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Hazardous Materials Management Winter 2011 By Annex Business Media
By Richard P. Fisher 1 , Allan Lewandowski 2 , Tesfayohanes W. Yacob 3, † , Barbara J. Ward 3 , Lauren M. Hafford 3 , Ryan B. Mahoney 3 , Cori J. Oversby 3 , Dragan Mejic 1 , Dana H. Hauschulz 1 , R. Scott Summers 3 , Karl G. Linden 3, * and Alan W. Weimer 1, *
Almost half of the world’s population is living without access to sanitation services that are safe, reliable, and minimize public health risk of human waste exposure. Modern flush-based sanitation networks are unsustainable: substantial resources, namely water and fuel, are required to bring human waste to centralized treatment facilities. Moving toward sustainable sanitation requires the implementation of innovative renewable energy technologies for stabilization and disinfection of waste, at the local or household scale, where minimal inputs of water, electricity or chemicals are required. A novel solar thermal disinfection toilet prototype has been constructed and is assessed for overall solar to receiver efficiency in treating waste without electrical, chemical, or water inputs from municipal supply. The measured solar to receiver efficiency is 28%, incorporating the capturing and concentration of sunlight and transmission of the energy to the receiver. For a typical sunny day, the current system can achieve thermal treatment of 0.8 kg human waste in roughly 100 min. The novel toilet is available for any location in the world with sufficient sunlight and irradiance data, and is scalable by adding solar collectors for sizes from single dwellings to communities.
Today, 4.2 billion people, or roughly 55% of the world’s population, lack access to safely managed sanitation services defined as systems which safely manage human excreta from containment to eventual disposal or reuse [1, 2]. A majority of these people live in Eastern and Southern Asia, Sub-Saharan Africa, Latin America and the Caribbean. Climate refugee and homeless camps, and COVID-19 infections [3, 4, 5] are on the rise globally. A lack of safe sanitation leads to risk of infection, disease, environmental damage, as well as secondary impacts such as malnutrition, anxiety, adverse birth outcomes, antimicrobial resistance, and decreased economic productivity. Urban centers will face growing challenges of demand for water and sanitation services and rural communities must address the service gap experienced by people in those areas. For nations with populations that lack sanitation, the implementation of a sanitation system can require significant behavioral changes, high demands on water resources, as well as untenable costs to individual households. Novel alternatives to conventional sanitation that will allow access to improved sanitation for both urban and rural populations can make a significant impact on health and the environment.
G9a/glp Inhibition During Ex Vivo Lymphocyte Expansion Increases In Vivo Cytotoxicity Of Engineered T Cells Against Hepatocellular Carcinoma
Appeals to the environmental engineering community at-large for alternatives to flush-based sanitation systems have been made as early as 1971 [6]. As more people connect to public sewer networks, improvements in health, environmental or economic outcomes for low- and middle-income nations are not likely to bear fruit if sewage is not treated before flowing out of the sewers and back into local water resources [7]. It has been estimated that more than 70% of fecal waste generated each year in low- and middle-income cities is released to the environment without adequate treatment [8, 9, 10]. As regions become more developed and exert higher demand on their resources, flush-based sanitation networks are not a sensible solution due to the high cost of sewage treatment [11]. Many alternative sanitation technologies have been developed as off-the-grid waste treatment processes with varying degrees of success regarding adoption of alternative technologies [12]. Recovering resources from waste is becoming increasingly attractive globally, for low- [13] and high-income [14] countries alike that face mounting pressure to accommodate growing populations that produce growing amounts of waste with limited energy, water, and land resources [15].
A novel Sol-Char prototype sanitation toilet system is described and quantified. It is used to disinfect human waste by utilizing renewable solar energy and, under certain conditions, can pyrolyze the waste to form biochar [16, 17, 18, 19]. A schematic of the Sol-Char disinfection system is shown in Figure 1 with a photograph shown in Figure S1. It con sists of (1) reflective parabolic solar concentrators, (2) optical fiber bundles for transmitting concentrated sunlight for heating, (3) a squat-plate toilet, and (4) an insulated solar thermal receiver. Concentrated solar power (CSP) is generated by eight reflective parabolic concentrators that are coupled to fused silica or borosilicate optical fiber bundles. These bundles carry the concentrated solar power to the outer diameter of the feces pyrolysis receiver, made from stainless steel. Optical fibers are ubiquitous around the world and are used as waveguides for low-flux, low-power data transmission and communication [20].
The concept of solar concentrators using fiber optics for delivery of sunlight [21] was first proposed over forty years ago [22]; however, the successful demonstration of this approach was only made possible after the development of improved fiber optic technology for communications. The growth in the use of fiber optics for a number of applications outside of solar, enabled by glass fibers of sufficient purity and low enough cost, has spurred their use in solar thermal systems [23, 24, 25, 26, 27, 28, 29], solar lighting [30, 31, 32], photovoltaics [33] and photoreactors [34, 35]. The opportunity for using fiber optics for solar thermal power is enormous as it would safely allow bringing concentrated solar indoors for domestic applications such as heating the underside of a cook plate and heating a water tank, in addition to this current application of disinfecting feces. Of course, such uses are dependent on lower cost fibers with efficient transmission and on the ability to efficiently couple concentrated solar energy to the fiber inlet. Kribus [26] directly assessed the challenges of fiber optic cost that will likely limit fiber optic systems to small scale. Such demonstrations have been very encouraging and show the potential for both good performance and achievement of high temperature [36]. Nakamura and Senior demonstrated the use of optical fibers supplying concentrated solar power from parabolic reflectors to a high-temperature receiver [37].
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The Sol-Char sanitation system (Figure S1) includes multiple concentrators on a single tracked platform with multiple fiber optic bundles delivering concentrated sunlight to a stationary receiver. A flat turning mirror is added in front of the nominal focal point of each parabolic concentrator to redirect the beam back down the optical axis and to simplify, and shorten, the fiber optic bundle routing. A quartz homogenizing rod with polished ends was used to reduce the peak flux on the fiber bundle entrance. This also served to slightly shorten the bundle length at the expense of two additional surfaces for Fresnel reflection. The fiber bundles are attached at the back of the parabolic concentrator and routed to the receiver. The length of each bundle is sufficient to account for daily azimuthal tracking of the concentrator array and distance to the treatment system.
Here, the concentrator design, methods for solar thermal to fiber optics coupling, transmission through different types of fibers, flux distribution, power measurements, measured efficiency throughout the network, and a simplified model for the receiver are described. Delivery of concentrated solar radiation via fiber optic bundles offers design flexibility for small systems by allowing the receiver to be located away from the focal point of the concentrator. This project demonstrated the ability to focus sunlight from small-diameter parabolic dishes onto relatively large diameter fiber bundles and deliver that sunlight into a stationary receiver. Both fused silica and borosilicate fiber bundles were tested. The energy requirements for this process drove the small-scale design.
The solar concentrators were designed to provide enough heat to the receiver (3750 kJ/day) such that the feces from 4 to 8 people (0.2–0.4 kg waste per person per day) were dried, disinfected and potentially pyrolyzed in the daylight hours of a typical sunny day. Assuming operation of the system for 4 h per day at direct normal irradiance (DNI) of 800 W/m
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, the instantaneous power delivered is approximately 1120 W. The parabolic solar concentrators, shown
The Sol-Char sanitation system (Figure S1) includes multiple concentrators on a single tracked platform with multiple fiber optic bundles delivering concentrated sunlight to a stationary receiver. A flat turning mirror is added in front of the nominal focal point of each parabolic concentrator to redirect the beam back down the optical axis and to simplify, and shorten, the fiber optic bundle routing. A quartz homogenizing rod with polished ends was used to reduce the peak flux on the fiber bundle entrance. This also served to slightly shorten the bundle length at the expense of two additional surfaces for Fresnel reflection. The fiber bundles are attached at the back of the parabolic concentrator and routed to the receiver. The length of each bundle is sufficient to account for daily azimuthal tracking of the concentrator array and distance to the treatment system.
Here, the concentrator design, methods for solar thermal to fiber optics coupling, transmission through different types of fibers, flux distribution, power measurements, measured efficiency throughout the network, and a simplified model for the receiver are described. Delivery of concentrated solar radiation via fiber optic bundles offers design flexibility for small systems by allowing the receiver to be located away from the focal point of the concentrator. This project demonstrated the ability to focus sunlight from small-diameter parabolic dishes onto relatively large diameter fiber bundles and deliver that sunlight into a stationary receiver. Both fused silica and borosilicate fiber bundles were tested. The energy requirements for this process drove the small-scale design.
The solar concentrators were designed to provide enough heat to the receiver (3750 kJ/day) such that the feces from 4 to 8 people (0.2–0.4 kg waste per person per day) were dried, disinfected and potentially pyrolyzed in the daylight hours of a typical sunny day. Assuming operation of the system for 4 h per day at direct normal irradiance (DNI) of 800 W/m
Doing Business In (insert Country Name Here)
, the instantaneous power delivered is approximately 1120 W. The parabolic solar concentrators, shown
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