• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 23
  • 3
  • Tagged with
  • 33
  • 33
  • 14
  • 10
  • 10
  • 9
  • 8
  • 7
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Desalcoolização de cerveja : avaliação da remoção de etanol de soluções aquosas por osmose direta

Ambrosi, Alan January 2016 (has links)
O consumo de cervejas não alcoólicas tem aumentado nos últimos anos devido, principalmente, às novas e restritivas leis de trânsito, às preocupações com a saúde ou por razões religiosas. Entre as estratégias de produção das cervejas não alcoólicas ou com baixo teor de álcool estão os processos de separação por membranas, alternativas de grande interesse na remoção do etanol de cervejas tradicionais, pois não promovem impacto térmico no produto. A osmose direta é uma técnica de membranas que tem passado por avanços significativos na última década, apresentando potencial de aplicação na remoção de etanol de soluções aquosas e, consequentemente, na obtenção de cervejas não alcoólicas. No entanto, até o momento, nenhum estudo relacionado à sua utilização na remoção de compostos orgânicos voláteis, como o etanol de soluções aquosas ou bebidas, é encontrado na literatura. Neste contexto, o objetivo deste trabalho é avaliar a viabilidade da utilização da técnica de osmose direta para a esse fim. Em um primeiro momento, membranas comerciais de osmose direta foram caracterizadas de acordo com suas propriedades morfológicas, químicas e de desempenho hidráulico para que pudessem ser comparadas no restante do trabalho, que foi dividido em diversos estudos. Estes estudos avaliaram os efeitos de variáveis de operação sobre o desempenho do processo de remoção de etanol de soluções aquosas: a velocidade de escoamento, a temperatura, a concentração e o tipo do agente osmótico, o pH da solução osmótica e o tipo de membrana. Finalmente, um estudo efetivo sobre a desalcoolização completa de cerveja comercial foi realizado para suportar a aplicabilidade da técnica de OD. Os resultados mostraram que os parâmetros estudados possuem influência sobre as variáveis de resposta do processo, como fluxo permeado total, fluxo inverso de soluto e fluxo de etanol e que estes podem ser otimizados para aumentar o desempenho na desalcoolização. As características da cerveja sem álcool obtida no último estudo foram diferentes daquelas da cerveja tradicional com álcool e alguns motivos como elevado tempo de operação, baixa seletividade da membrana para compostos de aroma e alto fluxo inverso do agente osmótico foram responsáveis pelas alterações. O trabalho demonstrou que é possível utilizar a osmose direta para a remoção de etanol de soluções aquosas e, consequentemente, para a desalcoolização de cervejas. / The consumption of non-alcoholic beer has increased in the last years mainly due to the stricter traffic laws, to personal health concerns or even due to religious reasons. Among the strategies for production of non-alcoholic or low alcohol beers are the membrane separation processes. Membrane-based processes are alternatives of great interest for removing the ethanol from beer because low operating temperatures can be used, avoiding the thermal impact caused on the product by traditional thermal technologies. Forward osmosis (FO) is a membrane technology that has been significantly improved in the last decade, presenting a potential of application to ethanol removal from aqueous solutions and, consequently, for producing non-alcoholic beers. However, until now, no study related to the removal of ethanol from aqueous solutions or beverages using FO is found in the literature. In this context, the main objective of this doctorate thesis is to evaluate the possibility of using the forward osmosis technology for ethanol removal from beer and other aqueous solutions. Initially, commercial forward osmosis membranes were characterized according to morphological and chemical properties and to their hydraulic performance in order to be compared in the following work, which was divided in several studies. These studies evaluated the effects of operating parameters, such as the crossflow velocity, the osmotic solution temperature, concentration and pH, the osmotic agent characteristics, and the membrane characteristics on the performance of ethanol removal from aqueous solutions process. Finally, an effective study about beer dealcoholization was performed to support the applicability of the forward osmosis. Results showed that the studied parameters have influence on response variables such as total permeate flux, reverse solute flux and ethanol flux, and that these parameters can be optimized to enhance the dealcoholization performance. The characteristics of the dealcoholized beer obtained in the last study were different from that of traditional beer in the beginning of dealcoholization process and some reasons such as the prolonged experiment time, the low selectivity of the membrane to flavor compounds and high reverse osmotic agent flux were responsible for these significant changes. This thesis demonstrated that it is possible to take advantage of the forward osmosis technology to remove ethanol from aqueous solutions and consequently dealcoholize beer.
12

Forward Osmosis Desalination Using Thermoresponsive Hydrogels as Draw Agents; An Experimental Study

January 2019 (has links)
abstract: Hydrogel polymers have been the subject of many studies, due to their fascinating ability to alternate between being hydrophilic and hydrophobic, upon the application of appropriate stimuli. In particular, thermo-responsive hydrogels such as N-Isopropylacrylamide (NIPAM), which possess a unique lower critical solution temperature (LCST) of 32°C, have been leveraged for membrane-based processes such as using NIPAM as a draw agent for forward osmosis (FO) desalination. The low LCST temperature of NIPAM ensures that fresh water can be recovered, at a modest energy cost as compared to other thermally based desalination processes which require water recovery at higher temperatures. This work studies by experimentation, key process parameters involved in desalination by FO using NIPAM and a copolymer of NIPAM and Sodium Acrylate (NIPAM-SA). It encompasses synthesis of the hydrogels, development of experiments to effectively characterize synthesized products, and the measuring of FO performance for the individual hydrogels. FO performance was measured using single layers of NIPAM and NIPAM-SA respectively. The values of permeation flux obtained were compared to relevant published literature and it was found to be within reasonable range. Furthermore, a conceptual design for future large-scale implementation of this technology is proposed. It is proposed that perhaps more effort should focus on physical processes that have the ability to increase the low permeation flux of hydrogel driven FO desalination systems, rather than development of novel classes of hydrogels / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019
13

Desalcoolização de cerveja : avaliação da remoção de etanol de soluções aquosas por osmose direta

Ambrosi, Alan January 2016 (has links)
O consumo de cervejas não alcoólicas tem aumentado nos últimos anos devido, principalmente, às novas e restritivas leis de trânsito, às preocupações com a saúde ou por razões religiosas. Entre as estratégias de produção das cervejas não alcoólicas ou com baixo teor de álcool estão os processos de separação por membranas, alternativas de grande interesse na remoção do etanol de cervejas tradicionais, pois não promovem impacto térmico no produto. A osmose direta é uma técnica de membranas que tem passado por avanços significativos na última década, apresentando potencial de aplicação na remoção de etanol de soluções aquosas e, consequentemente, na obtenção de cervejas não alcoólicas. No entanto, até o momento, nenhum estudo relacionado à sua utilização na remoção de compostos orgânicos voláteis, como o etanol de soluções aquosas ou bebidas, é encontrado na literatura. Neste contexto, o objetivo deste trabalho é avaliar a viabilidade da utilização da técnica de osmose direta para a esse fim. Em um primeiro momento, membranas comerciais de osmose direta foram caracterizadas de acordo com suas propriedades morfológicas, químicas e de desempenho hidráulico para que pudessem ser comparadas no restante do trabalho, que foi dividido em diversos estudos. Estes estudos avaliaram os efeitos de variáveis de operação sobre o desempenho do processo de remoção de etanol de soluções aquosas: a velocidade de escoamento, a temperatura, a concentração e o tipo do agente osmótico, o pH da solução osmótica e o tipo de membrana. Finalmente, um estudo efetivo sobre a desalcoolização completa de cerveja comercial foi realizado para suportar a aplicabilidade da técnica de OD. Os resultados mostraram que os parâmetros estudados possuem influência sobre as variáveis de resposta do processo, como fluxo permeado total, fluxo inverso de soluto e fluxo de etanol e que estes podem ser otimizados para aumentar o desempenho na desalcoolização. As características da cerveja sem álcool obtida no último estudo foram diferentes daquelas da cerveja tradicional com álcool e alguns motivos como elevado tempo de operação, baixa seletividade da membrana para compostos de aroma e alto fluxo inverso do agente osmótico foram responsáveis pelas alterações. O trabalho demonstrou que é possível utilizar a osmose direta para a remoção de etanol de soluções aquosas e, consequentemente, para a desalcoolização de cervejas. / The consumption of non-alcoholic beer has increased in the last years mainly due to the stricter traffic laws, to personal health concerns or even due to religious reasons. Among the strategies for production of non-alcoholic or low alcohol beers are the membrane separation processes. Membrane-based processes are alternatives of great interest for removing the ethanol from beer because low operating temperatures can be used, avoiding the thermal impact caused on the product by traditional thermal technologies. Forward osmosis (FO) is a membrane technology that has been significantly improved in the last decade, presenting a potential of application to ethanol removal from aqueous solutions and, consequently, for producing non-alcoholic beers. However, until now, no study related to the removal of ethanol from aqueous solutions or beverages using FO is found in the literature. In this context, the main objective of this doctorate thesis is to evaluate the possibility of using the forward osmosis technology for ethanol removal from beer and other aqueous solutions. Initially, commercial forward osmosis membranes were characterized according to morphological and chemical properties and to their hydraulic performance in order to be compared in the following work, which was divided in several studies. These studies evaluated the effects of operating parameters, such as the crossflow velocity, the osmotic solution temperature, concentration and pH, the osmotic agent characteristics, and the membrane characteristics on the performance of ethanol removal from aqueous solutions process. Finally, an effective study about beer dealcoholization was performed to support the applicability of the forward osmosis. Results showed that the studied parameters have influence on response variables such as total permeate flux, reverse solute flux and ethanol flux, and that these parameters can be optimized to enhance the dealcoholization performance. The characteristics of the dealcoholized beer obtained in the last study were different from that of traditional beer in the beginning of dealcoholization process and some reasons such as the prolonged experiment time, the low selectivity of the membrane to flavor compounds and high reverse osmotic agent flux were responsible for these significant changes. This thesis demonstrated that it is possible to take advantage of the forward osmosis technology to remove ethanol from aqueous solutions and consequently dealcoholize beer.
14

Desalcoolização de cerveja : avaliação da remoção de etanol de soluções aquosas por osmose direta

Ambrosi, Alan January 2016 (has links)
O consumo de cervejas não alcoólicas tem aumentado nos últimos anos devido, principalmente, às novas e restritivas leis de trânsito, às preocupações com a saúde ou por razões religiosas. Entre as estratégias de produção das cervejas não alcoólicas ou com baixo teor de álcool estão os processos de separação por membranas, alternativas de grande interesse na remoção do etanol de cervejas tradicionais, pois não promovem impacto térmico no produto. A osmose direta é uma técnica de membranas que tem passado por avanços significativos na última década, apresentando potencial de aplicação na remoção de etanol de soluções aquosas e, consequentemente, na obtenção de cervejas não alcoólicas. No entanto, até o momento, nenhum estudo relacionado à sua utilização na remoção de compostos orgânicos voláteis, como o etanol de soluções aquosas ou bebidas, é encontrado na literatura. Neste contexto, o objetivo deste trabalho é avaliar a viabilidade da utilização da técnica de osmose direta para a esse fim. Em um primeiro momento, membranas comerciais de osmose direta foram caracterizadas de acordo com suas propriedades morfológicas, químicas e de desempenho hidráulico para que pudessem ser comparadas no restante do trabalho, que foi dividido em diversos estudos. Estes estudos avaliaram os efeitos de variáveis de operação sobre o desempenho do processo de remoção de etanol de soluções aquosas: a velocidade de escoamento, a temperatura, a concentração e o tipo do agente osmótico, o pH da solução osmótica e o tipo de membrana. Finalmente, um estudo efetivo sobre a desalcoolização completa de cerveja comercial foi realizado para suportar a aplicabilidade da técnica de OD. Os resultados mostraram que os parâmetros estudados possuem influência sobre as variáveis de resposta do processo, como fluxo permeado total, fluxo inverso de soluto e fluxo de etanol e que estes podem ser otimizados para aumentar o desempenho na desalcoolização. As características da cerveja sem álcool obtida no último estudo foram diferentes daquelas da cerveja tradicional com álcool e alguns motivos como elevado tempo de operação, baixa seletividade da membrana para compostos de aroma e alto fluxo inverso do agente osmótico foram responsáveis pelas alterações. O trabalho demonstrou que é possível utilizar a osmose direta para a remoção de etanol de soluções aquosas e, consequentemente, para a desalcoolização de cervejas. / The consumption of non-alcoholic beer has increased in the last years mainly due to the stricter traffic laws, to personal health concerns or even due to religious reasons. Among the strategies for production of non-alcoholic or low alcohol beers are the membrane separation processes. Membrane-based processes are alternatives of great interest for removing the ethanol from beer because low operating temperatures can be used, avoiding the thermal impact caused on the product by traditional thermal technologies. Forward osmosis (FO) is a membrane technology that has been significantly improved in the last decade, presenting a potential of application to ethanol removal from aqueous solutions and, consequently, for producing non-alcoholic beers. However, until now, no study related to the removal of ethanol from aqueous solutions or beverages using FO is found in the literature. In this context, the main objective of this doctorate thesis is to evaluate the possibility of using the forward osmosis technology for ethanol removal from beer and other aqueous solutions. Initially, commercial forward osmosis membranes were characterized according to morphological and chemical properties and to their hydraulic performance in order to be compared in the following work, which was divided in several studies. These studies evaluated the effects of operating parameters, such as the crossflow velocity, the osmotic solution temperature, concentration and pH, the osmotic agent characteristics, and the membrane characteristics on the performance of ethanol removal from aqueous solutions process. Finally, an effective study about beer dealcoholization was performed to support the applicability of the forward osmosis. Results showed that the studied parameters have influence on response variables such as total permeate flux, reverse solute flux and ethanol flux, and that these parameters can be optimized to enhance the dealcoholization performance. The characteristics of the dealcoholized beer obtained in the last study were different from that of traditional beer in the beginning of dealcoholization process and some reasons such as the prolonged experiment time, the low selectivity of the membrane to flavor compounds and high reverse osmotic agent flux were responsible for these significant changes. This thesis demonstrated that it is possible to take advantage of the forward osmosis technology to remove ethanol from aqueous solutions and consequently dealcoholize beer.
15

Sustainability Evaluation of Hybrid Desalination Systems: Multi Effect Distillation – Adsorption (MED-AD) and Forward Osmosis – Membrane Distillation (FO-MD)

Son, Hyuk Soo 12 1900 (has links)
Water is life for all living organisms on earth, and all human beings need water for every socio-economic activity in their daily lives. However, constant challenges are faced in securing quality water resources due to environmental pollution, a growing demand, and climate changes. To overcome imminent worldwide challenges on water resources, desalination of seawater and saline wastewater became inevitable, and significant efforts have been deployed by the desalination research community to advance the technology. However, there is still a gap to take it to a higher sustainability and compatibility compared to conventional water treatment technologies. Among all efforts, the hybridization of two or more processes stands among the promising solutions for sustainable desalination, which synergizes benefits of multiple technologies. To evaluate the sustainability of hybrid desalination technologies, two different systems, namely; (i) multi-effect distillation – adsorption (MED-AD) and (ii) forward osmosis – membrane distillation (FO-MD), are investigated in this study. The method developed for the analysis of primary energy consumption in complex desalination systems is used to evaluate the performance of the MED-AD pilot facility at King Abdullah University of Science and Technology (KAUST). Results of the MED-AD pilot operation showed an improvement in water production with a higher energy efficiency under the same operating conditions (near the ambient temperature with the solar thermal system). For the FO-MD hybrid system, an investigation is carried out on a novel in-house integrated module and a comparative analysis with the conventional module is provided. An isolation barrier carefully placed in the novel design enhanced the hybrid performance by reducing both concentration and temperature polarization. In addition, the FO-MD hybrid process is evaluated for brine reclamation application in a SWRO-MD-FO system. The sustainability of the proposed system and the potential of a flexible sustainable operation are presented with the experimental study with real seawater and brine from the full-scale desalination plant.
16

Study of Thermally Responsive Ionic Liquids for Novel Water Desalination and Energy Conversion Applications

Zhong, Yujiang 04 1900 (has links)
The rapidly expanding of the global population in the 21st-century forces people facing two serious problems: water scarcity and energy shortage. Enormous continuous studies focus on providing enough fresh water and energy in a sustainable way. This thesis aims at exploring novel membrane processes based on thermally responsive ionic liquids with the upper critical solution temperature (UCST ILs) for water desalination and energy conversion from low-grade heat energy to electricity. A UCST IL protonated betaine bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]) was first experimentally studied as a novel draw solute in a thermal forward osmosis (FO). A 3.2 M [Hbet][Tf2N] solution can be obtained via spontaneous phase separation from an IL and water mixture at room temperature. By heating and maintaining the temperature above 56°C, this solution can draw water from high-salinity solution up to 3.0 M, 5 times salty as the sea water. The IL draw solution can be easily regenerated by phase separation. Conducting the FO process at higher temperatures can also increase the water flux. According to the different choices of the freshwater polishing step, the electric energy consumption in this novel process was estimated as 26.3% to 64.2% of conventional one-step sea water reverse osmosis. Two UCST ILs with better performance, [Hbet][Tf2N] and choline bis(trifluoromethylsulfonyl)imide ([Choline][Tf2N]), were selected as the agents in a novel closed-loop thermally responsive IL osmotic heat engine (TRIL-OHE) to convert low-grade thermal energy to electricity. The specific energies of the [Hbet][Tf2N] system and the [Choline][Tf2N] system are 2500 kJ/t and 3700 kJ/t, which are 2.7 and 4.0 times of the seawater and river water system, respectively. The maximum power density measured from a commercial FO membrane is 1.5 W/m2 for the [Hbet][Tf2N] system and 2.3 W/m2 for the [Choline][Tf2N] system, leaving a big room to improve if highly permeable membranes are used. Another notable advantage of the TRIL-OHE is the heat released from the cooling stage can be largely recovered. A rigorous energy balance showed with a 70% heat recovery, the energy efficiency could be increased from around 20% to 70% of the Carnot efficiency in both UCST ILs systems.
17

A performance and energy evaluation of a dye drawn forward osmosis (FO) system for the textile industry

Rahman, Mohammed January 2020 (has links)
Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2020 / Continuous growth in the world population has raised significant fears with regards to the sustainability of energy and water resources. Globally, water is an indispensable resource as it is essential for the sustenance of human, animal and plant life. Water is essential for all forms of life and plays a pivotal role in economic growth. The textile industry is one of the greatest consumers of water, it is, therefore, necessary to effectively treat the large amounts of wastewater before discharge to the environment. It is estimated that annually, more than 700,000-tonnes of textile wastewater is produced by the dyeing industry. Textile wastewater is generally characterised by electrolytes, suspended solids, mineral oils and multiple textile dyes, and has therefore been classified as one of the most polluting wastewaters. These dyes are toxic and, in most cases, are not biodegradable. The presence of very small amounts (i.e. < 1 ppm) of dyes in water has aesthetic impacts and is thus undesirable. It is, therefore, necessary to treat textile wastewater before discharging. Currently, membrane technology is widely used for wastewater treatment, as well as water purification. Forward osmosis (FO) is a promising technology for both these applications. FO is characterised by the flow of water through a semipermeable membrane from a feed solution (FS) characterised by the low solute concentration or low osmotic pressure (OP) to a draw solution (DS) characterised by the high solute concentration or high OP, due to the OP gradient across the membrane. The FO process eliminates the need for high hydraulic pressure, as required in traditional membrane technologies, and also has low fouling tendencies. Furthermore, FO has the advantage of lower energy requirements and membrane replacement costs. However, there are still many disadvantages such as reverse solute flux (RSF), membrane fouling, and concentration polarisation (CP) amongst others that still need to be addressed. Therefore, more research needs to be done in light of these limitations to better understand and mitigate these limitations to increase the effectiveness and efficiency of the FO process. This study aimed to evaluate a dye-driven FO system for the reclamation of water from textile wastewater and synthetic brackish water (BW5) by investigating the effects of membrane orientation, system flowrate, change in DS, and membrane fouling on the FO systems performance and energy consumption. The FS used was BW5 with sodium chloride (NaCl) content of 5 g/L whereas Reactive Black 5 (i.e. a reactive dye) and Maxilon Blue GRL (i.e. a basic dye) dyes were used as a DS, respectively. The membrane utilised was a cellulose triacetate (CTA) membrane and was tested in FO mode and pressure retarded osmosis (PRO) mode whilst the system flowrate was adjusted to 400, 500 and 600 mL/min, respectively. Experiments were performed using a bench-scale FO setup which comprised of an FO membrane cell, a double-head variable speed peristaltic pump, a digital scale, two reservoirs for the FS and DS, respectively, a digital multiparameter meter and a digital electrical multimeter to measure system energy consumption. Each experiment comprised of six steps: baseline 1 (membrane control), main experiment (dye-driven FO experiment), baseline 2 (membrane control repeat), membrane cleaning, membrane integrity (membrane damage dye identification) and membrane cleaning (preparation for next experiment). The baseline 1 and baseline 2 experiments operated for 3 h whilst each membrane cleaning procedure operated for 30 min. The main experiments operated for 5 h in the FO mode and 4 h in PRO mode whilst the membrane integrity experiments operated until a minimum of 10 mL water was recovered. Results showed that the PRO mode achieved both higher forward flux (𝐽𝑤) (i.e. 8.87, 8.71 and 9.13 L/m2.h for flowrates of 400, 500 and 600 ml/min) and water recovery (𝑅𝑒) rates compared to FO mode (i.e. 6.60, 6.88 and 7.58 L/m2.h for flowrates of 400, 500 and 600 ml/min). The variation of flowrates had little to no influence on the 𝐽𝑤, 𝐽𝑠 and 𝑅𝑒 of the system. The system consumed less energy in PRO mode (i.e. 381 kWh/m3 average consumption for all three flowrates) than FO mode (i.e. 417 kWh/m3 average consumption for all three flowrates). It was also observed that at a higher DS 𝑂𝑃, the system consumed less energy. Therefore, selecting an optimum initial 𝑂𝑃 is essential for a FO process to minimise the pumping energy. Furthermore, a change in DS from Reactive Black 5 dye to Maxilon Blue GRL dye had no significant impact on the system performance and energy consumption. In this study, no significant membrane fouling was observed, however, minute traces of fouling in the form of foreign functional groups could be observed in the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectrums of the used membranes. Additionally, the observation of negligible changes in baseline 2 (membrane control) Re and Jw results suggested the possible occurrence of membrane fouling during the main experiment (dye-driven FO system).
18

Self-Sufficient Wastewater Reuse with Intermediate Dehydration and with Consideration of Product Recovery.

Sun, Jian January 2013 (has links)
Municipal wastewater treatment has a long history of local handling with recovery of toilet wastes for use in agriculture and to some extent energy recovery from biogas by use of local handling. This may be seen as ―the first way‖ further developed by septic tanks and infiltration and recovery as in Ecological Sanitation and use of urine separation toilets. However, problems related to water borne diseases and odor problems successively gave rise to ―the second way‖ with central wastewater systems with large investments in water and sewer nets and increasingly better technologies for water treatment and wastewater treatment. This technology may treat municipal wastewater to a drinking water quality and recover part of energy and nutrients contents for eco-cycling. The problems noted and which are quite obvious are affordability in poor countries and the need for much energy supply and with negative effects of emission of greenhouse gases. Ways should be better evaluated to obtain both an effluent wastewater of drinking water quality and at the same time be self-sufficient with energy, obtain products with a commercial value and comply with methods to reduce the amounts of released greenhouse gases. It is suggested that an intermediate dehydration step should be used by dividing the main stream into two streams, one to which water has been transferred by methods as forward osmosis or freezing and one remaining concentrated stream that could be treated more efficiently. New technologies should be considered for electricity production as use of fuel cell technology and forward osmosis. Methods to diminish greenhouse gas emissions include avoidance of such redox potentials and process conditions that lead to greenhouse gas emissions and binding of carbon dioxide in algae and plants and in clatharates.
19

Evaluation of Different Forward Osmosis Membrane Cleaning Strategies for Produced Water Streams Treatment

Alamoudi, Talal 07 1900 (has links)
Forward osmosis (FO) as a novel membrane separation technology has recently been investigated in various water treatment applications. The natural mass transfer process between two solutions driven by the osmotic pressure difference leads to many operational advantages in the FO process, such as low energy consumption and minimal fouling problems. It makes FO a feasible technology for the treatment of produced water (PW). Although previously, the treatment of PW using FO has been investigated, osmotic backwashing (OB) is not systematically examined for water flux recovery of the PW fouled FO membranes. Moreover, the cleaning of FO membranes used for the simultaneous treatment of different PW streams was never previously attempted. In this study, OB was thoroughly investigated for the cleaning of PW-fouled FO membranes. Also, FO membrane chemical cleaning using SDS and NaOH solutions was examined too. To investigate OB, the cleaning efficiency of a 60 min OB cleaning protocol was examined under different FO operating modes in (5 x 20 h) experiments using synthetic desalter effluent as FO feed solution (FS) and 1.2 M NaCl solution or water-oil separator outlet (WO) as draw solutions (DS). The AL-FS (active layer facing FS) mode outcompeted the AL-DS (active layer facing DS) mode, achieving a flux of 12.9 LMH and 80.1% water reclamation when using WO as a DS. Therefore, this FO configuration 5 was selected when evaluating the cleaning protocols. Moreover, after evaluating different OB methods, the 30 min OB protocol achieved the highest system efficiency rate of 95% and was studied for the treatment of real PW streams. The SDS and NaOH chemical cleaning methods achieved flux recovery rates of 99% and 98% by the end of the third treatment cycle, respectively, outperforming the 89% flux recovery rate of the optimized OB protocol. Although the investigated cleaning methods were able to restore the system performance, a substantial increase in RSF was observed due to mainly irreversible colloidal fouling. This study demonstrates the feasibility of OB and chemical cleaning in restoring FO system performance for the simultaneous treatment of PW streams
20

Integrating Microbial Electrochemical Technology with Forward Osmosis and Membrane Bioreactors: Low-Energy Wastewater Treatment, Energy Recovery and Water Reuse

Werner, Craig M. 06 1900 (has links)
Wastewater treatment is energy intensive, with modern wastewater treatment processes consuming 0.6 kWh/m3 of water treated, half of which is required for aeration. Considering that wastewater contains approximately 2 kWh/m3 of energy and represents a reliable alternative water resource, capturing part of this energy and reclaiming the water would offset or even eliminate energy requirements for wastewater treatment and provide a means to augment traditional water supplies. Microbial electrochemical technology is a novel technology platform that uses bacteria capable of producing an electric current outside of the cell to recover energy from wastewater. These bacteria do not require oxygen to respire but instead use an insoluble electrode as their terminal electron acceptor. Two types of microbial electrochemical technologies were investigated in this dissertation: 1) a microbial fuel cell that produces electricity; and 2) a microbial electrolysis cell that produces hydrogen with the addition of external power. On their own, microbial electrochemical technologies do not achieve sufficiently high treatment levels. Innovative approaches that integrate microbial electrochemical technologies with emerging and established membrane-based treatment processes may improve the overall extent of wastewater treatment and reclaim treated water. Forward osmosis is an emerging low-energy membrane-based technology for seawater desalination. In forward osmosis water is transported across a semipermeable membrane driven by an osmotic gradient. The microbial osmotic fuel cell described in this dissertation integrates a microbial fuel cell with forward osmosis to achieve wastewater treatment, energy recovery and partial desalination. This system required no aeration and generated more power than conventional microbial fuel cells using ion exchange membranes by minimizing electrochemical losses. Membrane bioreactors incorporate semipermeable membranes within a biological wastewater treatment process. The anaerobic electrochemical membrane bioreactor described here integrates a microbial electrolysis cell with a membrane bioreactor using conductive hollow fiber membrane to produce hydrogen gas, treat wastewater and reclaim treated water. The energy recovered as hydrogen gas in this system was sufficient to offset all the electrical energy requirements for operation. The findings from these studies significantly improve the prospects for simultaneous wastewater treatment, energy recovery and water reclamation in a single reactor but challenges such as membrane biofouling and conversion of hydrogen to methane by methanogenesis require further study.

Page generated in 0.054 seconds