Abstract This article assesses nitrifying and heterotrophic activity potentials, aiming to ward o... more Abstract This article assesses nitrifying and heterotrophic activity potentials, aiming to ward off future efficiency losses in biological treatment systems. For this purpose, we used biomass developed in two-hybrid fluidized bed reactors (FBRs) treating vinasse from ethanol and sugar beet production. FBRs filled with sepiolite and granular activated carbon (GAC) were used with short cycle aeration (25/15 and 15/15 min) and different hydraulic retention times (4.9 and 7.4 h). At the end of each operational condition, attached and suspended fractions of biomass from both FBRs were collected for activity bioassays. Specific nitrification bioassays suggested that nitrification performance (53–100% for sepiolite FBR and 72–93% for GAC FBR) was associated with the limit of the nitrifiers' potential when the environmental conditions were favorable. On the other hand, low denitrification efficiencies observed in the FBRs (25–44% for sepiolite FBR and 22–65% for GAC FBR) occurred due to low electron availability ...
This study proposes a new approach to selecting a biofilm carrier for immobilization using dissol... more This study proposes a new approach to selecting a biofilm carrier for immobilization using dissolved oxygen (DO) microsensors to measure the thickness of aerobic and anaerobic layers in biofilm. The biofilm carriers tested were polyurethane foam, mineral coal (MC), basaltic gravel, and low-density polyethylene. Development of layers in the biofilm carrier surface was evaluated using a flow cell device, and DO profiles were conducted to determine the size of the layers (aerobic and anaerobic). MC was the biofilm carrier selected due to allowing the development of larger aerobic and anaerobic layers in the biofilm (896 and 1,058 μm, respectively). This ability is supposed to improve simultaneous nitrogen removal by nitrification and denitrification biological processes. Thus, as a biofilm carrier, MC was used in a fixed-bed sequencing batch biofilm reactor (FB-SBBR) for treatment of wastewater with a high ammonia concentration (100–400 mgNH4+-N L−1). The FB-SBBR (15.0 L) was filled wi...
Real textile wastewater containing high salinity (up to 12.6 g·kg−1) and surfactant (up to 5.9 mg... more Real textile wastewater containing high salinity (up to 12.6 g·kg−1) and surfactant (up to 5.9 mg·L−1 of linear alkylbenzene sulfonate – LAS) was submitted to biological treatment for colour (up to 652 mg Pt-Co·L−1) and sulphate (up to 1,568.6 mg SO4−2·L−1) removal. The influence of ethanol and molasses supplementation was firstly evaluated in anaerobic batch reactors for the removal of dyes and sulphate. Subsequently, aiming to remove aromatic amines (dye degradation by-products), an anaerobic–aerobic continuous system supplemented with molasses was applied. Supplementation had no influence on colour removal (maximum efficiencies around 70%), while it improved sulphate reduction (23% without supplementation against 87% with supplementation), and conferred robustness to the reactors, which recovered quickly after higher salinity impact. The aerobic reactor removed aromatic amines when the level of surfactants was lower than 1.0 mg LAS·L−1, but the performance of the system was hinde...
The use of anaerobic reactors for domestic sewage treatment has increased significantly since the... more The use of anaerobic reactors for domestic sewage treatment has increased significantly since the UASB configuration started to be efficiently applied for this purpose in the beginning of the 1980s. Nowadays, hundreds of UASB reactors, or similar anaerobic units, are used in domestic sewage treatment systems, particularly in developing countries. These units have been operated at ambient temperature, normally higher than 20°C, at hydraulic detention time in the range of 6 to 10 hours, and organic loading rates lower than 3.0 kg COD.m−3.d−1. They have presented COD removal efficiencies in the range of 65% to 80%. Besides, new configurations have been developed and assayed in research centres, aiming to amplify the range of application and to improve process performance. At the same time, research is being conducted on the post-treatment of anaerobic effluents attempting to offer alternatives to the existing conventional systems. It takes into consideration not only sanitation and env...
Two anaerobic fixed-structured bed reactors were fed with synthetic wastewater simulating the sol... more Two anaerobic fixed-structured bed reactors were fed with synthetic wastewater simulating the soluble fraction of sugarcane vinasse to evaluate the interference of sulfidogenesis on methanogenesis. The reactors running in parallel were subjected to the same operating conditions. The influent organic matter concentration (in term of chemical oxygen demand (COD)) remained close to 4,000 mgCOD L−1 and the hydraulic retention time was 24 hours. One reactor, the methanogenic (control reactor), received sulfate only to provide the sulfur required as a nutrient to the methanogenic biomass. The other one, the sulfidogenic/methanogenic reactor (SMR), received sulfate concentration corresponding to COD/sulfate ratios of 4, 5 and 3. In the last phase, the COD removal efficiencies were higher than 96% in both reactors and the SMR achieved 97% of sulfate removal efficiency (COD/sulfate ratio of 3 and influent sulfate concentration close to 1,300 mgSO42− L−1). Both reactors also had similar metha...
This paper presents and discusses the potential for use of pilot-scale anaerobic sequencing batch... more This paper presents and discusses the potential for use of pilot-scale anaerobic sequencing batch biofilm reactors (ASBBR) for the treatment of industrial wastewater containing high sulfate concentration. The pilot-scale ASBBR reactor (total volume=1.2 m3) containing biomass immobilized in inert support (mineral coal) was operated at sulfate loading rates varying from 0.15 to 1.90 kgSO4-2/cycle (cycle of 48h) corresponding to sulfate concentrations of 0.25 to 3.0 gSO4-2.L-1. Domestic sewage and ethanol were utilized as electron donors for sulfate reduction. The mean sulfate removal efficiencies remained in the range of 88 to 92% in the several sulfate concentrations obtained from 92 operational cycles. As post-treatment unit for the generated effluents by the sulfate reduction was used another reactor ASBBR in pilot-scale (total volume=385,0 L) with same inert support for biomass immobilization and different granulometry. The mean COD removal (mean influent=1450 mg.L-1) achieved 88%...
This study aimed to verify the occurrence of environmental and microbial conditions of a support ... more This study aimed to verify the occurrence of environmental and microbial conditions of a support medium applied in a structured-bed reactor for a high-protein content wastewater treatment. An up-flow structured-bed reactor submitted to recirculation and intermittent aeration (SBRRIA) was operated with an hydraulic retention time (HRT) of 11.2±0.6 h and continuous feeding. COD (chemical oxygen demand) removal efficiencies remained above 90% in all experimental conditions. In conditions with a reduced COD/N ratio, NH 4 +-N oxidized efficiencies were greater than 90%, resulting in total-N removal efficiency of 81.5±5.3%. Biomass samples were submitted to tests with dissolved oxygen (DO) microsensors and scanning electron microscope (SEM) for biofilm characterization. The stratification in aerobic and anoxic zones enabled the establishment of different nitrogen degradation pathways, through the development of specific microrganisms such as cocci clusters Nitrosococcus-like organism and ...
Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic d... more Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic denitrification, and may have potential for nitrogen removal of low-strength wastewaters, such as anaerobically pre-treated domestic sewage. This study evaluated the fundamentals and kinetics of this process in batch reactors containing suspended and immobilized cells. Batch tests were performed for different NOx−/S2− ratios and using nitrate and nitrite as electron acceptors. Autotrophic denitrification was observed for both electron acceptors, and NOx−/S2− ratios defined whether sulfide oxidation was complete or not. Kinetic parameter values obtained for nitrate were higher than for nitrite as electron acceptor. Zero-order models were better adjusted to profiles obtained for suspended cell reactors, whereas first-order models were more adequate for immobilized cell reactors. However, in the latter, mass transfer physical phenomena had a significant effect on kinetics based on biochemica...
Abstract This article assesses nitrifying and heterotrophic activity potentials, aiming to ward o... more Abstract This article assesses nitrifying and heterotrophic activity potentials, aiming to ward off future efficiency losses in biological treatment systems. For this purpose, we used biomass developed in two-hybrid fluidized bed reactors (FBRs) treating vinasse from ethanol and sugar beet production. FBRs filled with sepiolite and granular activated carbon (GAC) were used with short cycle aeration (25/15 and 15/15 min) and different hydraulic retention times (4.9 and 7.4 h). At the end of each operational condition, attached and suspended fractions of biomass from both FBRs were collected for activity bioassays. Specific nitrification bioassays suggested that nitrification performance (53–100% for sepiolite FBR and 72–93% for GAC FBR) was associated with the limit of the nitrifiers' potential when the environmental conditions were favorable. On the other hand, low denitrification efficiencies observed in the FBRs (25–44% for sepiolite FBR and 22–65% for GAC FBR) occurred due to low electron availability ...
This study proposes a new approach to selecting a biofilm carrier for immobilization using dissol... more This study proposes a new approach to selecting a biofilm carrier for immobilization using dissolved oxygen (DO) microsensors to measure the thickness of aerobic and anaerobic layers in biofilm. The biofilm carriers tested were polyurethane foam, mineral coal (MC), basaltic gravel, and low-density polyethylene. Development of layers in the biofilm carrier surface was evaluated using a flow cell device, and DO profiles were conducted to determine the size of the layers (aerobic and anaerobic). MC was the biofilm carrier selected due to allowing the development of larger aerobic and anaerobic layers in the biofilm (896 and 1,058 μm, respectively). This ability is supposed to improve simultaneous nitrogen removal by nitrification and denitrification biological processes. Thus, as a biofilm carrier, MC was used in a fixed-bed sequencing batch biofilm reactor (FB-SBBR) for treatment of wastewater with a high ammonia concentration (100–400 mgNH4+-N L−1). The FB-SBBR (15.0 L) was filled wi...
Real textile wastewater containing high salinity (up to 12.6 g·kg−1) and surfactant (up to 5.9 mg... more Real textile wastewater containing high salinity (up to 12.6 g·kg−1) and surfactant (up to 5.9 mg·L−1 of linear alkylbenzene sulfonate – LAS) was submitted to biological treatment for colour (up to 652 mg Pt-Co·L−1) and sulphate (up to 1,568.6 mg SO4−2·L−1) removal. The influence of ethanol and molasses supplementation was firstly evaluated in anaerobic batch reactors for the removal of dyes and sulphate. Subsequently, aiming to remove aromatic amines (dye degradation by-products), an anaerobic–aerobic continuous system supplemented with molasses was applied. Supplementation had no influence on colour removal (maximum efficiencies around 70%), while it improved sulphate reduction (23% without supplementation against 87% with supplementation), and conferred robustness to the reactors, which recovered quickly after higher salinity impact. The aerobic reactor removed aromatic amines when the level of surfactants was lower than 1.0 mg LAS·L−1, but the performance of the system was hinde...
The use of anaerobic reactors for domestic sewage treatment has increased significantly since the... more The use of anaerobic reactors for domestic sewage treatment has increased significantly since the UASB configuration started to be efficiently applied for this purpose in the beginning of the 1980s. Nowadays, hundreds of UASB reactors, or similar anaerobic units, are used in domestic sewage treatment systems, particularly in developing countries. These units have been operated at ambient temperature, normally higher than 20°C, at hydraulic detention time in the range of 6 to 10 hours, and organic loading rates lower than 3.0 kg COD.m−3.d−1. They have presented COD removal efficiencies in the range of 65% to 80%. Besides, new configurations have been developed and assayed in research centres, aiming to amplify the range of application and to improve process performance. At the same time, research is being conducted on the post-treatment of anaerobic effluents attempting to offer alternatives to the existing conventional systems. It takes into consideration not only sanitation and env...
Two anaerobic fixed-structured bed reactors were fed with synthetic wastewater simulating the sol... more Two anaerobic fixed-structured bed reactors were fed with synthetic wastewater simulating the soluble fraction of sugarcane vinasse to evaluate the interference of sulfidogenesis on methanogenesis. The reactors running in parallel were subjected to the same operating conditions. The influent organic matter concentration (in term of chemical oxygen demand (COD)) remained close to 4,000 mgCOD L−1 and the hydraulic retention time was 24 hours. One reactor, the methanogenic (control reactor), received sulfate only to provide the sulfur required as a nutrient to the methanogenic biomass. The other one, the sulfidogenic/methanogenic reactor (SMR), received sulfate concentration corresponding to COD/sulfate ratios of 4, 5 and 3. In the last phase, the COD removal efficiencies were higher than 96% in both reactors and the SMR achieved 97% of sulfate removal efficiency (COD/sulfate ratio of 3 and influent sulfate concentration close to 1,300 mgSO42− L−1). Both reactors also had similar metha...
This paper presents and discusses the potential for use of pilot-scale anaerobic sequencing batch... more This paper presents and discusses the potential for use of pilot-scale anaerobic sequencing batch biofilm reactors (ASBBR) for the treatment of industrial wastewater containing high sulfate concentration. The pilot-scale ASBBR reactor (total volume=1.2 m3) containing biomass immobilized in inert support (mineral coal) was operated at sulfate loading rates varying from 0.15 to 1.90 kgSO4-2/cycle (cycle of 48h) corresponding to sulfate concentrations of 0.25 to 3.0 gSO4-2.L-1. Domestic sewage and ethanol were utilized as electron donors for sulfate reduction. The mean sulfate removal efficiencies remained in the range of 88 to 92% in the several sulfate concentrations obtained from 92 operational cycles. As post-treatment unit for the generated effluents by the sulfate reduction was used another reactor ASBBR in pilot-scale (total volume=385,0 L) with same inert support for biomass immobilization and different granulometry. The mean COD removal (mean influent=1450 mg.L-1) achieved 88%...
This study aimed to verify the occurrence of environmental and microbial conditions of a support ... more This study aimed to verify the occurrence of environmental and microbial conditions of a support medium applied in a structured-bed reactor for a high-protein content wastewater treatment. An up-flow structured-bed reactor submitted to recirculation and intermittent aeration (SBRRIA) was operated with an hydraulic retention time (HRT) of 11.2±0.6 h and continuous feeding. COD (chemical oxygen demand) removal efficiencies remained above 90% in all experimental conditions. In conditions with a reduced COD/N ratio, NH 4 +-N oxidized efficiencies were greater than 90%, resulting in total-N removal efficiency of 81.5±5.3%. Biomass samples were submitted to tests with dissolved oxygen (DO) microsensors and scanning electron microscope (SEM) for biofilm characterization. The stratification in aerobic and anoxic zones enabled the establishment of different nitrogen degradation pathways, through the development of specific microrganisms such as cocci clusters Nitrosococcus-like organism and ...
Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic d... more Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic denitrification, and may have potential for nitrogen removal of low-strength wastewaters, such as anaerobically pre-treated domestic sewage. This study evaluated the fundamentals and kinetics of this process in batch reactors containing suspended and immobilized cells. Batch tests were performed for different NOx−/S2− ratios and using nitrate and nitrite as electron acceptors. Autotrophic denitrification was observed for both electron acceptors, and NOx−/S2− ratios defined whether sulfide oxidation was complete or not. Kinetic parameter values obtained for nitrate were higher than for nitrite as electron acceptor. Zero-order models were better adjusted to profiles obtained for suspended cell reactors, whereas first-order models were more adequate for immobilized cell reactors. However, in the latter, mass transfer physical phenomena had a significant effect on kinetics based on biochemica...
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Papers by Eugenio Foresti