No description available.

The rising use of mineral-based fertilizer and water for agricultural operations to feed a growing population has polluted water bodies and depleted resources. In addition, nutrient contamination has caused eutrophication and wastewater concerns that conventional wastewater treatment cannot solve. Thus, meeting new water treatment regulations and procuring more value-added products from these procedures is crucial. Conductive ultrafiltration membranes precipitate and extract struvite, an ecologically good fertilizer, from synthetic livestock effluent. This technique produces solid fertilizer and irrigation-quality water. Since the recovery process relies on electrochemical hydrolysis and local pH modulation along the membrane surface, pH correction does not need chemical additions. The system was tested using cow effluent with up to 1,000 mg/L of nitrogen and phosphorus. Analytical tests showed that the precipitates were struvite and that up to 65% of the phosphorus and nitrogen were removed in the first 30 minutes of electrochemical filtration. Low membrane fouling and flux drop made the recovery technique successful. A mathematical model of N, P, and Mg ions in an external electric field explained the fouling and precipitation tests. Thus, precipitation happens near the membrane but not on it. This reduces surface fouling. Forward osmosis was used to make struvite with less energy. A voltage near the FO membrane enabled magnesium to migrate opposite into the feed chamber, where it reacted with ammonium and phosphate in the feed solution to form struvite. Electrical charging increased struvite recovery by 77% and water recovery by 39%. Ion migration may have reduced dilutive and concentrative polarization on the draw and feed sides of the FO membrane, causing the rise. High external voltage, draw concentration, and draw pH made water recovery and struvite precipitation simpler. This study suggests that reverse salt flow might improve FO systems' nutrition and water recovery. These devices were combined with microbial electrolytic cells to generate electricity and prevent biofouling. FO treatment was investigated using vacuum membrane distillation for sustainability and zero discharge. Constant draw solution reconcentration yields more steady flux values than the typical lowering flux. The research will increase knowledge of treatment system synergy in water reclamation and nutrient recovery. It also identifies possible obstacles to development. / Environmental Engineering

No description available.

Current treatment of wastewater can effectively remove the contaminants; however, the effluent is still not widely reused because of some undesired substances like pathogens and trace organic chemicals. To promote water reuse, membrane-based technologies have emerged as a robust and more efficient alternative to current treatment practice. Among these membrane processes, forward osmosis (FO) utilizes an osmotic pressure gradient across a semi-permeable membrane to reclaim high-quality water. Still, several key challenges remain to be addressed towards broader FO application, including energy-intensive draw regeneration to yield product water and salinity buildup in the feed solution. To bypass energy-intensive draw regeneration, commercial solid fertilizers was utilized as a regeneration-free draw solute (DS), harvesting fresh water towards direct agricultural irrigation. However, using nutrient-rich fertilizers as DS resulted in an elevated reverse solute flux (RSF). This RSF, known as the cross-membrane diffusion of DS to the feed solution, led to deteriorated solute buildup on the feed side, reduced osmotic driving force, increased fouling propensity, and higher operation cost. To effectively mitigate solute buildup while achieving energy-efficient water reclamation, a parallel electrodialysis (ED) device was integrated to FO for DS recovery in the feed solution. The salinity in the feed solution was consistently controlled below 1 mS cm-1 via the hybrid FO-ED system. Considering solute buildup is merely a consequence of RSF, direct control of RSF was further investigated via operational strategy (i.e., an electrolysis-assisted FO) and membrane modification (i.e., surface coating of zwitterion-functionalized carbon nanotubes). Significantly reduced RSF (> 50% reduction) was obtained in both approaches with minor energy/material investment. With two major bottlenecks being properly addressed for energy-efficient water reclamation, FO was further integrated with a microbial electrolysis cell (MEC) to achieve integrated nutrient-energy-water recovery from high-strength wastewater (i.e., the digestor centrate). The abovementioned research projects are among the earliest efforts to address multiple key challenges of FO during practical application, serving as a cornerstone to facilitate the transformation of current water/wastewater treatment plant to resource recovery hub in order to ensure global food-energy-water security. / Doctor of Philosophy / Exploring alternative water supply, for instance via reusing wastewater, will be essential to deal with the global water crisis. Current wastewater treatment can effectively remove the contaminants; however, the treated wastewater is still not widely reused due to the possible presence of residual contaminants. In recent years, membrane-based technologies have emerged as a promising treatment process to produce clean water. Among all available membrane technologies, forward osmosis (FO) takes advantage of the osmotic pressure difference across a special membrane to extract fresh water from a low-salinity FEED solution (for example, wastewater) to a high-salinity DRAW solution. The reclaimed fresh water can be reused for other applications. Still, the FO process is facing several critical challenges for broader applications. The first challenge is that additional energy is required to separate clean water from the diluted DRAW solution, leading to notably increased energy consumption for the FO process. To bypass this energy-intensive separation, commercial solid fertilizers was utilized as a separation-free DRAW solution for FO process. Once the clean water is extracted to the DRAW solution (fertilizer), the diluted fertilizer solution together with the fresh water can be directly used for agricultural irrigation. The second challenge is that, when fertilizer is applied as the DRAW solution, nutrient rich fertilizers can penetrate the FO membrane and escape to the FEED solution (wastewater). This phenomenon is known as the reverse solute flux (RSF). RSF can result in many adverse effects, such as wastewater contamination and increased operational cost. To prevent this, we used an additional device named electrodialysis to effectively recapture the “escaped” fertilizers in the FEED solution. Besides this indirect approach to recover escaped fertilizers, we also investigated direct approaches to control RSF, including operational strategy and membrane modification. With two major challenges being properly addressed for energy-efficient water reclamation, FO was further combined with a microbial electrolysis cell (MEC) to achieve multiple resource recovery from wastewater, including water, nutrient, and energy components. The above mentioned research projects are among the earliest efforts to address multiple key challenges of FO during water and resource recovery from wastewater to ensure global food-energy-water security.

The nitritation-anammox process is an efficient and cost-effective approach for biological nitrogen removal, but its application in treating mainstream wastewater remains a great challenge. The key objectives of this dissertation are to develop nitritation-anammox process to treat wastewater with low-nitrogen strength, understand the fundamental microbiology, and optimize its operation through experimental studies and mathematic modeling. Chapter 2 showed that the nitritation-anammox process has been successfully developed in an upflow membrane-aerated biofilm reactor, where pure oxygen was delivered via gas-permeable membrane module. Chapter 3 demonstrated that hybrid anaerobic reactor (HAR) could be an effective pretreatment method to provide a relatively low COD/N ratio for nitritation-anammox reactor. In Chapter 4, a novel mathematical model has been proposed to evaluate the minimum DO requirement for the nitritation-anammox reactor to achieve the maximum TN removal under various COD/N scenarios (controlled by HRTHAR). Chapters 5 and 6 designed an OsAMX system by linking nitritation-anammox to forward osmosis to remove the reverse-fluxed ammonium while using ammonium bicarbonate as a draw solute. The microbial community structures and dynamics, spatial distributions in these bioreactors were characterized by high-throughput sequencing and fluorescent in situ hybridization techniques. The studies in this dissertation have demonstrated that nitritation-anammox process is a promising alternative for sustainable mainstream treatment with the appropriate pretreatment approach and operation optimization. / PHD

Modifying photopolymer structure on the molecular and nanoscale level permits tailoring materials for use in a wide variety of applications. Understanding the fundamentals behind polymer structure at these levels permits the control of material properties. This work gains insight into the modification of structure on two levels, the nanoscale by use of structure templates and the molecular scale through the modification of polymer network formation. Lyotropic liquid crystals (LLCs) are a type of self-assembling surfactant system, which in combination with photopolymerization can be used to template ordered nanostructure within polymer materials. This structure can be controlled and utilized to influence the properties of a polymer material. This research examines materials used as templating agents and the types of nanostructures that may be obtained. Additionally, their effects upon the LLC templating process and material properties is determined. Structured polymers are created using LLC templates in pursuit of materials for use in water purification processes and electrochemical devices. Through a more complete understanding of the fundamentals of the templating process, the work presented here extends the LLC templating technique to a greater variety of materials and applications in the water remediation and energy storage fields. The second portion of this research is the use of reversible addition fragmentation chain transfer (RAFT) to modify photopolymer networks. RAFT agents are utilized to control the propagation reaction to create networks with increased homogeneity between network crosslinks. By increasing the uniformity of the polymer network, increases in polymer elongation and toughness as well as decreases in polymer modulus are observed. The effects of RAFT agent addition on the network formation and the final properties of the photopolymer is examined. By understanding the mechanisms behind this modification technique, photopolymers can be extended into new applications where increased elongation and toughness is valued.

No description available.

Forward osmosis (FO) is an emerging technology for water treatment due to their ability to draw freshwater using an osmotic pressure gradient across a semi-permeable membrane. However, the lack of draw agents that could both produce reasonable flux and be separated from the draw solution at a low cost stand in the way of widespread implementation. This study had two objectives: evaluate the performance of three materials — peptone, carboxymethyl cellulose (CMC), and magnetite nanoparticles (Fe3O4 NPs) — as potential draw agents, and to use multi-criteria decision matrices to systematically prioritize known draw agents from literature for research investigation. Peptone showed water flux and reverse solute flux values comparable to other organic draw agents. CMC’s high viscosity made it impractical to use and is not recommended as a draw agent. Fe3O4 NPs showed average low fluxes (e.g., 2.14 LMH) but discrete occurrences of high flux values (e.g., 14 LMH) were observed during FO tests. This result indicates that these nanoparticles have potential as draw agents but further work is needed to optimize the characteristics of the nanoparticle suspension. Separation of the nanoparticles from the product water using coagulation was shown to be theoretically possible if only electrostatic and van der Waals forces are taken into account, not steric repulsion. If coagulation is to be considered for separation, research efforts on development of nanoparticle suspensions as FO draw agents should focus on development of electrostatically stabilized nanoparticles. A combination of Fe3O4 NP and peptone showed a higher flux than Fe3O4 NPs alone, but did not produce additive or synergistic flux. This warrants further research to investigate more combinations of draw agents to achieve higher flux than that obtained by individual draw agents. Potential draw agents were prioritized by conducting a literature review of draw agents, extracting data on evaluation criteria for draw agents developed over the past five years, using these data to rank the draw agents using the Analytical Hierarchy Process (AHP) and Technique for Order of Preference by Similarity to Ideal Solutions (TOPSIS). The evaluation criteria used in the ranking matrices were water flux, reverse solute flux, replenishment cost, regeneration cost, and regeneration efficacy. The results showed that the top five ranked draw agents were P-2SO3-2Na, TPHMP-Na, PEI-600P-Na, NaCl, and NH4-CO2. The impact of the assumption made during the multi-criteria decision analysis process was evaluated through sensitivity analyses altering criterion weighting and including more criteria. This ranking system provided recommendations for future research and development on draw agents by highlighting research gaps.

Membrane filtration processes such as micro-, ultra- and nanofiltration as well as reverse osmosis are frequently used in industrial water treatment and waste water treatment. They use a high physical pressure difference as a driving force to press water through a semi-permeable membrane and produce purified water. For this reason, large amounts of energy are required. In contrast, forward osmosis is an innovative membrane filtration process that uses the naturally occurring osmotic pressure gradient between two liquids to generate the water flow through the semi-permeable membrane. In forward osmosis, one liquid with low osmotic pressure is concentrated (so-called Feed Solution) and a second liquid is diluted (so-called Draw Solution). If 'pure' water is to be obtained, a second treatment stage is necessary to regenerate the draw solution. Due to its natural driving force, forward osmosis offers the potential for energy-efficient treatment of water from various sources. This makes it a promising process for further concentration of aqueous product and waste water streams. For this reason, the application possibilities and the potential of forward osmosis in the industrial water sector were examined in more detail within the scope of this thesis. Within laboratory tests, forward osmosis treatment of different liquid streams of a dairy, an automobile production as well as a semiconductor production was examined. The core of the laboratory test set-up was a membrane test cell for flat sheet membranes with an effective membrane area of 48 cm². Special forward osmosis membranes from various manufacturers were used. The feed and draw solutions were circulated and increasingly concentrated or diluted during the course of the experiment. The permeate flow was determined by recording the change in mass. Conductivity measurements as well as analyses of the examined waters before and after the experiments allowed conclusions to be drawn about possible solute diffusion through the membrane. In addition to the laboratory tests, a model was developed and validated to simulate the experiments. Three partially adapted models from literature were used. The average permeate fluxes achieved in the laboratory experiments with real industrial water depended mainly on the osmotic pressure difference between feed and draw solution. The permeate fluxes were between 0.1 and 19.4 L/(m²⸱h) for the automotive industry, between 7.9 and 21.0 L/(m²⸱h) for the dairy industry and between 10.5 and 33.4 L/(m²⸱h) for the semiconductor industry. The reverse solute fluxes determined were between 37.7 and 21.3 g/(m²⸱h), between 4.1 and 12.2 g/(m²⸱h) and between 8.0 and 40.9 g/(m²⸱h). Within modelling, the tests with waters from automobile production were simulated. For the most part, the permeate fluxes could be well represented. The calculation of the reverse solute fluxes sometimes showed large deviations from the actual measurements. Standardized membrane performance tests were used to evaluate the development of permeate flux and to indicate fouling. Depending on the substances contained in the water, fouling occurred in the test series. In addition, deposits on the membrane surface were visible in some tests. However, the visible deposits did not always lead to a decrease in permeate flow. In an exemplary cleaning test, the membrane performance could be restored by rinsing with sodium hydroxide solution and hydrochloric acid. As a result of this thesis, different forward osmosis application scenarios in the examined industrial enterprises could be developed. For economic reasons, those scenarios in which both the feed and the draw solution are industrial waters and two liquids are treated simultaneously in one step are of particular interest. The use of an artificial Draw Solution and its treatment is unnecessary in this case. Such application scenarios could be derived for dairy and semiconductor production. No suitable Draw Solution could be identified in the investigated automobile production, which is why only applications with an artificial Draw Solution are conceivable here. In general, the critical points when using forward osmosis are the reverse solute flux through the membrane, the deterioration of the membrane performance due to fouling and the economic efficiency of the process. More in-depth investigations are required here. / Membranfiltrationsverfahren wie die Mikro-, Ultra- und Nanofiltration sowie die Umkehrosmose werden häufig in der industriellen Wasseraufbereitung sowie Abwasserbehandlung eingesetzt. Sie nutzen einen hohen physikalischen Druck-unterschied als Triebkraft, um Wasser durch eine semipermeable Membran zu pressen und gereinigtes Wasser zu erzeugen. Dafür sind große Energiemengen nötig. Im Gegensatz dazu ist die Vorwärtsosmose ein innovatives Membranfiltrationsverfahren, welches den natürlich vorkommenden osmotischen Druckgradienten zwischen zwei Flüssigkeiten nutzt, um einen Wasserfluss durch die semipermeable Membran zu erzeugen. Dabei wird eine Flüssigkeit mit niedrigem osmotischen Druck aufkonzentriert (sog. Feed Solution) und eine zweite Flüssigkeit verdünnt (sog. Draw Solution). Soll „reines“ Wasser gewonnen werden, ist eine zweite Aufbereitungsstufe zur Regeneration der Draw Solution notwendig. Durch die natürliche Triebkraft bietet die Vorwärtsosmose das Potenzial zur energieeffizienten Behandlung von Wässern verschiedener Herkunft. Damit ist sie ein vielversprechendes Verfahren zur weitergehenden Aufkonzentrierung von wässrigen Produkt- und Abwasserströmen. Aus diesem Grund wurden die Einsatzmöglichkeiten und das Potenzial der Vorwärtsosmose im industriewasser-wirtschaftlichen Bereich im Rahmen dieser Arbeit näher untersucht. Im Rahmen von Laborversuchen wurde die Aufbereitung von verschiedenen Flüssigkeitsströmen einer Molkerei, einer Automobilproduktion sowie einer Halbleiter-fertigung mittels Vorwärtsosmose untersucht. Kernstück der Laborversuchsanlage war eine Membrantestzelle für Flachmembranen mit einer wirksamen Membranfläche von 48 cm². Zum Einsatz kamen spezielle Vorwärtsosmosemembranen verschiedener Hersteller. Die genutzten Feed und Draw Solutions wurden im Kreislauf geführt und im Versuchsverlauf zunehmend aufkonzentriert bzw. verdünnt. Über die Erfassung der Masseänderung wurde der Permeatfluss bestimmt. Leitfähigkeitsmessungen sowie Analysen der untersuchten Wässer vor und nach den Versuchen ließen Schlussfolgerungen über eventuell auftretende Stoffdiffusion durch die Membran zu. Zusätzlich zu den Laborversuchen wurde ein Modell zur Simulation der Experimente erstellt und validiert. Dabei wurden drei, teilweise adaptierte, Modellansätze aus der Literatur verwendet. Die durchschnittlichen Permeatflüsse, welche bei den Laborversuchen mit reellen industriellen Wässern erreicht wurden, hingen vorrangig von der osmotischen Druckdifferenz zwischen Feed und Draw Solution ab. Die Permeatflüsse lagen für die Automobilindustrie zwischen 0,1 und 19,4 L/(m²⸱h), für die Molkerei zwischen 7,9 und 21,0 L/(m²⸱h) und für die Halbleiterindustrie zwischen 10,5 und 33,4 L/(m²⸱h). Die ermittelten Salzrückflüsse betrugen zwischen 37,7 und 21,3 g/(m²⸱h), zwischen 4,1 und 12,2 g/(m²⸱h) sowie zwischen 8,0 und 40,9 g/(m²⸱h). Im Rahmen der Modellierung wurden die Versuche mit Wässern der Automobilproduktion nachgebildet. Dabei konnten die Permeatflüsse größtenteils gut dargestellt werden. Die Berechnung der Salzrückflüsse wies gegenüber den tatsächlichen Messungen mitunter große Abweichungen auf. Durch standardisierte Membranleistungstests konnte die Entwicklung des Permeatflusses evaluiert und Fouling nachgewiesen werden. In Abhängigkeit der Wasserinhaltsstoffe trat Fouling in den Versuchsreihen auf. Zusätzlich waren bei einigen Versuchen Ablagerungen auf der Membranoberfläche sichtbar. Jedoch führten die sichtbaren Ablagerungen nicht in allen Fällen zu einem Rückgang des Permeatflusses. In einem exemplarisch durchgeführten Reinigungsversuch konnte die Membranleistung durch Spülprozesse mit Natronlauge und Salzsäure wiederhergestellt werden. Als Ergebnis der Arbeit konnten verschiedene Anwendungsszenarien für den Einsatz der Vorwärtsosmose in den untersuchten Industriebetrieben entwickelt werden. Hierbei sind aus wirtschaftlichen Gründen vor allem jene Szenarien interessant, bei denen sowohl die Feed als auch die Draw Solution industrielle Wässer sind und zwei Flüssigkeiten simultan in einem Schritt aufbereitet werden. Der Einsatz einer künstlichen Draw Solution und deren Aufbereitung ist in diesem Fall unnötig. Solche Anwendungsszenarien konnten für die Molkerei sowie die Halbleiterherstellung abgeleitet werden. In der untersuchten Automobilproduktion konnte keine geeignete Draw Solution identifiziert werden, weshalb hier lediglich Anwendungen mit einer künstlichen Draw Solution denkbar sind. Als kritische Punkte beim Einsatz der Vorwärtsosmose stellten sich der auftretende Salzrückfluss durch die Membran, die Verschlechterung der Membranleistung durch Fouling sowie die Wirtschaftlichkeit des Verfahrens heraus. Hier besteht weitergehender Forschungsbedarf.

Landfill leachate contains valuable, recoverable organics, water, and nutrients. This project investigated leachate treatment and resource recovery from landfill leachates by innovative methods such as forward osmosis (FO), bioelectrochemical systems (BES), and advanced oxidation. In this study, a microbial fuel cell (MFC) removed 50-75% of the ammonia from a leachate through the electricity driven movement of ammonium to the cathode chamber followed by air stripping at high pH (> 9). During this process, the MFC system removed 53-64% of the COD, producing a net energy of 0.123 kWh m-3. Similarly, an integrated microbial desalination cell (MDC) in an FO system recovered 11-64% of the ammonia from a leachate; this was affected by current generation and hydraulic retention time in the desalination chamber. The MDC-FO system recovered 51.5% of the water from a raw leachate. This increased to 83.5% when the FO concentrate was desalinated in the MDC and then recirculated through the FO unit. In addition, the project investigated humic acid (HA) recovery from leachate during the synergistic incorporation of FO, HA recovery, and Fenton's oxidation to enhance leachate treatment and to reduce Fenton's reagent requirements. This led to the investigation of harmful disinfection byproducts (DBPs) formation during Fenton's oxidation of landfill leachate. The removal of leachate UV-quenching substances (humic, fulvic, and hydrophilic acids) using an MFC and a chemical oxidant (i.e., sodium percarbonate) with a focus on energy production and cost efficiency were also studied. BES treatment can reduce leachate organics concentrations; lower UV absorbance; recover ammonia; and, in combination with FO, recover water. Although BES is promising, significant work is needed before its use in landfill leachate becomes practical. FO application to leachate treatment must consider the choice of an appropriate draw solute, which should require minimal effort for regeneration. Resources like HA in leachate deserve more attention. Further efforts can focus on purification and application of the recovered products. The emerging issue of DBP formation in leachate treatment also requires attention due to the potential environmental and human health effects. The broader impact of this study is the societal benefit from more sustainable and cost-efficient leachate treatment. / Doctor of Philosophy / On average, each of us produces 3 – 4 pounds of solid waste every day. In the U.S., the yearly generation of solid waste is 250 million tons, while the global generation is 1.1 billion tons. The global management cost of solid waste is around 200 billion dollars. About half of U.S. municipal solid waste ends up in landfills, in China, this number is 80%. Among the different municipal solid waste (MSW) management approaches, landfilling is the most common because of its low cost and relatively low maintenance requirements. In a landfill, the combination of precipitation and solid waste degradation produce leachate, a complex wastewater. A ton of municipal solid waste can generate 0.05–0.2 tons of leachate in its lifetime during the process of landfilling. Leachate contains a vast array of pollutants, which can result in major environmental impact and adverse human health risk if not contained and treated appropriately. At present, leachate is mostly treated biologically, without any resource recovery. Among the myriad recoverable resources in landfill leachates, water and ammonia are the most abundant. We applied innovative approaches such as, bioelectrochemical systems, forward osmosis, advanced oxidation to recover resources and remove contaminants from leachate simultaneously. We also incorporated these novel technologies to help each other. For instance, we recovered humic fertilizer from leachate prior to advanced oxidation (i.e., Fenton’s oxidation) that helped the reduction of Fenton’s reagent requirements. The next step of our study could be the pilot scale application of the proposed techniques so that it can be applied in field. The broader impacts of this study include improvements in sustainability and cost efficiency of leachate treatment that can benefit the society.