The first two chapters of this dissertation focus on the child health outcomes in brief, child diarrheal incidence in India, and child growth measures in Rwanda. The third chapter examines the determinants of timely access to health care in emergency departments in the United States. All three essays are different in their area of interest, data sources, and methodology.ESSAY 1 India has recorded the highest number of child diarrheal deaths at the global level. Oral Rehydration Therapy (ORT) would just provide hydration and few mineral supplements for infected children. However, their malnutrition and weakened immune system cannot be reversed. Malnutrition affects child growth, and causes stunting, and makes them susceptible to other forms of infections. The rotavirus vaccine provides a pseudo-sense of protection from non-rotaviral diarrhea. Preventing diarrhea right away from the source of the infection would be a better solution. Since most diarrheal pathogens are water borne, disinfection treatment of drinking water at the point of use could prevent diarrheal incidence of children and adults as well. Household data from the National Family and Health Survey and their estimators viz., Propensity Score Matching (PSM), and Inverse Probability Weights Regression Adjustment (IPWRA) have been employed to examine the effects of water treatment techniques in households. This chapter attempted a novel approach in studying all the popularly used water treatment techniques currently practiced in India in one study. They have been ranked for multi-value treatment effects model. Water filters with ceramic candles are more effective than other point-of-use water treatment techniques, followed by chlorination, water purifiers, and boiling. ESSAY 2 Rwanda is a sub-Sahara African country affected by genocide with a patriarchal family structure system. Higher poverty and gender imbalance were not alleviated by gender equality being on the political agenda. Despite the highest female representation in the parliament in the world, gender equality and liberty are confined to elite women. Additionally, flawed laws for women's equality made women's empowerment a paradoxical phenomenon. Women at the gross root levels, i.e., community and household, are still dependent or interdependent on men (husband/father). This has been confirmed by the findings in Chapter 3, that is, for most decisions, women are taken jointly with their partners. A minimal percentage of women are autonomous in their decisions and in their home. This study made an attempt to examine the mother’s autonomy in Rwanda and its impact on child health. Mother’s autonomy is negatively related to child’s height and weight for their age. Although the expected association between mother’s autonomy and child height/weight is positive, it would also depend on the historical and cultural context of the country of interest. Instrumental variable analysis is used to study women’s autonomy due to its complex and endogenous nature. Spousal educational difference and marriage-to-birth interval are valid instruments but weakly identified. ESSAY 3 An increasing burden on emergency services that exceeded its resources led to congestion in the emergency department (ED), with patients waiting for physicians on the examination bed and for inpatient bed transfer. This creates a blockage between access to healthcare and emergent patients. ED measures adopted to reduce ED congestion, boarding, and waiting times, such as ambulance diversion management, fast tracking of patients with low acuity, and bed coordination do not effectively control waiting time and boarding. ED crowding is a patient flow, but not necessarily a hospital resource deficiency. This is evident from the findings that even EDs with new treatment spaces still keep patients waiting for an inpatient bed, however, they reported a shorter wait time for the physician. Optimal utilization of nurses by floating them to needy units is effective in timely transfers of patients to inpatient beds compared to EDs without floating nurses.

Research interest in Additive Manufacturing (AM) as an enabling technology for customizable parts is rapidly expanding. While much AM research focus is on high performance feedstocks and process optimization to obtain parts with improved mechanical properties, interest in the environmental applications of AM has recently increased. The lower cost and greater accessibility AM is leading to novel environmental research solutions in wastewater treatment and toxicity reduction by capitalizing on the increased affordability and accessibility of 3D printing (3DP) technologies for customizable, high surface area structures. The novelty and focus of this dissertation is exploration of Material Extrusion (MatEx) based Fused Filament Fabrication (FFF) of filled polymer composites as a disruptive technology enabler for deployable and retrievable structures in environmental media for adsorption, destruction and toxicity reduction of harmful chemicals. This dissertation addresses research questions that generally answer, "why AM for environmental applications?". The inherent layer-by-layer design provides larger surface area structures for interaction with contaminated media. Polylactic acid (PLA) was selected due to its green sources and biocompatibility relative to synthetic polymers and its wide processing window allowing shear thinning and "printability" despite the elevated viscosity and modulus of highly filled composites. The filler selected for contaminant adsorption was microporous zeolite, which has affinity for ammonia, radionuclides and Per- and Polyfluorinated Substances (PFAS). The filler selected for contaminant destruction was photocatalytic TiO2 nanoparticles which can degrade organic chemicals, harmful algal bloom toxins and PFAS. A preliminary research hurdle was overcome by demonstrating that immobilization of zeolite and TiO2 in a PLA binder matrix did not prevent adsorption or free radical release, respectively. The first major research objective involved investigation of high surface area printed PLA-zeolite geometries with different zeolite loadings and found that while ammonia was reduced, there were diminishing returns with increased loading in terms of mass standardized adsorptive performance due to insufficiently exposed zeolite. The research solution leveraged AM print process parameters to increase the macroporosity of the printed composite structure to create voids and channels allowing water infiltration and chemical adsorption to zeolite. Faster printing of larger roadways generated macrostructural voids that were maintained by extrusion at lower temperature for rapid solidification. The second research objective involved compounding different loadings and dispersion states of TiO2 in PLA to demonstrate immobilization of TiO2 closer to UV-light penetration water improves photocatalysis. Higher 32% w/w TiO2 loadings were heavily agglomerated and more difficult to print process due to high viscosity, rapid liquid-solid transition (G'>G") and particle network recovery during printer retractions, leading to nozzle clogging. Lower 20% w/w loading was more conducive to larger production printing due to lower viscosity, longer viscosity recovery times for retractions and thus generally a wider processing window. While altering twin screw processing parameters reduced TiO2 agglomerates in filaments, leading to increases in crystallinity (due to seeding effects and chain scission) and lower viscosity recovery, photocatalytic performance was not significantly improved. Evidence presented showed that larger particle agglomerates were more toward the inside of printed surfaces and thus less available to UV-light irradiation. This location of larger particles is supported by previous theoretical and empirical investigations showing larger particles migrate at a faster velocity away from the outer walls of confined extrudates within non-Newtonian flow fields due to normal forces, leaving more smaller particles toward outer surfaces. This research provided novel contributions to the environmental and AM research communities and pioneered a convergence of these fields into an interdisciplinary community of practice focused on better characterization and processing in environmental applications to improve structure-environmental property relationships. Future research should build on these findings to enhance performance through multi-functional materials that adsorb and destroy contaminants. The reactive surface area should be further increased through by high surface area designs and print parameter optimized porous structures providing a continuum of meso- to microporosity as confirmed by chemical flux and mass transfer studies for additional AM technologies (e.g., Direct Ink Write). / Doctor of Philosophy / Engineers and hobbies alike have great interest in Additive Manufacturing (AM), or 3D Printing, to customize parts and new designs. More recently, environmental scientists and engineers have turned to 3D printing to solve environmental problems due to the lower cost and user-friendliness of desktop machines. This research dissertation focuses on how 3D printing can allow for iterative improvements in customizable, high surface area structures to reduce chemical concentrations in water by either adsorbing or destroying the chemicals. Water is clearly a critical resource for ecosystems, recreation and drinking supplies as national security, human and ecosystem health are tied to clean water. This research addresses why 3D printing is interesting and effective for environmental solutions. Briefly the layer-by-layer design provides larger surface area structures for interaction with contaminated media. The common 3D printer feedstock Polylactic Acid (PLA) was selected since it is non-toxic and can be relatively easy to print even if modified by adding rigid filler particles for research. Micron-scale (zeolite) and nano-scale (Titanium Dioxide) particles were mixed with the polymer to make printable filaments to adsorb and destroy contaminants, respectively. This research demonstrated the proof-of-concept by removing ammonia, methylene blue dye and a harmful algal toxin from water. The materials produced are also applicable to both conventional organic pollutants and emerging contaminants of concern in the popular news such as Per- and Polyfluorinated Substances (PFAS), which were used as flame retardants and non-stick surfaces. This research ties the material properties of the experimental micro- and nano-composite filaments to how the materials extrude and solidify during 3D printing and how well the resulting printed structures work for reducing contaminant levels in water. Altering the parameters and conditions at which these materials are processed and 3D printed can significantly change their structure, density, porosity and distribution of particles and in turn increase effectiveness. The results provide new contributions to both the environmental and AM research communities and pioneers interdisciplinary collaborative ideas for these different subject matter experts to work together to better understand how handling and processing of these materials can improve their performance in environmental applications. New work should leverage the ideas and principles presented here to further improve performance, ease of production and scale-up of multifunctional material structures for multiple classes of chemicals that are of concern in surface and drinking water.

This research presents a critical evaluation of chitin- and chitosan-based materials as innovative treatment alternatives for water contaminated with insensitive munitions (IMs) compounds. Specifically, chitin, chitosan, amineunctionalized chitin (AFC) were evaluated for adsorptive removal of these compounds. Cellulose and cellulose triacetate were evaluated for adsorptive performance for comparison. Chitosan-graphene oxide (CSGO) composite membranes were evaluated for removal via adsorption and filtration and compared against nanofiltration and reverse osmosis membranes in the current market. Insensitive munitions evaluated include nitrotriazolone (NTO), nitroguanidine (NQ), and 2,4-dinitroanisole (DNAN); 2,4,6-trinitrotoluene (TNT) was also studied as a traditional munition for comparison. AFC is an effective adsorbent for NTO, DNAN, and TNT. Cellulose triacetate was the only commercially available biopolymer adsorbent effective at removing munitions compounds from solution; only DNAN and TNT were removed. CSGO membranes effectively removed NTO, DNAN, and TNT, but removal performance degraded with time. Overall, this research shows that the materials studied are viable options for removing IM and traditional munitions from water.

Increasing population across the globe paved the way for rapid growth in industrialization. Pharmaceuticals, automotive, textiles, agriculture, electronics, electrical and many other industries discharge different types of heavy metals, dyes and organic contaminants into ground water. These discharges are released into lakes and rivers without prior treatment causing huge environmental impact to the environment. Among different remediation techniques, adsorption was considered the most promising method because of its low-cost and high efficiency. Biomass is considered as the most practical and renewable source for production of bio products and biofuels. Biomass is also used for carbon sequestration and as an essential element to produce hydrochar and biochar which are considered as the 21st century black gold. Hydrochar and biochar can be used as an excellent low-cost adsorbent for the removal of heavy metals, dyes and organic contaminants from water. This dissertation work focuses on, firstly, development of novel oxone treated hydrochar as an adsorbent for the efficient removal of Pb(II) and Methylene Blue (MB) from aqueous solutions. Secondly, preparing novel ozone oxidized hydrochar treated with polyethyleneimine for removal of Remzol Brilliant Blue (RBB) and Remzol Reactive Black (RRB) dyes from aqueous solutions. Thirdly, producing high-performance CO2 activated biochar as an adsorbent for efficient removal of Aniline from aqueous solution. All prepared hydrochar and biochar adsorbents were characterized by SEM, TGA, FTIR, Elemental analysis, conductometric titration, and N2 adsorption-desorption isothermal analyses (BET and BJH). The adsorption capacities were determined by Atomic absorption spectrometry (AAS) and Ultraviolet–visible spectroscopy (UV-VIS) respectively. The adsorption capacity of each prepared biochar or hydrochar was determined and both kinetic and isothermal studies were performed. The optimal preparation conditions and adsorption parameters were determined for each adsorbent.

As a result of the EPA?s Disinfection Byproduct Rule, the Northeast Mississippi Regional Water Supply District requested that the Environmental Technology and Applications Laboratory at Mississippi State University conduct a study to develop techniques to comply with new TOC regulations. This study involved the use of jar testing and Enhanced Coagulation in a laboratory setting over a period of twelve months to optimize the various coagulants evaluated in this study. Iron (III) sulfate, aluminum sulfate, aluminum chloride, aluminum chlorohydrate, and a number of polyaluminum chlorides were evaluated in this study. Coagulants were evaluated on both a treatment effectiveness and economical basis. It was determined that an acidified alum solution performed best at meeting EPA standards for total organic carbon reduction, as well as being economically feasible.

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Nitrogen is an essential nutrient for plant and animal life; however, its presence in concentrations exceeding assimilative capacities of receiving water bodies is undesirable. Therefore, the form and concentration of total nitrogen released in wastewater effluents is of great concern. During the course of this study, the nitrogen analysis was performed on the various unit processes of the Florida Technological University wastewater treatment plant. The average percent removal of nitrogen between plant influent and clarifier effluent was 30.5% during the month of August 1975. It is believed that the nitrogen removal is attributed to luxury uptake by the biomass through the plant. The clarifier effluent was highly nitrified containing an average ammonia nitrogen concentration of 0.76 milligrams per liter and a nitrate nitrogen concentration of 16.47 milligrams per liter. The extent to which nitrification took place was 93 - 98% with an average of 96.5% for the month of August.

There are many reports indicating the presence of various emerging contaminants (ECs) in treated wastewater and other water sources. The detection of such contaminants in the environment and the ability of these contaminants to pose potential threats to the environment at very low concentrations have led to a need for more efficient treatment technologies. Cyclodextrins (CDs) have gained significant interest as an alternative adsorbent for water and wastewater treatment because of their unique physico-chemical characteristics and excellent selectivity towards organic compounds. The property of CD to form inclusion complexes with various molecules through host-guest interactions has made it a useful compound for the removal of a number of contaminants from water and wastewater. The overall goal of the study is to identify and develop a novel adsorbent for the removal of ECs of interest. The specific objectives are a) to synthesize various beta-cyclodextrin (BCD) based adsorbents by coating BCD onto different supports such as silica, filter paper, iron oxide, and zeolite, b) to perform batch and column experiments using the developed adsorbents, c) to evaluate the performance of the adsorbents in different water matrices such as MQ water, simulated wastewater in presence of humic acid, and real municipal wastewater, d) to study the regeneration potential of the adsorbents. In this research, various (BCD) based hybrid adsorbents were synthesized and their performances were evaluated based on the removal of selected ECs. At first, chemically bonded BCD onto silica particles as hybrid adsorbents were synthesized by using crosslinking agents and copolymers. Three different methods were used to synthesize 14 different BCD coated silica adsorbents. The adsorbent prepared by reacting BCD with hexamethylene diisocyanate (HMDI) as crosslinking agent and dimethyl sulfoxide (DMSO) as solvent showed best results in removing the ECs studied. The adsorbent showed more than 95% removal of 17β-estradiol (in single component) and more than 90% of most of the estrogens (mixture of 12), more than 99% of perfluorooctanoic acid (PFOA) (in single component) and more than 90% of most of the PFCs (mixture of 10), and a maximum of 90% removal in case of BPA. The adsorption capacity of the developed adsorbent was observed to be higher for the removal of 17β-estradiol and PFOA than that of commercially available activated carbon (F400) in MQ water. In order to represent the real environmental scenario, further batch experiments were conducted for the removal of two PFCs (PFOA and PFOS (perfluorooctane sulfonic acid)), 17β-estradiol, and BPA at environmentally relevant concentrations from wastewater. The adsorbent was effective in removing the ECs that were spiked in the secondary effluent of a municipal wastewater treatment plant. Furthermore, the adsorbent was successfully regenerated with methanol over four cycles without significant loss in its adsorption capacity for the removal of PFOA and estrogens. Ozonation as an alternative method of regeneration was also used and the process was also very effective in regenerating the adsorbent over seven successive cycles for the removal of BPA and 17β-estradiol. The characterization of the adsorbents using FTIR, TGA, and TEM confirmed the coating of BCD onto silica particles. The TGA results showed high thermal stability of the adsorbent (upto 300oC). As an alternative to chemical impregnation, another method of synthesis was developed where various BCD based hybrid adsorbents were synthesized by physically impregnating hydroxypropyl BCD (hpBCD) polymer onto three different supports: iron oxides, zeolite, and filter paper. The hpBCD impregnated filter papers were synthesized by solvent evaporation method and different adsorbents were synthesized by varying the polymer loadings. The polymer loading was optimized based on the performance of the modified (polymer impregnated) filter paper in terms of its filtration capacity as well as adsorption capacity to remove PFOA and BPA. The magnetic adsorbent was prepared by mixing hpBCD polymer with iron oxide (Fe3O4) particles. It was observed that by increasing the mixing time of the support (Fe3O4) with the polymer from 48 to 96 hr, the adsorption capacity of the adsorbent (hpBCD polymer coated Fe3O4) could be significantly enhanced. The same approach was also used to synthesize hpBCD polymer coated zeolite adsorbent and both adsorbents (hpBCD/zeolite and hpBCD/Fe3O4) were effective in removing the selected ECs from MQ water, simulated water, and wastewater. / Civil Engineering