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关键词： Membrane bioreactor   Enzymatic hydrolysis   Cellulose   Kinetic model   Product separation   Product inhibition  

摘要： Bioethanol production from lignocellulosic biomass depends on enzymatic cellulose hydrolysis to generate glucose. However, enzyme inhibition by the product is one of the several problems making lignocelluloses refractory to this process. To resolve this, we designed a membrane bioreactor (MBR) with an inverted dead-end filtration concept for simultaneous removal of the product during the reaction. Polyethersulfone membranes were used, and their selectivity in allowing only product permeation was proven. The effects of different water fluxes and initial substrate concentrations were investigated. Additionally, a detailed kinetic model based on the mechanistic steps was developed to predict the dynamic behavior of the system, and the kinetic parameters were estimated by fitting the experimental data. The MBR yield increased from 7% without product separation to 45% with product separation. Both kinetic and statistical models showed good agreement (R-2: 0.96 and 0.97, respectively). According to the statistical model, the optimal conditions were a substrate concentration of 2.67 g/L and a water flux of 0.8 mL/min, which achieves a maximum yield of 86.7%. Our novel MBR and kinetic model allow for a better understanding of the dynamic behavior of this important reaction-diffusion system and can be used to predict, design, and optimize similar MBRs.

关键词： Textile industry  

摘要： A laboratory-scale pilot plant of moving bed biofilm reactor coupled with membrane bioreactor (MBBR-MBR) was studied with regard to wastewater treatment in the textile industry, and the reuse feasibility of treated water was investigated. The pilot plant comprised two connected parts: an aerobic tank filled with carriers and a submerged membrane tank. The MBBR-MBR system reduced the hydraulic retention time to 1 day, which is very promising compared with conventional biological treatment in the textile industry. The removal efficiency of chemical oxygen demand reached 93%, which is almost the maximum for a biological process treating this type of wastewater, as well as the colour removal performance, which achieved 85%. Additionally, 99% of total suspended solids were removed due to filtration. Furthermore, new dyeing processes reusing the treated water were performed. The quality of the new dyed fabrics with treated water was compared with reference fabrics. Colour differences between new dyed fabrics and reference fabrics were found to be within the general requirement of the textile industry (Delta E-CMC(2:1) < 1). The reuse of treated water in new dyeing processes is beneficial both for the industry and for the environment, because the textile sector is an intensive water consumer during both the dyeing and finishing processes.

关键词： Old landfill leachate   Membrane bioreactor   Saccharomyces cerevisiae   Air-stripping/absorption   Ammonia nitrogen  

摘要： A membrane bioreactor inoculated with commercial baker's yeast (Saccharomyces cerevisiae) (MBRy) integrated to an air-stripping/absorption (AS/AB) as pre-treatment (aiming ammonia recovery) or a post-treatment (polishment step) was assessed for the landfill leachate treatment. The effect of chemical oxygen demand (COD) and nitrogen (N) ratio (C:N) on the performance of the MBRy was also investigated. At high COD/N ratio, high organic matter removal in terms of COD (71 +/- 4%) and ammonia removal (97 +/- 3%) was observed. Lower COD/N ratio favored yeast growth in the mixed liquor even under adverse conditions. The results of ammonia removal and recovery, and economic analysis demonstrated that the best way to integrate the AS/BS processes is as pre-treatment of MBRy. The ammonia concentration in the AS/AB process feed was a key factor to achieve the market specification. Although pH and temperature adjustment were adequate to promote ammonia removal/recovery, the AS operation at high temperatures showed the highest ammonia removal rate (99%). Therefore, the integration of AS/AB with MBRy allows obtaining a permeate with a final concentration of 2902 +/- 374 mg L-1 of COD and 9 +/- 7.5 mg L-1 of ammonia. Although it was possible to reach the Brazilian discharge standard for ammonia (20 mg L-1), it was not possible to reach the standard for COD, where the remaining fraction is recalcitrant organic matter, requiring the integration of a physico-chemical process. It should be noted that the proposed route allowed recovery 7 kg of ammonia per m( )(3)of treated leachate.

关键词： Life cycle impact assessment   Anaerobic digestion   Digestate   Global warming potential   Eutrophication potential  

摘要： Purpose This study aims to develop a prototype of zero-organic waste model using the integrated system of single-stage anaerobic digester (AD) and oxidation-ditch membrane bioreactor (OD-MBR) to convert organic wastes from food waste and sludge from OD-MBR system to biogas for cooking as well as to co-treat liquid digestate from AD with building wastewater in order to produce reclaimed water as a sustainable model for building application. Methods In order to investigate the optimal condition in operating the AD/OD-MBR system to lower organic waste pollution to promote sustainable urban development, LCA with SimaPro 8 software was used to evaluate the environmental impact such as global warming, acidification and eutrophication potentials for six different operating conditions of AD/OD-MBR system for management of food waste and building wastewater. Results and Discussion The evaluation by LCA shows that the proposed AD/OD-MBR system can effectively control the environmental impact from liquid digestate and sludge that are discharged into environment. The eutrophication potential of the integrated AD/OD-MBR system is reduced to the lowest value of 4.66 kg PO(4)(3-)as compared to the values of 713.77 and 75.12 kg PO43- that are obtained from sole OD-MBR and sole AD, respectively. Moreover, global warming potential of AD/OD-MBR is lower than that of AD system. Conclusions The proposed integrated AD/OD-MBR system can efficiently minimize the impacts from global warming and eutrophication potentials. It can be a model of prototype zero-organic waste for building water and organic waste management with water recycling for garden and landscape use. [GRAPHICS] .

关键词： Anaerobic treatment   Thermophilic temperature   Organic loading rate   Organic removal   Biogas production   Kinetic modeling  

摘要： Performance and kinetic analysis of anaerobic moving bed bioreactor (AnMBBR) and upflow anaerobic hybrid reactor (UAHR) were investigated for the treatment of synthetic textile desizing wastewater (TDW) under organic loading rate (OLR) of 0.6-12 kgCOD/m(3)/day at thermophilic temperature (55 degrees C). The effects of increase in temperature (from 35 to 55 degrees C) on anaerobic treatment efficiency were studied. In the kinetic study for COD removal, first order substrate removal, Grau second order and modified Stover-Kincannon models were applied. By increasing temperature from 35 degrees C to 55 degrees C, COD removal, volumetric biogas production and methane content were increased 1.22, 2.58 and 1.08 times in AnMBBR. Whilst in the case of UAHR the increment for the aforementioned parameters were 1.10, 2.51 and 1.10 times, respectively. By increasing OLR from 0.6 to 6 kgCOD/m(3)/day, above 60% and 70% COD removal was observed, while the biogas increased from 0.12 to 0.97 L/*** and 0.13-1.22 L/*** for AnMBBR and UAHR, respectively. Up to an optimum OLR (6 and 8 kgCOD/m(3)/day for AnMBBR and UAHR) volumetric biogas production was also increased, simultaneously. Grau second order and modified Stover-Kincannon were found to be the best fit models (R-2 = 0.99). Biogas production and methane content in biogas were comparatively better in the case of real textile desizing wastewater due to lower sulfate concentration in the feed.

关键词： Culture media   Mist bioreactor   Misting rate   Physicochemical properties   Ultrasonic  

摘要： The mist bioreactor has been proved to have a higher performance relative to the liquid phase reactor. The water and conventional media (MS, 1/2MS, and B5) were tested in a mist bioreactor to evaluate the performance of the misting system. The physicochemical properties of liquids were measured at 0 (Fresh state) and when treated by ultrasonic system for 1 and 2 h. At a given airflow rate, the misting rate for different heights of various media was determined. The results demonstrated that the electrical conductivity of all media increased with the duration of sonication. The ultrasonic effect caused an increase in surface tension of MS and 1/2MS, while the pH of MS and 1/2MS reduced with ultrasonic treatment. The inverse trends were observed for water and B5 for these properties. The misting rate increased by increasing liquid height to a maximum value, then decreased to a minimum value at the highest height. For all liquids studied in this experiment, this maximum value of misting performed at height ranged between 3 and 4 cm. The maximum and minimum values of the ultrasonic misting rate belonged to MS (2.78 x 10(-2)g/s) at height 3 cm and B5 (0.52 x 10(-2)g/s) at height 1 cm, respectively.

关键词： Algal membrane bioreactor (AMBR)   HRT   Greywater treatment   Biomass production   Removal efficiency  

摘要： For bioreactors, hydraulic retention time plays a very important role in biomass production. The effectiveness of Algal-based Membrane Bioreactor (AMBR) has not been adequately explored for domestic greywater treatment. The present study aims to assess AMBR's efficiency for treating domestic greywater operating at four hydraulic retention times (HRTs) of 1-7 d. Microalgal biomass production, removal efficiency, fouling characteristics, and net energy efficiency of the AMBR were optimized. The experimental study showed that algal biomass productivity increased with decreasing HRT, and the highest productivity (48 mg/L/d) was achieved at 2 d of HRT. Independent of HRT, 94 % BOD and 96 % anionic surfactant (AS) removals were achieved, while the highest TN and TP removals (59.5 % and 34.5 %) were achieved at HRT of 7 d. Effluent monitoring revealed that microalgae assimilation was the primary path-way of TN and TP removals. Membrane fouling frequency decreased with increasing HRT, and the lowest fouling was found at 7d of HRT. The highest methane yield (0.332 m(3)/d) and the net energy return NER (1.04) were estimated at HRT of 2 d. Overall, HRT of 2 d would be optimum for AMBR operation and can be modeled as a self-sustainable greywater treatment system with zero power requirements. The present study provides the basis for establishing the guidelines for AMBR design for the treatment and recycling of greywater. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Wastewater   Sustainable treatment   Microalgae   Carbon capture   Nutrient removal   Algal lipid  

摘要： This study investigated the possibility of coupling anaerobic hydrolysis in an anaerobic membrane bioreactor (AnMBR) with mixotrophic microalgae cultivation in a membrane photobioreactor (MPBR) for the sustainable treatment of municipal wastewater. Using the hydrolyzed wastewater discharged from AnMBR, Chlorella pyrenoidosa in MPBR grew in a mixotrophic mode and realized rapid growth. During the stable operation, MPBR achieved average carbon capture rate of 42.82 mg L-1 d-1 and algal lipid production rate of 19.66 mg L-1 d-1. The average reduction in TN, TP, and TOC during stable operation was 96.7%, 98.0%, and 95.9%, respectively. Mass balance analysis showed that the overall system captured 14.76 mg of carbon from the atmosphere per liter of wastewater treated. Therefore, this AnMBR-MPBR hybrid system simultaneously realized advanced treatment of municipal wastewater, efficient production of algal lipid, and carbon capture from atmosphere, and thus has a good potential in the sustainable treatment of municipal wastewater.

关键词： Membrane bioreactor   Critical flux   Floc characteristics   Reliability analysis   Fouling mechanism  

摘要： Membrane fouling occurs when the operating flux exceeds a certain point (i.e., critical flux). Critical flux has therefore been widely adopted to determine the initial operating flux in membrane bioreactor (MBR) processes. The flux steeping method currently used to measure the critical flux is time-consuming and uneconomical. This study was conducted to develop a novel approach for the evaluation of critical flux. Given that particle fouling is dominant during the initial fouling stage, we hypothesized that particle properties may be closely related to critical flux. A critical flux prediction model with an R-2 of 0.9 was therefore derived, which indicates that particle properties regulate critical flux. The results imply that most of the fouling potential during the early stages of operation is caused by SS, and that the formation of cakes that comprise large particles is the dominant fouling mechanism. The new method proposed in this study reduced the measurement cost and time to evaluate critical flux by 3.5-and 8 times, respectively, compared to the flux-stepping method. In terms of practical application, the applicability of the model equation was identified by system reliability analysis, which indicates that the system failure increases significantly as the standard deviation of the variables increases. This study demonstrated that the prediction of critical flux and system reliability can be achieved through particle characteristic measurement. A similar approach is expected to be employed in real MBR plants as an economical and convenient fouling control strategy to solve problems involving resource shortages.

关键词： Bioreactors  

摘要： Biochemical reactors (BCRs) have a longstanding history in the environmental field;however, they have only been recently employed as a tool in water treatment of the mining sector. As this field of technology continues to grow, bioreactors are gaining interest in the world of "passive" water treatment and the technology is modernizing at a rapid rate.