A comprehensive comparative study on microwave- assisted pyrolysis products derived from raw and digested organic waste, with emphasis on sewage sludge, food waste, and livestock manure.

This study focused on characterizing sewage sludge, food waste, and livestock manure, representative of continuously generated organic wastes, along with their anaerobic digestion residues. Microwave assisted pyrolysis was employed to investigate the relationship between the properties of the raw organic wastes and the resulting pyrolysis products, utilizing the R-program for analysis. Evaluation of the pyrolysis products of these six organic wastes revealed that char yield was primarily influenced by ash and fixed carbon contents, with higher yields observed in residues from anaerobic digestion compared to the original organic waste. Liquid and gaseous product quantities were found to increase with volatile content, while high-fat content within the volatile fraction notably enhanced liquid product yields, impacting syngas production. Analysis of syngas composition indicated a negative correlation between high nitrogen content in the feedstock and H2 generation. Furthermore, examining the correlation between chemical properties of organic waste and pyrolysis products revealed a proportional increase in protein components with nitrogen content, suggesting potential improvements in pyrolysis efficiency through raw material pretreatment enhancements by the R program.

Comparison of pyrolysis gasification of livestock manure, food wastewater, and their co-digested sludge.

For energy recovery, anaerobic digestion is applied to organic waste, such as livestock manure (LM) and food wastewater (FW). Digested sludge(DS), a residue from the anaerobic co-digestion of LM and FW, is another type of organic waste that can be converted into energy through pyrolysis. This study compared the pyrolysis characteristics of LM, FW, and DS. The product content varied with the pyrolysis temperature, rate of temperature increase, reaction time, and final reaction temperature. Gas production from FW and DS was similar; however, gas production from LM was low. As the pyrolysis temperature increased, the H2 content increased, and the CO2 content decreased, respectively. At 1000 °C, the H2 content of LM increased to 45%, and FW produced the most gas but the lowest H2 content. The H2/CO ratios of LM and FW ranged from 3.5 to 5.2, while those of DS ranged from 5.5 to 12.4, with the highest values. The carbon conversion rate was the highest for the gaseous products of LM (30-54%) and lowest for the gaseous products of digested sludge (26-36%). Conversely, the cold gas efficiency was the highest for the DS and lowest for the LM. Following anaerobic digestion, the DS generated less tar than the untreated LM and FW, showed higher efficiency in gas generation and gas properties, and exhibited a higher value as a char fuel.

Grouping of unused agricultural by-product biomass for fuel conversion in South Korea through multivariate analysis.

While biomass holds significance as a resource, its abundance in South Korea is limited. Therefore, in this study analyzed the chemical characteristics of agricultural by-products produced and evaluated their fuel potentiality. To achieve this objective, multivariate analysis was utilized to create biomass clusters with diverse feature. All investigated biomass types showed heating values of at least 12.6 MJ/kg, adhering to South Korea's Bio-solid recovered fuel (SRF) standard, once the moisture content was reduced to 20 % or less. However, the biomasses only met the heating value of Level 3 of the European standard for SRF, which is at least 15 MJ/kg. Groups were formed based on a multivariate analysis using four variables: the high heating value, and carbon, nitrogen, and ash contents. The groups were centered around wood chips and hog fuel, with a cluster of lignocellulosic biomass materials surrounding them. The clusters formed around four groups. When the biomasses in each group were mixed, the combustion characteristics were compared to the ignition, maximum, and burn-out temperatures. Utilizing biomass grouping, by-products from agriculture and livestock in South Korea can be effectively employed as energy sources.

Evaluation of the adsorption performance and thermal treatment-associated regeneration of adsorbents for formaldehyde removal.

Indoor air pollution remains a major concern, with formaldehyde (HCHO) a primary contributor due to its long emission period and associated health risks, including skin allergies, coughing, and bronchitis. This study evaluated the adsorption performance and economic efficiency of various adsorbents (biochar, activated carbon, zeolites A, X, and Y) selected for HCHO removal. The impact of thermal treatment on adsorbent regeneration was also assessed. The experimental apparatus featured an adsorption column and HCHO concentration meter with an electrochemical sensor designed for adsorption analysis. Zeolite X exhibited the highest adsorption performance, followed by zeolite A, zeolite Y, activated carbon, and biochar. All adsorbents displayed increased HCHO removal rates with an extended length/diameter (L/D) ratio of the adsorption column. Zeolite A demonstrated the highest economic efficiency, followed by zeolite X, activated carbon, zeolite Y, and biochar. Higher L/D ratios improved economic efficiency and prolonged the replacement cycle (the optimal timing for adsorbent replacement to maintain high adsorption performance). Sensitivity analysis of adsorbent regeneration under varying thermal treatment conditions (150, 120, and 80°C) and durations (60, 45, and 30 min) revealed minimal changes in adsorption efficiency (±3%). The results indicated the potential of adsorbent regeneration under energy-efficient thermal treatment conditions (80°C, 30 min). In conclusion, this study underscores the importance of a comprehensive assessment, considering factors such as adsorption performance, replacement cycle, economic efficiency, and regeneration performance for the selection of optimal adsorbents for HCHO adsorption and removal.Implications: This study underscores the importance of adsorption technology for the removal of formaldehyde and similar volatile organic compounds (VOCs), highlighting the potential of alternative adsorbents, such as environmentally friendly biochar, in addition to traditional strategies, such as activated carbon and zeolites. Our findings demonstrate the feasibility of adsorbent regeneration under energy-efficient thermal treatment conditions. These results hold promise for improving indoor air quality, reducing environmental pollutants, and enhancing responses to air contaminants like fine dust and VOCs.

Syngas generation from different types of sewage sludge using microwave-assisted pyrolysis with silicon carbide as the absorbent.

In this study, the pyrolysis of sewage sludge was explored through microwave-assisted pyrolysis. Three kinds of sludge (primary sludge, waste-activated sludge, and digested sludge) from a sewage treatment process were used. All three kinds of sewage sludge had a low microwave absorption capacity; therefore, an absorber was added to enable microwave-assisted pyrolysis. By using silicon carbide as the heating element, it was possible to increase the temperature within a short time by applying microwaves. During the microwave-assisted pyrolysis of sewage sludges, the amount of gas generated and the H2 and CO fraction of the produced gas increased as temperature increased. The pyrolysis of waste-activated sludge produced the greatest quantity of gas. However, the primary sludge produced the highest amount of syngas in terms of H2 and CO, which indicate the high-quality of the syngas.

Hydrothermal carbonization improves the quality of biochar derived from livestock manure by removing inorganic matter.

The application of hydrothermal carbonization to improve biomass-derived energy sources is crucial because of insufficient supplies of fossil fuels and concerns associated with the impact of fossil fuels on the environment. Hydrothermal carbonization technology has been developed to circumvent the energy-intensive drying step required for the thermal conversion of high-moisture organic feedstocks into fuel. In this study, the quality of livestock manure was upgraded, and its energy density was increased through hydrothermal carbonization at various temperatures. The evolution of waste biomass under hydrothermal carbonization was chemically analyzed. The increased carbon content of the resulting biochar upgraded its fuel properties, leading to energy savings in the treatment process. After hydrothermal carbonization, the H/C and O/C ratios were lower owing to chemical conversion. The optimal temperature for hydrothermal carbonization was approximately 220 °C. The inorganic content resulted in a lowered degree of agglomeration and reduced the likelihood of fouling during combustion. The thermogravimatric analysis also provided the changing combustion characteristics due to the increased fixed carbon content. Fourier transform infrared spectra revealed that hydrothermal carbonization reaction reduced the numbers of C-O and C-H functional groups and increased the number of aromatic C-H functional groups. The equilibrium moisture content decreased rapidly when hydrothermal carbonization was conducted at temperatures higher than 200 °C, and the initial moisture content was reduced by 75% after hydrothermal carbonization at 300 °C.

Designing of reverse vending machine to improve its sorting efficiency for recyclable materials for its application in convenience stores.

Plastics have multiple applications in disposable products, high-end technology parts, etc., owing to their functionality and manufacturing flexibility. However, their increased use has increased the global proportion of plastic wastes, which creates a serious environmental issue, thereby, creating a demand for plastic waste management techniques. Improving the efficiency of resource recovery by appropriate sorting and collection systems is necessary for successful plastic recycling. Therefore, this study proposed a three-step optimization process of a reverse vending machine (RVM), a small automatic recyclable waste sorter/collector system, for acquiring an optimal design and enhanced efficiency. The RVM system categorized recyclable wastes as plastics, glass, and cans using barcode, vision, and near infrared sensors. The average sorting efficiency of the designed RVM system was 94%, 95% for polyethylene terephthalate, and 98% for glass bottles. Therefore, the RVM system, with the average sorting efficiency of 95%, is suitable for application in on-site sorting in small-sized areas, such as convenience stores, which generate wastes on a small scale.Implications: This study proposed a three-step optimization process of a reverse vending machine (RVM), a small automatic recyclable waste sorter/collector system, for acquiring an optimal design and enhanced efficiency. The RVM system is suitable for application in on-site sorting in small-sized areas, such as convenience stores, which generate wastes on a small scale.

Trend and Prospect of Study on Chinese Medical History - Diversification of the Study on Medical History Study Through Integration and Communication.

This study has focused on studying Chinese medical history for the past 10 years (2010-2019). There has been no overall introduction to how the study of Chinese medical history has been carried out so far in Korea. To understand the trend for the recent 10 years, understanding of the period before that is needed. This study had classified the study trend of Chinese medical history from the 1950s when the study of Chinese medical history started in full swing until the last 10 years into the following three periods: First period: internal study period on Chinese medical history (the 1950s-1980s) Second period: external study period on Chinese medical history (the 1980s-1990s) Third period: diverse study period on Chinese medical history through integration and communication (2010-2019) There can be an opinion that various studies by each period have not been adequately reflected, and the classification has been excessively simplified. For example, the internal study has been considerably performed in the second period, and the consciousness of conflict between the internal study and external study remains in the third period. Nonetheless, the keywords that connote each period's characteristics for the past 70 years are considered the keywords presented above. The study of Chinese medical history has mainly placed importance on the modern times. Indeed, no change has been present as well. However, the fact that the study on the Chinese pre-modern medical history in Korean academia for the past 10 years has quantitatively grown from just a comparison of the number of papers can be identified. Also, the researchers and study themes have been confirmed to be diversified. In the past, ancient Chinese medicine was understood as a connection between Taoism and medicine. The environmental history researchers dealt with the connection between natural disasters and diseases, and just a few studies in the fields of medicinal herb distribution and the viewpoint of the body were carried out. Meanwhile, studies from the pre-Qin Dynasty to the Han Dynasty were carried out based on new data such as the archaeological relics and bamboo and wooden slips in the Korean academia for the past 10 years. Discovering new data is undoubtedly a driving force to activate studies. Studies on the Tang Dynasty Medical System and laws based on 'Chunsungryeong' are significant achievements connecting the Qin Dynasty & Han Dynasty and the Song Dynasty & Yuan Dynasty. Identification of each period's medical system in medical history is the most essential thing, and the combination of environment and medical history is conducted. It is significant to examine medical history from the viewpoint of the academic disciplines' integration. Approaching medical history from the female viewpoint has already started in the U.S., Europe, and Taiwan, and it is nice that such a study has been conducted in Korean academia. There are not many researchers on Chinese medical history in Korean academia. As several researchers have led the study, the study's concentration on specific periods or specific themes cannot be denied. The integration of systematic research achievements from the pre-Qin Dynasty until the Qing Dynasty is still minimal. Specifically, the study on pre-modern medical history targets a more extensive period than the study on modern medical history; therefore, researchers' density is low. This is why the possibility of intersection is not high in the period, region, and theme between researchers. This can be the source of an evaluation that study on medical history chain is sparse. It is wistful that the study continuity or systematic research is lacking. To overcome such a limitation, existing researchers need to conduct collaborative joint planning and research centered on particular themes through cooperation. They need to complement the study's sparse part in medical history through multidisciplinary co-research. Beyond the research centered on country study history, attempts to understand history as global history are being carried out. Studies on the exchange and interrelations between Western medicine and Chinese medicine have been performed in Chinese medical history. Nonetheless, studies on the exchange and interrelations of medical knowledge, medical systems, medicinal herbs, medical books, medical workforce, and diseases (epidemics) from global history are insufficient. Studies on a medical history that started from Chinese science and technology development history in the 1950s are developing to discuss one theme diversely. Plenty of studies on Chinese medical history need to be performed in various fields, including environmental history, the history of women, archeology, humanities, humanities therapy, integrated medical humanities, medical literature, medical theory, and medical system, which are the traditional fields.

Characteristics of vegetable crop cultivation and nutrient releasing with struvite as a slow-release fertilizer.

Struvite precipitation is an effective method to remove and recover ammonia and phosphate from livestock wastewater. Struvite has properties similar to those of the traditional ammonium-phosphate fertilizer, which does not burn the roots owing to its slow-release characteristics. Struvite is an effective fertilizer as its nutrient-releasing rate is very slow. But the release rate of ammonia and phosphate in soil depends on the size of crystals. In this study, the nutrient-releasing pattern of three types of struvite crystals and liquid fertilizer was compared using soil column. X-Ray fluorescence spectrometry was conducted to investigate the potential use of struvite as a fertilizer. Various struvite crystalline fertilizers were evaluated for their fertilizer performance by cultivating potted vegetable crops. The nitrogen removal efficiency of zeolite-seeded struvite was higher than that of no seed struvite. The ammonia nitrogen removal efficiency was more than 99% irrespective of the kind of zeolite. The soil column test revealed that nutrient releasing from liquid fertilizer and zeolite-seeded struvite recovered from livestock wastewater was 11 and 63 days, respectively. Struvite recovered from livestock wastewater contained more than 20% (w/w) potassium oxide; however, the concentration of heavy metals, such as copper and zinc, was very low. Therefore, we considered that the synthesized struvite using livestock wastewater has high value as fertilizer. The recovered struvite was effective under appropriate concentrations to cultivate all the applied vegetable crops in this study.

A numerical study on the behavior of coastal waste particles in a wind-power sorting system for renewable fuel production.

In this study, a Computational Fluid Dynamics (CFD) to analyze the coastal waste particles in a wind-power sorting system is applied to produce renewable fuel using commercial CFD package (ANSYS-CFX code). The numerical methodology results predicted various coastal waste shredded inside the sorting machine. Furthermore, to identify the effect of working conditions on separation characteristics, a parametric study is performed. These study findings will offer appropriate a wind-power sorting conditions according to the purpose of using coastal waste. Under basic conditions, the characteristics of coastal waste particle behavior and the sorting of waste particles were analyzed, and the behavioral changes of diverse particles were identified by changing the airflow rate to improve the sorting performance. As a result, an appropriate airflow rate, Qair = 85 m3/min, at which the change in the airflow rate can simultaneously meet the conditions for both the recovery of the combustibles and the removal of the incombustibles, was selected with the selection efficiency rate was 92%, and the combustibles content was 99%. Based on the results of the analysis, the particle characteristics of sorting were identified to reduce and recycle the coastal waste.

Characterized hydrochar of algal biomass for producing solid fuel through hydrothermal carbonization.

The aim of this work was to study the characterized hydrochar of algal biomass to produce solid fuel though hydrothermal carbonization. Hydrothermal carbonization conducted at temperatures ranging from 180 to 270 °C with a 60 min reaction improved the upgrading of the fuel properties and the dewatering of wet-basis biomasses such as algae. The carbon content, carbon recovery, energy recovery, and atomic C/O and C/H ratios in all the hydrochars in this study were improved. These characteristic changes in hydrochar from algal biomass are similar to the coalification reactions due to dehydration and decarboxylation with an increase in the hydrothermal reaction temperature. The results of this study indicate that hydrothermal carbonization can be used as an effective means of generating highly energy-efficient renewable fuel resources using algal biomass.

Effect of hydrothermal pre-treatment (HTP) on poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion.

This study is an assessment of the hydrothermal pre-treatment (HTP) of poultry slaughterhouse waste (PSW) sludge for the enhancement of the solubilization, physical properties, and biogas production through anaerobic digestion. This assessment was carried out to ascertain the optimal HTP temperature. The solubilization and physical properties efficacy was investigated by capillary suction time (CST), time to filter (TTF), and particle size. In addition, the anaerobic digestion was investigated through biochemical methane potential (BMP) tests and subsequent statistical analysis using the modified Gompertz model. HTP was found to have improved the solubilization of the PSW sludge with increasing HTP temperature. In addition, the results of the CST, TTF, and particle size decreased with increasing HTP temperature. These results of the assessment that was conducted in this study confirm that the HTP process indeed modifies the physical properties of PSWs to enhance the solubilization of organic solids. Nevertheless, the results of the BMP tests and the modified Gompertz model analysis show that the optimal HTP temperature of PSWs for anaerobic digestion is 190°C. These findings show that to achieve high conversion efficiency, an accurately designed pre-treatment step must be included in the overall anaerobic digestion process for wastewater treatment.

Selection and Management of Medical Official during the Yuan Dynasty.

Although the healthcare system of the Yuan Dynasty followed that of the Song Dynasty, there are certain differences between these two dynasties in terms of practices. Including appointing 'Yihus' in 'Zhusehuji' and setting up 'Guanyitijusi' to oversee Yihus, the Yuan Dynasty developed an effective management system for their physicians and, soon after the coronation of Khubilai, built 'Yixue (Medical school)' all over its territories in order to establish an organized and substantial medical training system. Moreover, the Yuan Dynasty not only revived the civil service examination system system between 1314 and 1320 as well as the medical examination system, but also increased the quota for qualification to twice that of Confucian examination in Song. These changes resulted in producing many brilliant people at the time. In the second half of the reign of Emperor Chengzong it was decided that the incompetence of the government healthcare organizations and the abundance of charlatans could not be neglected any longer. Existing policies and systems was limited in educating and training proper physicians, and this problem was not restricted to the field of medicine. The need for new systems that could reform the social order led to the restoration of the civil service examination system. The civil service examination system for Confucianism and for medicine began in 1314 and 1316, respectively. The purpose of the medical examination system was to select medical officials. The medical examination system which started in 1316 had a significant impact on the medicine of the Yuan dynasty for many reasons. Firstly, the qualification to apply to the medical examination did not remain constricted to 'Yixue' but opened to all 'Zhusehuji'; and secondly, the examination system did not have a restriction on the number of applicants was not restricted. The most important aspect of the examination system was that the number of test takers that passed the first test was one hundred and the number of passers of the second test were thirty, which were not low compared to the number of passers of the Confucianism examination. As such, the impact of the medical examination on the Yuan society was substantial. The Confucian examination selected 300 persons to pass the first test. The second test had 100 test takers which was equally divided among the four social classes at 25 percent each. The medical system selected 100 persons in the first test and 30 in the second. What is important is that unlike the Confucian examination system, the medical system was not divided into four classes. Hypothetically, the 30 qualified persons could all be South Chinese. In terms of the number of passers, it was much more promising for the South Chinese to flourish through the medical test than through Confucian examination test. Such facts support the claim that the Yuan Dynasty emphasized the field of medicine compared to the Song Dynasty. Although the Song Dynasty implemented the civil service examination system early on, the medical system was not implemented until 1115, which started with the founding of 'Yixue' across the country and assigning student capacity. During the Song Dynasty, the number of students in the medical system was 15 percent of that in the Confucianism system, and compared to that in Yuan, it raised to 30 percent, which is twofold. The indications of the Yuan Dynasty valuing medicine and making an effort to educate and train medical experts can be seen in the 'Yihu system', 'Guanyitijusi', Yixuetijusi', and medical school as well as the ratio of the medical system capacity.

Changes in bacterial and archaeal communities in anaerobic digesters treating different organic wastes.

The goal of this study was to characterize microbial communities in anaerobic batch digesters treating different representative organic sources (sewage sludge, food waste, septage). Among the digesters, the anaerobic digester of food waste had the highest methanogen density, producing a peak value methane yield of 813.2mLCH4/gVS. In all the digesters, acetoclastic Methanosarcinales and hydrogenotrophic Methanomicrobiales were the most dominant methanogen groups, but their proportion among the methanogens varied depending on the organic sources. The bacteria community in the anaerobic digestion (AD) of food waste and septage was distinctly different from that found in the AD of sewage sludge (primary sludge and waste activated sludge). Shifts in both bacterial and archaeal community structures could be related to differences in chemical properties, production, and accumulation of intermediates digested from organic wastes having different characteristics. These findings could prove useful in optimizing the microbial community to enhance AD process treating organic wastes.

Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production.

The filamentous alga Hydrodictyon reticulatum harvested from a bench-scale wastewater treatment pond was used to evaluate biogas production after ultrasound pretreatment. The effects of ultrasound pretreatment at a range of 10-5000 J/mL were tested with harvested H. reticulatum. Cell disruption by ultrasound was successful and showed a higher degree of disintegration at a higher applied energy. The range of 10-5000 J/mL ultrasound was able to disintegrated H. reticulatum and the soluble COD was increased from 250 mg/L to 1000 mg/L at 2500 J/mL. The disintegrated algal biomass was digested for biogas production in batch experiments. Both cumulative gas generation and volatile solids reduction data were obtained during the digestion. Cell disintegration due to ultrasound pretreatment increased the specific biogas production and degradation rates. Using the ultrasound approach, the specific methane production at a dose of 40 J/mL increased up to 384 mL/g-VS fed that was 2.3 times higher than the untreated sample. For disintegrated samples, the volatile solids reduction was greater with increased energy input, and the degradation increased slightly to 67% at a dose of 50 J/mL. The results also indicate that disintegration of the algal cells is the essential step for efficient anaerobic digestion of algal biomass.