The master’s thesis deals with the design of a boiler for RDF combustion, based on the required power output and superheated steam parameters. The first part of the thesis focuses on combustion calculations. Boiler efficiency is also calculated in this chapter, using the heat balance efficiency method. The main part of the thesis consists of dimensional design and heat transfer calculations. The precision of the calculations is checked at the end of the thesis along with the chlorine corrosion, which is considered because of the higher amount of chlorine in the fuel. The thesis comes with a basic schematic of the designed boiler.

This master thesis deals with design of grate biomass boiler with 50 t/h power. A fuel of the boiler is a mixture of contaminated biomass and woodchips. The boiler produces steam with parameters of 4,2 MPa and 420 °C. Stochiometric and thermal calculations are based on given fuel composition and output steam parameters. Heat exchangers are designated in accordance with the calculations. General drawing of the boiler is attached to this document. Anti-corrosion measures are considered, due to chlorine content in biomass. Hydraulic and aerodynamic losses and dew point of the flue gas is calculated in the end.

The thesis is focused on the possibility of intoxication by selected chemicals at home or in public places. Especially the danger of carbon monoxide poisoning. We’re assessing the current state of the level of awareness and prevention in the Czech Republic. The thesis prepared an overview of the current state of intoxication busy the carbon monoxide in the Czech Republic and the level of medical procedures. There are evaluated measures, which are aimed to reduce the frequency of poisoning. The outcome of the thesis is to design a set of measures, which are designed to eliminate health risks to the population and raise public awareness. The thesis was carried out their own research facilities, household detectors, carbon monoxide at a pre-selected location.

The diploma thesis focuses on the water distribution system functioning without chlorine-based disinfectant. This thesis contains research of documented cases of examples of drinking water distribution systems both abroad and in the Czech Republic, which do not use disinfectants. Moreover, the thesis pay attention to chlorine and its effects on bacteria. The thesis deals with the first assessment of water supply structure, which determines whether the water supply structure is suitable for operating without disinfectant. The thesis describes the process of transition to the disinfectant-free operation and determines the undesired events, which may occur with the ending of the use of disinfectant. As a part of the research, the thesis examines the water supply system in village Kateřinice, to determine if it is suitable for operation without disinfectant.

The effect of sub-lethal chlorine stress on various strains/serotypes of Salmonella on biofilm formation and thermal resistance was studied. The effect of oxidative stress (induced by 150 ppm of chlorine in TSB) on Salmonella biofilm formation on polystyrene and stainless steel surfaces at three temperatures (4°C, 30°C, and room temperature) in nutrient rich (full strength TSB) and nutrient limited conditions (1/10th TSB) was evaluated. On polystyrene surface, chlorine stressed S. Heidelberg (strain ID 72), S. Newport (strain ID 107) and S. Typhimurium (ATCC 14028) formed stronger (P < 0.05) biofilms at 30°C. On stainless steel, the chlorine stressed S. Heidelberg (ATCC 8326) and S. Enteritidis (ATCC 4931) at room temperature formed stronger (P < 0.05) biofilms as compared to the non-stressed control cells. The thermal resistance of short-term (1h) and long-term (27d) chlorine stressed Salmonella Heidelberg and S. Typhimurium were compared with the non-stressed controls at three different temperatures (55°C, 58°C and 61°C) and two growth phases (logarithmic and stationary). The short-term stressed log phase cells (both serotypes) were found to be more sensitive (P< 0.05) to thermal inactivation in TSB. Upon long-term sub-lethal chlorine exposure, Salmonella developed a rugose morphotype on tryptic soy agar at 37°C. The rugose morphotype provided significant thermal protection (P< 0.05) against heat stress as compared to smooth morphotype. In chicken broth, at 55°C, short-term chlorine stressed stationary phase S. Typhimurium displayed a higher D55 value compared to non-stressed cells. The findings from this research reveal that some Salmonella strains have the potential to form stronger biofilms and exhibit higher thermal tolerance upon exposure to sub-lethal chlorine concentration.

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<p>The World Health Organization reports 9% of the world’s population lack access to an improved drinking water source. Safe drinking water is a major global challenge, especially in rural areas where according to UNICEF 80% of those without access to improved water systems reside. While water, sanitation, and hygiene (WASH) related diseases and deaths are common outcomes of unsafe water, there is also an economic burden associated with unsafe water. These burdens are most prominent in rural areas in less developed nations. Slow sand filters (SSFs), or biological sand filters (BSF), are ideal water treatment solutions for these low resource regions. SSFs are the oldest municipal drinking water treatment system and improve water quality by removing suspended particles, dissolved organic chemicals, and other contaminants, effectively reducing turbidity and associated taste and odor problems. Removal of turbidity from the water enables the use of low-cost disinfection methods such as chlorination. While the working principles of slow sand filtration remained the same, the design, sizes and application of slow sand filters have been customized over the years. The first chapter of thesis reviews these adaptations and their performance on contaminant removal, and specifically addresses engineering aspects of slow sand filters that are not widely understood, even by those that implement SSFs in the field.</p> <p>The second and third chapters detail an SSF-based water treatment and monitoring system that seeks to provide portable water to rural schools and communities. Piping drinking water to remote rural areas from centralized treatment facilities requires huge capital investments. On the other hand, delivering drinking water by the less expensive point‐of‐use technologies often results in improper operation, and lack of proper documentation on water quality and usage.</p> <p><br></p> <p>The strategy documented in this research for addressing this problem is to produce drinking water at the point-of-use, and then establish and document drinking water quality through cellphone-based monitoring of this water. By doing both (point-of-use treatment and cellphone-based monitoring), we are effectively using to advantage the best of both worlds. Decentralized (point-of-use) water treatment systems can be deployed in rural communities to produce potable water. Integrating a cellphone-enabled colorimeter-turbidity meter (CT meter), developed as part of this research, into the water treatment system will provides water quality data to ensure public health safety. The integrated water system included slow sand filtration, chlorination, and phone-based monitoring (i.e., the CT meter). To establish larger-scale (thousands of schools) feasibility, pilot treatment systems were established in 3 rural schools in Kenya. This pilot network was established through the collaborative efforts of: (i) The research team at Purdue, (ii) MaJi Safi International (MSI), a Purdue related startup based in Eldoret, Kenya, and (iii) several western Kenya Schools.</p> <p><br></p> <p>The second chapter of details the design and testing of the CT meter at Purdue. The third chapter evaluates, through pilot field tests in Kenyan schools, the integrated water treatment and monitoring system for economic and technical viability. The CT meter performance was successful both in the lab and in the field. The water systems that were installed, used daily, and monitored with the CT meter, consistently produced portable water that met the local regulatory drinking water standards.</p>

The presence of postharvest sanitizers has shown to be an effective approach to reducing microbial cross contamination in agricultural washing operations. However, choosing an appropriate sanitizer can be challenging due to produce commodity, processing conditions and interference with organic load. Current research shows a wide variety of methods to mimic the organic load of vegetable processing conditions, with paddle mixing and blender as the most commonly used. Controlling and understanding the physiochemical properties of wash water is key in maintaining sanitizer efficacy. The effects of simulated wash water preparation method on the physiochemical properties were tested at 0 and 50 COD(mg/L) and no significant difference was observed. However, at high levels of organic load results showed a significant difference between turbidity values at 1,500 COD. Free residual chlorine titration methods were compared, using DPD-titrimetric and Iodometric method. Results showed a significant difference between titration methods in organic load heavy environments. Commercially available chlorine based sanitizers, Pure Bright™ Germicidal Bleach and Clorox® Germicidal Bleach, were compared to a concentrated solution of sodium hypochlorite. Pure Bright™ Germicidal Bleach showed to perform the best by reducing 7 log CFU/ml of E. coli O157:H7 after 30 seconds in no organic load environments, whereas Clorox Germicidal bleach was able to reduce 7 log CFU/ml of E. coli O157:H7 after 30 minutes. These studies aim to provide best management practices for small in medium growers in the implementation of antimicrobial solutions for the maintenance of water quality in postharvest washing solutions.