• Journal of the East Asian Society of Dietary Life
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• v.25 no.4
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• pp.710-719
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• 2015

This study was undertaken to identify factors affecting school food waste generation using a questionnaire. The subjects were 254 high school students (male; 156, female; 98) in Sacheon, Gyeongnam divided into three groups of low (${\leq}1/week$), moderate (2~3/week), and high (${\geq}4/week$) according to the frequencies of food waste. The questionnaires consisted of general characteristics, anthropometric values, dietary habits, health-related behaviors, self-perceptions of food waste, snacking patterns, and nutrition knowledge. The main reasons behind food waste were 'too much food' in the low (20.9%) and moderate (32.2%) groups, and 'no appetite' in the high group (p<0.01). The main types of food waste were rice (44.2%) > fish (18.6%) > vegetables (14.0%) in the low group, rice (54.2%) > Kimchi/vegetables (15.3%) in the moderate group, rice (56.0%) > vegetables (20.0%) > Kimchi (16.0%) in the high group (p<0.01). School food waste was significantly affected by age, gender, monthly allowance, school grade, weight, BMI, regularity of meals, time of meals, type of breakfast, starting age of smoking, and cost for snacking.

• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.366-376
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• 2014

Purpose: In the process of anaerobic digestion, stirring of the digester and feeding of organic waste into the digester have been considered important factors for digestive efficiency. The objective of this study was to determine the most appropriate conditions for both stirring interval of the digester and organic feeding frequency in order to improve anaerobic digestion performance. Methods: A 5-L anaerobic digester was used to conduct continuous batch tests to process swine manure and food waste. Four different stirring intervals of the digester were used: 5 min/h, 10 min/2 h, 15 min/3 h, and 20 min/4 h. Results: The application of swine manure to the digester every 5 min/h resulted in the highest production of biogas as well as the highest removal rates of volatile solids (VS) and total chemical oxygen demand. Stirring the digester with a mixture of swine manure and food waste at intervals of 5min/h and 10min/2 h produced the highest biogas yields of 515.3 mL/gVS and 521.1 mL/gVS, respectively. To test different supply frequencies, organic waste was added to the digester in either a 12-hor 24-h cycle. The 24-h cycle produced 1.5-fold greater biogas production than that during the 12-h cycle. Conclusions: Thus, from the above results, to optimize anaerobic digestion performance, the ideal stirring condition must be 5min/h for swine manure feeding and 10min/2h for co-digestion of food waste and swine manure in a 24-h cycle.