Dissertations / Theses on the topic 'Trace organic removal'

With the continual concern over the presence of naturally occurring and anthropogenic inorganic and trace organic contaminants in the aquatic environment there is a growing need for the implementation of innovative treatment processes for the elimination of these contaminants from natural waters and wastewater effluents. While conventional treatment methods are ineffective in the removal of emerging contaminants such as steroidal hormones and pesticides, membrane technology, including electrodialysis (ED), has been highlighted as a potential treatment option. However, the clear lack of fundamental understanding of the behaviour of contaminants in ED is a current limitation for its extensive utilisation and is a critical issue that needs to be addressed. ED processing potentialities have not been fully exploited and more research is needed to account for all the key parameters such as contaminant physicochemical properties, solution chemistry and the presence of organic matter. The purpose of this study was to elucidate the mechanisms of inorganic and trace organic contaminant removal by ED. The inorganic contaminants fluoride, nitrate and boron were selected due to their ubiquitous nature in the environment and public health concerns resulting from longterm exposure. The hydrated radius and strength of hydration shells played a significant role in ionic transport, whereby nitrate with a smaller hydrated radius was removed more effectively (94.1 %) than fluoride (68.3 %) with a larger hydrated radius. While fluoride and nitrate removal was pH independent, the pH dependent speciation of boron enhanced its removal with increasing pH. Territorial binding and/or complexation of the inorganics with organic matter enhanced removal. The removal of a range of trace inorganics (e.g. arsenic, calcium, magnesium, uranium) from a brackish groundwater from a remote Australian community was investigated. Undissociated inorganics were not transported through the membranes, whereas dissociated inorganics were due to electrostatic attraction. At acidic-neutral conditions ionic transport was the dominant removal mechanism. At neutral to alkaline conditions insoluble carbonate species precipitated and deposited as a membrane scaling layer (60 μm). This has serious implications for the long-term practical applicability of ED to treat real waters as scaling increased ED stack resistance (pH 3: 27.5 4, pH 11: 50 4) and decreased total dissolved solids removal (pH 3: 99 %, pH 11: 89.5 %). While the treatment of trace organics by other membrane processes has been widely studied, their fate in ED and interaction with ED membranes is relatively unknown. Trace contaminant-membrane interaction studies were undertaken to quantify the partitioning of trace organics; namely steroidal hormones and the pesticide endosulfan, to ED membranes by measuring membrane-water partition coefficients (log KM). The extremely high sorption capacity of the membranes was attributed to hydrogen bonding between the trace organic and membrane functional groups. Hormone sorption during ED was influenced by solution pH and organic matter. In the case of estrone, membrane sorption decreased at pH 11 (487 μg/cm3) compared to pH 7 (591 μg/cm3) due to dissociation and membrane electrostatic repulsion .At pH 11, repulsion between dissociated estrone and HA coupled with membrane electrostatic attraction resulted in increased sorption. The findings from this study highlight that the transport of trace contaminants will depend largely on the characteristics of the membranes used in the ED process as well as the physicochemical characteristics of the contaminants, their interaction with the ED membranes and the presence of other inorganic and/or organic compounds. The knowledge gained has direct applications to current problems and uncertainties in water and wastewater treatment with regards to the fate and transport of contaminants.

Advanced oxidation processes (AOPs) are commonly used for the destruction of persistent trace organic contaminants (TOrCs) that survive conventional wastewater treatment processes. Three types of AOPs, UV/H2O2, sunlight photolysis and photo-Fenton are experimentally investigated and mathematically quantified to anticipate the fate of TOrCs during oxidation processes, specifically addressing the significant effect of reaction by-products and water matrix on oxidation efficiencies. Hydrogen peroxide UV photolysis is among the most widely used AOPs for the destruction of TOrCs in waters destined for reuse. Previous kinetic models of UV/H2O2 focus on the dynamics of hydroxyl radical production and consumption, as well as the reaction of the target organic with hydroxyl radicals. In this work, we build a predictive kinetic model for the destruction of p-cresol by hydrogen peroxide photolysis based on a complete reaction mechanism that includes reactions of intermediates with hydroxyl radicals. The results show that development of a predictive kinetic model to evaluate process performance requires consideration of the complete reaction mechanism, including reactions of intermediates with hydroxyl radicals. Applying the model to an annular flow-through reactor with reflecting walls, the model mathematically demonstrates that the wall reflectivity significantly enhances the rate of conversion of the target, accounting for the UV light reflection from the reacting walls, as well as the hydrodynamics of the annular flow. Direct and indirect sunlight photolysis is critically important in the breakdown of contaminants in effluent wastewater. The fate of a suite of TOrCs and estrogenic activity were investigated in an effluent-dependent stream. Some TOrCs, which are not sufficiently attenuated through biodegradation and soil adsorption were destructed obviously with distance of travel in the stream. Independent experiments, conducted in batch reactor with 17α-ethinylestradiol (EE2) spiked in effluent showed that attenuation of estrogenic compounds maybe due in part to indirect photolysis caused by formation of reactive species from sunlight absorption. Further investigation was conducted using selective probe compounds to characterize reactive species. And results showed that singlet oxygen generated from excited state of effluent organic matter was responsible for essentially all observed transformations of targets in the effluent in Tucson. To mathematically quantify the photo-Fenton AOP, a kinetic model is proposed for the photolysis of Fe3+ hydroxo complexes at low pH (pH ≤ 3.0). The model incorporates elementary reactions of the Fenton-like and UV/H2O2 system. Iron speciation and photochemical parameters, including the molar absorptivities of light-absorbing species and the quantum yields of Fe3+ and FeOH2+ hydrolysis are experimentally validated. However, the predicted, time-dependent Fe2+ concentrations during Fe3+ photolysis are much lower than measured. The possible missing elements in the model could be (i) quenching of OH radicals by unknown species, or/and (ii) shielding of Fe2+ by unknown compounds at the beginning of the process.

Pollution of water by herbicides and heavy metals has caused world wide concern because of the adverse effects of these pollutants on the environment, humans and wildlife. This has resulted in tighter legislation being imposed on the levels of these pollutants in drinking water. For example, the European Union (EU) has set the legislation in the drinking water Directive Admissible Concentration for a single herbicide to a maximum of 0.1 ppb. Despite the tight environmental pollution controls, isolated cases of pollutants exceeding their limits are still encountered. This would suggest that research towards the efficient and effective removal of these pollutants will be an on-going process. In this study, sorption of copper and some selected herbicides e.g. atrazine, benazolin and 2,4-dichlorophenoxyacetic acid (2,4-D) was undertaken on a conventional activated carbon and its modified series. A low level detection method was developed using High Performance Liquid Chromatography (HPLC) and this system was used to quantify the sorption capacity of the herbicides. In order to understand the sorption mechanism of the targeted pollutants, physical and chemical characterisation of the adsorbents was undertaken using a variety of techniques. These include, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FT-IR) method, pore size distribution and surface area measurements, elemental analysis, sodium capacity determination, zeta potential and pH titration. The sorption data were presented and analysed by conventional adsorption isotherms. Sorption of the herbicides was favoured on carbon samples with least oxygen content while the uptake of copper was strongest in oxidised carbons. Kinetic experimental data were analysed by a pseudo second order model and the Boyd kinetic model. Molecular structural configurations and the physico-chemical properties of the adsorbent played a crucial role in the sorption behaviour of the herbicides.

Wastewater reuse is fast becoming an imperative issue based on the developments in water/wastewater engineering coupled with increasing pressures on water resources. Trace organic compounds (TOrCs) that exist in water/wastewater, are a serious threat once they were released in the environment. During the past decade, there has been much progress toward understanding the occurrence, fate and toxicology of trace organic pollutants that enter the environment in treated wastewater. The objective of the first part of this research was to evaluate the combined effects of sequential anaerobic/aerobic digestion on residual TOrCs, concentrating on chemicals that are responsible for observed estrogenic/androgenic activities in biosolids. Full-scale digestion was simulated using bench-scale bioreactors in which the primary independent variables were retention time, temperature, and oxygen loading during aerobic digestion. Treatment-dependent changes in estrogenic/androgenic activity and concentrations of specific Endocrine disrupting compounds (EDCs) were measured. Results suggest that standard mesophilic anaerobic digestion increases the total estrogenic/androgenic activity of sludge while aerobic digestion was effective in the reduction of estrogenic/androgenic activity as a supplementary treatment stage. The second part of the study was focused on the fate of TOrCs and estrogenic activity in water and sediment of the Santa Cruz River, which is effluent dependent except during infrequent periods of rainfall/runoff in Tucson area. Several sampling campaigns were carried out from 2011 to 2013. Results suggest that some organic TOrCs, including those that contribute to estrogenic activity, were rapidly attenuated with distance and time of travel in the Santa Cruz River. Indirect photolysis of estrogenic compounds through the river might play an important role for the observation of estrogenic activity changes in the SCR. Hydrophobic TOrCs may accumulate in river sediments during dry weather periods. Riverbed sediment quality is periodically improved through storm-related scouring during periods of heavy rainfall and runoff. Wastewater effluent can be applied to the algal biodiesel industry based on regional water stress across the world. In the third part of the research, reclaimed wastewater was explored for this purpose, simultaneously satisfying the needs for water, macronutrients such as nitrogen and phosphorus, and micronutrients necessary for growth of microalgae. At the same time, algal growth in conventionally treated wastewater will improve water quality through the same nutrient removal processes and perhaps by lowering residual levels of trace organics that are an impediment to potable reuse. Results showed that metals levels in most municipal wastewaters are unlikely to disrupt growth, at least by metals tolerant microalgae like Nannochloropsis salina. Cells can grow without inhibition on nutrients from treated municipal wastewater or a centrate stream derived from wastewater treatment. The results also suggest while wastewater provides a suitable nutrient source for algal growth, there is simply not enough municipal wastewater available to support a meaningful biofuels industry without water recycling and nutrient recovery/reuse from spent algae. The last part of the dissertation was the application of water/wastewater treatment techniques, specifically advanced oxidation processes (AOPs) in other industrial sectors. In the integrated circuit production industry, chemical formulations used for megasonic cleaning typically contain hydroxides, peroxides and carbonates, which can affect particle removal efficiency and feature damage. The role of carbonates and ammonia in modulating the oxidation power of megasonic irradiated alkaline solutions through the scavenging of hydroxyl radicals by varying levels of carbonates, bicarbonates, ammonia and solution temperatures on net generation of hydroxyl radicals for applications in semiconductor industry was investigated in this study. The simulation of actual megasonic cleaning process was carried out at acoustic frequency of ~ 1 MHz and different power densities. Carbonate ions were better scavengers of hydroxyl radicals than bicarbonate ions. The effect of bulk solution temperature revealed that the rate of generation of hydroxyl radicals at a power density of 8 W/cm² increased with temperature from 10-30°C, which suggests an increase of transient cavitation with temperature.

Nanofiltration (NF) is an attractive option for the treatment of wastewater e.g. municipal wastewater and landfill leachate. However, membrane fouling can be a major obstacle in the implementation of this technology. Fouling of nanofiltration membranes by hu-mic acids (HA) was investigated using bisphenol A (BPA) as an indicator chemical to dif-ferentiate between various mechanisms that may lead to a change in solute rejection. Three commercially available NF membranes were investigated and an accelerated foul-ing condition was achieved with a foulant mixture containing humic acids in an electro-lyte matrix. The effects of membrane fouling on the rejection of BPA were interpreted with respect to the membrane pore sizes and the fouling characteristics. Results report-ed here indicate that calcium concentration in the feed solution could be a major factor governing the humic acid fouling process. Moreover, a critical concentration of calcium in the feed solution was observed, at which membrane fouling was most severe. Mem-brane fouling characteristics were observed by their influence on BPA rejection. Such influence could result in either an increase or decrease in rejection of BPA by the three different membranes depending on the rejection mechanisms involved. It is hypothe-sised that these mechanisms could occur simultaneously and that the effects of each might not be easily distinguished. However, it was observed that their relative contribu-tion was largely dependent upon membrane pore size. Pore blocking, which resulted in a considerable improvement in rejection, was prominent for the more open pore size TFC-SR2 membrane. In contrast, the cake-enhanced concentration polarisation (CECP) effect was more severe for the tighter NF270 and NF90 membranes. For hydrophobic solutes such as BPA, the formation of the fouling layer could also interfere with the so-lute-membrane interaction, and therefore, exert considerable influence on the separa-tion process. The combined impact of humic acid fouling and CaCO3 scaling on the rejection of trace organic contaminants by a commercially available nanofiltration membrane was inves-tigated in this study. Due to the presence of humic acid in the feed solution, CaCO3 scal-ing behaviour differed substantially from that of a pure CaCO3 solution. A prolonged induction period was consistently observed prior to the onset of membrane scaling. In addition, membrane scaling following humic acid fouling did not result in a complete loss of permeate flux. This is consistent with the absence of any large CaCO3 crystals. In fact, the CaCO3 crystals on the membrane surface were quite small and similar in size, which would result in a relatively porous cake layer. At the onset of CaCO3 scaling the rejection of all three trace organic contaminants started to decrease dramatically. The observed decrease in rejection of the trace organic contaminants was much more se-vere than that reported previously with a single layer of either organic or colloidal foul-ing. Such severe decrease in rejection can be attributed to the extended cake-enhanced concentration polarisation effect occurring as a result of the combination of membrane fouling and scaling. The porous CaCO3 scaling layer could lead to a substantial cake-enhanced concentration polarisation effect. In addition, the top CaCO3 scaling layer could reduce the wall shear rate within the underlying humic acid fouling layer, causing an additional concentration polarisation (CP) effect.:1 INTRODUCTION 1 1.1 Fundamentals of NF/RO 1 1.1.1 Solute transport through NF/RO membranes 2 1.1.2 Separation mechanisms 3 1.1.2.1 Steric size exclusion 3 1.1.2.2 Donnan effect 3 1.1.2.3 Electrostatic repulsion 4 1.1.2.4 Adsorption 4 1.1.3 Environmental applications of NF/RO 5 1.1.4 Drinking water treatment from groundwater and surface water sources 5 1.1.5 Water/Wastewater reclamation 7 1.2 Classification and materials of NF/RO membranes 7 1.2.1 Membrane classes 7 1.2.2 Membrane materials 8 1.2.3 Organic membrane materials 9 1.2.3.1 Polyamide membranes 9 1.2.3.2 Cellulose acetate membranes 9 1.2.4 Inorganic membrane materials 10 1.3 Removal of trace organic contaminants 11 1.3.1 Impact of membrane characteristics 14 1.3.1.1 Molecular weight cut-off/pore size 14 1.3.1.2 Surface charge 14 1.3.1.3 Hydrophobicity/hydrophilicity 15 1.3.1.4 Surface morphology 15 1.3.2 Impact of feed characteristics 17 1.3.2.1 pH value 17 1.3.2.2 Ionic strength 18 1.3.2.3 Organic matter 19 1.3.2.4 Presence of divalent ions 20 1.3.2.5 Presence of foulants 20 1.3.2.6 Temperature 20 1.3.3 Impact of solute characteristics 22 1.3.3.1 Molecular weight 22 1.3.3.2 Molecular size (length and width)/molecular volume 22 1.3.3.3 Minimum projection area/Equivalent width 23 1.3.3.4 Charge 23 1.3.3.5 Hydrophobicity/hydrophilicity 24 1.3.4 Impact of operational characteristics 25 1.3.4.1 Transmembrane pressure/permeate or transmembrane flux 25 1.3.4.2 Cross-flow velocity/recovery/concentration polarisation 25 1.3.5 Impact of fouling on rejection 26 1.3.5.1 Organic fouling 28 1.3.5.2 Colloidal fouling 30 1.3.5.3 Inorganic fouling (scaling) 31 1.3.5.4 Biological fouling 32 1.3.6 Impact of membrane cleaning on rejection 32 1.3.6.1 Changes of membrane morphology due to cleaning 32 1.3.6.2 Impact on rejection of TrOCs due to cleaning 33 1.3.7 Validation at pilot and full scale systems 35 2 MEMBRANE FOULING IN THE NANOFILTRATION OF LANDFILL LEACHATE AND ITS IMPACT ON TRACE CONTAMINANT REMOVAL 37 2.1 Introduction 37 2.2 Materials and Methods 40 2.2.1 Analytical reagents and chemicals 40 2.2.2 Nanofiltration membrane 40 2.2.3 Membrane filtration set-up and protocol 41 2.2.4 Analytical technique 42 2.3 Results and discussion 42 2.3.1 Landfill leachate characterisation 42 2.3.2 Physico-chemical properties of bisphenol A 43 2.3.3 Influence of the calcium concentration on the flux 44 2.3.4 Influence of fouling on the rejection of organic contaminants 46 2.4 Conclusions 48 3 CHARACTERISING HUMIC ACID FOULING OF NANOFILTRATION MEMBRANES USING BISPHENOL A AS A MOLECULAR INDICATOR 50 3.1 Introduction 50 3.2 Materials and methods 52 3.2.1 Model NF membranes and membrane characterisation 52 3.2.2 Model trace organic contaminant 52 3.2.3 Organic foulant 53 3.2.4 Membrane filtration set-up 54 3.2.5 Filtration protocol 55 3.2.6 Analytical technique 56 3.3 Results and discussions 56 3.3.1 Membrane characteristics 56 3.3.2 Membrane fouling behaviour 58 3.3.3 Change of membrane hydrophobicity 61 3.3.4 Effects of organic fouling on the nanofiltration of BPA 63 3.3.5 Effects of organic fouling on rejection: the mechanisms 65 3.4 Conclusions 67 4 EFFECTS OF FOULING AND SCALING ON THE REJECTION OF TRACE ORGANIC CONTAMINANTS BY A NANOFILTRATION MEMBRANE: THE ROLE OF CAKE-ENHANCED CONCENTRATION POLARISATION 69 4.1 Introduction 69 4.2 Materials and methods 71 4.2.1 Nanofiltration membrane 71 4.2.2 Chemicals and reagents 71 4.2.3 Crossflow membrane filtration system 72 4.2.4 Experimental protocol 73 4.2.5 SEM-EDS analysis 74 4.2.6 Analytical methods 75 4.3 Results and discussion 75 4.3.1 Membrane characteristics 75 4.3.2 Membrane fouling and scaling development 76 4.3.3 Effects of fouling/scaling on the membrane rejection behaviour 79 4.3.4 Cake-enhanced concentration polarisation 85 4.4 Conclusions 87 5 SUMMARY AND CONCLUSIONS 88 6 REFERENCES 94 7 ACKNOWLEDGEMENTS 112

Although wastewater treatment plants are a line of defense in minimizing indiscriminate output of microconstituents to natural waters, we do not possess a fundamental understanding of the mechanisms involved in microconstituent removal during wastewater treatment. With this in mind, experiments were designed to investigate the factors that can influence the fate of four microconstituents, carbamazepine (CBZ), 17alpha-ethinylestradiol (EE2), iopromide (IOP), and trimethoprim (TMP), during biological suspended culture treatment. Specifically, the role that various ecological members of biological treatment systems play in biotransforming these compounds was evaluated. Sorption assays were performed with inactivated biomass samples (ammonia oxidizing bacteria (AOB), laboratory enriched heterotrophic cultures free of active nitrifiers with low (Ox⁻) or high (Ox⁺) oxygenase activity, and a nitrifying activated sludge (NAS) from a full-scale wastewater treatment plant) to determine whether partitioning dictates removal of individual microconstituents. No microconstituents sorbed to the AOB culture. Neither CBZ nor IOP sorbed to Ox⁻, Ox⁺ and NAS cultures; however, EE2 and TMP sorbed to the Ox⁻, Ox⁺ and NAS biomass. Sorption was positively influenced by the presence of exopolymeric substances (EPS) associated with the cultures. The protein content of EPS affected EE2 and TMP sorption more appreciably than the polysaccharide content of EPS. Further experiments were performed to investigate microconstituent biodegradation by AOBs, Ox⁻ and Ox⁺ cultures. The influence of growth state and oxygenase activity on biotransformation by each culture was also evaluated. Results indicate that EE2 was the only microconstituent that was amenable to biotransformation by batch cultured AOB and heterotrophic cultures. EE2 was biotransformed but not mineralized by AOB chemostat and batch cultures. TMP was not transformed by AOB batch or chemostat cultures; however both EE2 and TMP were transformed by Ox⁻ and Ox⁺ chemostat cultures. Radiolabeled studies showed that EE2 was mineralized by this culture. Kinetically, AOBs dominated EE2 transformation to monohydroxylated metabolites; however, both Ox⁻ and Ox⁺ cultures further degraded and mineralized EE2 and metabolites generated by AOBs. These results indicate that biotransformation of EE2 by NAS may be limited by heterotrophic activity whereas TMP fate may be a function of heterotrophic activity only. Oxygenase activity did not limit EE2 or TMP biotransformation in chemostat cultures. Subsequent experiments that were performed to identify the factors that influence heterotrophic degradation of EE2 and TMP indicated that the presence of readily biodegradable substrates slows EE2 and TMP biotransformation. The impact of slowly biodegradable substrates like EPS on EE2 and TMP degradation was unclear. These results suggest that EE2 and TMP are most amenable to biodegradation in bioreactors where endogenous conditions dominate.
Ph. D.

Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs). This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established. A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter. Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH. The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.

Non-point sources (NPS) of pollution are non-discernable, diffuse sources of pollution that are often difficult to localize and in turn mitigate. NPS can include stormwater runoff, agricultural/aquaculture wastes and wastes from small decentralized wastewater treatment systems, such as conventional septic systems. The mitigation of these NPS is imperative to reduce their potential detrimental effects on the water environment. This dissertation addresses novel treatment technologies for the mitigation of nutrients, particularly nitrogen, in Recirculating Aquaculture Systems (RAS) and onsite wastewater treatment systems (OWTS). The removal of trace organics limiting RAS production and water reuse were also investigated. The first question this dissertation addressed is: Can the application of a UV-TiO2 reactor reduce the concentration of off-flavor compounds in RAS? In the UV-TiO2 reactor, spray-coated TiO2 plates were placed in an aluminum reactor and exposed to UV light. The process was applied in both a full-scale sturgeon RAS and a bench-scale RAS for the degradation of Geosmin (GSM) and 2-methylisoborneol (MIB). Improved performance on the removal of GSM and MIB was observed when the UV-TiO2 was applied as a batch reactor since it allowed for a longer treatment time without the effect of constant production of the compounds in the biological treatment processes. Treatment performance of UV-TiO2 was affected by GSM and MIB concentrations and dissolved oxygen. No harmful effects were observed on other water quality parameters when the UV-TiO2 reactor was operated as a batch or side stream process. The second question this dissertation addressed is: Does the application of Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) in RAS improve nutrient and off-flavor compound removal when compared to conventional heterotrophic denitrification? T-SHAD combines tire mulch as an adsorbent and sulfur oxidizing denitrification for the removal of NO3--N from the aquaculture waters. Adsorption studies showed the tire has significant adsorption capacity for the off-flavor compounds GSM and MIB but can be limited by contact time and, possibly, the presence of competing organic matter in RAS. The application of T-SHAD as an effluent polishing step in RAS with a high empty bed contact time (EBCT) of 720 min removed 96.6% of NO3--N and 69.6% of GSM. The application of T-SHAD within RAS as denitrification side treatment for NO3--N removal resulted in lower EBCT (185 min) that limited NO3--N removal to 21% and showed no significant removal of off-flavor compounds. The comparison between T-SHAD and a molasses fed heterotrophic upflow packed bed reactor (UPBR), showed no significant differences in N species concentrations as well as off-flavor compound removal. However, high production of SO42- resulted from sulfur oxidizing denitrification (SOD) processes was noted. Hybrid Adsorption and Biological Treatment Systems (HABiTS), is composed of two biofilters in series employing ion exchange (IX) and nitrification for removal of NH4+ and tire scrap coupled with sulfur chips and oyster shells for both adsorption and SOD of NO3-. The third question addressed in this dissertation is: What IX/adsorption media best balances both ammonium removal and cost effectiveness for application in OWTS? Adsorption isotherms performed with different media materials showed that the zeolite material, clinoptilolite, was the best medium for the nitrification stage of HABiTS due to its high IX capacity for NH4+and cost. An adsorption capacity of 11.69 mg g-1 NH4+-N when in competition with other cations present in septic tank effluents was determined by the IX model fit to the data. The cost of clinoptilolite is significantly higher than the other media materials tested. However, the high adsorption capacity would allow for low dosages that can be combined with non-adsorptive material reducing overall costs. The fourth question this dissertation addressed is: How is the BNR process within HABiTS affected by IX? Results from side-by-side biofilter studies with HABiTS and a conventional nitrification/denitrification biofilter showed that the combined IX and nitrification in HABiTS can allow for faster startup, sustain variable loading, and achieve over 80% removal of NH4+ at a hydraulic loading rate of 0.34 m3 m-2-d-1 when compared to the conventional biofilter with 73% removal. Under lower loading rates the biological treatment was enhanced and dominated the NH4+ removal processes in both columns. The addition of a denitrification stage decreased Total Inorganic Nitrogen (TIN) by 53.54% and 40.97%, for the HABiTS treatment and the control treatment, respectively, under loading rates of 0.21 m3 m-2-d-1. Further decrease of NH4+-N loading rates results in high desorption of exchanged NH4+ in the clinoptilolite, resulting in lower TIN removal efficiencies (28.7%) when compared to the conventional control treatment (62%). The final question addressed in this dissertation is: Does the proposed hybrid system enhance the removal of TIN in OWTS under transient loading conditions? Further studies with HABiTS and the conventional biofilter were performed to determine N removal performance on an hourly basis. It was found that the performance of HABiTS varies with daily and hourly loads, particularly when recovering from periods of very low loading to high loadings and vice versa. If recovering from low loading periods, IX is observed for HABiTS and the biofilter outperforms the conventional treatment in overall TIN removal. However, recovery from a high loading period results in release of NH4+-N stored in the clinoptilolite and increased production of NO3--N that could affect the performance of the denitrification stage.

Endocrine disrupters and trace organic contaminants are recently recognized contaminants in wastewaters. Current concept is the multibarier approach where the contaminants are removed from the water cycle both by water and wastewater treatment facilities, as well as natural die-away. In this thesis work LC/MS/MS determination of selected EDC compounds, namely, diltiazem, progesterone, estrone, carbamazepine, benzyl butyl phthalate and acetaminophen, at ultra trace levels, have been carried out by optimizing analytical parameters. In addition, new methods were developed for their analysis in sludge samples at sub ppb levels. Following optimization and method development, occurrence of these contaminants in wastewaters and their removal in two full-scale and two pilot-scale membrane biological reactors (MBRs) was studied. Progesterone, estrone and acetaminophen were completely removed from wastewater by biodegradation. CBZ and diltiazem were not removed at all during the study. There was little effect of flux and sludge retention times on the removal of selected EDCs in these membrane plants. In SBR combined with membrane filtration, 13 different micropollutants, including Fluoxetine (FLX), Ibuprofen (IBP), Naproxen (NPX), Diclofenac (DCF), Carbamazepine (CBZ), Trimethoprim (TMP), Roxithromycin (ROX), Erythromycin (ERY), Sulfamethoxazole (SMX), Diazepam (DZP), Galaxolide (GLX), Tonalide (TON), Celestolide (CEL). CEL, GLX, TON and FLX were removed by adsorption onto the sludge while ROX, ERY, SMX, IBP and NPX were removed by biological degradation. The CBZ, DZP, TMP and DCF were not removed by biodegradation or adsorption. Whereas, following the addition of powdered activated carbon, all these compounds were removed entirely from the wastewater stream by accumulating in sludge.

Philosophiae Doctor - PhD
Organic and inorganic pollutants are two broad classes of pollutants in the environment with their main sources from waste waters that are indiscriminately dumped from chemical related industries. Among the organic pollutants are dyes that come as effluents from the textile industries. Toxic metals are the main inorganic pollutants with their sources from industries such as mining, electroplating, batteries etc. The presence of both classes of pollutants in the aquatic environment poses a serious threat to aquatic organisms and humans who depend on these waters for domestic purpose. Therefore, this research focused on the fabrication of materials and designing of methods for removal of both classes of pollutants from their aqueous solutions.

Managed aquifer recharge (MAR) is a low-energy subsurface water treatment system with the potential of being an important component of sustainable water reuse schemes. Alongside common wastewater contaminants, MAR systems have been shown to attenuate a range of trace organic chemicals (TOrCs). Despite several factors being possibly important for TOrC attenuation, many have not been investigated in depth. This research effort investigated three factors affecting attenuation of the moderately degradable TOrCs: primary substrate, adaptation of the microbial community to presence of TOrCs, and groundwater temperature. The overall goal was to optimize TOrC attenuation using different MAR configurations considering how these factors affect TOrC attenuation. The primary substrate composition and concentration significantly impacted attenuation of the moderately degradable TOrCs. Lower primary substrate concentrations and more refractory carbon generally resulted in better TOrC transformation, a more diverse microbial community in the infiltration zone and more diverse capabilities for TOrC degradation. The enzyme group cytochrome P450 may be important for TOrC transformation since its genes were more abundant under carbon-starving primary substrate conditions. Adaptation of the microbial community by pre-exposure to TOrCs was not required in order to degrade them. However, adaptation to the primary substrate was necessary for TOrC biotransformation due to its effect on the microbial community. Attenuation of most TOrCs was unaffected by changes in temperature. Some moderately degradable TOrCs, however, were better attenuated at higher temperatures likely due to increased microbial activity. Others were better degraded at lower temperatures likely due to favorable sorption conditions. In the context of applying MAR systems to potential water reuse schemes within Saudi Arabia, a reconnaissance study of TOrC occurrence in treated wastewater effluents was undertaken. Most of the TOrCs targeted were detected at similar concentrations to US effluents at comparable plants. One of the plants studied, however, displayed a significantly different TOrC footprint from the other treatment plants due to the large number of international visitors in its sewershed. Findings from this occurrence study as well from other tasks provided inputs to a risk assessment framework to compare the effectiveness of MAR systems as part of a multiple-barrier water reuse scheme.

博士
國立中山大學
環境工程研究所
101
We found numerous factors deteriorate the quality of drinking water in water treatment plant (WTP). These problems are caused by the performance of WTP processes and heterotrophic microbial growth in water distribution network. In this study, analysis on water quality items of raw water sampled from various water treatment processes in advanced and traditional WTP and pipeline networks. We conducted to explore: (a) the efficiency of traditional and advanced water treatment processes in removing trace organics; (b) fluctuations in the concentration of assimilable organic carbon (AOC) during the water treatment process; (c) the applicability of the AutoNet (6.03) method for constructing an AOC forecast model in an artificial neural network (ANN). The sampling period was December, 2009 to November, 2010 and raw water was sampled once a month. Raw water was obtained from two reservoirs. An analysis of the trace organics, such as total organic carbon (TOC), dissolved organic carbon (DOC), UV254, and AOC. The results of removal of the advanced and traditional WTP showed that the pre-ozone contactor, pulsator, and biological activated carbon (BAC) filter used in advanced WTP had AOC removal rates of 19%, 36%, and 22%, respectively. This proved that pre-ozone contactor, pulsator, and BAC filters can effectively remove AOC. The growth rates of TOC and DOC in the pre-ozone contactor were 5% and 7%, respectively. In a traditional WTP, the flat bottom coagulation-sedimentation basin was the most effective in AOC removal (39%). The rapid sand filter only removes 3% of the AOC. The TOC and DOC pre-chlorination growth rates were 3% and 2%, respectively. The variations in the forecasted ANN values were based on the 13 water quality values rom the sample analyses, which varied from 13.6% ~ 27.4%. Based on the simulated forecasts, it is recommended that advanced WTP should regularly monitor the total dissolved solids (TDS) and NH3-N values. Traditional WTP should regularly monitor the DOC, UV254, and water temperature values. In the pre-ozone treatment units of the advanced WTPs, the ozone concentrations varied from 1.0 mg/L to 1.24 mg/L and were affected by the eutrophication of algae in the lake water and the consumption of other materials. This led to the insufficient oxidation of AOC, which converted AOC-P17 to AOC-NOX. The quantity of AOC-P17 generated in the pellet softening treatment unit reached 73.9%. This may be related to the release of the AOC-P17 through the mechanism of humic acid dissolved in alkaline environments. When combined with alkali agents, humic acid becomes a cation and trace metal ion adsorbent that produces an ion-exchange reaction. The sediment releasing project combined with the Chengcing Lake Reservoir sediment excavation projects can remove 14.1% of the TOC in the raw water. During the current study, the mean TOC value of the Jen-Yi-Tan Reservoir was 1.25mg/L, which was slightly higher than the 0.8 mg/L at the Chengcing Lake Reservoir. If sediment excavation projects coordinate the regular release of sediment on the sedimentation basin of intake, the AOC of the raw water at the intake can be reduced. After the pre-chlorination of the GWWTP, the AOC-NOX growth rate was 183% and the primarily removed organic matter was AOC-P17. The AOC-NOX with low molecular weight could not be effectively removed. It is recommended that based on the raw water characteristics of each WTP, installing additional membrane-based treatment units and maintaining water distribution networks to prevent leaks in advanced WTPs be the feasible short-term goal to reduce the AOC in drinking water.

碩士
國立交通大學
工學院碩士在職專班永續環境科技組
96
The cost and consumption of ultra pure water (UPW) in the semiconductor industry has dramatically grown with advances in integrated circuit (IC) design. In addition to questions regarding the economics of UPW treatment, concerns have developed over the restrictions on the water supply and the environmental impact of contaminants in discharged wastewater. It has been suggested that, to help resolve such water usage problems, the wastewater from the rinse stages of IC manufacturing steps should be recycled and reused. Trace organics have been identified as the serious contaminant responsible for more than 90% of all micro-contamination problems that affect IC production yields. Since total organic carbon (TOC) accounts for a large proportion of the impurities found in rinsing wastewater, which is hard to deal with, utmost care should be paid to the TOC level. The TOC-UV by 185 nm UV rays is the most representative unit in UPW system for reducing/degrading organics. The aim of this study is to on-site evaluate the performance of TOC-UV (185 nm) of UPW system. The values of TOC were measured at each treatment unit in order to obtain the TOC baseline. Furthermore, plant M and plant P were selected as the models to differentiate the removal efficiencies of TOC-UV units in the make-up system and the polishing loop, respectively. For the optimization and the examination experiments of TOC-UV units sizing, UV lamps and units were shut down in turns to assess the significance to TOC variations. At last, the cost for system operation and the maintenance, and the consumable parts replacement of UV units for the consideration in annual maintenance were also calculated. The results reveal that up to 70% TOC were removed in the make-up system; the remaining TOC was further treated by the polishing loop in the UPW system. In addition, the increase in TOC values when UV lamps were turned off can be ignored due to the fact that TOC values were under the specification of 1 ppb during the optimization and examination experiments. The results can be useful for saving and reducing the running cost and the consumable materials replacement at the annual maintenance of plant M and plant P.