Conventional desalination plant, municipal water supply and wastewater treatment system are among the most electricity-intensive facilities. Microbial Desalination Cell (MDC) has emerged as a promising technique to capture the chemical energy stored in wastewater directly for desalination, which has the potential to solve the high energy consumption issue in desalination industry as well as wastewater treatment system. The MDC is composed of two critical components, the electrodes (anode and cathode), and the ion-exchange membranes separating the two electrodes which drive anions migrate towards the anode, and cations migrate towards the cathode. The multiple components allow us to manipulate the configuration to achieve most efficient desalination performance. By coupling with Donnan Dialysis or Microbial Fuel Cell, the device can effectively achieve boron removal which has been a critical issue in desalination plants. The uncertainty of water quality of the final desalinated water caused by contaminant back diffusion from the wastewater side can be theoretically explained by two mechanisms, Donnan exchange and molecule transport which are controlled by bioelectricity and concentration gradient. Scaling and fouling is also a factor needs to be taken into consideration when operating the MDC system in real world. With mathematical modeling, we can provide insight to bridge the gap between lab-scale experiments and industrial applications. This study is expected to provide guidance to enhance the efficiency as well as the reliability and controllability of MDC for desalination. / Ph. D. / Water and energy are the world’s most valuable resources. The recent emerging technology, Microbial Desalination Cell (MDC), however, can achieve wastewater treatment, desalination for fresh water production, and energy generation simultaneously. Owing to the anodophilic microorganisms working as organic matter consumer and electron generator, the wastewater can be cleaned and the device can generate electricity through electron flow to drive ion separation for salt removal in the solution. The MDC can be constructed in versatile configurations. Decoupled configuration of anode and cathode allows flexibility of operation and maintenance. Although the MDC has wastewater adjacent to seawater which are separated by a piece of anion exchange membrane, the microorganisms and viruses are effectively blocked by the membrane which has tiny pore size around 1 nm. Back diffusion of contaminants in wastewater into the desalinated water is minimal under bioelectricity generation condition. The MDC has proved to successfully remove various inorganic ions by itself as well as remove non-dissociable boron when coupled to other devices, such as Donnan Dialysis or Microbial Fuel Cell. The water product quality can meet irrigation guideline. Through mathematical modeling tools, we can better understand the MDC process, analyze it, and make informative predictions.

Yes / Fly ash is a toxic industrial waste, mainly consisting of silica and alumina particles, that has been found discharged into the environment. It is proposed that alginate, a naturally occurring biopolymer, can bind to these minerals and thus play a role in water purification. The binding forces involved in this process consist of weak interactions, such as van der Waals forces and electrostatic interactions. Although the attachment of alginate to mineral surfaces is mainly governed by its carboxylate groups, hydroxyl moieties could play a role in the interaction between the polymer and minerals. This work aims to use the SiO2 and Al2O3 particles as models for fly ash and to show the use of alginate biopolymers (fluorescently labelled with an aminonaphthaline sulfonate fluorophore (AmNS)) to coagulate them. The addition of simple electrolytes like NaCl and CaCl2 encourages the coiling of the polymer chain at high pH values which has an effect on its capability to bind to the inorganic particles. A combination of fluorescence and ICP-MS demonstrated that alginate has a considerable adsorption affinity for Al2O3, whereas it attracts SiO2 weakly. The adsorption process is pH dependent: strong adsorption was observed at low pH values. The dependence of adsorption on the mineral (Al2O3 and SiO2) concentration was also examined under different pH conditions: the adsorption amount was observed to increase by increasing the solid concentration. Adsorption isotherms obtained at low and high mineral concentrations were found to be Henry in type.

The goal of this research was to characterize the effects of temperature changes on the denitrification process in a biological nutrient removal (BNR) system. Specifically, there were three objectives. First, the effects of temperature changes on denitrification rates by a bacterial population from a BNR system were investigated. Next, the role which PHAs (poly-beta-hydroxyalkanoates) played in the denitrification process were examined. Finally, the effect of temperature changes on the production and consumption rates of PHAs was determined. Sacrificial batch experiments were performed to assess the kinetic and chemical trends present in the denitrification process. Mixed liquor from the last anaerobic zone of a pilot scale BNR system was injected into vials. These vials were pre-purged with nitrogen gas in order to prevent dimolecular oxygen (02) from being entrained in the mixed liquor. Next, the vials were placed on a shaker table for 30 minutes in order to allow all external COD to be consumed. Following this, each vial was injected with nitrates and various macronutrients. This process was repeated for three different sets of batch tests; each set was identical except for the added substrate. One set received no added substrate while the other two received either acetate or glucose. Vials were sacrificed over a period of three hours and analyzed for nitrate, phosphate, PHB (polybeta-hydroxybutyrate), PHV (poly-beta-hydroxyvalerate), glucose and acetate. / Master of Science

Anaerobic digestion is widely used for stabilization of solids in sewage sludges. Recent changes in the priorities and goals of digestion processes are focusing more attention on the efficiency of these processes. Increasing hauling cost and restrictions for land applications are two factors which are driving the increased attention to digestion efficiency. Noxious odor production from the land applied biosolids is another important issue related to digestion efficiency. Existing anaerobic digestion or aerobic digestion processes failed to provide simultaneous solution to biosolids related problems i.e. simultaneous VS reduction, better dewatering of biosolids and lesser odors from the biosolids. Studies done by Novak et al. (2004) using different activated sludges show that anaerobic-aerobic digestion and aerobic-anaerobic digestion both increase volatile solids reduction compared to a single digestion environment. They proposed that there are 4 VS fractions in sludges: (1) a fraction degradable only under aerobic conditions, (2) a fraction degradable only under anaerobic conditions, (3) a fraction degradable under both anaerobic and aerobic conditions, and (4) a non degradable fraction. It has also been found (Akunna et al., 1993) that anaerobic-aerobic sequential treatment of wastewater can help in achieving substantial nitrogen removal. These results suggest that sequential anaerobic-aerobic digestion can address multiple biosolid related problems. This study was designed to understand the effect of sequential anaerobic-aerobic digestion on the properties of resulting effluent biosolids. The study was carried out in two operation phases and during both phases one digester was maintained at thermophilic conditions and the other at mesophilic temperature conditions. In first operation phase (Phase-I) thermophilic digester was operating at 20 day SRT and mesophilic anaerobic digester was at 10 day SRT. The aerobic digesters following anaerobic digesters were operating at 6 day SRT. In second operation phase (Phase-II), both thermophilic and mesophilic anaerobic digesters were operating at 15 day SRT and both had two aerobic digesters operating in parallel at 3 day and 6 day SRTs. In addition, batch experiments were also conducted to measure the performance of aerobic-anaerobic digestion sequence. Another study was carried out to understand the nitrogen removal mechanism during aerobic digestion of anaerobic digested sludge. The feed sludge was spiked with four different concentrations of nitrate and nitrite. It was observed during the study that aerobic digestion of anaerobic sludge helps in achieving higher Volatile solid reduction (~65% vs ~ 46% for mesophilic digestion and ~52% for thermophilic digestion). This result supports the hypothesis concerning the different fractions in volatile solids. Experimental results also show that the increase in VSR upon increasing anaerobic digestion SRT (more than 15 days) is less than the increase in the VSR due to the same increment of aerobic digestion SRT. Reduction in COD and VFA were also measured to be more than 50% during aerobic digestion. Investigation of nitrogen fate during the sequential anaerobic-aerobic digestion show more than 50% total nitrogen removal. Higher nitrogen removal was in thermophilic anaerobic – aerobic digester combination than that in mesophilic anaerobic–aerobic combination. The most probable reason for the removal was simultaneous nitrification and denitrification. Higher concentration of readily available VFA from thermophilic anaerobic digested sludge provide advantage in denitrification in following aerobic digester. The resulting biosolids produced during sequential digestion process were also analyzed for dewatering properties and odor production. Proteins and polysaccharides concentrations were observed to decrease during aerobic digestion for thermophilic anaerobic - aerobic digestion combination, while in another combinations polysaccharide concentrations increases at aerobic phase with 3 day digestion. The concentration of polysaccharides decreases at higher digestion period of 6 and 9. The result of decrease in polysaccharide and protein was reflected by the reduction in the polymer dose consumption and decrease in the optimum CST for the biosolids resulting from the sequential anaerobic aerobic digestion. Experimental results from odor experiments show that odor production potential of the biosolids decreases with increase in both anaerobic phase SRT and aerobic phase SRT. Thermophilic biosolids produces comparatively low odors but for longer periods, while mesophilic biosolids produces higher magnitude of odors during storage but only for comparative shorter period. Aerobic digestion of anaerobic sludge helps in reducing more than 50% odor production, but freeze-thaw cycle experiment shows that in both anaerobic and sequential anaerobic – aerobic digested sludges have higher potential for odor production. Higher aerobic digestion SRTs (6 days and above) shows more potential of reducing odors, but more experimental work is required to be done. / Master of Science

Triglycerides are the majority lipid component of most biochemical mixtures and are virtually water insoluble. Lipid removal is desired prior to protein purification processing to decrease nonspecific fouling of downstream chromatographic matrices. Transgenic pig milk was used as a model system to study delipidation from therapeutic protein sources. The majority of triglycerides was extracted from stable lipid micelles and removed with a method that can be incorporated in downstream protein purification processing without denaturing the target protein. An efficient delipidation treatment used TNBP, a non-polar solvent, to extract lipid micelles and then phase transfer milk lipids into a TNBP-swelled dextran particulate. A batch incubation of a whey/TNBP mixture with pre-swollen Sephadex LH-20 or hydroxyalkoxypropyl dextran (HAPD) beads at 4 C for 24 hours removed 67 + 2 % (0.645 mg triglycerides/ml Sephadex LH-20) and 71 o + 1 % (0.628 mg triglycerides/ml HAPD) of the triglycerides present in the skimmed transgenic whey, respectively. Fully swollen beads removed 20% more triglycerides than beads which were wetted but not swollen in TNBP, indicating that a larger phase volume and internal adsorption of the lipids onto the Sephadex matrix dominates over surface adsorption. Polyclonal ELISAs indicated that 89 + 6% of the recombinant human Protein C was still present in the transgenic whey after this delipidation treatment, indicating this treatment did not denature or harm the target protein. / Master of Science

Yes / This study used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and a jar test apparatus to investigate the molecular weight (MW) and turbidity removal potential of Hibiscus seeds. Three Hibiscus species were assessed: okra crude extract (OCE), sabdariffa crude extract (SCE), and kenaf crude extract (KCE). Furthermore, purified versions of each [i.e., purified okra protein (POP), purified sabdariffa protein (PSP), and purified kenaf protein (PKP)] obtained from anionic exchange were evaluated. The results show that whereas the crude extracts had multiple proteins with MW sizes between 11 and 82 kDa, the purified samples consisted of a single coagulant protein band around 39 kDa. In each case, significant turbidity removal was recorded with the purified proteins; POP, PSP and PKP achieved approximately 98%, 94%, and 90% removal, respectively, at a reduced dosage of ≤0.6  mg/L. However, OCE and SCE achieved lower turbidity removal of 86% and 85% using 40-mg/L doses, respectively, whereas KCE recorded only 73% turbidity removal with a 60-mg/L dose. Sludge generation by crude and purified proteins was approximately 25% of sludge produced by aluminum sulfate and had the additional benefit of being biodegradable. Therefore, the coagulant protein in Hibiscus plant seeds has potential applications for improvements to accessing clean water in developing countries.

Yes / The total energy consumption of many Reverse Osmosis (RO) plants has continuously improved as a result of manufacturing highly impermeable membranes in addition to implementing energy recovery devices. The total energy consumption of the RO process contributes significantly to the total cost of water treatment. Therefore any way of keeping the energy consumption to a minimum is highly desirable but continues to be a real challenge in practice. Potential areas to explore for achieving this include the possibility of optimising the module design parameters and/or the associated operating parameters. This research focuses on this precise aim by evaluating the impact of the design characteristics of membrane length, width, and feed channel height on the total energy consumption for two selected pilot-plant RO process configurations for the removal of chlorophenol from wastewater. The proposed two configurations, with and without an energy recovery device (ERD), consist of four cylindrical pressure vessels connected in series and stuffed with spiral wound membranes. A detailed steady-state model developed earlier by the authors is used here to study such impact via repetitive simulation. The results achieved confirm that the overall energy consumption can be reduced by actually increasing the membrane width with a simultaneous reduction of membrane length at constant membrane area and module volume. Energy savings of more than 60% and 54% have been achieved for the two configurations with and without ERD respectively using process optimization. The energy savings are significantly higher compared to other available similar studies from the literature.

Phosphorus (P) is a nutrient that is essential for crops, but it is a non-renewable resource. P recovery from wastewater would lessen P pollution and extend the P supply for fertilizers. Filamentous microalgae can remove soluble inorganic P from water and assimilate it into recyclable biomass. To further develop this concept by using P-depleted filamentous microalgae, this research pursued three goals: to determine (1) the biomass-specific P uptake rates of Tribonema minus and Uronema sp., (2) how long Uronema sp. can be cultivated in P-depleted state (not P-starved) and continue substantial uptake, and (3) if the P dosing rates impact the uptake response and/or productivity of Uronema sp. Raceway tanks were given little or no soluble P to generate P-depleted biomass. The P-depleted biomass was then used for uptake contact experiments in which P uptake rates and biomass P content were measured. The long duration (0-10 h) uptake rates were not substantially different for T. minus and Uronema sp., but Uronema sp. tended to uptake more quickly in the short duration (0-2 and 0-3 h) of the contact period. Other experiments focused on prolonged deprivation, during which the raceways received P every day or every three days, although the mass of P dosed over the long term was equivalent in all raceways. Uronema sp. could be cultivated in a P-depleted state for an average of 10 days before the biomass was unable to have substantial P uptake. The uptake rates for these two dosing regimens were assumed to be the same because the 0-6 hour average rate was 0.33 mg P/g VSS-h (dosed every day) and 0.36 mg P/g VSS-h (dosed every three days). Future studies should confirm if Uronema sp. consistently assimilates more P at a faster rate in the winter compared to the spring, as observed in the present study.

L'estimation des abondances de population est essentielle pour comprendre les dynamiques de population, les interactions entre espèces et estimer les risques de transmission d'agents pathogènes dans les populations. Plusieurs méthodes d'échantillonnages, basées sur des hypothèses spécifiques permettent d'estimer ces abondances : les méthodes par comptages uniques, par « distance sampling », par échantillonnages successifs ou par capture marquage recapture. Nous nous sommes intéressés à l'abondance des tiques Ixodes ricinus, vecteurs de nombreux agents pathogènes. Cette abondance est classiquement estimée par le nombre de tiques capturées lors d'échantillonnages uniques réalisés sur différentes unités d'observation. Cependant, de nombreuses études remettent en cause cette hypothèse forte et suggèrent que le taux d'échantillonnage est variable selon les conditions d'échantillonnage (type de végétation,…) mais ne prennent pas en compte ce taux d'échantillonnage pour autant. A partir d'une méthode d'échantillonnage par « removal sampling » (RS), (i) nous avons montré que les conditions environnementales influençaient le taux d'échantillonnage et l'indicateur d'abondance usuel i.e. le nombre de tiques capturées lors d'un seul échantillonnage (ii) nous avons proposé une méthode pour détecter l'indicateur d'abondance, basés sur le nombre cumulé de capture, le moins soumis aux variations du taux ; (iii) par une approche Bayésienne hiérarchique, nous avons estimé simultanément l'abondance de tiques des unités d'observation et la valeur du taux d'échantillonnage en fonction du type de végétation et de l'heure d'échantillonnage. Nous avons montré que le taux d'échantillonnage sur des arbustes (entre 33,9 % et 47,4%) était significativement inférieur au taux d'échantillonnage sur des feuilles mortes (entre 53,6 % et 66,7%). De plus, nous avons montré que le modèle RS tend vers un modèle de Poisson iid lorsque la taille de la population N0 tend vers l'infini ce qui pose des problèmes d'indétermination pour estimer les paramètres N0 et τ, le taux d'échantillonnage. Nous avons également montré que (i) les estimateurs Bayésiens divergent lorsque les lois a priori sont des lois vagues ; (ii) les lois a priori β(a, b) avec a > 2 sur τ conduisaient à des estimateurs Bayésien convergents. Enfin, nous avons proposé des recommandations quant au choix des lois a priori pour τ afin d'obtenir de bonnes estimations pour N0 ou pour τ. Nous discutons de la pertinence des méthodes RS pour les tiques et des perspectives envisageables pour (i) estimer le risque acarologique représenté par la population de tiques potentiellement actives sur une unité d'observation, (ii) estimer un risque à l'échelle d'une parcelle, à savoir comment répartir l'effort d'échantillonnage entre le nombre d'unités d'observation et le nombre d'échantillonnages successifs par unités d'observation. / The estimation of animal abundance is essential to understand population dynamics, species interactions and disease patterns in populations and to estimate the risk of pathogens transmission. Several sampling methods such as single counts, distance sampling, removal sampling or capture mark recapture could be used to estimate abundance. In this study, we are investigated the abundance of Ixodes ricinus ticks, which are involved in the transmission of many pathogens. Tick abundance is commonly estimated by the number of nymphs captured during a single observation (a cloth dragged on a given surface). In this case, analyses of abundance patterns assumes that the probability of detecting a tick, hence the sampling rate, remains constant across the observations. In practice, however, this assumption is often not satisfied as the sampling rate may fluctuate between observation plots. The variation of sampling rate is never taken into account in estimations of tick abundance. Using a removal sampling design (RS), (i) we showed that the sampling rate and the usual abundance indicator (based on a single drag observation per spot) were both influenced by environmental conditions ; (ii) we proposed a method to determine the abundance indicator the least influenced by sampling rate variations ; (iii) using a hierarchical Bayesian model, we estimated simultaneously the abundance and the sampling rate according the type of vegetation, and the time of sampling. The sampling rate varied between 33,9 % and 47,4 % for shrubs and 53,6 % and 66,7 % for dead leaves. In addition, we show that the RS model tends to Poisson iid model when the population size N0 tends to infinite. This result conduct to infinite estimations for N0. We show that (i) Bayesian estimators were divergent for vague prior ; (ii) β(a, b) prior for a > 2 on τ conduct to convergent estimators. Then, we proposed recommendations for prior choice for τ parameter to give good estimations of N0 or τ. We discuss the relevance of RS for ticks and the possible perspectives to (i) estimate the acarologic risk associated to all potential active ticks for given spot, (ii) estimate the risk at the larger scale, i.e. how to distribute the sampling effort between number of spot and number of consecutive sampling by spot.

The treatment of deep carious lesions (DCLs) represents a challenge for dentists, as these lesions require removal of dentin in proximity to the pulp that represents a higher risk of ending in pulp exposure. There is increasing evidence supporting minimally invasive caries removal methods, such as stepwise excavation procedure (SWP), instead of non-selective (complete) dentin caries removal for the treatment of DCLs. However, recent research has indicated that dentists have not completely adopted less invasive caries removal methods for the management of DCLs. These studies have been primarily conducted in Europe or South America; thus, few studies have been conducted in the United States to understand dentists’ management options of deep carious lesions in permanent teeth. Additionally, the proportion of dentists who would be willing to adopt less invasive carious tissue removal is unknown, especially in the United States. This dissertation consists of three studies that analyzed the effectiveness of SWP, the factors associated with success, an assessment of its costs and the acceptability of this treatment among U.S dentists. Study I assessed the patient factors predicting a successful SWP by retrospectively investigating a sample from the University of Iowa College of Dentistry from January 2004 through December 2012. Study I showed that SWPs showed a 75% success rate when evaluated within 36 months of the initial treatment. Patients who had a successful SWP treatment were slightly younger than patients whose SWP treatment was not successful. Study II performed a cost-effectiveness analysis by comparing SWP vs. the standard caries treatment (complete caries removal). Study II showed that SWP significantly reduced cost, resulting in an average savings of 64% compared to TCR over a 5-year period. Study III consisted of a statewide survey that contacted 1,434 Iowa dentists with the aim of identifying the most important factors that influence dentists’ decisions for DCLs treatment using conjoint analysis. From the total, 36.4% (n=522) clinicians answered the survey. One of the main study findings was that among the three factors (hardness of dentin, depth of the lesion and patient age) depth of the lesion was the most important factor influencing dentists’s decision when selecting a less invasive caries removal method. Study III did not find any significant association between years of practicing dentistry, type of practice and practice setting regarding being willing to select a less invasive caries removal method. In conclusion, this dissertation has demonstrated that the stepwise caries removal is a cost-saving and highly successful treatment for the management of deep caries lesions. Studies I and II have shown that this method has a high clinical success rate and less long-term treatment costs. Regarding the acceptability of SWP among clinicians, this dissertation has shown that most dentists in Iowa would consider less invasive caries methods for a DCL; however, these techniques have not been completely adopted and accepted among American dentists. Thus, dentists should be trained in less invasive caries methods, given instruction about which criteria they should use to assess a DCL, and provide them with the best evidence-based strategies for managing deep lesions. The findings of this dissertation should engage stakeholders to provide dentists with professional incentives for using these techniques. Specifically, our results support the idea that SWP minimizes costs while providing the appropriate patient care.