. Syntrophorhabdus, Syntrophus and Syntrophobacter) and the hydrogenotrophic methanogens (Methanoregula, Methanolinea and Methanospirillum) that consume the biodegradation products. The estimated bioenergy generation potential (range of 0.39–0.64 kWh·m⁻³-sewage considering the COD removed) for full-scale TP-sewage treatment plants evidences the feasibility of energetic recovery in the domestic sewage anaerobic treatment.
... The time series samples were collected each hour, until TBBPA reached concentrations below the quantification limit (<0.1 μg L − 1 ), extracted, and analysed by LC-ESI-MS/MS. A first-order kinetic model with a residual concentration (Camargo et al., 2002) was adjusted to the experimental data (Equation (1)). ...
Tetrabromobisphenol A (TBBPA) is the most used flame retardant worldwide and has become a threat to aquatic ecosystems. Previous research into the degradation of this micropollutant in anaerobic bioreactors has suggested several identities of putative TBBPA degraders. However, the organisms actively degrading TBBPA under in situ conditions have so far not been identified. Protein-stable isotope probing (protein-SIP) has become a cutting-edge technique in microbial ecology for enabling the link between identity and function under in situ conditions. Therefore, it was hypothesized that combining protein-based stable isotope probing with metagenomics could be used to identify and provide genomic insight into the TBBPA-degrading organisms. The identified ¹³C-labelled peptides were found to belong to organisms affiliated to Phytobacter, Clostridium, Sporolactobacillus, and Klebsilla genera. The functional classification of identified labelled peptides revealed that TBBPA is not only transformed by cometabolic reactions, but also assimilated into the biomass. By application of the proteogenomics with labelled micropollutants (protein-SIP) and metagenome-assembled genomes, it was possible to extend the current perspective of the diversity of TBBPA degraders in wastewater and predict putative TBBPA degradation pathways. The study provides a link to the active TBBPA degraders and which organisms to favor for optimized biodegradation.
... In these samples, TBBPA and carbohydrates concentrations were quantified. A first-order kinetic model with a residual concentration (Camargo et al., 2002) was adjusted to the experimental data (Eq. (1)). ...
... Each sampling point represented the different hydraulic retention times, ranging from 0 to 12 h. Taking into account that the ASBBR behaved as an ideal plug-flow reactor, as presented by Carneiro et al. (2019), the experimental data obtained along the bioreactor spatial profile were adjusted by a first-order kinetic model with residual concentration, as previously described by Camargo et al. (2002) and shown in Eq. (4). In this expression, C is the concentration (SMX or COD) in the liquid phase, C 0 is the influent concentration (SMX or COD), C R is the residual concentration in the effluent stream (SMX or COD), HRT is the hydraulic retention time (in h), and k 1 is the first-order kinetic constant (in h −1 ). ...
Sulfamethoxazole (SMX) is one of the antibiotics most frequently detected in effluents from conventional wastewater treatment plants, which increases the concern about the possible impacts on the aquatic biota and public health regarding the emergence of bacteria resistant to this drug. Anaerobic fixed bed reactors are supposed to enhance antibiotic biodegradation due to the biofilm formation in the reactor. In this context, this study evaluated the dynamics of the microbial community in the biofilm of three inoculum sources taken from Upflow Anaerobic Sludge Blanket (UASB) reactors for the biodegradation of SMX in anaerobic structured bed biofilm reactor (ASBBR) with: poultry slaughterhouse sludge (PS), brewery sludge (BS) and domestic sewage sludge (SS). The ASBBR reached high COD (Chemical Oxygen Demand) removal (> 84%) and biomethane yield (> 276 mLCH4 g−1 CODremoved) for all inocula. The bioreactor operation with PS inoculum presented the best SMX removal (90 ± 5%), while the BS and SS inocula resulted in 84 ± 6% and 70 ± 5% removal, respectively. The kinetic profiles of COD and SMX removal indicated the occurrence of cometabolic biodegradation of sulfonamide. The molecular biology analysis showed that the microbial community of the SS inoculum suffered significant changes during the ASBBR operation for the Archaea and Bacteria domains and the biomass of PS presented more similarity to the inoculum, indicating a better SMX adaptation, in agreement with the higher SMX removal. Furthermore, the diversity of the Archaea domain (mainly Methanosaeta and Methanosarcina) increased in the biomass after each reactor operation compared to the raw inocula, indicating that the methanogenic pathway was favored during the anaerobic digestion. The experimental results showed that the inoculum source plays an important role in the SMX biodegradation during the biological wastewater treatment.
... Moreover, the immobilized biomass resists better against toxic compounds (acids, metals…), stress conditions (organic solvent, salinity, inhibiting elements, osmotic pressure, dehydration, self-destruction), and changes in physicochemical parameters (pH, temperature, O 2 …) (Camargo et al., 2002;Muhamad et al., 2015;Velkova et al., 2018). This is important particularly in favor of wastewater purifying bacteria known for their sensitivity to pH, temperature, oxygen…, that consequently can achieve higher yields. ...
In this study, a synthetic dairy effluent (SDE) containing high levels of COD and nitrogen was treated in a fixed-bed bioreactor (FBBR) under the influence of the variations in residence time, aeration conditions and temperature. The tests performed continuously in a single step and the same reaction vessel allowed to define a 96 h cycle comprising two anoxic/aerobic phases of 48 h each. Sequential anoxic and aerobic conditions improved the removal of TKN and NH4⁺ by a factor of 2.5, whereas low temperature (10–15 °C) significantly decreased the nitrogen and COD removal rate. Overall, outcomes showed a successful growth of the biomass that reached (5.8 ± 0.31) × 10⁶ CFU/mL, and high removal efficiency of COD (93.5 ± 8.1%), NO3⁻ (99.2 ± 19%), TKN (87.5 ± 16.1%), and NH4⁺ (55.8 ± 8.3%), and hence complied with Moroccan standards. The FBBR system, therefore, can be applied successfully to remove COD and nitrogen from wastewater.
... In order to assess the reactor biodegradation kinetics, an ideal plugflow model was used based on previous hydrodynamic studies (Carneiro et al., 2019) by adjusting the experimental data to a first-order kinetic model with residual concentration, described by Camargo et al. (2002) and expressed by Eq. (12). In this expression, S is the concentration in the aqueous phase, S R is the residual concentration, S 0 is the concentration in the feed stream and k 1 is the first-order kinetic constant. ...
Antibiotic compounds, notably sulfamethoxazole (SMX) and ciprofloxacin (CIP), are ubiquitous emerging contaminants (ECs), which are often found in domestic sewage. They are associated with the development of antimicrobial resistance. Operational parameters, e.g. organic loading rate (OLR), hydraulic retention time (HRT) and sludge retention time, may influence EC biodegradation in wastewater treatment plants. This study assessed the impact of the OLR variation on the biodegradation of CIP and SMX, applying two configurations of anaerobic fixed bed reactors: anaerobic packed bed biofilm reactor (APBBR) and anaerobic structured bed biofilm reactor (ASBBR). A significant reduction in the biodegradation of SMX (APBBR: 93-69%; ASBBR: 94-81%) and CIP (APBBR: 85-66%; ASBBR: 85-64%) was observed increasing OLR from 0.6 to 2.0 kgCOD m − 3 d − 1. The decrease in the HRT from 12 to 4 h resulted in higher liquid-phase mass transfer coefficient (APBBR: k s from 0.01 to 0.05 cm h − 1 ; ASBBR: k s from 0.07 to 0.24 cm h − 1), but this was not enough to overcome the decrease in the antibiotic-biomass contact time on biofilm, thus reducing the bioreactors' performance. The ASBBR favored biomethane production (from 7 to 17 mLCH 4 g − 1 VSS L − 1 d − 1) and biodegradation kinetics (k bio from 1.7 to 4.2 and for SMX and from 2.1 to 4.8 L g − 1 VSS d − 1 for CIP) due to the higher relative abundance of the archaea community in the biofilm and the lower liquid-phase mass transfer resistance in the structured bed. CIP and SMX cometabolic biodegradation was associated to the hydrogenotrophic methanogenesis (mainly Meth-anobacterium genus) in co-culture with fermentative bacteria (notably the genera Clostridium, Bacillus, Lactivibrio, Syntrophobacter and Syntrophorhabdus). The anaerobic fixed bed biofilm reactors proved to be highly efficient in biodegrading the antibiotics, preventing them from spreading to the environment.
... There is a requirement for good mixing as the biomass settling determines the system performance. This mixing can be performed by an agitator or a recycling stream, to ensure sufficient mass transfer is seen during the reaction time [59,76,88,89]. Usage of inert supports such as polyurethane foam has been recommended to ensure high organic compound removal efficiency and high solids retention [88]. ...
... This mixing can be performed by an agitator or a recycling stream, to ensure sufficient mass transfer is seen during the reaction time [59,76,88,89]. Usage of inert supports such as polyurethane foam has been recommended to ensure high organic compound removal efficiency and high solids retention [88]. ASBR has received scant attention in the literature to date for whiskey distillery/brewery wastes; however a high quality gas with 77 ± 5% of biomethane has been achieved for AD of malt whiskey pot ale using ASBR [90]. ...
... In order to evaluate the reactor removal kinetics, an ideal plug-flow model was used based on previous hydrodynamic studies, which is isothermal, in steady-state, and pseudo-homogenous, resulting in an apparent kinetic parameter (k app ), which embodies the intrinsic kinetic parameter, convective and diffusive mass transfer phenomena. Considering this, the experimental data was adjusted to a first-order kinetic model with residual concentration, described by Camargo et al. (2002) and expressed by Eq. (6). In this expression, C is the concentration in the bulk liquid, C 0 is the concentration in the influent stream, θ h is the hydraulic retention time; k app is the apparent first-order kinetic constant, and C R is the residual concentration, when the reaction rate value was zero. ...
This study assessed the applicability of fixed bed bioreactors in two configurations - anaerobic structured bed reactor (ASBR)and anaerobic packed bed reactor (APBR)- in the removal of Sulfamethoxazole (SMX)and Ciprofloxacin (CIP), two antibiotics frequently detected in sanitary sewage. The problem of these pharmaceuticals as emerging contaminants in conventional sewage treatment systems is mainly because they encourage the development and spread of resistance genes in bacteria. Both reactors had similar performances, and the antibiotics were highly removed - APBR: 85 ± 10% for SMX and 81 ± 16% for CIP; ASBR: 83 ± 12% for SMX and 81 ± 15% for CIP. The ASBR showed to be potentially more feasible in operating and economic terms compared to the APBR, as the former presents a smaller amount of support material in the bed. SMX was completely biotransformed, while the influence of the sorption mechanism was observed for CIP, as its presence was detected sorbed onto biomass throughout the reaction bed of the reactors, with a partition coefficient (log K D )of around 2.8 L·kg ⁻¹ TSS. The degradation kinetics of the pharmaceuticals were fitted using a first-order kinetic model, whereby the reactors behaved as plug flow ones, indicating the possibility of optimizing the operation for a hydraulic retention time of 6 h. The removal kinetics was more favorable for CIP (higher apparent constant kinetic - k CIPapp > k SMXapp ), since its biodegradation is linked to the biomass, which is more concentrated in the bed bottom layer. The experimental results showed the potential of anaerobic fixed bed reactors in removing environmentally relevant concentrations of SMX and CIP found in sewage.
