Effect of Environmental Factors on Water and Excreta Temperature in Pipes with Various Materials and Configurations
คำสำคัญ:Human Excreta, Pipes, Solar Radiation
Introduction: Environmental Factors such as light intensity, ambient temperature, and humidity can affect to the thermophilic compostion of source-separated faces at temperatures >50°C for at least one week to ensure safe sanitation. (WHO; 2006) Thus, an experiment was devised to study how to achieve these sanitizing temperatures within the pipes of various materials, exposed to ambient environmental conditions in northeast Thailand.
Aims: 1) To compare the internal temperature of four experimental materials: PVC, iron, stainless steel and aluminum in a 3x2 experimental configuration: three pipe configurations- unpainted, painted black, and painted black with parabolic reflector and two media- water and excreta; 2) To study the relationship between environmental factors, including ambient temperature, light intensity, and humidity and the internal temperature of the media.
Methods: There were two experiments from July 2017 to January 2018. The first experiment used water as a media. The second experiment used excreta as a media. Each experiment had three groups of pipes, each group with four pipes of different materials. The four pipe materials were PVC, iron, stainless steel, and aluminum. The three groups used a different configuration: unpainted, painted black, and painted black with a parabolic reflector. Each pipe was 3 inches diameter, 1 meter in length, tilted 15 degrees towards the southern horizon, and placed at a height 0.65 meters off the ground. Solar parabolic troughs were made from aluminum sheets (1.2 x 1.52 m) using shape from Surawattanawan & Limboonrung (2011). The temperature in each experimental unit was measured every hour during the daytime (09.00 to 17.00) and ambient temperature, light intensity humidity and cloud cover were collected also.
Results: With water as a media, a maximum internal temperature at 80°C was found in iron painted black with a parabolic reflector, with an average temperature at 39.8±13.2 °C (mean±S.D.). The ambient air
temperature had the highest correlation with the temperature of experimental units (r = 0.51 in unpainted aluminum) followed by light intensity (r=0.22 in unpainted PVC).
With human excreta as a media, a maximum temperature at 71°C was found in aluminum painted black with a parabolic reflector, with an average temperature at 44.40±7.03°C. Light intensity had highest correlation with temperature of experimental units (r=0.27 in aluminum with parabolic reflector) follow by ambient temperature (r=0.19 in iron with parabolic reflector).
Conclusion: Solar radiation can increase temperatures of water and excreta to levels that may inactivate very strong pathogens. Iron, aluminum, and stainless steel, painted black with the addition of a parabolic reflector, could achieve temperatures higher than 65 °C in sunny weather.
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