Treating High Salinity Produced Water Using Hybrid Membrane Processes: Electrocoagulation-Microfiltration/Ultrafiltration-Membrane Distillation-Crystallization

Produced water (PW) is considered the largest industrial wastewater stream in the world. PW generated from oil and gas operations generally contains a range of contaminants including high total dissolved solids, high total suspended solids, polar and nonpolar organic compounds, and low surface tension dissolved species. Treating PW is very challenging and applying only membrane-based technologies is not sufficient due to membrane fouling, which affects their long-term performance. Hence, integrated membrane processes are required to treat PW effectively. Hybrid membrane processes, which may result from combining a conventional process with a membrane separation, could be used to address the issues of fouling (and wetting), and maximize water recovery. In this dissertation, several hybrid membrane processes are reviewed and the effects of important parameters that determine the performance of these hybrid systems are discussed. While the highly impaired PW is often deep well injected, there is a great deal of interest in treating and recovering this water for beneficial uses. However, the need to use multiple unit operations is essential if these wastewaters are to be recovered. Electrocoagulation (EC) is considered a promising pretreatment technology. In this study, the use of aluminium electrodes for electrocoagulation as a pretreatment operation was investigated. The effects of electrode arrangement, applied current, reaction time, initial pH, and inter electrode distance on the quality of the treated water have been investigated. EC results showed good removal of turbidity (95%), total suspended solids, TSS (90%), and total organic carbon, TOC (70%) by carefully choosing the reaction conditions. Sedimentation was used to separate the treated water from the sludge. The quality of the feed PW can strongly affect the performance of the EC. In addition, a combined electrocoagulation – microfiltration – membrane distillation (EC-MF-MD) process had been used to treat PW. In this work, EC was followed by MF to pretreat the wastewater prior to MD. After EC, the TOC was reduced from 120 mg L-1 to 64 mg L-1. Tangential flow MF using a 0.1 micrometer pore size polyethersulfone membrane was used to separate the particulate matter after EC and to further reduce the TOC to 44 mg L-1. MD was used to desalinate the pretreated PW resulting in a high quality treated water (reducing the total dissolved solids (TDS) concentration from 245,300 mg L-1 to 56 mg L-1). Three membranes with very different surface morphology were tested here: commercially available polyvinylidene fluoride, electrospun poly (vinylidene fluoride-co-hexafluoropropylene) nanofibers and multiwalled carbon nanotube coated polytetrafluoroethylene. The surface properties of an ideal membrane that is resistant to wetting and provides high flux is likely to depend on the TDS and properties of the PW. The integrated electrocoagulation-ultrafiltration-membrane distillation and crystallization process (EC-UF-MDC) was also used to treat PW. The focus of this work was to determine the feasibility of this integrated process for increasing water recovery. The results of this work suggest that optimizing the various unit operations in this integrated process could be used to recover PW. Dissolved organic compounds are known to foul the hydrophobic membrane used in MD. In this study, a significant reduction in membrane fouling was obtained by EC pretreatment, which can lead to a long-term durability of MD system. In addition, the use of MDC can help mitigate the scale formation. Also, treating PW will preserve surface and groundwater, which form 80% of the water utilized in hydraulic fracturing, and reduce the amount of PW directly disposed in Class II disposal wells, which further address the main cause of earthquakes. Finally, the integrated EC-MF pilot-scale system will be used to pretreat and reuse PW. The EC reactor (37.5 L) was built based on experiences gained from working with a laboratory scale (1 L). The integrated process will be evaluated at Texas Tech University (TTU). The design and construction of the EC-MF system are discussed in this work. The pilot-scale system has a capacity of treating 3600 L/day PW. The system layout is also discussed in this study. The EC-MF process was designed based on 70% feed water recovery. Turbidity, TSS, and TOC analysis will be obtained for samples collected during the 5 days operation. The goal of this work is to achieve a reduction of 95, 90, and 70% for turbidity, TSS, and TOC, respectively, which is the pretreated PW quality needed to be further treated by TTU

Treating High Salinity Produced Water Using Hybrid Membrane Processes: Electrocoagulation-Microfiltration/Ultrafiltration-Membrane Distillation-Crystallization

Produced water (PW) is considered the largest industrial wastewater stream in the world. PW generated from oil and gas operations generally contains a range of contaminants including high total dissolved solids, high total suspended solids, polar and nonpolar organic compounds, and low surface tension dissolved species. Treating PW is very challenging and applying only membrane-based technologies is not sufficient due to membrane fouling, which affects their long-term performance. Hence, integrated membrane processes are required to treat PW effectively. Hybrid membrane processes, which may result from combining a conventional process with a membrane separation, could be used to address the issues of fouling (and wetting), and maximize water recovery. In this dissertation, several hybrid membrane processes are reviewed and the effects of important parameters that determine the performance of these hybrid systems are discussed. While the highly impaired PW is often deep well injected, there is a great deal of interest in treating and recovering this water for beneficial uses. However, the need to use multiple unit operations is essential if these wastewaters are to be recovered. Electrocoagulation (EC) is considered a promising pretreatment technology. In this study, the use of aluminium electrodes for electrocoagulation as a pretreatment operation was investigated. The effects of electrode arrangement, applied current, reaction time, initial pH, and inter electrode distance on the quality of the treated water have been investigated. EC results showed good removal of turbidity (95%), total suspended solids, TSS (90%), and total organic carbon, TOC (70%) by carefully choosing the reaction conditions. Sedimentation was used to separate the treated water from the sludge. The quality of the feed PW can strongly affect the performance of the EC. In addition, a combined electrocoagulation – microfiltration – membrane distillation (EC-MF-MD) process had been used to treat PW. In this work, EC was followed by MF to pretreat the wastewater prior to MD. After EC, the TOC was reduced from 120 mg L-1 to 64 mg L-1. Tangential flow MF using a 0.1 micrometer pore size polyethersulfone membrane was used to separate the particulate matter after EC and to further reduce the TOC to 44 mg L-1. MD was used to desalinate the pretreated PW resulting in a high quality treated water (reducing the total dissolved solids (TDS) concentration from 245,300 mg L-1 to 56 mg L-1). Three membranes with very different surface morphology were tested here: commercially available polyvinylidene fluoride, electrospun poly (vinylidene fluoride-co-hexafluoropropylene) nanofibers and multiwalled carbon nanotube coated polytetrafluoroethylene. The surface properties of an ideal membrane that is resistant to wetting and provides high flux is likely to depend on the TDS and properties of the PW. The integrated electrocoagulation-ultrafiltration-membrane distillation and crystallization process (EC-UF-MDC) was also used to treat PW. The focus of this work was to determine the feasibility of this integrated process for increasing water recovery. The results of this work suggest that optimizing the various unit operations in this integrated process could be used to recover PW. Dissolved organic compounds are known to foul the hydrophobic membrane used in MD. In this study, a significant reduction in membrane fouling was obtained by EC pretreatment, which can lead to a long-term durability of MD system. In addition, the use of MDC can help mitigate the scale formation. Also, treating PW will preserve surface and groundwater, which form 80% of the water utilized in hydraulic fracturing, and reduce the amount of PW directly disposed in Class II disposal wells, which further address the main cause of earthquakes. Finally, the integrated EC-MF pilot-scale system will be used to pretreat and reuse PW. The EC reactor (37.5 L) was built based on experiences gained from working with a laboratory scale (1 L). The integrated process will be evaluated at Texas Tech University (TTU). The design and construction of the EC-MF system are discussed in this work. The pilot-scale system has a capacity of treating 3600 L/day PW. The system layout is also discussed in this study. The EC-MF process was designed based on 70% feed water recovery. Turbidity, TSS, and TOC analysis will be obtained for samples collected during the 5 days operation. The goal of this work is to achieve a reduction of 95, 90, and 70% for turbidity, TSS, and TOC, respectively, which is the pretreated PW quality needed to be further treated by TTU

Evaluating One-Step Catalytic Free Method Including Hydrolysis, Esterification, Transesterification, and Degradation Reactions to Produce Biodiesel from Soybean Oil

Due to the environmental and economic impacts of diesel fuel based on petroleum, several studies have been done to find an alternative source of energy. Biodiesel is considered one of these alternative sources. It is a renewable source of energy produced from vegetable oils and animal fats. There are two main reaction routes used to produce biodiesel (fatty acid methyl esters). Transesterification reaction is the first route used to convert triglycerides to fatty acid methyl esters (FAMEs), while hydrolysis followed by esterification reactions are the second route employed to convert triglycerides to free fatty acids (FFA) and then further converted to FAMEs. The traditional method used to produce FAMEs is the catalytic method, such as acid and alkali-catalyzed. However, a common drawback of these two methods is they are very sensitive to the presence of water. The free-catalytic method (supercritical methanol method) was, also, developed to generate FAMEs. The major drawback in this method is the severe conditions, of temperature and pressure used to produce FAMEs. The objective of this study was to evaluate the one-step catalytic free method at subcritical conditions using soybean oil (SBO), methanol (MeOH), and water (H2O) as reactants. Two system configurations were investigated, continuous and batch systems. A variety of conditions were tested, such as reaction time, temperature, and molar ratio (SBO:MeOH:H2O). Furthermore, a kinetic model described by four reactions (transesterification, hydrolysis, esterification, and degradation) was developed depending on current and previous studies done to produce FAMEs. Theoretical results of this model showed a sufficient agreement with experimental results due to obtaining an accepted standard error of estimate (3.86 and 6), which can indicate how much experimental and theoretical results are different, in both batch and continuous systems, respectively. This model showed that the optimum biodiesel yield values are ((83% and 55%) in batch and continuous systems, respectively, which occurred under sub-critical conditions and 1:39:22 molar ratio of SBO:MeOH:H2O. Also, the effects of degradation reactions were explained in this work. In general, the results in this study establish a strong understanding about all the reactions which happened in a one-step sub-critical method

Removal of Emerging Contaminants from Wastewater Streams Using Membrane Bioreactors: A Review

Water is a very valuable natural resource. As the demand for water increases the presence of emerging contaminants in wastewater has become a growing concern. This is particularly true when one considers direct reuse of wastewater. Obtaining sufficient removal of emerging contaminants will require determining the level of removal for the various unit operations in the wastewater treatment process. Membrane bioreactors are attractive as they combine an activated sludge process with a membrane separation step. They are frequently used in a wastewater treatment process and can operate at higher solid loadings than conventional activated sludge processes. Determining the level of removal of emerging contaminants in the membrane bioreactor step is, therefore, of great interest. Removal of emerging contaminants could be by adsorption onto the biomass or membrane surface, biotransformation, size exclusion by the membrane, or volatilization. Given the fact that most emerging contaminants are low molecule weight non-volatile compounds, the latter two methods of removal are usually unimportant. However, biotransformation and adsorption onto the biomass are important mechanisms of removal. It will be important to determine if the microorganisms present at given treatment facility are able to remove ECs present in the wastewater

Integrated Electrocoagulation, Ultrafiltration, Membrane Distillation, and Crystallization for Treating Produced Water

Produced water (PW) generated from hydraulic fracturing operations was treated using an integrated electrocoagulation, ultrafiltration, membrane distillation, and crystallization process (EC UF MDC). The aim was to determine the viability of this integrated process for maximizing water recovery. The results obtained here indicate that optimizing the various unit operations could lead to increased recovery of PW. Membrane fouling limits all membrane separation processes. A pretreatment step to suppress fouling is essential. Here, removal of total suspended solids (TSS) and total organic carbon (TOC) was achieved by electrocoagulation (EC) followed by ultrafiltration (UF). The hydrophobic membrane used in membrane distillation may be fouled by dissolved organic compounds. Reducing membrane fouling is essential to increase the long-term durability of the membrane distillation (MD) system. In addition, combining membrane distillation with crystallization (MDC) can help reduce scale formation. By inducing crystallization in the feed tank, scale formation on the MD membrane was suppressed. The integrated EC UF MDC process can impact Water Resources/Oil & Gas Companies. Conservation of surface and groundwater is possible by treating and reusing PW. Additionally, treating PW reduces the amount of PW disposed in Class II disposal wells and promotes more environmentally sustainable operations

Innovative Approaches to Poultry Processing Wastewater Treatment: The Stainless Steel Ultrafiltration Membrane as a Viable Option

In pursuit of sustainability, we explored replacing conventional dissolved air floatation (DAF) in poultry processing wastewater (PPW) treatment with a precisely tuned 0.02 µm stainless-steel ultrafiltration (SSUF) membrane. SSUF is a robust, homogenously porous membrane with strong chemical resistance, ease of cleaning, and exceptional resistance to organic fouling. Unlike polymeric membranes, it can be regenerated multiple times, making it a cost-effective choice due to its compatibility with harsh chemical cleaning. The PPW used for the study was untreated wastewater from all processing units and post-initial screening. Our study revealed the SSUF membrane’s exceptional efficiency at eliminating contaminants. It achieved an impressive removal rate of up to 99.9% for total suspended solids (TSS), oil, grease, E. coli, and coliform. Additionally, it displayed a notable reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN), up to 90%, 76%, and 76%, respectively. Our investigation further emphasized the SSUF membrane’s ability in pathogen removal, affirming its capacity to effectively eradicate up to 99.99% of E. coli and coliform. The measured critical flux of the membrane was 48 Lm−2h−1 at 38 kPa pressure and 1.90 m/s cross-flow velocity. In summary, our study highlights the considerable potential of the SSUF membrane. Its robust performance treating PPW offers a promising avenue for reducing its environmental impact and advocating for sustainable wastewater management practices

Measurement model of e-SQ dimensions and users' satisfaction in Malaysia IHL

Quality of e-service is one of the critical factors that decide the success or failure of organizations. It may increase competitive advantages as well as enhance the relationships with the customers. Achieving high e-service quality and user satisfaction are challenging since they depend fundamentally on user perception and expectation which can be tricky at times. To date, there is no agreement as to what service quality is, and how it should be measured, whether it is a function of statistical measures of quality including physical defects or managerial judgment, or it is a function of customer perception about the services. This paper deep-dived the quality of e-services offered by five Malaysian Institutes of High Learning (IHL) including two private and three public universities. A quantitative approach was utilized to collect the data and AMOS 21 was used to analyze the data and develop the measurement model. The paper aims to find the relationship between e-service quality dimensions and the user satisfaction by using Conformity Factor Analysis (CFA) test with 320 students in the target universities. The research results indicated that the measurement model has acceptable values and ready to conduct the Structural Equation Model (SEM) for the relationship between e-SQ dimensions and user satisfaction. Achieving high user satisfaction can enhance the competitive advantage of the universities in their respective target markets

Analysis of significant dimensions of e-service quality in Malaysian universities

The measure of e-service quality in higher education is very critical due to their importance in attracting students and retaining tuition-based returns. The literatures show lack of study on e-SQ in Malaysian universities. This gap should be considered because universities suffer from a continuous rivalry to attract students not only to achieve high income, but also to improve the universities ranking. This research aims to fill this gap by defining the significant dimensions for measuring e-service quality in higher education in Malaysia to help universities to enhance their e-services to exceed their competitors and achieve high tuition-based returns. Nine dimensions are proposed for evaluating e-services in Malaysian universities. These dimensions are selected from the common scales of e-service quality as they can affect the students' perceives and expectations towards the services. Moreover, the selected dimensions are covered all the aspects of e-service quality in higher education in terms of their variation and their contents. A pilot study based on structured questionnaire is conducted with the students of five universities to collect the data necessary for the research. EFA analysis is conducted by using SPSS software package to analyze the data and come out with the new e-SQ dimensions. The results revealed that six dimensions are of great importance in evaluating the e-services provided by the Malaysian universities