京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第19348号 / 地環博第141号 / 新制||地環||28(附属図書館) / 32350 / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)教授 藤井 滋穂, 教授 高岡 昌輝, 准教授 田中 周平 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

No description available.

No description available.

MSc(Eng), Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2010

Water polluted by metals and phosphates can be hazardous to both the environment and human health. The aim of this study was used to improve understanding of the adsorption properties of low-cost, green adsorbents for removal of pollutants from aqueous solution. Biochar was used as an adsorbent, which was produced from the gasification of pine wood waste and the fast pyrolysis of Douglas fir. Biochar is a bio-renewable product that can easily be modified, and the cost is lower compared to other adsorbents like activated carbon. The gasifier produced biochar was modified by coating the biochar surface with chitosan. Douglas fir biochar, produced by pyrolysis, was used in Mg/Al-layered double hydroxides (LDHs) and magnetization modifications. The Mg/Al-LDHs were prepared by co-precipitation using solutions of Mg and Al salts and NaOH treatment. The magnetization modification of the biochar was prepared by magnetite (Fe3O4) precipitation onto the biochar’s surface from Fe2+/Fe3+ solution upon NaOH treatment. Chapter I provides an introduction into biochar production, uses, and modification methods. Chapter II is a study of the aqueous adsorption Cu2+ and Cd2+ metals using chitosan coated and uncoated gasifier biochars. Chapter III focused on the removal of phosphate from aqueous solutions. Different ratios of Mg:Al in the LDHs were used to test the ratio’s affect on the adsorption properties of the modified adsorbents. Chapter IV describes the removal of phosphate from water using LDH modified biochars that are magnetized. This study looks at how the order in which the modifications were done influences the biochars adsorption ability. The surface chemistry and composition of each biochar in chapters II-IV were examined by SEM, SEM-EDX, TEM, PZC, XRD, elemental analysis, and surface area measurements. Each biochar’s adsorption ability was studied by pH effects, kinetics, and maximum capacity for the analyte.

The utilization of activated sludge as feedstock for biofuel and oleochemical production was investigated. Initial studies included optimization of biodiesel production from this feedstock through in situ transesterification. Results of these studies indicated that activated sludge biodiesel is not economically viable. This was primarily due to relatively low yields and the high economics of feedstock dewatering. Strategies to increase biofuel yield from activated sludge were then evaluated. Bacterial species present in activated sludge are known to produce a wide variety of lipidic compounds as carbon and energy storage material and as components of their cellular structures. In addition to lipidic compounds, activated sludge bacteria might also contain other compounds depending on wastewater characteristics. Among these bacterial compounds, only the saponifiable ones can be converted to biodiesel. The unsaponifiable compounds present in the activated sludge are also important, not only for biofuel production, but also for a wide variety of applications. Characterization of lipids in activated sludge revealed that it contains significant amount of polyhydroxyalkanoates, wax esters, acylglycerides and fatty acids. It also contains Template Created By: James Nail 2010 sterols, steryl esters and phospholipids as well as small but detectable amounts of hydrocarbons. This indicated that activated sludge could be also an inexpensive source of oleochemicals. Another strategy that was evaluated was lipid-enhancement by fermentation of activated sludge. Since the majority of products from petroleum oil are used as transportation fuel, the aim here was to increase the saponifiable lipids in activated sludge bacteria by applying a biochemical stimulus (i.e. high C:N ratio). Results showed that application of this stimulus increased the amount of saponifiable lipids, particularly triacyglycerides, in the activated sludge. Furthermore, fermentation homogenized the lipids in the sludge regardless of its source. This solidified the concept of utilizing wastewater treatment facilities as biorefineries. To support the utilization of other compounds in raw activated sludge for biofuel production, a model compound was chosen for catalytic cracking experiments. Results indicated that catalytic cracking of 1-octadecanol over H+ZSM5 proceeds via dehydration, producing octadecene. The octadecene then undergoes a series of reactions including β-C─C bond scission, alkylation, oligomerization, dehydrocyclization and aromatization producing aromatics, paraffins and olefins suitable for fuel applications.

Nitrogen pollution in the environment creates challenging problems globally and locally and can be effectively controlled by a significant reduction in nitrogen release into the natural water system. In addition, nutrients in high-strength wastewater can be recovered as valuable resources such as different types of ammonium solutions for industrial and agricultural utilizations. Selective ammonia separation from high-strength wastewater can be achieved by bipolar membrane electrodialysis (BMED), a relatively new ion exchange technology. A series of 8 bench-scale BMED experiments with bipolar membranes and cation exchange membranes were performed under various voltage applications. Ammonia in the wastewater was rapidly separated and recovered as a high purity ammonium hydroxide solution. BMED operation for 30 minutes at 5.0 V per cell pair was found to be ideal for high purity ammonium hydroxide production and low electrical energy consumption. Additionally, effective organic fouling control and low energy consumption were achieved. The experiments showed a decrease in the feed pH making it ideal for applications in solid-state anaerobic digestion with leachate recirculation. The application of leachate recirculation in solid-state anaerobic digestion (SSAD) has proven effective for mobilizing nutrients and diluting toxic byproducts to enhance biogas production. The leachate after recirculation contains accumulated ammonia and an increased pH and requires water and chemicals for dilution and pH adjustment prior to recirculation. The data from the experiments were used to construct a numerical model for a hypothetical lab-scale and pilot-scale bipolar membrane electrodialysis and solid-state anaerobic digestion with leachate recirculation (BMED-SSAD) system. A final ammonia concentration of less than 2000 mg-N/L in the reactor was found to be achievable by lab-scale (6 mA/cm2) and pilot-scale (12 mA/cm2) BMED-SSAD and low electric energy consumption. The results suggest that BMED is an attractive solution for ammonia separation from high-strength wastewater. / Thesis / Master of Applied Science (MASc)

Excessive release of nitrogen (e.g., ammonia and organic nitrogen) into natural water systems can cause serious environmental problems such as algal blooms and eutrophication in lakes and rivers, threating the aquatic life and ecosystem balance. Membrane aerated biofilm reactor (MABR) and anaerobic ammonia oxidation (Anammox) are new technologies for wastewater treatment with an emphasis on energy-efficient nitrification and denitrification. Microplastic (MP) is an emerging contaminant in wastewater and sludge treatment that has a negative effect on the environment and public health. For these relatively new technologies and contaminants, mathematical models can enhance our understanding of the removal mechanisms, such as reaction kinetics and mass transport. In this study, mathematical models were developed and utilized to simulate the removal of nitrogen and MP in biological reactions in wastewater treatment processes. Firstly, a comprehensive MABR model was developed and calibrated using a pilot-scale MABR operation data to estimate the important process parameters where it was found that biofilm thickness, liquid film thickness and C/N ratio are key parameters on nitrification and denitrification. Secondly, a mathematical model for Anammox process was developed and calibrated using previous experimental results to simulate the wastewater treatment using Anammox process, reflecting the importance of dissolved oxygen on the nitrogen removal using Anammox bacteria. Thirdly, a granule-based Anammox mathematical model was built and calibrated using other simulation results from previous Anammox studies, showing the significance of operational conditions (e.g., granule diameter and dissolved oxygen) on the success of Anammox enrichment process. Fourthly, an enzyme kinetic mathematical model was constructed and calibrated with lab-scale experiments to simulate the MP reduction using hydrolytic enzymes under various experimental conditions where it was found that anaerobic digesters can be an innovative solution for MP removal during the wastewater treatment processes. Based on the main findings in this study, it can be concluded that mathematical models calibrated with various experimental results are efficient tools for determining the important operational parameters on the nitrogen and MP removal and helping in the design and operation of large-scale removal applications. / Thesis / Doctor of Philosophy (PhD) / Nitrogen and microplastic (MP) are serious contaminants in wastewater that can cause critical environmental and public health problems. Nitrogen can cause algal blooms, threatening the aquatic ecosystem while MP can be ingested by the biota (e.g., fish and seabirds), causing serious damage in the food chain. Nitrogen removal in the conventional biological wastewater treatment is relatively expensive, requiring high energy cost and large footprint for the wastewater treatment facilities. MP removal is also difficult in the conventional wastewater and sludge treatment processes. Therefore, new technologies, including membrane aerated biofilm reactor (MABR), anaerobic ammonia oxidation (Anammox) and hydrolytic enzymes processes, are implemented to improve the nitrogen and MP removal with a reduced energy and resources consumption in wastewater and sludge treatment processes. Numerical models are considered as an efficient tool for better understanding of these novel technologies and the competitive biological reaction in these technologies coupled with accurate estimation of process rates of the reactions. In this thesis, different numerical models were developed and calibrated to estimate the important model parameters, assess the effect of operational conditions on the removal mechanisms and determine the dominant parameters on the removal of nitrogen and MP in the wastewater treatment processes. These numerical models can be used for better understanding of the removal mechanisms of nitrogen and MP, helping in the design and operation of removal systems and addressing novel technologies in large-scale nitrogen and MP removal applications.

An increasing number of countries worldwide is becoming water-stressed, sub-Saharan Africa being one of the most recurrent regions within this discourse. Tanzania, one of the countries in the region, is no exception: large population growth has increased pressure on its precious water resources. The largest city, Dar es Salaam, has a poorly maintained and dimensioned water supply and wastewater system. However, as this system expands and more people are given access to the water network, the water consumption of the city is expected to increase. This is problematic for the whole city; however, peri-urban areas suffer the most from its consequences, e.g. periodical water shortages. This report seeks to investigate the potential for saving water in one of these peri-urban areas, Kibondemaji, by looking at fields of application and techniques for reuse of wastewater from showers. This is done via a literature review and interviews in the field in order to analyse and compare the different systems – reuse for tap water, irrigation and toilet flushing. The interviews showed that there is wide acceptance within the community for water reuse for toilet flushing but not for tap water or irrigation. Reuse for toilet flushing also requires less treatment than other fields of application, thus being the most promising technique for implementation in Kibondemaji.

No description available.