Influence of the applied organic load (OLR) on textile wastewater treatment using submerged anaerobic membrane bioreactors (SAMBR) in the presence of redox mediator and powdered activated carbon (PAC).

This paper evaluated the treatment of textile wastewater in submerged anaerobic membrane bioreactors (SAMBR) operated on a bench scale. Particularly, the influence of operational conditions, such as the applied organic rate (OLR) and the dilution factor (for toxicity attenuation) of the textile wastewater, was evaluated on color and organic matter removal. In addition, the effect of powdered activated carbon (PAC) on SAMBR-1 and the addition of yeast extract (source of the redox mediator riboflavin) were also investigated. The results showed that reducing the textile wastewater dilution factor from 10? (phase 1) to 4? (phase 2) and 0? (no dilution) decreased the COD and color removal efficiencies in both SAMBRs, probably due to an increase in the toxic load. Nevertheless, PAC adsorbed toxic compounds found in the textile wastewater and helped biomass acclimatization, which led to higher COD and color removal efficiencies in SAMBR-1. The presence of yeast extract enhanced color removal efficiencies 3-fold in both SAMBRs when they were fed with undiluted textile wastewater

Anaerobic digestion of hemicellulose hydrolysate produced after hydrothermal pretreatment of sugarcane bagasse in UASB reactor.

In the context of a sugarcane biorefinery, sugarcane bagasse produced may be pretreated generating a solid and liquid fraction. The solid fractionmay be used for 2G bioethanol production,while the liquid fraction may be used to produce biogas through anaerobic digestion. The aimof this study consisted in evaluating the anaerobic digestion performance of hemicellulose hydrolysate produced after hydrothermal pretreatment of sugarcane bagasse. For this, hydrothermal pretreatmentwas assessed in a continuous upflowanaerobic sludge blanket (UASB) reactor operated at a hydraulic retention time (HRT) of 18.4 h. Process performance was investigated by varying the dilution of sugarcane bagasse hydrolysate with a solution containing xylose and the inlet organic loading rate (OLR). Experimental data showed that an increase in the proportion of hydrolysate in the feed resulted in better process performance for steps using 50% and 100% of real substrate. The best performance condition was achieved when increasing the organic loading rate (OLR) from 1.2 to 2.4 g COD/L?d, with an organic matter removal of 85.7%. During this period, the methane yield estimated by the COD removal would be 270 L CH4/kg COD.Nonetheless,when further increasing the OLR to 4.8 g COD/L?d, the CODremoval decreased to 74%, together with an increase in effluent concentrations of VFA (0.80 g COD/L) and furans (115.3 mg/L), which might have inhibited the process performance. On the whole, the results showed that anaerobic digestion of sugarcane bagasse hydrolysate was feasible and may improve the net energy generation in a bioethanol plant, while enabling utilization of the surplus sugarcane bagasse in a sustainable manner

Pharmaceuticals oxidation by chlorine and byproducts formation in aqueous matrices in bench scale.

F?rmacos e desreguladores end?crinos s?o encontrados em ?guas naturais brasileiras, incluindo alguns mananciais de abastecimento, tamb?m em fun??o da baixa cobertura de coleta e tratamento de esgotos no Brasil. Nesse cen?rio, o presente trabalho intentou avaliar a remo??o de tr?s f?rmacos - sulfametoxazol (SMX), diclofenaco (DCF) e 17?-estradiol (E2) - em ?gua destilada por meio da oxida??o com cloro (hipoclorito de s?dio), variando-se a dose de cloro e o tempo de contato em ensaios de batelada. As solu??es cloradas foram analisadas, ainda, por cromatografia acoplada ? espectrometria de massas para identifica??o de eventuais subprodutos de oxida??o. Para tempo de contato de 10 min e dose de cloro de 1,5 mg.L-1, foi observada remo??o m?dia de 61% para DCF, 36% para E2 e 33% para SMX. Apenas para o DCF verificou-se diferen?a estatisticamente significativa (?=0,05) para dose de cloro de 3,0 mg.L-1. A oxida??o seguiu modelo cin?tico de pseudossegunda ordem, com valores de k2 de 0,0168 L.?g.min-1 para SMX (para ambas doses testadas), de 0,0133 e 0,0798 L.?g.min-1 para DCF, e de 0,0326 e 0,0289 L.?g.min-1 para E2, para doses de cloro de 1,5 e 3,0 mg.L-1, respectivamente. Por fim, verificou-se que o aumento do tempo de contato favoreceu a oxida??o dos f?rmacos, ainda que com a perspectiva de forma??o de subprodutos para SMX e E2.Pharmaceuticals and endocrine disrupting compounds are found in Brazilian natural waters, including some water sources for public supply, also due to the low coverage of sewage collection and treatment in Brazil. This study investigated the removal of three pharmaceutical compounds - sulfamethoxazole (SMX), diclofenac (DCF) and 17?-estradiol (E2) - from aqueous solutions by means of chlorine oxidation (sodium hypochlorite) by varying the dose of chlorine and contact time in batch tests. The chlorine solutions were examined by chromatography attached to the mass spectrometry in order to identify the oxidation by-products. For 10 min contact time, mean removal values of 61% were observed for DCF; 36% for E2; and 33% for SMX, when the chlorine dose was 1.5 mg L-1. Just for DCF there was a statistically significant difference (?=0.05) in the removal efficiency when increasing the chlorine dose to 3.0 mg.L-1. The oxidation followed the kinetic model of pseudo-second order, with k2 values of 0.0168 L.?g.min-1 for SMX (at both chlorine doses tested); 0.0133 and 0.0798 L.?g.min-1 to DCF; and 0.0326 and 0.0289 L.?g.min-1 to the E2 at chlorine doses of 1.5 and 3.0 mg L-1, respectively. Finally, it was verified that an increase of the contact time favored the oxidation of all pharmaceuticals tested, although with the perspective of by-products formation for SMX and E2

Use of aqueous two-phase PEG-salt systems for the removal of anionic surfactant from effluents.

Linear alkylbenzene sulfonates (LAS) are synthetic anionic surfactants that are extensively used in many industries. As a result, large volumes of effluents containing high levels of these compounds are discharged into water bodies, causing risks to aquatic flora and fauna. Then, there is a need for environmentally safe and economically viable technologies for the removal of LAS from aqueous matrices. The present work evaluates the use of aqueous two-phase systems (ATPS) composed of PEG and sulfate salts for this purpose, considering the effects of tie line length (TLL), molar mass of polymer, and type of cation-forming salt on the partitioning behavior of LAS. All the LAS partition coefficient (KLAS) values were greater than unity, and the LAS extraction efficiencies (%ELAS) were higher than 97%. The system consisting of PEG 1500 ? (NH4)2SO4 ? H2O provided the highest KLAS (1083.34) and %ELAS (99.9%), indicating that the method provided good extraction of LAS to the top phase. This system was applied using a real effluent sample in laboratory-scale experiments as well as in bench-scale batch trials. The results obtained at the laboratory scale showed %ELAS values greater than 98%, while the best KLAS value obtained in the batch experiments was 8.50 (?1.75) (%ELAS ? 78.17%). These values demonstrated the potential of ATPS for the removal of LAS from industrial effluents

Tratamento de efluentes de indústria têxtil utilizando Reatores Anaeróbios de Membranas Submersas (SAMBR) com e sem carvão ativado em pó (CAP).

O principal objetivo deste estudo foi investigar o uso de um biorreator anaeróbio de membrana submersa (SAMBR) na presença e ausência de carvão ativado em pó (CAP) em seu interior para o tratamento de efluente sintético contendo azo corante modelo e efluente têxtil real. Além disso, o projeto comparou o desempenho dos reatores SAMBR com um reator anaeróbio de manta de lodo (UASB) convencional, de forma a determinar os principais parâmetros do processo, a capacidade do uso do extrato de levedura como mediador redox, e avaliar se uso do CAP diminuía o acúmulo de metabólitos formados (aminas aromáticas e ácidos graxos voláteis) e a colmatação da membrana. Os reatores foram operados (T = 35 oC e TDH = 24h) em 4 fases operacionais, tendo a fase 1 como etapa de adaptação, fases 2 e 3 de operação dos reatores com efluente sintético, na ausência e presença de extrato de levedura, respectivamente, e a fase 4 de alimentação dos reatores com efluente têxtil real. Os principais resultados da pesquisa podem ser sistematizados como a seguir: i) O SAMBR exibiu um excelente desempenho na remoção de matéria orgânica (DQO), cor, turbidez e ácidos graxos voláteis (AGV), quando operado com efluente sintético e efluente têxtil real; ii) A presença do CAP no interior do SAMBR-1 contribuiu para uma melhor estabilidade do reator, diminuindo a concentração de AGV, favorecendo a adaptação dos micro-organismos aos subprodutos tóxicos obtidos a partir da degradação anaeróbia dos azo corante (ex aminas aromáticas) e reduzindo o efeito de colmatação nas membranas; iii) O uso do extrato de levedura mostrou-se capaz de acelerar a cinética de degradação dos azo corantes, contribuindo para uma melhora na eficiência de remoção de cor do sistema. O elevado desempenho na eficiência de remoção de DQO (91%) e cor (94%) apresentado pelo reator SAMBR operado na presença de CAP e extrato de levedura durante a fase com efluente têxtil real, indica que o acoplamento de membranas de microfiltração com CAP e possíveis fontes de mediador redox leva a produção de um efluente de alta qualidade, o qual pode ser reaproveitado no setor têxtil. Dessa forma a análise integrada dos resultados gerados por esta pesquisa contribui de forma relevante para o avanço do conhecimento nas áreas de degradação anaeróbia de azo corantes e uso de biorreatores anaeróbios de membrana submersa (SAMBR) no tratamento de efluentes de indústria têxtil.The main objective of this research was of evaluate the use of a Submerged Anaerobic Membrane Bioreactor (SAMBR) in the presence and absence of Powdered Activeted Carbon (PAC) for the treatment of synthetic effluent containing model azo dye and genuine textile wastewater. The work compared the performance between two SAMBR and Upflow Anaerobic Sludge Blanket (UASB). This study also evaluated the main parameters of the process and the capacity of the yeast extract to act as redox mediator and the influence of the PAC in the adsorption of by-products (eg. aromatics amines and Volatile Fatty Acids (VFA) ) and substance that cause fouling in the membrane. The reactors were operated at 35°C with an HRT of 24 h during four operational phases. The phase 1 was a stage of adaptation of the biomass. In the phases 2 and 3 the reactors were fed with synthetic effluent in the presence and absence of yeast extract respectively, while that in the phase 4 were fed with genuine textile effluent. The main results of the work can be summarized as follows: i) The SAMBR-1 with PAC presented excellent performance in the removal efficiencies of Chemical Oxygen Demand (COD), color, turbidity and VFA, when was feed with synthetic effluent and textile effluent; ii) The presence of the PAC inside SAMBR-1 enhanced reactor stability, decreasing the VFA concentration, favoring the adaptation of microorganisms to toxic by-products obtained in the anaerobic degradation of the azo dyes (eg. aromatic amines) and also minimizing the fouling in the membrane; iii) The use of the yeast extract was capable of accelerate the kinetics of degradation of the azo dyes, enhanced the color removal in the system. The best performance in the removal efficiencies of COD (91%) and color (94%) was show by SAMBR-1 (with PAC) in the presence of yeast extract when operated with genuine textile effluent, indicates that the coupling of microfiltration membranes with PAC and redox mediator (yeast extract) improved the quality of the effluent, facilitating the reuse in textile sector. Thus the integrated analysis of the results generated by this research contributes significantly to the advancement of knowledge in the areas of anaerobic degradation of azo dyes and the use of SAMBR in the treatment of effluents from textile industry

Aproveitamento energético a partir da digestão anaeróbia de hidrolisado hemicelulósico gerado pelo pré-tratamento por auto-hidrólise do bagaço de cana-de-açúcar considerando o contexto da biorrefinaria.

Programa de Pós-Graduação em Engenharia Ambiental. Núcleo de Pesquisas e Pós-Graduação em Recursos Hídricos, Pró-Reitoria de Pesquisa e Pós Graduação, Universidade Federal de Ouro Preto.Este trabalho teve como principal objetivo otimizar a partir de um planejamento experimental as variáveis operacionais temperatura (T), tempo (t) e razão sólido-líquido (RSL) para a auto-hidrólise (AH) do bagaço de cana-de-açúcar (BC), visando produzir um hidrolisado hemicelulósico (HH) com características propícias para digestão anaeróbia (DA) e produção bioquímica de metano (PBM). Os resultados indicaram que os HH gerados em condições severas de AH com maior solubilização de hemiceluloses e com maiores teores de açúcares, C5-C6, não foram os mais adequados para produção de metano. Provavelmente isto tenha ocorrido pelo acúmulo de compostos tóxicos e/ou recalcitrantes (furanos e fragmentos de lignina). Condições mais moderadas (170°C, 35 min e RSL = 0,33 g BC.mL H2O-1) geraram um HH com maior PBM (0,79 Nm3 CH4. kg COT-1), o que foi confirmado pela ferramenta estatística de desejabilidade. O HH obtido a partir da condição DC2 gerada pelo modelo de desejabilidade (178,2°C, 43,6 min e RSL = 0,24 g BC .ml H2O-1) apresentou as menores concentrações de compostos tóxicos, o que culminou com menor acúmulo de ácidos graxos voláteis (AGVs) e maiores PBM (1,56 Nm3 CH4. g COT-1) durante a DA. O modelo de Gompertz foi usado para ajustar os dados de produção de CH4 durante a DA. O melhor HH apresentou uma taxa máxima de produção de metano (RCH4) de 2,6 mmol CH4.d-1. Além disso, a digestão anaeróbia foi realizada em dois estágios (acidogênico-metanogênico, DA-2S), em reatores descontínuos, no qual o estágio acidogênico atuou como uma fase prévia de hidrólise e biodetoxificação. Isto permitiu a utilização de condições mais severas de pré-tratamento do BC por AH, T = 178,6°C e t = 55 min (DC3) e T = 182,9°C e t = 40,71 min (DC4), que, resultaram em maior extração de hemiceluloses do BC (DC3 = 77,40% e DC4 = 73,90%), o que consequentemente melhorou o balanço energético líquido do processo proposto gerando uma energia livre de 3,15 MJ.kg BC-1 a partir da combustão do biogás gerado na digestão anaeróbia em dois estágios do hidrolisado hemicelulósico.This study aimed to optimize through design of experiments, the process variables (temperature ‒ T, time ‒ t and solid‒to‒liquid ratio ‒ SLR) for sugarcane bagasse (Himmelsbach et al.) autohydrolysis (AH) to obtain hemicellulose hydrolyzates (HH) prone to anaerobic digestion (AD) and biochemical methane production (BMP). The results indicated that severe AH conditions, which lead to maximum hemicelluloses dissolution and sugar content in the HH, were not the best for BMP, probably due to the accumulation of toxic/recalcitrant compounds (furans and lignin). Mild AH conditions (170oC, 35min and SLR=0.33) led to the highest BMP (0.79 Nm3.kgTOC‒1), which was confirmed by the desirability tool. HH produced by AH carried out at the desired condition DC2 (178.6oC, 43.6 min and SLR=0.24) showed the lowest accumulation of inhibitory compounds and volatile fatty acids (VFA) and highest BMP (1.56 Nm3.kgTOC‒1). The modified Gompertz model best fit the experimental data and led to a maximum methane production rate (R) of 2.6 mmol CH4.d‒1 in the best condition. In additional, the anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T = 178.6°C and t = 55 min (DC3) and T = 182.9°C and t = 40.71 min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1 = 68.07%, DC2 = 48.99%, DC3 = 77.40% and DC4 = 73.90%), which consequently improved the net energy balance of the proposed process generating a net energy of 3.15 MJ.kg BC-1 from anaerobic digestion in two-stage of hemicellulose hydrolysate

Application of residual yeast as a source of redox mediators for the anaerobic decolorization of a model azo dye.

This work investigated the anaerobic degradation of the model azo dye Remazol Yellow Gold RNL in batch reactors using discharged residual yeast as the source of redox mediators (RM). Two yeast lysis methods (mechanical lysis and sonication) were tested and optimized to produce a riboflavin-rich yeast lysate. The reactors were operated at 25 oC for 48 hours, evaluating the effect of external carbon source (glucose) and RM (from residual yeast lysate and commercial yeast extract) addition. The results showed that color removal efficiencies for the batch reactors fed with commercial yeast extract reached 90%, whereas those fed with discharged yeast lysate reached 80% (sonication) and 73% (mechanical lysis). These values were statistically higher when compared to reactors operating without RM (48 to 66%), demonstrating that yeast extract enhances azo dye degradation in anaerobic conditions and that the residual yeast is a cheap and alternative source of carbon and of the RM riboflavin

EPS and SMP dynamics at different heights of a submerged anaerobicmembrane bioreactor (SAMBR).

Membrane bioreactors (MBR) technology for wastewater offers many advantages over conventional tech-nologies such as high effluent quality, less footprint and others. The main disadvantage of membranebioreactors (MBR) is related to membrane fouling, which is mainly caused by extracellular polymericsubstance (EPS) and soluble microbial products (SMP). This research studied EPS and SMP dynamics atdifferent heights of a submerged anaerobic membrane bioreactor (SAMBR). The SAMBR was operatedunder two organic loading rates (OLR) (0.79 and 1.56 kg/m3d) and was fed with synthetic wastewaterwith glucose as the carbon source. The results showed percentages of chemical oxygen demand (COD)removal above 95% and the highest COD removal rates were observed at the bottom of the reactor (>83%)for both OLR. The EPS showed a stratification with highest quantities in the supernatant. For the SMP thehighest concentration was in the bottom of SAMBR where utilization predominated associated productswhereas in the SAMBR supernatant predominated biomass associated products. The OLR change led to asignificant increase in SMP accumulation but not in EPS. These facts showed that EPS and SMP dynamicin the SAMBR seemed to be mainly influenced by biological activity, total suspended solids concentrationand substrate composition

Evaluation of soluble microbial products and aromatic amines accumulation during a combined anaerobic/aerobic treatment of a model azo dye.

The current work have investigated the accumulation of soluble microbial products (SMP) and aromatic amines in anaerobic reactors followed by aerobic reactors (Ar1 or Ar2) during the azo dye Remazol Golden Yellow RNL (RGYRNL) degradation. One anaerobic reactor (An2) contained powdered activated carbon (PAC) in its interior, while another one (An1) was used as control. The results have shown the efficiency of COD and color removal in the combined system An1/Ar1 was higher than 70%, while in the An2/ Ar2 system the COD and color removal was above 85% and 90%, respectively, in all three operational phases. The aerobic reactors were capable of removing most of the residual organic matter, volatile fatty acid (VFA) and aromatic amines, generated during the anaerobic step, and the presence of PAC inside reactor An2 ensured higher operational stability since it minimized the toxic effects caused by anaerobic degradation byproducts. The presence of PAC contributed to reduce SMP accumulation in phases 2 (CODSMP = 32.40 mg/L) and 3 (CODSMP = 21.61 mg/L) and enhanced the effluent quality

Degradation of a model azo dye in submerged anaerobic membrane bioreactor (SAMBR) operated with powdered activated carbon (PAC).

This work investigated the anaerobic degradation of the model azo dye Remazol Yellow Gold RNL in an upflow anaerobic sludge blanket reactor (UASB) and two submerged anaerobic membrane (SAMBR) bioreactors, one of which (SAMBR-1) was operated with powdered activated carbon (PAC) in its interior. The reactors were operated at 35 _C with a hydraulic retention time of 24 h in three operational phases, aimed to assess the effect of external sources of carbon (glucose) or redox mediator (yeast extract) on the removal or color and organic matter. The results showed that removal efficiencies of COD (73e94%) and color (90e94%) were higher for SAMBR-1 when compared to SAMBR-2 (operated without PAC) and UASB reactors. In addition, the presence of PAC in SAMBR-1 increased reactor stability, thereby leading to a lower accumulation of volatile fatty acids (VFA). The microfiltration membrane was responsible for an additional removal ofw50% of soluble residual COD in the form of VFA, thus improving permeate quality. On its turn, PAC exhibited the ability to adsorb byproducts (aromatic amines) of azo dye degradation as well as to act as source of immobilized redox mediator (quinone groups on its surface), thereby enhancing color removal