Evaluation of Antimicrobial Metals for Enhanced Performance of Household Water Treatment Methods

Household water treatment and safe storage (HWTS) technologies play an increasingly important role in the reduction of global burden of waterborne disease, putting the capacity to treat unsafe drinking water directly into the hands of the consumer without reliance on centralized treatment or piped water systems. HWTS technologies differ in their ability to reduce viral, bacterial, and parasitic contaminants. Microbial reduction targets for HWTS performance set by the World Health Organization (WHO) are based on acceptable risk levels and log10 reductions. One approach to improve microbial reductions to meet performance targets is the incorporation of antimicrobial metals, which have been utilized for disinfection for centuries. The aim of this research was to evaluate copper, silver, and iron incorporated into ceramic water filters for improved E. coli and MS2 bacteriophage reductions and to determine the kinetics and magnitude of E. coli and MS2 inactivation with copper and silver ions as additives to water for solar disinfection (SODIS) and safe storage. The incorporation of copper, silver, and iron additives generally improved the reductions of E. coli by the ceramic water filters to reach the WHO Highly Protective (4 log10 reduction) target for bacteria, but viral reductions remained well below the WHO Protective (3 log10 reduction) target. Leached copper and silver ions in the filter effluent contributed to additional disinfection of E. coli and MS2 with overnight storage time. For stored water, copper and silver ions at concentrations allowable for drinking water showed the capacity to meet WHO Protective targets for virus reductions after overnight storage due to an apparent synergistic disinfection effect between copper and silver ions. Copper and silver ion additives also significantly increased the inactivation rates of bacteria and more notably viruses in SODIS. E. coli reductions were evaluated on selective and non-selective media, and differences in log10 reductions indicated the ability of E. coli to resuscitate initially after sub-lethal injury by metals and/or solar irradiation, but this effect decreased as exposure times increased. Incorporation of antimicrobial metal additives for ceramic water filters, SODIS, and stored water requires further study but shows promise for improved microbial reductions by HWTS technologies.Doctor of Philosoph

Review on green biomass-synthesized metallic nanoparticles and composites and their photocatalytic water purification applications: progress and perspectives

In recent years, the use of biomass for the cost-effective synthesis of nanoparticles has emerged as a promising green technology. Because of their remarkable properties, such as tunable surface plasmon resonance characteristics and high surface areas, bio-synthesised nanomaterials are receiving more scientific and academic attention for their use in various application sectors, especially as catalysts in environmental remediation. Green synthesized nanomaterial's can efficiently contribute to the degradation of a wide range of organic pollutants, including dyes, into harmless by-products. These particles have a cure for recalcitrant organic and inorganic pollutants due to their photocatalytic properties, which largely depend on the production of reactive oxygen species under sunlight or UV illumination. This comprehensive review systematically covers up-to-date knowledge on recent developments in the green synthesis of nanoparticles and composites using plants and microorganisms, unravels underlying mechanisms, and highlights their application areas. It then provides detailed information on their applications in the degradation of potentially toxic organic dyes and the removal of other emerging pollutants, including heavy metals and antibiotics. Finally, the current challenges and perspectives of this technology for future applications are discussed

Wastewater Treatment: Current and Future Techniques

This book examines the state-of-the-art water and wastewater treatment methods that can be applied to develop a sustainable treatment technique in the future. Of the several high-quality articles submitted, twelve were published after the peer-review process, with an acceptance rate of 59 percent. In the first section of this book, the articles include the occurrence and removal of emerging contaminants in water bodies. Moreover, the presence of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in water sources is discussed in detail. Subsequently, the removal of polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs), and dye with different physicochemical methods is investigated. In another section of this book, the removal of ammonia with anaerobic ammonium oxidation (anammox) is studied. Additionally, the elimination of heavy metals using the adsorption process, as an effective method, is discussed. Moreover, the performance of membrane bioreactors in the elimination of pollutants from landfill leachate is investigated in another article in this book. In addition to this, green and sustainable wastewater technologies (GSWTs) have recently attracted the attention of researchers. Therefore, nanoremediation and microalgae-based systems are discussed as the GSWTs

Developing an environmentally appropriate, socially acceptable and gender-sensitive technology for safe-water supply to households in arsenic affected areas in rural Bangladesh

To confront the arsenic crisis in Bangladesh, several options for a safe water supply in the rural As-affected areas are available. Most of these options have shown a minimum scope to mitigate arsenic-related risks because of their poor performance and non-acceptability by the rural households. In this research, therefore, the development of an appropriate technology for an As-free, safe drinking water supply is considered from a local perspective and a societal context. To achieve the goal and objectives of this research, four research questions were formulated (Chapter 1). The first research question is about the technological and socio-economic performance of community-based pipeline water supply systems that use deep aquifers. The second question deals with available and currently implemented household-level arsenic removal technologies in rural Bangladesh. The third addresses the weaknesses, limitations, strengths and advantages of the technologies in terms of a number of technological, social, economic and gender indicators. Fourth, the question is posed of the most promising arsenic removal option for rural house¬holds in terms of its techno¬logical performance and social acceptability and suitability from a gender perspective. The occurrence of As in the Delta region is of geochemical origin and its distribution in the groundwater has distinct regional patterns and depth trends. An overview of the arsenic problem in Bangladesh is given in Chapter 2. The overall objective of the research was to develop a socially appropriate and gender-sensitive household-level As removal filter. Technical, socio-economic and cultural aspects were incorporated in this research to assess the development of a sustainable innovation through multi- and interdisciplinary approaches. The technical validation of the systems was carried out through laboratory-based research, to address the efficiency, robustness, operational and maintenance convenience, safety and viability of the technology. For the social research, the model by Spaargaren and Van Vliet (2000) was adjusted to address the filter’s suitability in terms of lifestyle, domestic time-space structures, affordability, standards of comfort, cleanliness, convenience and modes of provision. In addition, I also considered the household resource-based affordability during the operation and maintenance phase, in terms of a socio-technological and gender perspective. A conceptual model was developed to guide the research and to answer the research questions (Chapter 1). The socio-economic data on the main concepts of this research work were collected through a survey (Appendix 2). In this research, a synthesis of knowledge resulting from disciplinary, open-ended collaboration and local perspectives is achieved. Such a transdisciplinary research approach ensures an integration of knowledge through the participation of a variety of stakeholders, including end users, and mutual learning between the different stakeholders, such as users of the Modified Garnet Homemade Filter (MGH Filter), caretakers, village committees, implementing organizations and donors, users of water, households, and women. The community–based piped water supply in Bangladesh There are several alternative sources to get safe and As-free drinking water in Bangladesh. A community-based piped water supply system using deep aquifers is one of them. In this research, three community-based piped water supply systems were compared to evaluate their technological and economic sustainability, the sustainability of using deep aquifers for the long term, and the social and gender appropriateness of the systems, based on the users’ perspective (Chapter 4). The technical performance of the three systems in different geological conditions was found satisfactory in terms of their efficacy, water quality, adequacy of the water supply, and operations and maintenance. The water is As- and Fe-free and is of good taste. The concentration of As is below the limiting range of drinking water in Bangladesh (50µgL-1As), as well as within the WHO and new EPA standards (10µgL-1As). The sustainable use of deep aquifers for a longer period is a serious issue. To address the sustainability, hydro-geological factors need to be well understood. Overextraction of water from deep aquifers could induce a downward migration of dissolved As and permanently destroy the deep resource. Only one system is practicing chlorination to disinfect the water in the overhead tank, while the other two systems do not have such a provision. However, the field data reveal that the three systems are technologically acceptable and do not require disposal of contaminated sludge. The women who are using one of the three water supply systems are satisfied about the water supply systems. They think the systems reliable in their delivery of adequate water and convenient and comfortable for the women users. Women can get water close to their house, which saves collection time and a physical burden. The appointed caretakers are operating the systems efficiently, including maintenance and the collection of the monthly bill from the beneficiaries. The economical sustainability seems to be satisfactory, provided the initial costs are subsidized by external financial assistance with only a little contribution from the communities, which varies from five to seven percent of the total capital cost. The community participation in sharing the installation cost for the system and the monthly bill are fixed, based on the economical condition of the households. However, a drawback of the community-based piped water system is disruption of the system due to its sensitivity to power failure, which is a big problem in Bangladesh. Other shortcomings are the limitations to extend the system to meet the increasing demand of the village people. On the long term, economical sustainability factors need to be considered, such as the availability of funds and the participation of the users in the system’s management, which were absent in all three systems. Currently available and implemented household-level arsenic removal technologies The application of arsenic removal technologies to provide safe drinking water in rural areas plays a vital role where other, alternative options and safe aquifers are not easily available and where community-based pipeline water supply systems are not feasible. In this research, physico-chemical and biological as well as conventional techniques for the removal of arsenic were reviewed (Chapter 5). Based on literature, an inventory was carried out of 40 available and currently implemented technologies at the household level in terms of their arsenic removal efficiency, cost and users’ acceptance. All the technologies remove As from the water to a limited extent. Therefore, there is scope for further development of these technologies. A multiple-criteria analysis (MCA) approach was applied to select a technology for the further development of an appropriate arsenic removal filter for household-level use. In the research, based on the integrated assessments, the MCA-GARNET technology was selected for further development. An assessment of the performances of the three governmentally certified arsenic removal technologies for rural household use was carried out (Chapter 5). This research concludes that the government’s investments in an improved water supply so far have failed to meet the needs of the poor villagers, because they are not able to buy the costly Alcan and Read-F filters. Even the relatively cheap Sono filter proved to be unaffordable for the poorest. Furthermore, assessing the As removal efficiency and life span of these filters is difficult at this preliminary stage, and so is predicting how the disposal of the spent filter materials will be carried out by the users. The As leaching from the sludge/waste generated by the three treatment processes is dependent on the type of removal mechanism and the ultimate sludge disposal methods. Development of a chemical-free arsenic removal technology for household use In this research, by the active participation of potential end users and other stakeholders, I have included local knowledge and social and gender perspectives in the process of the development of an innovative As removal filter (MGH filter) (Chapter 6). The MGH filter efficiency and breakthrough point were studied at different operational variables, such as filter bed thickness, types of filter media and flow rate. The toxicity of the spent material was addressed by a TCLP test. The developed filter meets the Bangladesh standard for arsenic in drinking water (50µgL-1). It can reduce the arsenic concentrations of the shallow tube well water samples from 160-959µgL-1 to 0-50µgL-1. It can also remove bacteriological contamination in terms of total coliform and fecal coliform counts from >500 to 0 cfu/100 mL-1 . The filter consists of two-bucket filters in series, each with three filter material layers of 14 cm thickness each, containing sand, brick chip and sand (Figure 7.1). The first-class brick chips of 1.3 cm size and Sylhet coarse sands were found to be the most efficient. The major advantage of this unit is that it does not require any daily addition of chemicals and can be operated at a high flow rate. It needs to be cleaned regularly to prevent bacterial contamination, while its maintenance requires treatment with bleaching powder at 15-day intervals. The filter is cost–effective and viable; the investments and operational cost are about € 10.8-13.4 and € 0.11-0.14 per 100 liters of treated water, respectively. In this research, a multi-perspective and participatory socio-technological assessment of the filter’s performance during the field level application was carried out in two phases: the trial phase during March 2008 and the evaluation phase during July 2008 (Chapter 7). Eight MGH filters were distributed among eight households in the research area in Kumarbhog. In this research, the multi-perspective assessment comprised interdisciplinary and transdisciplinary approaches to evaluate the performance of the filters for household use. Both quantitative and qualitative methods of data collection and analysis were used. The suitability and acceptability of the filters were evaluated through systematic observation, interviewing, FGDs and eight case studies of the filter users. The compatibility and appropriate¬ness of the filter were viewed from a gender pers¬pective, since access to safe water is an important practical gender need of women, directly related to their domestic and reproductive role. Women of the selected eight rural households adopted the technology and ran the filters successfully during the trial phase. As elsewhere in developing countries, in Bangladesh too, rural women are the managers of water for household use. They hardly participate in income generation. The male household head controls the allocation of household income and expenditures, which caused problems when women wanted to re-install their filter. The household survey revealed that sometimes, women cannot be bothered to fetch safe water from far away and, instead, drink the con¬taminated water from their own shallow tube wells. Having the appliance inside the house complied well with the social norms and religious restrictions (purdah) that women have to abide by. In these circumstances, the MGH filter was eagerly accepted by the eight households, because it reduced women’s social and physical burden to fetch As-free, safe water far from their home. In the evaluation phase, some filters were unused because the women could not persuade their husbands to purchase the necessary filter bed materials. During the evaluation phase, the performance of the filters declined compared to the trial phase, because not all users followed the instructions on its operation and maintenance, such as proper chlorination and clean¬liness of the appliance. Disposal of spent filter material was carried out in different ways by the MGH filter users, but more investigation is needed to enable an environmentally friendly disposal of the As-rich sludge. A new filter system has been developed that can be used by women at the household level. In terms of the simplicity of construction, operation and maintenance, As removal efficiency, and bacterial removal efficiency, its technical performance is good. It is also very cost-effective. However, because such a system always needs to be completely safe for producing drinking water, on the long term as well as under local and household conditions other than those investigated in this research project, further evaluation and additional research will be necessary. In this research, the filter was field-tested under controlled conditions for a month and evaluated after three months. Considering the need for arsenic treatment options in Bangladesh and other developing countries, further research on the performance of the MGH technology could have important positive implications for a safe water supply. Therefore, to allow for seasonality, the MGH filter should be pilot-tested and properly developed over a period of at least a year, in different geographical conditions. A social, economic and technical validation of the MGH filter should be included in the pilot-testing in different parts of the country by applying interdisciplinary and transdisciplinary approaches. Because women are the collectors and managers of drinking water, doing the validation in different parts of the country allows for variation in women’s roles and position and the local socio-cultural context. The MGH filter should be submitted for certification by the government of Bangladesh after further testing and development. The technological principle of the MGH filter may be used to research and develop a community-based low-cost arsenic removal water supply system in rural areas. The results of this research testify to the feasibility of a gender-sensitive, socially acceptable and technologically sound, sustainable solution to the problem of the As contamination of water for household use in rural areas in Bangladesh. <br/

Disinfection of Stored Water by Antimicrobial Granular Metallic Particles

Granular metals may be practical and useful for point-of-use (POU) water disinfection. This study evaluated cloth pouches containing different proportions of granular copper, zinc, and silver, or brass, as reusable point-of-use disinfectants in stored drinking water. Pouch performance was characterized by metal release into test waters and microbial reduction over a 48 hour storage period. Over 48 hours, most pouches (comprised by mass of 50-90% pure copper granules, 10-50% pure zinc granules, and 1% pure silver granules) achieved 2.1-2.5 and 3.0-3.5 log10 reductions of fecal indicators E. coli and MS2, respectively, meeting WHO 'protective' antimicrobial performance targets. Total metal concentrations in test waters were below levels of health concern with <0.15 mg/L copper, <0.002 mg/L silver, and usually < 3mg/L zinc. Further experimentation is recommended to better characterize and improve pouch performance. Overall, granular metals have potential to be antimicrobial as POU disinfectants in drinking water.Master of Science in Public Healt

Biogenic production of Gold and Silver Nanoparticles using extracts from indigenous Australian plants: Their synthesis, optimisation, characterisation and antibacterial activities

Today, the primary focus of nanotechnology is the creation of nanometre scale materials, techniques and applications. The main driver for this intense nanotechnologybased research is the unique material properties that occur at the nanometre scale which are significantly different to those at the bulk scale. Importantly, because of their size nanoparticles can act as bridge between bulk materials and molecular structures. Therefore, an important aspect of nanotechnology is the synthesis of nanoparticles of different compositions and the ability to directly control particle parameters such as size, shape and size distribution. Since the material composition and related material parameters will ultimately determine the overall properties of the nanoparticles. Furthermore, there is also a need to develop reliable, sustainable and eco-friendly protocols for manufacturing nanoparticles. In recent years there has been a convergence between biological based technologies, green chemistry and nanotechnology. This convergence has the potential to produce clean technologies that can significantly reduce environmental and human health risks resulting from toxic chemicals and solvents generally used in conventional nanoparticle manufacturing processes. The biogenic synthesis of nanoparticles via plant extracts has the potential to significantly reduce or eliminate the use of hazardous substances. Worldwide, alternative eco-friendly green chemistry based techniques for biosynthesising metal nanoparticles using various plant species has been actively investigated in recent years. However, finding suitable plant species and developing effective protocols to biosynthesis metal nanoparticles with predetermined physiochemical properties still remains a challenge. Taking up the challenge, this thesis for the first time examines the biogenic properties of three indigenous Australian plant species to produce (Au) gold and (Ag) silver nanoparticles. Plant species studied were Eucalyptus macrocarpa (rose of the west), Xanthorrhoea glauca (grass tree) and Anigozanthos manglesii (red and green kangaroo paw). The thesis is composed of five case studies that deal with the discovery, biosynthesis optimisation & particle characterisation, and identification of Ag nanoparticle/plant antimicrobial properties. The studies reveal all three plant species were effective bio-factories capable of manufacturing of Ag and Au nanoparticles. Subsequent antimicrobial studies using Ag nanoparticles biosynthesised using Xanthorrhoea glauca and Anigozanthos manglesii were found to be effective agents against bacterial pathogens such as Deinococcus, Escherichia coli and Staphylococcus Epidermis. The research for the first time has demonstrated that three indigenous Australian plant species are capable of producing nanoparticles with unique physiochemical properties and the nanoparticles have the potential to be used in antibacterial pharmaceuticals

Relationship Between Nanoparticles and Higher Plants

The study of relationship between vascular plants and nanoparticles was subdivided in two branches, in particular the first part of the research was focused on the investigation the plants capacity to synthetize nanoparticles (NPs) inside their tissues and which are the principal molecules involved in the process. Subsequently the principal aim of the research was focused on the study of possible toxic effects caused by the NPs when they enter in contact with the plants during their first development stages and along their entire life cycle. In order to investigate the plant capacity to synthetize NPs B. juncea, M. sativa and F. rubra plants were exposed for 24 hours in a hydroponic system to a solution of silver nitrate (AgNO3) at 1000 ppm. All three plant species show high uptake and translocation of Ag. The ultrastructural analyses and microanalyses of electron dense aggregates present in roots stems and leaves in all three plant species confirm the presence of AgNPs and for the first time was confirmed in F. rubra. The content of reducing sugars and antioxidant substances analyzed were quite different between species thus suggesting it is unlikely that a single substance is responsible for this process. The focus of experiments move to the investigation of possible toxic effects caused by the interaction of NPs with plants during their first development stages. For this purpose H. vulgare seedlings were exposed to increasing concentration of cerium (Ce) and titanium (Ti) NPs for 24 hours in order to check the possible genotoxic effects and H. vulgare seeds for 7 days for testing the possible phytotoxic effects. Difference between treated plants with CeNPs and controls were observed in RAPD band pattern and a reduction in the in cell division, while the TiNPs resulted ineffective. The phytotoxic effects were checked at cellular level by monitoring the oxidative stress in term of reactive oxygen species (ROS) generation and ATP content. Again the CeNPs result to have an effect on these parameters while the TiNPs resulted ineffective. The materials were used also for check the NPs uptake and their translocation in the seedling tissues. The NPs uptake were confirmed at root level for both NPs whereas the NPs translocation weren\u2019t confirmed but only the elements. The toxic effects of NPs were checked along the entire plant life cycle, for this purpose H. vulgare plants were grown to physiological maturity in soil enriched with either Ce NPs or TiNPs at increasing concentration and their combination. The growth cycle of CeNPs and TiNPs plants was about 10 days longer than the controls. In CeNPs treated plants the number of tillers, leaf area and the number of spikes per plant were reduced whereas TiNPs stimulated plant growth and compensated for the adverse effects of nCeO2. Concentrations of Ce and Ti in aboveground plant fractions were minute. The fate of nanomaterials within the plant tissues was different. Crystalline TiNPs aggregates were detected within the leaf tissues whereas CeNPs was not present in the form of nanoclusters. The kernels obtained from the previous experiment were used to check if the treatment have got some effects on their nutritional quality. For this purpose the mineral nutrients, amylose, \u3b2-glucan, amino acid and crude protein (CP) concentrations in H. vulgare kernels were measured. Ce and Ti accumulation were not enhanced by MeNPs trereatments. However, CeNPs and TiNPs impacted the nutritional quality of H. vulgare kernels in contrasting ways. Both MeNPs reduced amylose and increased amino acid and CP content. Potassium and S were both negatively impacted by MeNPs, while B only under at lower concentration of CeNPs. On the contrary Zn and Mn concentrations were improved under lower concentration TiNPs and Ca at both nTiO2 treatments