A novel approach for the production of soy protein isolates was investigated integrating electroacidification and membrane ultrafiltration. The effect of electroacidification on the ultrafiltration performance and physicochemical properties of the soy protein extracts was obtained by comparing an electroacidified (pH 6) and a non-electroacidified (pH 9) soy protein extract. The effect of membrane fouling on the permeate flux decline was studied in a hollow fiber and a dead end ultrafiltration system. Due to more significant membrane fouling, the permeate flux was always lower for the electroacidified extract, resulting in at least 1.5-fold increase in the total fouling resistance compared to the non-electroacidified extract. The total amount of protein deposited on the membrane surface during unstirred dead-end ultrafiltration was comparable (about 7 mg/cm2) for both soy protein extracts. The discrepancy between the total fouling resistance and the protein deposition estimates was attributed to the formation of denser (less permeable) fouling deposit for the electroacidified extract, which was supported by scanning electron microscopy studies of fouled membranes. The removal of carbohydrates and minerals was evaluated for direct ultrafiltration and two-stage discontinuous diafiltration using a hollow fiber system. The carbohydrate removal results were always consistent with the theoretical predictions, indicating that the carbohydrates were freely permeable across the membrane. In contrast, the minerals were partially retained by the membrane, but to a higher extent for the non-electroacidified extract, which demonstrated that the electroacidification pretreatment enhanced the mineral removal during the ultrafiltration. Incorporation of the diafiltration step improved the ash (mineral) and carbohydrate removal. Stronger electrostatic interactions between soy proteins, calcium/magnesium, and phytic acid (antinutrient) at alkaline pH resulted in less efficient removal of calcium, magnesium, and phytic acid during the ultrafiltration of the non-electroacidified extract compared to the electroacidified extract. Consequently, the soy protein isolates produced by electroacidification and the hollow fiber ultrafiltration had a lower mineral and phytic acid content. The protein content was at least 88 % (dry basis), with or without the electroacidification pretreatment. The study of the viscosity revealed that the electroacidification pretreatment reduced the viscosity of the soy protein extract, which resulted in a lower axial pressure drop increase during the ultrafiltration of the electroacidified extract compared to the non-electroacidified extract. Adjusting the pH of the electroacidified extract to 9 and the pH of the non-electroacidified extract to 6 had a great impact on the particle size distribution but only a marginal effect on the viscosity of the pH adjusted extracts. This indicated that the pH and the particle size distribution were not responsible for the viscosity difference between the electroacidified and the non-electroacidified soy protein extracts. It was proposed that the electroacidification pretreatment had some impact on the water hydration capacity of the soy proteins, which consequently affected the viscosity.

The goal of drinking water treatment is to produce and deliver safe water to the consumers. To achieve these objectives water treatment plants are designed based on the concept of the multibarrier approach which combines several drinking water treatment processes in order to increase the reliability of the system. The presence of pharmaceutically active compounds (PhACs), personal care products (PCPs) and endocrine disrupting compounds (EDCs) in drinking water sources is becoming a concern, because of chronic and indirect human exposure to contaminant mixtures at sub-therapeutic levels via drinking water consumption. Membrane filtration can be an efficient treatment process to remove microorganisms and/or trace organic contaminants from drinking water sources. However, membranes are confronted by a major limitation: membrane fouling. Fouled membranes suffer from a loss in performance either leading to a reduction in flux or a higher pressure requirement. Generally, membrane fouling increases the need for membrane maintenance measures such as backwashing and chemical cleaning which has a negative impact on the operating costs and membrane life time. Severe membrane fouling may even impact permeate quality and/or compromise membrane integrity. The aim of this study was to establish if biofiltration pretreatment without prior coagulation would be able to control membrane fouling in natural waters. The second objective investigated the removal of trace organic contaminants by individual treatment processes (i.e. biofiltration and membrane filtration). Parallel to this work, the presence and concentration of selected trace organic contaminants in Grand River (Ontario, Canada) were determined. The trace organic contaminants investigated included atrazine, carbamazepine, DEET, ibuprofen, naproxen, and nonylphenol. Direct biofiltration pretreatment (no coagulation) significantly reduced both reversible and irreversible fouling of ultrafiltration membranes. Results showed that the different degree of reduction of hydraulically reversible fouling was primarily attributed to the absolute concentration of a specific fraction of the dissolved organic matter (i.e. biopolymers) in the biofilter effluent (i.e. membrane feed). The study also suggests that the composition of biopolymers rather than their absolute concentration is important for the control of irreversible fouling. High pressure membranes such as nanofiltration membranes are also subjected to fouling. Results showed that biofiltration pretreatment was able to achieve fouling control but membrane characteristics (i.e. molecular weight cut off) influence the efficiency of the pretreatment. This study also showed that not only biopolymers but also humic substances and low molecular weight acids are being rejected by nanofiltration membranes. Selected trace organic contaminants were detected in Grand River water in the low ng/L range with detection frequencies between 48 to 100%. Seasonal occurrence patterns could be explained by compound use and possible degradation mechanisms. These results confirm the impact of human activities on the Grand River. This study showed that under the right conditions rapid biofiltration is capable of completely removing biodegradable emerging contaminants at ng/L concentrations. DEET, ibuprofen, and naproxen were biodegradable and therefore amenable to removal while carbamazepine and atrazine were recalcitrant. Factors such as empty bed contact time, influent concentration, and temperature influenced the biodegradation kinetics. Finally, both membrane and contaminant properties influenced the degree of rejection achieved by nanofiltration membranes. Results showed that steric hindrance and electrostatic repulsion were the major rejection mechanisms. Several benefits are associated with the use of direct biofiltration for drinking water treatment. These benefits include: the removal of easily biodegradable organic matter leading to biologically stable effluents; the removal of biodegradable trace organic contaminants contributing to the multibarrier approach; the absence of chemicals coagulation which is of advantage for operations in isolated areas; the simple operation and maintenance which is an advantage for locations with limited trained operators; and finally if used prior to membrane filtration biofiltration pretreatment can control membrane fouling.

A novel approach for the production of soy protein isolates was investigated integrating electroacidification and membrane ultrafiltration. The effect of electroacidification on the ultrafiltration performance and physicochemical properties of the soy protein extracts was obtained by comparing an electroacidified (pH 6) and a non-electroacidified (pH 9) soy protein extract. The effect of membrane fouling on the permeate flux decline was studied in a hollow fiber and a dead end ultrafiltration system. Due to more significant membrane fouling, the permeate flux was always lower for the electroacidified extract, resulting in at least 1.5-fold increase in the total fouling resistance compared to the non-electroacidified extract. The total amount of protein deposited on the membrane surface during unstirred dead-end ultrafiltration was comparable (about 7 mg/cm2) for both soy protein extracts. The discrepancy between the total fouling resistance and the protein deposition estimates was attributed to the formation of denser (less permeable) fouling deposit for the electroacidified extract, which was supported by scanning electron microscopy studies of fouled membranes. The removal of carbohydrates and minerals was evaluated for direct ultrafiltration and two-stage discontinuous diafiltration using a hollow fiber system. The carbohydrate removal results were always consistent with the theoretical predictions, indicating that the carbohydrates were freely permeable across the membrane. In contrast, the minerals were partially retained by the membrane, but to a higher extent for the non-electroacidified extract, which demonstrated that the electroacidification pretreatment enhanced the mineral removal during the ultrafiltration. Incorporation of the diafiltration step improved the ash (mineral) and carbohydrate removal. Stronger electrostatic interactions between soy proteins, calcium/magnesium, and phytic acid (antinutrient) at alkaline pH resulted in less efficient removal of calcium, magnesium, and phytic acid during the ultrafiltration of the non-electroacidified extract compared to the electroacidified extract. Consequently, the soy protein isolates produced by electroacidification and the hollow fiber ultrafiltration had a lower mineral and phytic acid content. The protein content was at least 88 % (dry basis), with or without the electroacidification pretreatment. The study of the viscosity revealed that the electroacidification pretreatment reduced the viscosity of the soy protein extract, which resulted in a lower axial pressure drop increase during the ultrafiltration of the electroacidified extract compared to the non-electroacidified extract. Adjusting the pH of the electroacidified extract to 9 and the pH of the non-electroacidified extract to 6 had a great impact on the particle size distribution but only a marginal effect on the viscosity of the pH adjusted extracts. This indicated that the pH and the particle size distribution were not responsible for the viscosity difference between the electroacidified and the non-electroacidified soy protein extracts. It was proposed that the electroacidification pretreatment had some impact on the water hydration capacity of the soy proteins, which consequently affected the viscosity.

The goal of drinking water treatment is to produce and deliver safe water to the consumers. To achieve these objectives water treatment plants are designed based on the concept of the multibarrier approach which combines several drinking water treatment processes in order to increase the reliability of the system. The presence of pharmaceutically active compounds (PhACs), personal care products (PCPs) and endocrine disrupting compounds (EDCs) in drinking water sources is becoming a concern, because of chronic and indirect human exposure to contaminant mixtures at sub-therapeutic levels via drinking water consumption. Membrane filtration can be an efficient treatment process to remove microorganisms and/or trace organic contaminants from drinking water sources. However, membranes are confronted by a major limitation: membrane fouling. Fouled membranes suffer from a loss in performance either leading to a reduction in flux or a higher pressure requirement. Generally, membrane fouling increases the need for membrane maintenance measures such as backwashing and chemical cleaning which has a negative impact on the operating costs and membrane life time. Severe membrane fouling may even impact permeate quality and/or compromise membrane integrity. The aim of this study was to establish if biofiltration pretreatment without prior coagulation would be able to control membrane fouling in natural waters. The second objective investigated the removal of trace organic contaminants by individual treatment processes (i.e. biofiltration and membrane filtration). Parallel to this work, the presence and concentration of selected trace organic contaminants in Grand River (Ontario, Canada) were determined. The trace organic contaminants investigated included atrazine, carbamazepine, DEET, ibuprofen, naproxen, and nonylphenol. Direct biofiltration pretreatment (no coagulation) significantly reduced both reversible and irreversible fouling of ultrafiltration membranes. Results showed that the different degree of reduction of hydraulically reversible fouling was primarily attributed to the absolute concentration of a specific fraction of the dissolved organic matter (i.e. biopolymers) in the biofilter effluent (i.e. membrane feed). The study also suggests that the composition of biopolymers rather than their absolute concentration is important for the control of irreversible fouling. High pressure membranes such as nanofiltration membranes are also subjected to fouling. Results showed that biofiltration pretreatment was able to achieve fouling control but membrane characteristics (i.e. molecular weight cut off) influence the efficiency of the pretreatment. This study also showed that not only biopolymers but also humic substances and low molecular weight acids are being rejected by nanofiltration membranes. Selected trace organic contaminants were detected in Grand River water in the low ng/L range with detection frequencies between 48 to 100%. Seasonal occurrence patterns could be explained by compound use and possible degradation mechanisms. These results confirm the impact of human activities on the Grand River. This study showed that under the right conditions rapid biofiltration is capable of completely removing biodegradable emerging contaminants at ng/L concentrations. DEET, ibuprofen, and naproxen were biodegradable and therefore amenable to removal while carbamazepine and atrazine were recalcitrant. Factors such as empty bed contact time, influent concentration, and temperature influenced the biodegradation kinetics. Finally, both membrane and contaminant properties influenced the degree of rejection achieved by nanofiltration membranes. Results showed that steric hindrance and electrostatic repulsion were the major rejection mechanisms. Several benefits are associated with the use of direct biofiltration for drinking water treatment. These benefits include: the removal of easily biodegradable organic matter leading to biologically stable effluents; the removal of biodegradable trace organic contaminants contributing to the multibarrier approach; the absence of chemicals coagulation which is of advantage for operations in isolated areas; the simple operation and maintenance which is an advantage for locations with limited trained operators; and finally if used prior to membrane filtration biofiltration pretreatment can control membrane fouling.

ABSTRACT SULPHATE REMOVAL BY NANOFILTRATION FROM WATER Karabacak, Asli M.Sc., Department of Environmental Engineering Supervisor: Prof. Dr. &Uuml / lk&uuml / Yetis Co-advisor: Prof. Dr. Mehmet Kitis December 2010, 152 pages Excess sulphate in drinking water poses a problem due to adverse effects on human health and also due to aesthetic reasons. This study examines the nanofiltration (NF) of sulphate in surface water using a laboratory cross-flow device in total recycle mode. In the study, three NF membranes, namely DK-NF, DL-NF and NF-270, are used. The influence of the main operating conditions (transmembrane pressure, tangential velocity and membrane type) on the steady-state permeates fluxes and the retention of sulphate are evaluated. Kizilirmak River water is used as the raw water sample. During the experimental studies, the performance of NF is assessed in terms of the parameters of UVA254, sulphate, TOC and conductivity of the feed and permeates waters. Results indicated that NF could reduce sulphate levels in the surface water to a level below the guideline values, with a removal efficiency of around 98% with all three membranes. DK-NF and NF-270 membranes showed fouling when the surface water was fed directly to the system without any pre-treatment. MF was found to be an effective pretreatment option for the prevention of the membrane fouling, but no further removal of sulphate was achieved. Parametric study was also conducted. No change in flux values and in the removal of sulphate was observed when the crossflow velocity was lowered. The flux values were decreased as the transmembrane pressure was lowered / however there were not any decrease in the sulphate removal efficiency.

Three experimental studies were conducted to quantify the effects of system cycling, evaporator airflow, and condenser coil fouling on the performance of residential air conditioners. For all studies, the indoor dry-bulb (db) temperature was 80°F (26.7°C) db. The cycling study consisted of twelve transient tests conducted with an outdoor temperature of 95°F (35°C) db for cycle times of 6, 10, 15, and 24 minutes. Indoor relative humidities of 40%, 50%, and 60% were also considered. The evaporator airflow study consisted of twenty-four steady-state tests conducted with an indoor condition of 67°F (19.4°C) wet-bulb (wb) for evaporator airflows ranging from 50% below to 37.5% above rated airflow. Outdoor temperatures of 85°F (29.4°C) db, 95°F (35°C) db, and 105°F (40.6°C) db were also considered. The coil fouling study used a total of six condensers that were exposed to an outdoor environment for predetermined amounts of time and tested periodically. Three of the condensers were cleaned and retested during the periodic testing cycles. Testing consisted of thirty-three steady-state tests conducted with an indoor condition of 67°F (19.4°C) wb for outdoor exposure times of 0, 2000, 4000, and 8000 hours. Outdoor temperatures of 82°F (27.8°C) db and 95°F (35°C) db were also considered.

Die vorliegende Arbeit zeigt die Untersuchung des Einflusses mineralischer Braunkohlebestandteile auf die Ansatzbildung an Wärmeübertrageroberflächen. Unter Ansatzbildung in braunkohlebefeuerten Dampferzeugern werden die Bildung und Ablagerung von Feststoffen in rauchgasbeaufschlagten Bereichen der Brennkammer und der Elektrofilter verstanden. Hierzu wurde auf Basis von thermodynamischen Modellrechnungen ein Prognosemodell entwickelt, mit dessen Hilfe das Ansatzbildungsverhalten von Braunkohlen aus dem rheinischen Revier vergleichbar und bewertbar gemacht werden kann. Über die Ermittlung reaktiver und nichtreaktiver Aschebestandteile werden Nicht-Gleichgewichtszustände erfasst. Darüber hinaus wird die Güte der entwickelten thermochemischen Prognosemodelle anhand betrieblicher und experimenteller Erfahrungen bewertet. Darauf basierend werden Grenzen und Möglichkeiten der rechnerischen Methoden zur Vorhersage des Ansatzbildungsverhaltens ermittelt.

Thesis (M. Phil.)--University of Hong Kong, 1987.

Biofouling, or the formation of biofilm on membrane surfaces, can decrease the performance (decreased flux and/or increased operating pressure) of a reverse osmosis (RO) membrane system in a water treatment plant. However, biofilms have been used in water treatment systems to remove organic carbon from water via biofilters and successfully reduce biofilm growth downstream. This research investigates the possibility that the heterotrophic biofilm present on membrane surfaces removes nutrients from the treatment water, thereby making it nutrient deprived as it travels along the treatment train. This may potentially be exploited as an in situ biofilter to actively remove dissolved organic carbon (DOC) from the treatment water, thereby protecting downstream membrane surfaces from biofouling. Analysis of fouled membranes from the Dunedin water treatment plant in Dunedin, FL indicates the presence of biofilm on membrane surfaces in a gradient pattern with a higher level of fouling at the front of the element. Additionally, the community structure of the biofilm at the front of the element is unique with respect to the feed-water and downstream membrane material. Additionally, a carbon (and nitrogen) mass balance study was performed at the water treatment plant in Dunedin, FL through extensive sampling of DOC at multiple locations of the RO membrane system over a 20 month period. Plant-level mass balance results indicate a significant pool of DOC was consistently unaccounted for, and presumably assimilated or otherwise removed within the membrane system. Sampling also indicated a removal of total nitrogen. Additionally, the specific UV absorbance (SUVA) of the DOC in concentrate was consistently greater than that of the feed water, suggesting the removal of labile aliphatic carbon as the feed water travels through the feed channel of the membrane system. A pilot system was designed and built to operate under plant conditions (flow rate and pressure) to test if the biofilm on the surface of the membrane can have a protective effect for downstream membrane material. A fouled membrane element was pulled from the plant at the same time and general location as an autopsied element (to determine composition on the surface) and used in the pilot system. Feed and concentrate water from the pilot was directed to flat sheet modules for performance testing and surface characterization. This allowed for characterization of the two sections without disturbing the membrane element. Differences in performance and foulant deposition were characterized for the two sections as a function of carbon addition and flow rate. The results from this testing suggest the membrane element, or the biofilm on its surface, has both a performance and a foulant deposition benefit for downstream membranes as compared to feed membrane material. This benefit also displayed an increasing trend as the concentration of organic carbon fed into the system increases.

With increasing water reuse applications and upcoming stringent regulations for treated wastewater effluent discharge, wastewater plants need to consider alternative technologies beyond conventional treatment processes. The new regulations, Numeric Nutrient Criteria (NNC), may regulate discharge nitrogen and phosphorus concentrations to as low as 0.5 mg/L as N and 10 μg/L as P respectively. To meet these target requirements, system retrofitting to incorporate chemical or advanced nutrient removal systems possibly with membrane technology will most likely be required. Although microfiltration/ultrafiltration membranes coupled with biological processes, otherwise known as membrane bioreactors (MBR), remove contaminants and suspended solids, nutrient removal is minimal to none. This emphasizes the importance of the biological process in MBRs. This study evaluated and tested the improvement of biological nutrient removal (BNR) in an MBR system which can meet NNC regulations along with the optimization of membrane operation for the reduction of fouling and energy consumption. A pilot study was conducted at the City of Tampa wastewater treatment plant and was divided into four phases of experimentation using two submerged MBR membranes operated with modified biological configurations. Laboratory analyses and data collection were conducted during the experiments and the performance evaluated for each configuration. System configurations were also optimized throughout each phase of testing for nutrient removal. Important factors used in the development of an appropriate configuration included isolation of the membrane tank from the biological reactors in the design, control of the dissolved oxygen (DO) concentrations or specifically the oxidation reduction potential (ORP) during operation and appropriate internal recirculation rates between the reactors. The results of this study provided information relevant for the assessment of both the BNR process and membrane performance. Membrane performance data indicated the importance and effect of air scouring (despite energy consumption) on membrane fouling for long-term stable flux operation as well as the cleaning frequency whether chemical enhanced backwash (CEB) or clean-in-place (CIP). This assessment also discussed how BNR systems can be enhanced through the incorporation of important design factors to eliminate the inhibiting factors of nitrogen and phosphorus removal such as dissolved oxygen. One of the biological processes tested in this study achieved effluent nitrogen and phosphorus concentrations below 5 mg/L and 1 mg/L respectively. Although the process tested did not meet NNC criteria, it can be applied with chemical precipitation. This, in turn, can reduce the operating and maintenance (O&M) costs associated with the chemical precipitation of phosphorus.