• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.84-90
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• 2000

5L laboratory-scale anaerobic digester was used to study the effects of food size and washing rate of food waste on the mixed digestion with sewage sludge. Food waste was crushed with particle diameters of 4mm and 2mm and washed two to three times, and seven to eight times before feeding the batch digester. The digester with crushed of washed food waste showed better performance than that with uncrushed of unwashed to produce methane gas of reduce volatile solids. The digester with 2mm food waste showed 17.4% higher VS/TS reduction rate and 18ml higher methane production rate per gram VS input than that with uncrushed food waste, where VS and TS are volatile solid and total solids in the liquid effluent, respectively. Also food waste crushed eight times gave 8% higher VS/TS reduction rate and 11ml higher methane production rate per gram VS input than unwashed food waste.

• Journal of Environmental Science International
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• v.30 no.6
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• pp.429-439
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• 2021

Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k₁, the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.

• Journal of the Korean Dietetic Association
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• v.18 no.2
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• pp.126-140
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• 2012

The purpose of this study was to investigate elementary school students' perception of food waste as well as to identify factors affecting the plate waste rate of school foodservice in the Gyeongnam area. Questionnaires were distributed to 280 students from June 20 to July 5, 2011 and a total of 279 were analyzed. The results of this study were as follows. First, the main reason of plate waste was 'big portion size', which suggests that portion size should be adjusted. Second, the attitude for food waste reduction was 3.67 based on a 5-point Likert scale (1: strongly disagree, 5: strongly agree). Third, the average plate waste rate of school foodservice was 18.65%. Fourth, there were four factors affecting plate waste rate; balanced/unbalanced diet, satisfaction of school foodservice, need for nutrition education related to food waste, and attitude towards food waste reduction. The plate waste rates of the students who ate a balanced diet were significantly lower than those of the students who ate an unbalanced diet (P<0.001). The plate waste rates of the students who were satisfied with school foodservice were significantly lower than those of the students who were unsatisfied (P<0.001). The plate waste rates of the students who recognized the need for nutrition education were significantly lower that those of the students who did not recognize this (P<0.01). Finally, the students' attitudes towards food waste reduction were significantly negatively correlated with plate waste rate (P<0.01). In conclusion, in order to successfully reduce plate waste in school foodservice, nutrition education should be provided on proper portion size, balanced diet, and food waste. Further, introduction of partial self-service by school foodservice should be reviewed, and strategies for the improvement of school foodservice satisfaction should be applied.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.193-198
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• 2020

In this study, the validity of extracts from food waste as biocatalyst for indigo reduction was examined. Dried food wastes such as apple peel and corn waste were water-extracted and freeze-dried. The reducing power of extracts for indigo was evaluated by the oxidation-reduction potential(ORP) measurement of reduction bath and color strength(K/S value) of the fabrics dyed in the indigo reduction bath. Total sugar contents of the apple peel and corn waste extracts were 60.56% and 62.36%, respectively. Antioxidant activity was 64.78% for the extract of apple peel and 7.96% for the extract of corn waste. Indigo reduction took place quickly with both extracts, and maximum color strength was obtained up to 15.91 and 12.11 within 1-3 days, respectively. The oxidation-reduction potential of reduction bath was stabilized in the range of -500 ~ -620 mV according to the kinds of food waste and the extract concentration. At higher concentration of the extracts, reduction power was maintained for longer time and stronger color strength was obtained. Compared to sodium dithionite, the reducing power of the studied extracts was lower, but the reduction stability was superior to it. The studied extracts were effective biocatalyst as biodegradable and safe alternatives to sodium dithionite for indigo reduction.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.61-70
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• 2005

In order to reduce salt(as NaCl) contents in food waste and to improve the quality of discharged wastewater produced during the recycling process of food waste for the purpose of compost and feed stuff, a salt reduction process by added water into food waste was developed. The pilot plant with a rotary type salt reduction equipment to manage continuously 0.5 ton food waste per hour was constructed and the efficiency was tested. The amount of added water was calculated by the water content and the efficiency of dewatering process of food waste. Approximately 0.8 liter water per a kilogram of food waste was injected into the reactor in which food waste was pouring simultaneously, then diluted/mixed in a rotary reactor. About 1.1 liter of leachate including added water was generated, but the leachate contained a very high content of organic particles, so most particles were recovered by two step solid-liquid separation process. The first step was a gravitational filtering process using screens with a pore diameter of 1mm, and the second separation process was centrifugal process. Organic quality of food waste which had been desalted was maintained by inputting the entirely recovered organic particles. The efficiency of salt reduction of food waste was estimated by measuring a chloride anion by titration and salinity by a probe. The results by the two different measuring methods were always over 50%, and the quality of final wastewater was improved up to $200mg/{\ell}$ as TS(total solid) by an additional settling process after the two step solid-liquid separation process.

• Environmental Engineering Research
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• v.20 no.2
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• pp.171-174
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• 2015

This study investigates the possibility of applying food waste leachate to a municipal solid waste incinerator in order to effectively dispose of the material and to reduce the environmental impact. The spray positions and the quantity of the food waste leachate in municipal solid waste incinerator were adjusted to examine the stability of the process and the environmental effect. The rear of the first combustion chamber was found to be the desirable location for an environmental perspective in this study. At a food waste leachate injection rate of $2m^3/h$, the concentration of the emitted NOx decreased from 130 ppm to 40 ppm. The consumption of ammonia water was reduced by about 36% after adding the food waste leachate. The inclusion of the food waste leachate to the municipal incinerator also increased the amount of steam that was produced. The results of this research indicated that a positive outcome can be expected in terms of diversifying the treatment options for food waste leachate. The results also provide guidance for institutional framework to manage the incineration of the food waste leachate.

• Journal of the Korean Dietetic Association
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• v.7 no.4
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• pp.410-425
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• 2001

This study was designed to assess the waste management practices, source-reduction programs and related tasks in elementary school foodservice in Seoul. and Kyonggi Province Areas. A questionnaire mailed to 910 school foodservice managers in Seoul and Kyonggi province: a 202% (N=184) response rate was obtained. About 83.7% of school foodservice managers were responsible for managing solid waste. Most foodservice operations take the responsibility of food waste but not packaging wastes. The average disposal cost per month per person was about 19 won and income was about 35 won. Leftovers were mainly disposed with platewaste. Platewaste was reused for the livestook feed(68.0%), and some platewaste was composted(11.6%). Source reduction programs implemented in half of school foodservice operations were adjustment of portion size', checking the plate waste', 'working with classroom teachers on waste reduction campaign', 'providing information leaflet on food waste minimization', posting education materials, 'classroom instruction about food waste minimization', and 'improving cooking method. According to factor analysis based on importance rating. slid waste management activities of elementary school foodservice operations were divided to 7 dimensions such as communication and cooperation with others', 'employee training', 'product quality control, 'yield control', plate waste control', 'purchasing', and 'public relations'. As a result of Important-Performance Analysis(IPA), sine dimensions such as 'communication and cooperation with others' and 'plate waste control were identified in Focus Here' quardrant area which need more enhanced performance.

• Journal of the Korean Dietetic Association
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• v.13 no.4
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• pp.357-367
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• 2007

This research was performed to evaluate the effects of nutrition education on food waste reduction at school food service. A dietitian conducted nutrition education on environmental protection and proper eating attitude and poor eating habits for 3rd and 5th graders at an elementary school in Seoul. The effectiveness of the education was evaluated by surveying the students before and after the education; 375 responses were analyzed. A questionnaire was designed to compare changes of the students' attitudes and plate waste before and after education. Plate wastes of boiled black rice(p<0.05), potato soup(p<0.05), amaranthus herb salad(p<0.01), and cabbage kimchi(p<0.05) decreased significantly after education. Students' eating attitudes improved significantly(t= -6.22, p<0.01) after nutrition education. Major reasons the students did not eat all foods they were served were large portion sizes (30.59%), low menu preference (29.79%), and tastes (17.82%). The menus with high plate waste rates were cooked vegetable items (35.64%) and soup items (26.6%). After education, students' attitudes on ‘food waste pollutes the Earth(p=0.013)’, ‘food preparation for birthday parties(p<0.01)’, and ‘restaurant selection for eating out (p<0.01)’ changed significantly. After education, plate waste and portion sizes that the students perceived were not negatively correlated. In conclusion, nutrition education on proper eating habits and source reduction is an effective method to reduce food waste generation and to improve students' eating attitudes and awareness on environment.

• Korean Journal of Community Nutrition
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• v.12 no.6
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• pp.815-825
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• 2007

The study was designed to investigate food waste management practices and to identify factors affecting food waste generation at school food services. A total of 202 dietitians employed at elementary schools participated in the survey. The mean food waste weight per school was 77.54 kg, forty percent of the schools generated food waste of $50{\sim}100kg$ every day and 53% generated plate waste less than 50 kg. Three quarters of the dietitians perceived plate waste as a major component of the food waste and vegetable dishes were a major source of the plate waste. Half of the dietitians used a food waste pick-up service for waste disposal, which was the most preferred waste disposal method. Approximately 90% of the dietitians conducted education on plate waste reduction for students but their perceptions on the effectiveness of the education was inconsistent. The contents were environmental issues (70.3%) and unbalanced food choice (56.7%). According to factor analysis based on performance score, solid waste management practices were grouped into 'information collecting and education', 'supervision of production process', 'cooperation with related groups', and 'control over production planning'. Practices appertaining to 'cooperation with related groups', 'information collecting and education' factor need to be improved. Dietitians should pay attention to 'recycle and reuse of left over' practice. Waste generation differed significantly by dietitians' ages and working experience. In order to reduce plate waste, more effective education materials and methods need to be developed and support from principals, teachers, and parents is necessary.

• Environmental Engineering Research
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• v.23 no.3
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• pp.258-264
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• 2018

The objectives of this research were to 1) isolate and identify thermophilic bacteria for food waste treatment; 2) investigate the capability of food waste treatment using Bacillus species; and 3) develop air-dried Bacillus starters for food waste treatment. Five Bacillus species were isolated from food wastes and identified as Bacillus licheniformis (B. licheniformis) G1, Bacillus circulans C2, Bacillus subtilis (B. subtilis) E1, Bacillus vanillea F1, and Bacillus atrophaeus G2 based on 16S rDNA sequencing. Each identified Bacillus and the mixture of Bacillus species were cultivated in the standard food waste at $45^{\circ}C$ for 8 d. Changes in cell count, solid contents, and pH of the food waste were monitored during cultivation. Air-dried Bacillus cell powders were prepared using wheat flour and lactomil as excipients, and the cell count and survival rate were determined. The cell count of B. licheniformis G1 exhibited the highest number among the tested Bacillus (${\sim}10^8CFU/mL$). The greatest reduction in solid contents of food waste was achieved by B. subtilis E1 (22.6%). The mixture of B. licheniformis G1 and B. subtilis E1 exhibited a synergistic effect on the reduction of solid contents. Lactomil was determined as better excipient than wheat flour based on the greatest survival rate of 95%.