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1.
Water Sci Technol ; 80(3): 418-425, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596253

RESUMO

There are hundreds of full-scale upflow anaerobic sludge blanket (UASB) reactors in operation in various parts of the tropical world, notably in India and Latin America, Brazil being the holder of the largest park of anaerobic reactors for sewage treatment in the world. Despite the recognized advantages of UASB reactors, there are problems that have prevented their maximum operational performance. Neglecting the existence and delaying the solution of these challenges can jeopardize the important advances made to date, impacting the future of anaerobic technology in Brazil and in other countries. This work aims to evaluate the operational performance of five full-scale UASB reactors in Brazil, taking into account a monitoring period ranging between two and six years. The main observed design, construction, and operational constraints are discussed. Some outlooks for important upcoming developments are also provided, considering that most of the observed drawbacks can be tackled without significant increases on reactor costs.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Anaerobiose , Reatores Biológicos , Brasil , Índia
2.
Water Sci Technol ; 80(3): 487-498, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596260

RESUMO

Methylparaben and triclosan are antimicrobial agents widely used as preservatives in a variety of personal care and pharmaceutical products. Wastewater is considered the main source of these compounds in the environment. Expanded granular sludge bed (EGSB) reactors are a high rate technology for wastewater treatment based on biological processes and have been shown to be efficient in removing different types of compounds; however, little is known about the effect of contaminants such as methylparaben and triclosan on their behavior and effectiveness. In this study, we evaluate and compare the microbial and physicochemical behavior of EGSB systems during methylparaben and triclosan removal. The presence of different concentrations of pollutants had an influence on the cluster organization of microbial communities, especially bacteria. However, this did not affect the stability and performance of the EGSB systems. The banding patterns of the denaturing gradient gel electrophoresis of archaea demonstrated the constant presence and abundance of Methanosaeta concilii throughout all stages of operation, showing that this microorganism played a fundamental role in the stability of the reactors for the production of methane. The type of compound and its concentration influenced the expression of the mcrA and ACAs genes; however, these changes did not alter the stability and performance of the EGSB systems.


Assuntos
Parabenos/análise , Triclosan/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Reatores Biológicos , Esgotos
3.
Water Sci Technol ; 80(4): 634-643, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31661442

RESUMO

The effects of nitrite and nitrate on the integration of ammonium oxidization and sulfate reduction were investigated in a self-designed reactor with an effective volume of 5 L. An experimental study indicated that the ammonium oxidization and sulfate reduction efficiencies were increased in the presence of nitrite and nitrate. Studies showed that a decreasing proportion of N/S in the presence of NO2- at 30 mg·L-1 would lead to high removal efficiencies of NH4+-N and SO42--S of up to 78.13% and 46.72%, respectively. On the other hand, NO3- was produced at approximately 26.89 mg·L-1. Proteobacteria, Chloroflexi, Bacteroidetes, Chlorobi, Acidobacteria, Planctomycetes and Nitrospirae were detected in the anaerobic cycle growth reactor. Proteobacteria was identified as the dominant functional bacteria removing nitrogen in the reactor. The nitritation reaction could promote the sulfate-reducing ammonium oxidation (SRAO) process. NH4+ was converted to NO2 and other intermediates, for which the electron acceptor was SO42-. These results showed that nitrogen was converted by the nitrification process, the denitrification process, and the traditional anammox process simultaneously with the SRAO process. The sulfur-based autotrophic denitration and denitrification in the reactor were caused by the influent nitrite and nitrate.


Assuntos
Compostos de Amônio , Nitritos , Reatores Biológicos , Nitratos , Nitrogênio , Oxirredução , Sulfatos
4.
Water Sci Technol ; 80(4): 737-746, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31661453

RESUMO

Studies on laboratory-scale submerged aerobic fixed film reactor (SAFF) packed with synthetic media having specific surface area of 165 m2/m3 with a void volume of 89% were carried out to assess its performance under various organic loading rates (OLR) and hydraulic retention times (HRT). Synthetic wastewater having chemical oxygen demand (COD) and biochemical oxygen demand (BOD) of 400 ± 10% and 210 ± 10% mg/L respectively was fed and the reactor was subjected to OLRs ranging from 0.37 to 1.26 kg COD/m3.d. It was observed that steady sloughing of biofilm occurs within the SAFF reactor all the times and average concentration of sloughed biomass in the effluent was 26 mg/L. The COD and BOD removal efficiencies varied between 85 and 89% and 86 to 94%, respectively. The kinetic studies demonstrated that SAFF reactor followed Stover-Kincannon and Grau models, with high correlation coefficients (R2) of 0.9977 and 0.9916, respectively. Thus, the values of kinetic coefficients such as maximum substrate utilization rate, Umax = 64.1 g/(L.d); saturation value constant, KB = 72.31 g/(L.d) and Grau second-order substrate removal rate constant, Ks = 2.44 day-1 can be useful to develop and design large scale SAFF reactors. Finally, the study reveals that the optimum range for OLR can vary within 0.68-0.94 kg COD/m3.d.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Cinética
5.
Water Sci Technol ; 80(4): 762-772, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31661455

RESUMO

A comprehensive OPEX analysis for both municipal and industrial wastewaters has been conducted encompassing energy, critical component (membrane) replacement, chemicals consumption, waste disposal and labour. The analysis was preceded by a review of recent data on industrial effluent treatability with reference to published chemical oxygen demand (COD) removal data for four effluent types: food and beverage, textile, petroleum and landfill leachate. Outcomes revealed labour costs to be the most significant of those considered, contributing 50% of the OPEX for a 10,000 m3/day capacity municipal wastewater treatment works. An analysis of the OPEX sensitivity to 12 individual parameters (labour cost, flux, electrical energy cost, membrane life, feed COD, membrane cost, membrane air-scour rate, chemicals cost, waste disposal cost, mixed liquor suspended solids (MLSS) concentration, recirculation ratio, and transmembrane pressure) revealed OPEX to be most sensitive to labour effort and/or costs for all scenarios considered other than a large (100,000 m3/day capacity) works, for which flux and electrical energy costs were found to be slightly more influential. It was concluded that for small- to medium-sized plants cost savings are best made through improving the robustness of plants to limit manual intervention necessitated by unforeseen events, such as electrical/mechanical failure, foaming or sludging.


Assuntos
Eliminação de Resíduos Líquidos , Poluentes Químicos da Água , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Custos e Análise de Custo , Resíduos Industriais , Águas Residuárias
6.
Water Sci Technol ; 80(4): 794-805, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31661458

RESUMO

The removal of polycyclic aromatic hydrocarbons (PAHs) in activated sludge was evaluated using two laboratory-scale bioreactors, coupled or not with a disintegration system (sonication). Mass balances performed on each system underlined that PAHs removal was significantly improved after sludge disintegration, especially for the higher molecular weight PAHs studied, which tended to adsorb to suspended matter. A model was developed in order to study the effect of sludge disintegration on the content of dissolved and colloidal matter (DCM), and to predict the potential impacts on PAHs availability and degradation. Results showed that this new model was efficient for capturing apparent degradation improvement trends and for discriminating between the involved mechanisms. This study showed that DCM content increased after sludge disintegration, and proved to be the main driver for improving PAHs apparent degradation.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Esgotos , Reatores Biológicos
7.
Sheng Wu Gong Cheng Xue Bao ; 35(9): 1607-1618, 2019 Sep 25.
Artigo em Chinês | MEDLINE | ID: mdl-31559743

RESUMO

With the rapid development of modern biotechnology, fermentation process is increasingly important in industrial production. To guarantee the stability of products, fermentation process should be elaborately monitored and controlled. Biomass is an important parameter for on-line monitoring in bioprocesses because biomass can reflect cell growth in a bioreactor directly. In-situ microscope, a non-invasive and image-analysis based technology, can real-time monitor cells in biological process. This review summarizes the development and application of in-situ microscopy in biomass monitoring.


Assuntos
Biomassa , Microscopia , Reatores Biológicos , Biotecnologia , Fermentação
8.
Water Environ Res ; 91(10): 1205-1209, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31517427

RESUMO

This section presents a review of the scientific literature published in 2018 on topics relating to distributed treatment systems. This review is divided into the following sections: constituent removal, treatment technologies, planning and treatment management, and other topics.


Assuntos
Reatores Biológicos , Eliminação de Resíduos Líquidos
9.
Water Environ Res ; 91(10): 1253-1271, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31529649

RESUMO

Worldwide waste generation has become a topic of interest since the accumulation of this waste has prompted environmental hazards. Among which, anaerobic digestion provides green and efficient alternate solution for removal of toxic waste and energy production. Therefore, this review emphasizes on the recent data published in 2018 on topics related to anaerobic process, enhancement of biogas production, and fermentation efficiency. Furthermore, more focus was made on the factors influencing anaerobic digestion and the effect of trace elements as ionic salts as well as nanoparticles on overall biogas production, respectively. PRACTITIONER POINTS: Anaerobic digestion provide green and efficient alternate solution to deal with. This review focused on the conditions related to anaerobic process to improve biogas production and fermentation efficiency. The trace elements were focused on how to influence biogas production during anaerobic digestion.


Assuntos
Reatores Biológicos , Oligoelementos , Anaerobiose , Biocombustíveis , Fermentação
10.
Water Sci Technol ; 80(2): 223-231, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537758

RESUMO

In this study, we use an anaerobic-aerobic integrated denitrification (Fe/C-ZACID) device with an iron-carbon-activated carbon and zeolite composite filter to remove nitrogen from simulated low carbon-nitrogen ratio (C/N) sewage. The impacts of dissolved oxygen (DO) level, hydraulic retention time (HRT), C/N and nitrate recirculation ratio on denitrification performance were studied. The results show that when HRT was 6 h, DO was 3 ± 0.1 mg/L, influent C/N was 3, and nitrate recirculation ratio was 100%, and removal rates of 95% for ammonia and 85% for total nitrogen (TN) were achieved. A beaker comparison test demonstrated that this synergistic denitrification system included heterotrophic denitrification, physicochemical denitrification, iron autotrophic denitrification and hydrogen autotrophic denitrification, etc. The Fe/C-ZACID device has a high-efficiency nitrogen removal effect for low C/N ratio sewage and strong shock resistance, which provides technical support and a theoretical basis for advanced denitrification of rural domestic sewage.


Assuntos
Desnitrificação , Eliminação de Resíduos Líquidos/métodos , Zeolitas , Anaerobiose , Reatores Biológicos , Carvão Vegetal , Filtração , Ferro , Nitrogênio , Esgotos
11.
Water Sci Technol ; 80(2): 232-242, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537759

RESUMO

Continuously flushing moving bed sand filter was operated in pilot scale for phosphorus (P) and nitrogen removal with simultaneous particle removal. The wastewater tested was either final effluent from a municipal wastewater treatment plant (WWTP) with nitrogen removal in moving bed biofilm reactors (MBBRs) followed by coagulation and dissolved air flotation (DAF) for P and suspended solids (SS) removal, or different mixtures of this final effluent and effluent from the MBBR-stage. The study focused on the applicability to achieve low total phosphorus (TP) concentrations (below 0.1 mg/L) and suspended solids concentrations (below 10 mg SS/L), plus good denitrification (removal rate over 750 g NO3-N/m3-d), by treating wastewater having variable concentrations of TP (from 0.19 to 7.3 mg/L), SS (from 3 to 169 mg/L) and total nitrogen (from 8 to 27 mg/L). The target effluent TP limit was easily achieved when adding coagulant to WWTP effluent. With correct coagulant dose (Al/TP-molar ratio >4) and good particle removal the target effluent TP could also be reached when treating mixed WW with fairly high influent TP. Very high denitrification rates were achieved with adequate influent P concentration and external carbon source. Low denitrification rates were observed when limited by low concentrations of biodegradable carbon and phosphorus.


Assuntos
Desnitrificação , Fósforo , Eliminação de Resíduos Líquidos , Biofilmes , Reatores Biológicos , Nitrogênio
12.
Water Sci Technol ; 80(2): 317-328, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537768

RESUMO

Online monitoring of water quality parameters can provide better control over various operations in wastewater treatment plants. However, a lack of physical online sensors, the high price of the available online water-quality analyzers, and the need for regular maintenance and calibration prevent frequent use of online monitoring. Soft-sensors are viable alternatives, with advantages in terms of price and flexibility in operation. As an example, this work presents the development, tuning, implementation, and validation of an Extended Kalman Filter (EKF) on a grey-box model to estimate the concentration of volatile fatty acids (VFA), soluble phosphates (PO4-P), ammonia nitrogen (NH4-N) and nitrate nitrogen (NO3-N) using simple and inexpensive sensors such as pH and dissolved oxygen (DO). The EKF is implemented in a sequential batch moving bed biofilm reactor (MBBR) pilot scale unit used for biological phosphorus removal from municipal wastewater. The grey-box model, used for soft sensing, was constructed by fitting the kinetic data from the pilot plant to a reduced order version of ASM2d model. The EKF is successfully validated against the standard laboratory measurements, which confirms its ability to estimate various states during the continuous operation of the pilot plant.


Assuntos
Biofilmes , Reatores Biológicos , Eliminação de Resíduos Líquidos , Nitrogênio , Nutrientes , Águas Residuárias
13.
Water Sci Technol ; 80(2): 339-346, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537770

RESUMO

In this work, the integration of dynamic bioenergetic calculations in the IWA Anaerobic Digestion Model No. 1 (ADM1) is presented. The impact of bioenergetics on kinetics was addressed via two different approaches: a thermodynamic-based inhibition function and variable microbial growth yields based on dynamic Gibbs free energy calculations. The dynamic bioenergetic calculations indicate that the standard ADM1 predicts positive reaction rates under thermodynamically unfeasible conditions. The dissolved hydrogen inhibition approach used in ADM1 is, however, deemed as adequate, offering the trade-off of not requiring dynamic bioenergetics computation despite the need of hydrogen inhibition parameters. Simulations of the model with bioenergetics showed the low amount of energy available in butyrate and propionate oxidation, suggesting that microbial growth on these substrates must be very limited or occur via alternative mechanisms rather than dissolved hydrogen.


Assuntos
Anaerobiose , Modelos Teóricos , Reatores Biológicos , Hidrogênio , Cinética , Termodinâmica
14.
Water Sci Technol ; 80(2): 357-364, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537772

RESUMO

It is widely assumed that non-aerated selectors are very efficient in nutrient removal, and especially anaerobic basins may largely contribute to good sludge settleability as well. However, based on results measured in full-scale, this paper draws attention to the fact that with decreasing availability of readily biodegradable carbon source (rbCOD) being experienced worldwide, oxygen penetration into non-aerated basins through the uncovered surface may no longer be considered negligible. When the oxygen mass transfer is significant compared to the available influent rbCOD, non-aerated selectors should be regarded as basins with low dissolved oxygen (low DO) concentrations that may underperform with respect to nutrient removal and favor the growth of filaments, especially during low-loaded conditions. In order to fully exclude oxygen penetration, floating seals have been developed and applied at the North-Budapest Wastewater Treatment Plant in Hungary. Comparative full-scale studies showed prevention of significant amounts of influent rbCOD loss (up to 60 mg/L) through the application of this new technology. This amount of saved, non-oxidised but fermented carbon source could be accordingly used for enhancing biological P-removal. Due to the elimination of microaerophilic conditions, the undesirable growth of filamentous bacteria could also be avoided, leading to significantly better activated sludge settling.


Assuntos
Oxigênio , Eliminação de Resíduos Líquidos , Reatores Biológicos , Hungria , Esgotos
15.
Water Sci Technol ; 80(2): 387-396, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537775

RESUMO

Anaerobic mono-digestion and co-digestion are nowadays widely used in wastewater treatment plants (WWTP). However, the data processing of the conventional biochemical potential test (BMP) carried out to assess potential substrates should be enhanced to reduce the uncertainty of the results. In this study, two methodologies aiming to improve the data processing in anaerobic digestion studies were proposed. The methodologies aimed at the estimation of synergy in anaerobic co-digestion of organic waste and the standardization of the BMP test results by considering the activity of the inoculums under mono-digestion conditions. Both methodologies comprise the application of the Gompertz equation. For the first methodology, four cosubstrates and two types of substrates were used. Regarding synergy estimation, the cosubstrates dairy whey and grease sludge had an impact on the degradation kinetic. In regard to the second methodology, the results indicate that the activity of the inoculums exerts an influence on the BMP analysis, and it should be considered. This can be meaningful when comparing results among studies when different inoculums are used or even for studies where the same inoculum is used but it is taken at different reactor operational moments.


Assuntos
Reatores Biológicos , Eliminação de Resíduos Líquidos , Anaerobiose , Biocombustíveis , Esgotos , Águas Residuárias
16.
Bioresour Technol ; 293: 122051, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31472405

RESUMO

In this work, a 30-days batched mesophilic assay on pretreated food waste (PFW) under different inoculum/substrate (I/S) ratios (1:5, 1:2, 1:1, 2:1, 4:1 and 1:0) was carried out, to target the most important parameters in AD matrix on regulating iron (Fe) chemical speciation. Correlation coefficients were calculated within four Fe chemical forms and AD parameters of pH, volatile fatty acids (VFAs), inorganic acid radicals (IARs), and alkalinity. Results showed that IARs were not key factors on regulating Fe speciation. Without acidification, IARs showed weak correlations (coefficients < 0.40) with Fe chemical dynamics while other parameters showed stronger correlations (coefficients ≥ 0.60). Under acidification, VFAs initiated the conversion of exchangeable Fe into water soluble fraction. Residual fraction might play important role in regulating Fe shifting to more bioavailable states.


Assuntos
Ácidos Graxos Voláteis , Ferro , Anaerobiose , Reatores Biológicos , Alimentos
17.
Bioresour Technol ; 293: 122033, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31472408

RESUMO

This study focused on continuous-flow hydrogen production by Thermotoga neapolitana at a hydraulic retention time (HRT) decreasing from 24 to 5 h. At each HRT reduction, the hydrogen yield (HY) immediately dropped, but recovered during prolonged cultivation at constant HRT. The final HY in each operating period decreased from 3.4 (±0.1) to 2.0 (±0.0) mol H2/mol glucose when reducing the HRT from 24 to 7 h. Simultaneously, the hydrogen production rate (HPR) and the liquid phase hydrogen concentration (H2aq) increased from 82 (±1) to 192 (±4) mL/L/h and from 9.1 (±0.3) to 15.6 (±0.7) mL/L, respectively. Additionally, the effluent glucose concentration increased from 2.1 (±0.1) to above 10 mM. Recirculating H2-rich biogas prevented the supersaturation of H2aq reaching a value of 9.3 (±0.7) mL/L, resulting in complete glucose consumption and the highest HPR of 277 mL/L/h at an HRT of 5 h.


Assuntos
Thermotoga neapolitana , Archaea , Reatores Biológicos , Fermentação , Glucose , Hidrogênio
18.
Bioresour Technol ; 293: 122042, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31473374

RESUMO

In excess sludge digestion, organic matters cannot be digested adequately due to its high lignocellulose content. This study attempted to comprehensively evaluate the digestive performances of sludge with different lignocellulosic components (hemicellulose, cellulose and lignin). Results show that hemicellulose/dealkaline lignin addition (S6) presents the highest methane yield of 203.6 mL/gVS. Compared to hemicellulose, dealkaline lignin is hardly degraded (lower than 10%), while its participation can promote the degradation of other organics in the system. Additionally, solo cellulose feedstock is difficult to be hydrolyzed (only 40.1%) without hemicellulose and dealkaline lignin addition. VFAs composition analysis indicates that VFA inhibition occurs in the digester with hemicellulose, cellulose and dealkaline lignin addition (S8). Microbial diversities of different digestive systems show that the relative abundance of Euryarchaeota in the digester S6 (7.2%) is much higher than others, and some specific microbes (Bacteroidetas and Firmicutes) are enriched in the S5 (74.1%) and S8 (54.7%) digesters.


Assuntos
Reatores Biológicos , Esgotos , Anaerobiose , Lignina , Metano
19.
Bioresour Technol ; 293: 122039, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31476562

RESUMO

An anaerobic ammonium oxidation-upflow anaerobic sludge blanket (anammox-UASB) reactor was operated without temperature control during the four seasons and was therefore subjected to natural periodic temperature variations between 9 and 28 ℃. The anammox reactor had a high nitrogen removal ability at intermediate and low temperatures. The total nitrogen (TN) concentration of the influent increased from 200 to 1200 mg/L, the nitrogen removal efficiency was maintained at 90%, and the nitrogen removal rate (NRR) increased to 9.15 ±â€¯0.35 kg N/m3/d. The enrichment of anammox bacteria in the UASB granular sludge reached 53.8%, and the dominant bacteria changed from Candidatus Brocadia to Candidatus Kuenenia after several seasons of cultivation. Dynamics analysis revealed that the maximum reaction rate of the anammox-UASB sludge was 62.5 kg N/m3/d, reflecting the high potential nitrogen removal ability of the reactor.


Assuntos
Compostos de Amônio , Esgotos , Anaerobiose , Reatores Biológicos , Nitrogênio , Oxirredução , Temperatura Ambiente
20.
Bioresour Technol ; 293: 122006, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31476564

RESUMO

The rapid growth of nitrite-oxidizing bacteria (NOB) in reactor prevents the application of anaerobic ammonium oxidation (anammox) technology to main-stream wastewater treatment. How to eliminate NOB and reserve anaerobic ammonium oxidation bacteria (AnAOB) simultaneously becomes the biggest challenge. In this study two coupled biological aeration filters (BAFs) were built up to treat domestic sewage. In BAF1 nitrogen removal concentration was 21.4 mg/L via heterotrophic denitrification pathway. Backwash was conducted to BAF2 to improve nitrogen removal performance. After backwash Nitrospira proportion declined from 10.8% to 2.1%, while Candidatus Kuenenia percentage increased from 5.6% to 10.2%. Nitrogen removal concentration improved from 8.6 mg/L to 22.8 mg/L via anammox pathway in BAF2, and total nitrogen removal concentration reached to 44.2 mg/L in two coupled BAFs during aeration process. These findings could provide a new strategy for the application of anammox technology to main-stream wastewater treatment.


Assuntos
Microbiota , Nitrogênio , Reatores Biológicos , Desnitrificação , Esgotos
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