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Rapid technological advancements that employ various manufacturing processes have generated a wide spectrum of anthropogenic compounds, many of which generate municipal and/or hazardous waste. Disposal of such wastes have gone into landfills, as these are one of the most economically viable method of dispensation. Although fiscal mandates have been served, ecological concerns have arisen as a result of this practice. landfill disposal sites are subject to leachate generation, which might be followed by groundwater contamination, if not controlled. In keeping, attention has been focused on reversing the deterioration of aquatic and terrestrial environment through the collection and the treatment of leachate wastewater. As a cause of the magnitude of this problem, it has been necessary to explore methods that affect sufficiently but remain cost effective. Several alternatives have been developed; however, biological and physicochemical procedures have been widely used for treatment of leachates of diverse compositions, comprised of a variety of organic pollutants. While this particular method of treatment has been met with measurable success in terms of contamination removal, it has proven to be costly and technically challenging due to the special and temporal variability in leachate quantity and quality. Nevertheless, recirculation, despite the initial opposition, is, as yet, one of the best method available to manage modern landfills and treat their leachate. The benefits of leachate recirculation are explored here through modeling of the chemical oxygen demand (COD) and biological oxygen demand (BOD), and through a comparative presentations between the single pass and the recirculated leachates that are obtained from a full scale landfills. In this study, landfills leachate composition of BOD and COD are modeled as pseudo-first order kinetics, and the rates of disappearance of leachate contamination strength are estimated in terms of half-life concept. All data sets employed in the simulation were gathered ( and referenced) from full-scale landfill literature documentation. The results of this study confirmed the superiority of leachate recirculated landfills over single-pass leaching landfills.

ABSTRACT Supply of safe drinking water following disasters is essential for life support of the affected population. Recently, hurricane Katrina left New Orleans Louisiana, Biloxi Mississippi and several other Gulf Coast Cities without drinking water. There is a need to develop methods that can be easily mobilized and will consistently produce safe and aesthetically acceptable drinking water. Nanoparticles have been demonstrated to have remarkable adsorptive and catalytic properties. Enhancement in their reactivity can be attributed to very high surface areas, a unique morphology (many comer and edge sites), large porosities, and small crystallite sizes. Reactive naooparticles of metal oxides such as titania, zinc oxide and '- ceria exhibit remarkable abilities to reduce threats of highly toxic substances in water (Chjog, P., et al., 1999, Li, X.Z., et.al., 2000). They are effective at neutralizing a wide range of acids and toxic industrial chemicals with the added capability to mitigate chemical warfare agents. These materials may offer a substantial reactivity and capacity that is advantageous over competitive technologies, such as activated carbons. Depending on the need, the particles can be utilized in a dry powder, granular, slurry form, as well as incorporated within the membranes, which will result in an enhanced membrane surface that kills microorganism, chemically oxidizes organics and mitigates organic and biofouling on the membrane surface. Anatase Ti0 ₂ has both bactericidal and detoxifying (endotxin generated by E.Coli) capabilities. (Kikuchi, K., et.al., 1998). The coated film had different surface characteristic relative to the uncoated films in that the coated film was more hydrophilic, smoother and had a more neutral (less negative surface charge than the uncoated film. ii The solvent (water) mass transfer characteristics of the film were increased by TiO2 coating; however there was no significant differences in solute mass transfer between the TiO2 coated and·uncoated films as determined by mass transfer coefficients that were determined from flat sheet testing in a DI water and a surface water matrix. These results indicate that TiO2 nanoparticle coating of membranes does beneficially affect solute mass transfer diffusion controlled membrane processes by lower the energy required, and therefore the cost of operation of diffusion controlled membrane processes. Hence, more research is warranted for the determination of the beneficial effect of the coating of TiO2 nanoparticles on membrane films. Although the PEPA cell density measurements in the distilled water and surface water matrixes were somewhat contradictory, the HPC biofilm data decisively indicated that the TiO2 coating on the BW30LE films reduced biofilm growth, which indicates the TiO2 nanoparticles would reduce biofilm fouling in a membrane element containing BW30LE films.

Global water scarcity has necessitated the development of new technologies to provide clean and reliable water for the future. Current global infrastructure is insufficient to meet projected demand, and technologies that can provide efficient and low-cost water are urgently needed. Among the various water treatment methods developed over the years, adsorption has become a cost effective, easy to operate, and reliable method for water treatment. Nanoadsorption has emerged recently as an extension of traditional adsorption by combining the tried-and-true adsorption principles with unique material properties such as fast kinetics, large surface areas, and contaminant selectivity that can be used to remove a variety of contaminants. Unfortunately, these new adsorbents cannot be used in traditional adsorption settings such as columns and flow through systems because they cause high pressure drops, have poor mechanical strength, and are difficult to separate from water. In application, nanoadsorbents generally have been dispersed in water or embedded in macroscale hierarchical structures, but the risk of releasing contaminant containing nanoparticles into treated water necessitates a recovery or retention system. Nano enhanced dialytic purification involves utilizing a dialytic purification system that employs a membrane to separate a suspension of continuously recirculated nanomaterials from a stagnant solution or counterflowing stream of contaminated water. Contaminants diffuse down their concentration gradient, through the membrane, and into the nanomaterial suspension to be adsorbed. The nanomaterials are retained behind the membrane and act as a continual sink for the contaminants. This process was first exemplified in proof-of-concept experiments using a dialyzer with a single tubular membrane. Stagnant solutions of arsenic or lead were added into the lumen of the membrane and dialyzed using a flowing stream of ferrihydrite or hexagonal birnessite nanoparticles, respectively, over a three hour period. A greater than 90% removal was obtained from both experiments at sufficiently high adsorbent loading. The dialytic experiment between arsenic and ferrihydrite was compared to batch adsorption studies with a 94% removal efficiency at similar adsorbent loading. The dialytic experiment between lead and hexagonal birnessite was developed into a 2D axisymmetric CFD model using COMSOL Multiphysics® to study the process mathematically, and computational results were in good agreement with experimental data. The computational model was then extended to feature (for the first time) a 3D dialyzer with multiple working hollow fibers, counterflowing contaminant and adsorbent streams, and two treatment modalities – single-pass and multi-pass. These mass exchangers feature a larger surface area and improved diffusions rates over the single-fiber tubular membrane dialyzer. Methylene blue (MB) and powder activated carbon were used as the model contaminant and adsorbent. The computational model explored key parameters of the dialytic purification process and provided insight into the impact of parameter values on the overall removal of MB. Through these efforts, the dialytic purification process was successfully described mathematically, and the model can be used to explore real batch water treatment or pump and treat remediation applications to provide clean water for the future. The idea of utilizing nanoadsorbents retained behind a membrane to facilitate contaminant removal in a mass exchanger can also benefit analogous fields utilizing similar dialytic processes such as hemodialysis in the medical field and carbon dioxide removal in the petrochemical industry. / Environmental Engineering

Nonpoint source pollution from agricultural activities significantly impacts quality of receiving water bodies, including increases in stream sediments and nutrients, and occurrence of pesticides in both surface and ground water. Agricultural activities in the West Wellfield Interim Protection Area (WWIPA), located in West Dade County in South Florida, have potential to impact both the environmentally sensitive Everglades and Florida Bay, and the Biscayne aquifer. The Hydrological Simulation Program-Fortran (HSPF) has been used to simulate water and constituent transport in the WWIPA and to determine possible impacts. Surface runoff, groundwater recharge, and transport of sediments, nutrients and pesticides are simulated by this model. ARC/INFO Geographic Information Systems (GIS) is interfaced with HSPF to store, manage, and display data, and derive input parameters for the model. Results of HSPF simulations are also visually presented through GIS. A GIS user interface was developed for the study area. Menus were created through which the database can be queried to derive model parameters and to visually present results through maps. Model results show that sediments, nutrients and pesticides are present in surface runoff, and nutrients enter the ground water. Various model test runs were made to minimize pollution levels without hindering agricultural production. They include application of minimum required rates of fertilizers, replacement of fertilizers by sewage sludge, and the effect of future urbanization.