Drying methods for municipal solid waste quality improvement in the developed and developing countries: A review

Maw Maw Tun,Dagmar Juchelkova 대한환경공학회 2019 Environmental Engineering Research Vol.24 No.4

Nowadays, drying methods for municipal solid waste quality improvement have been adopted in the developed and developing countries to valorize wastes for a renewable energy source, reduce dependency on fossil fuel and keep safer disposal at landfills. Among them, biodrying, biostabilization, thermal drying and solar drying are the most common. Drying of municipal solid waste could offer several environmental and economic benefits. Therefore, this review highlighted the drying methods for municipal solid waste quality improvement around the world and compared them based on the reduction of moisture, weight and volume of municipal solid wastes against drying temperature and time by using statistical analysis. It was observed that the drying temperature of different drying methods accounted for 115 ± 40℃ for thermal drying, 59 ± 37℃ for solar drying, 55 ± 15℃ for biodrying and 58 ± 11℃ for biostabilization. Among the drying methods, thermal drying provided the shortest drying time. The moisture reduction, weight reduction, volume reduction and heating value increase of municipal solid waste could vary with drying temperature and time. Finally, the benefits and drawbacks of different drying methods were specified, and recommendations were made for the future efficient drying.

Nanoleakage of apical sealing using a calcium silicate-based sealer according to canal drying methods

Lee Yoon-Joo,Cho Kyung-Mo,Park Se-Hee,Lee Yoon,Kim Jin-Woo 대한치과보존학회 2024 Restorative Dentistry & Endodontics Vol.49 No.2

Objectives This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods. Materials and Methods Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate–based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann–Whitney U-tests (p < 0.05). Results The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different. Conclusions Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment. Objectives This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods. Materials and Methods Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate–based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann–Whitney U-tests (p < 0.05). Results The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different. Conclusions Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment.

전처리 조건 및 건조방법에 따른 건조대추의 품질특성 및 항산화 활성

김재원(Jae-Won Kim),이신호(Shin-Ho Lee),노홍균(Hong-Kyoon No),홍주헌(Joo-Heon Hong),박창수(Chang-Su Park),윤광섭(Kwang-Sup Youn) 한국식품영양과학회 2013 한국식품영양과학회지 Vol.42 No.8

건조 전처리와 건조방법에 따른 대추의 건조특성과 품질의 변화를 비교분석 하였다. 수분함량은 glyceol 전처리에서 유의적으로 낮았고 열풍건조가 천일 및 냉풍건조에 비해 건조효율이 높은 것으로 나타났다. 가밀도는 NaCl boiling 처리에서 가장 높았고, 가용성 고형분의 함량의 경우 열풍건조, 냉풍건조, 천일건조 순으로 높은 함량을 나타내었으며 전반적으로 glycerol 침지에서 높은 함량을 보였다. 적정도는 열풍건조가 타 건조 방법에 비해 높은 값을 나타내었으며, 전처리에 따라서는 무처리 및 glycerol 침지에서 높은 경향을 나타내었다. 반면 boiling 처리 시 대추 고유의 산도는 저하되는 것으로 나타났다. 당산비의 경우 천일건조에서 가장 높았으며 다음으로 냉풍건조 열풍건조 순으로 나타났고, 전처리에 따라서는 NaCl boiling> glycerol> 무처리 순으로 높은 함량을 나타내었다. 갈변도는 열풍건조, 냉풍건조, 천일건조 순으로, 전처리 방법에 따라서는 NaCl boiling, 무처리, glycerol 침지 순으로 높은 값을 나타내었다. 적색도의 경우 무처리가 NaCl boiling 및 glycerol 침지에 비해 유의적으로 높은 경향을 나타내었으며, boiling 처리한 건조대추의 경우 적색도는 감소하고 황색도는 증가하는 것으로 나타나 기호성이 다소 저하되는 것으로 관찰되었다. 건조방법에 따른 폴리페놀 함량은 열풍건조> 냉풍건조> 천일건조순으로 높은 함량이 검출되었으며, 전처리 방법 간에는 무처리 및 glycerol 침지가 NaCl boiling 처리에 비해 유의적으로 높았다. 반면 플라보노이드 함량에서는 boiling 전처리를 행한 모든 건조방법에서 높은 함량이 검출되었다. DPPH, ABTS 라디칼 소거활성은 유용성분의 함량과 항산화 활성간의 비례적인 상관관계를 나타내었으며, 열풍건조에서 유의적으로 높은 라디칼 소거활성을 나타내었다. 관능검사 결과 NaCl boiling 처리는 외관과 함께 품질이 가장 떨어지는 것으로 나타났으며, 종합적 기호도는 glycerol 침지가 가장 기호성이 높은 것으로 조사되었고 다음으로 무처리, boiling 순이었다. 이상의 결과 종합적 기호도 및 이화학적, 기능적 품질특성을 고려해 보았을 때 glycerol 전처리와 열풍건조방법을 효과적으로 이용하는 것이 건조효율 증대 및 품질손상을 억제할 수 있는 방안이 될 것으로 사료된다. This study was performed to determine the effects of pretreatment (NT: non-treatment, BTS: boiling treatment with 3% sodium chloride, DTG: dipping treatment in glycerol) and drying methods (sun drying, hot air drying, and cold air drying) on the physicochemical properties and antioxidant activities of dried jujube (Zizyphus jujuba Mill.) fruits. Our results show that moisture content is lower (P<0.05) with DTG, and that moisture content is lower with hot air drying compared to other drying methods. The bulk density was highest with BTS. The soluble solids content was highest with DTG. Additionally, the soluble solids content were highest in the following order: hot air drying> cold air drying> sun drying. The titratable acidity of hot air drying was highest of all the drying methods. The titratable acidity was higher with NT and DTG, and the brix and acid ratio of sun drying was higher than other drying methods. Among the drying methods, BTS showed the best browning-retarding effect, whereas boiling treatment affected quality and color. The total polyphenol content from hot air drying and NT or DTG treatment was relatively higher than the content from BTS. The flavonoid content was highest with BTS, and all dried jujube showed relatively high antioxidant activities. The sensory evaluation results indicated that the organoleptic scores for overall preference were higher in the NT and DTG treatment groups. These results suggest that pretreatment and drying methods affect the quality of dried jujube fruit, and show that glycerol treatment with hot air drying can be applied to the production of high quality dried jujube.

Effects of Drying Methods on Anthocyanin Contents of Colored Barley (Hordeum vulgare L.) cv. Boanchalbori

Song, Tae Hwa,Park, Tae Il,Han, Ouk Kyu,Yoon, Chang,Kang, Hyen Jung,Park, Kuang Geun The Korean Society of Grassland and Forage Science 2013 한국초지조사료학회지 Vol.33 No.4

This study investigated the effects of drying methods and drying time on the changes in anthocyanin content in colored barley. Colored barley cultivar Boanchalbori was harvested at a time when the anthocyanin content was the most and dried in afield. The harvested barley was then treated by two methods, sun drying and shade drying, for 4, 8, 24, and 32 h. The moisture content of the sun-dried barley decreased slightly faster than shade-dried samples, but the difference was not statistically significant. Chemical analysis indicated that the samples dried under shaded conditions had slightly higher crude fiber and lower nitrogen free extract, but the difference was not statistically significant. There was no difference in the total digestible nutrients between the two methods. In the case of sun-dried barley, the anthocyanin content decreased compared to the control and shade-dried samples after drying for 4 h (p < 0.05), was maintained at a constant level at 24 h, and then decreased at 32 h. In case of shade-dried barley, the anthocyanin content decreased gradually with the drying time, and a significant decrease was found at 24 h of drying (p<0.05) as compared to the control. The shade-dried method was more successful in reducing anthocyanin loss than the sun-dried method (p<0.05). There was a slight decrease in 1,1-Diphenyl-2-Picrylhydrazyl radical scavenging with drying time in the shade-dried method, and a significant decrease after 4 h with the sun-dried method. These results showed that covering with a two-layer awning was advantageous to dry colored barley in the field conditions.

건조방법에 따른 충주산 병풀의 영양성분과 생리활성

엄현주,신현영,지영미,권누리,윤향식,김인재,송용섭,유광원,Eom, Hyun-Ju,Shin, Hyun-Young,Ji, Yeong Mi,Kwon, Nu Ri,Yoon, Hyang-Sik,Kim, In Jae,Song, Yong-sup,Yu, Kwang-Won 한국식품영양학회 2021 韓國食品營養學會誌 Vol.34 No.2

Centella asiatica (CA) has been used as a nutritional plant as well as a traditional herbal medicine around the world. This study, quality component (proximate composition, total polyphenol, and triterpenoid compound), and antioxidant and anti-inflammatory activities of CA dried using various methods were investigated. Proximate compositions of CA with different drying methods included a large amount of carbohydrates, crude protein, crude ash, and crude fiber. Among the drying methods, cold drying provided the highest total polyphenol content and antioxidant activity, while hot-air drying at 75℃ provided the lowest total polyphenol content and antioxidant activity. In addition, when the major triterpenoid compounds of CA were analyzed, the highest content of asiaticoside of triterpenoid glycoside was obtained with all drying methods. With respect to the total triterpenoid, the highest content was obtained with cold drying (68.8 mg/g) whereas natural drying (31.4 mg/g) provided the lowest content. In anti-inflammatory activity of LPS-stimulated RAW 264.7 cells, EtOH extract of cold drying showed a significantly higher inhibitory activity in comparison to the other drying methods. In conclusion, it is considered that the cold drying method is suitable for industrial preparation of functional materials with high physiological ingredients, and antioxidant and anti-inflammatory activities from CA.

건조방법에 따른 대파의 품질특성

이정은,이현규,양차범 漢陽大學校 韓國生活科學硏究所 2002 韓國 生活 科學 硏究 Vol.- No.20

The quality properties of green onion as affected by drying was studied. The drying methods were hot-air drying, vacuum drying and freeze drying. The color (lightness, yellowness and ΔE) showed similar trend to drying methods. However, hot-air drying showed the greatest change in browning degree. The content of ascorbic acid was 26.48 ppm (hot-air drying), 52.29 ppm (vacuum drying) and 67.61 ppm (freeze drying). The rehydration rate of dried green onion were higher in the order of freeze drying>vacuum drying>hot-air drying. From the results, the quality properties of green onion in hot-air drying were higher decreased than those in vacuum drying and freeze drying methods, which were similarly changed.

다양한 건조방법에 따른 목이버섯의 품질 특성

최소라,유영진,안민실,송은주,서상영,최민경,한현아,송영주 한국약용작물학회 2014 한국약용작물학회지 Vol.22 No.6

In order to produce the high quality of dried-ear mushroom, various drying methods such as hot-air dryingat 40 ~ 80℃, freeze drying and drying in vinyl house were carried out. Drying hours of hot-air drying, freeze drying anddrying in vinyl house were 12.5 ~ 21.5, 36.0 and 72.0 hrs, respectively. Vitamin D2 content of sample was the highest as6.77 ㎍/g DW in drying in vinyl house and then followed by freeze drying as 5.90 ㎍/g DW and hot-air drying as1.89 ~ 5.01 ㎍/g DW. After dry, external appearance and color of mushrooms applied hot-air drying and drying in vinylhouse were better than freeze-dried one. After rehydration, water uptake of sample in drying in vinyl house and hot-air dryingat 50 ~ 60℃ were 17.8 and 19.3 ~ 21.0 times, respectively. The methods of drying in vinyl house and hot-air drying at50 ~ 60℃ also led to high hardness, good shape and resilience. As the results of production of dried-ear mushroom withhigh quality, we suggest that the best method for drying is the drying in vinyl house due to not only high vitamin D2 content,good external appearance and color after drying but also high hardness and good shape after rehydration.

중량측정법에 의한 하이드로젤 콘택트렌즈의 함수율 측정에 관한 연구

김태훈,예기훈,성아영 한국안광학회 2008 한국안광학회지 Vol.13 No.4

Purpose: The purpose of this study is to understand a relation of water content measurement with two different method, water removal method and dry method. Methods: 72 hydrogel contact lens containing various water content (ranged from 47% to 58%) were measured by the gravimetric method at 20oC and 21% of the humidity. We weighed the dried test specimen at room temperature for 30 min after cooling. Results: In dry blotting method, the water content was measured to 47.43.48%. The water contents was measured to 48.15.36% with wet blotting condition. It was found that wet blotting method showed the higher water content of about 7% than dry blotting method. In water content with two dry methods, each of results was measured by 47.89.06% and 49.56.06%. In case of microwave method, the water content was measured significantly higher water content of about 1.67% than vacuum oven method. However, no statistical difference was found (p>0.05). Conclusions: In water removal method (Dry blotting method and Wet blotting method) to weigh hydrated test specimen, wet blotting method showed significantly higher water content than dry blotting method. Also in case of dry methods (vacuum oven and microwave) to weigh dry test specimen, water content of microwave method showed higher water content than vacuum oven method, but it should be noted that microwave oven method must be used carefully to measure accurateness on the specimen position and wave power. 목적: 본 연구의 목적은 수분제거 방법과 건조 방법에 따른 함수율 측정에 관하여 알아보고자 하였다. 방법: 다양 한 함수율을 갖는(47%~58%) 72개의 하이드로젤 콘택트렌즈를 대상으로 중량측정법으로 함수율을 측정하였다. 실 험실 온도는 25oC, 습도는 21%로 유지하였다. 두 방법 모두 저온처리 후 실온에서 30분 건조하여 무게를 측정하는 방식으로 측정하였다. 결과: Dry blotting 방법은 함수율이 47.43±8.48%로 측정되었으며, Wet blotting 방법은 48.15 ±8.36%로 측정되었다. 또한 Wet blotting 방법으로 측정한 함수율이 약 0.7% 정도 높게 측정되었다. 건조 방법에 따른 함수율에서 vacuum oven을 사용하여 건조한 함수율이 47.89±8.06%, microwave oven을 사용하여 건조하여 측정한 함수율이 49.56±7.06%로 나타났으며, microwave oven을 사용하여 측정한 함수율이 약 1.67% 높은 함수율 을 나타내었으나 통계적으로 유의한 차이를 나타내지는 않았다(p>0.05). 결론: 렌즈의 함수된 무게를 측정하기 위한 Dry blotting 방법과 Wet blotting 방법 중 Wet blotting에 의한 방법이 무게가 높게 측정되었으며, 함수율 역시 더 높게 측정되었다. 또한 건조된 무게를 측정하기 위해 렌즈를 건조시키는 방법에 있어 vacuum oven을 사용한 건조 보다 microwave oven로 건조하여서 측정한 함수율이 더 높은 값을 나타내었으나 microwave oven을 사용할 경우 더 정확한 측정을 위해 그 microwave의 조사 강도나 시료의 위치에 있어 더욱 세심한 주의가 필요하다.

건조방법에 따른 고춧가루의 품질특성

임용래(Yongre Lim),경예나(Yena Kyung),정헌상(Heon Sang Jeong),김혜영(Hae Yong Kim),황인국(In Guk Hwang),유선미(Seon Mi Yoo),이준수(Junsoo Lee) 한국식품영양과학회 2012 한국식품영양과학회지 Vol.41 No.9

본 연구에서는 건조방법에 따른 고춧가루의 품질 변화를 비교하기 위하여 한 가지 품종의 고추를 PE House 건조,열풍건조, 원적외선 방법을 이용하여 건조한 다음, 건조조건별로 고춧가루의 수분함량 변화, pH, ASTA value 및 capsaicinoids와 vitamin C의 함량을 조사하였다. 건조 후 고춧 가루의 수분함량은 12.05∼14.01% 함유한 것으로 나타났으며, pH는 건조 전 생고추인 4.93보다 다소 높은 5.00∼5.54를 나타내었다. 고춧가루의 매운맛을 나타내는 총 capsaicinoids의 함량은 PE House 건조에서 224.40 mg/100 g으로 가장 높게 나타났으며, 열풍 70oC 건조에서 191.87 mg/100g으로 가장 낮게 나타났다. 하지만 건조방법에 따른 capsaicinoids 함량이 유의적 차이를 보이지 않았기 때문에, 매운맛 함량의 변화는 큰 차이를 나타내지 않았다. 고춧가루의 대표적 항산화제인 vitamin C 함량은 다른 건조방법 및 조건에 비해 PE House, 열풍 60oC과 원적외선 60oC에서 596.60∼648.31 mg/100 g으로 높은 수준의 함량을 나타내었다. 소비자가 고춧가루를 선택하는데 중요한 요소로 작용하는 ASTA value는 126.68∼156.77로 건조방법 및 조건에 따른 유의적 차이를 나타내지 않았다. 따라서 고추의 건조방법 및 조건을 낮은 온도 조건에서의 열풍, 원적외선 건조방법으로 결정한다면 고춧가루의 vitamin C의 손실을 최소화하고 PE House 건조에 비해 신속하며 오염을 예방하는 고품질의 고춧가루 제품을 생산할 수 있을 것으로 생각된다. Red pepper (Capsicum annuum L.) powder is widely used as a spice and flavor ingredient in the food industry. It is well known that during the drying process red pepper undergoes physico-chemical and nutritional changes. The objective of this study was to investigate the quality of red pepper powder according to drying method. Red pepper was dried by far-infrared drying, hot air drying, and polyethylene (PE) house drying. Average moisture content of dried red pepper powder from the three different drying methods was 12.5±0.3%. The pH level slightly increased from 4.93 before drying to 5.00∼5.54 after drying. Contents of capsaicinoids were highest (224.40 mg/100 g) in the PE house drying method and lowest (191.87 mg/100 g) in the hot air drying (70oC) method. However, capsaicinoid contents were not significantly different among the various drying methods. Vitamin C content decreased as temperature increased. Drying conditions, particularly temperature, lead to loss of vitamin C in red pepper, resulting in quality degradation. Taken together, these results demonstrate that the content of vitamin C, one of the major factors affecting pepper powder quality, was affected by drying temperature.

건조처리 조건에 따른 작약근 생리활성 성분 함량 변화

정명근,안영남,강광희,김재현 韓國作物學會 2002 Korean journal of crop science Vol.47 No.6

작약근이 수확되어 적절한 조제과정을 거쳐 약품으로서의 생약재 작약이 가공되는 과정 중 약성을 가장 크게 변화시키는 수치 및 건조방법의 차이가 작약근 함유 생리활성 성분의 함량변화에 미치는 영향을 조사하기 위하여 4년생 의성작약의 뿌리를 이용하여 코르크층을 제거한 거피근과 코르크층을 제거하지 않은 유피근으로 가공하고, 유피근, 거피근 모두 상온 음건, 50℃ 화력건조, 수증건법 및 동결건조 방법으로 건조한 후 이들에 함유된 작약근 생리활성 성분의 함량을 검토한 결과를 요약하면 다음과 같다. 1. 건조방법의 차이에 따른 paeoniflorin, albiflorin 및 (+)-taxifolin 3-O-β-D-glucopyranos의 함량은 상온 음건 조건의 건조법에서 가장 높은 양상을 나타내었고, 동결건조가 가장 낮은 함량을 나타내었다. 2. 건조방법에 따른 유피근과 거피근간의 paeoniflorin, albiflorin, (+)-taxifolin 3-O-β-D-glucopyranoside의 함량을 비교할 때 상온 음건을 제외한 모든 건조법에서 거피근의 함량이 더 높은 양상을 나타내었다. 3. gallic acid의 함량은 유.거피근 모두 80℃ 수증건법이 가장 높은 함량을 나타내었고, 동결건조법이 가장 낮은 양상을 나타내었다. 4. benzoic acid의 함량은 gallic acid와 상반된 양상을 나타내어 동결건조법이 유.거피근 모두 가장 높았고, 80℃ 수증건법이 가장 낮은 양상을 나타내었다. 5. 건조방법에 따른 (+)-catechin 및 (-)-epicatech고 함량은 동결건조법이 다른 건조법보다 높은 양상을 나타내었다. 6. paeoniflorin, albiflorin, (+)-taxifolin 3-O--β-D-glucopyranoside, (+)-catechin 및 benzoic acid의 함량은 건조 및 처리 온도가 증가할 수록 감소하는 양상을 나타내었다. This experiment was conducted to know the changes of bioactive component content in four-year-old peony (Paeonia lactiflora Pall.) root with various drying methods such as room temperature drying, 50~circC heat-air drying, room temperature drying after 80~circC boiling water treatment and freeze drying, and to establish the optimum drying method for high quality production of Paeoniae Radix. For this purpose, the contents of paeoniflorin, albiflorin and five phenolic compounds (gallic acid, benzoic acid, (+)-catechin, (-)-epicatechin and (+)-taxifolin 3-O-β -D-glucopyranoside) in peony root with different drying methods were analyzed by RP-HPLC. The contents of paeoniflorin, albiflorin and (+)-taxifolin 3-O-β -D-glucopyranoside at room temperature drying were higher than in the other drying methods and that of gallic acid at 80~circC boiling water treatment was the highest among that of all drying methods. In the case of freeze drying, the contents of (+)-catechin, benzoic acid and (-)-epicatechin were the highest among those of all drying methods. As increase of drying and treatment temperature, the contents of paeoniflorin, albiflorin, (+)-taxifolin 3-O-β -D-glucopyrano-side, (+)-catechin and benzoic acid were decreased.