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Biogas Recovery from MSW using Different Aeration Pretreatments
( Xu Qiyong ),( Tian Ying ),( Ko Jae Hac ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
Aeration pretreatment has been proven to be an efficient technology to facilitate waste stabilization in bioreactor landfills. In order to investigate the effects of different aeration pretreatments on biogas recovery, three simulated columns (A1, C1 and C2) were constructed and operated for 130 days. A1 simulated an anaerobic bioreactor. C1 was pretreated with a constant daily aeration frequency in the upper layer, while C2 had various daily aeration frequencies. Results indicated that aeration could effectively remove high volatile fatty acid (VFA) in leachate and accelerate methane productions in bioreactors. At the end of operation, about 44 L/kgdry mass and 53 L/kgdry mass methane were collected in C1 and C2, respectively, while nearly no methane was produced in A1. Correspondingly, aerobically pretreated bioreactors dramatically decreased their COD and VFA concentrations. In terms of methane formation in aerobically pretreated bioreactors, C2 was changed quickly from aerobic phase to methanogenic phase. Due to larger area affected by aeration pretreatment, biogases in C1 were generated in much greater rate. The total amount of methane generated from C2 was greater than that from C1.
( Eunil Cho ),( Qiyong Xu ),( Danling Xia ),( Jae Hac Ko ) 한국폐기물자원순환학회 2021 한국폐기물자원순환학회지 Vol.38 No.4
One of the significant challenges of food waste anaerobic digestion (AD) is the negative effect of high NaCl concentrations. This study investigated the effects of NaCl fluctuation on the methane generation of food waste AD under thermophilic and mesophilic conditions. Particularly, the effects of the shock loading of high NaCl concentration with/ without water dilution treatment were investigated. Generally, the methane generation decreased with increasing NaCl concentration. In addition, the sensitivity of the thermophilic AD to NaCl concentrations (5-10 g/L) was higher than that of the mesophilic AD. Furthermore, with an increase in the NaCl concentration from 0 to 30 g/L, the accumulative methane volumes of the thermophilic reactors decreased from 210 to 45 mL/gVS, and those of the mesophilic reactors decreased from 265 to 67 mL/gVS. Additionally, the pH of digestate decreased with increasing NaCl concentration. In contrast, the concentrations of the chemical oxygen demand and volatile fatty acid increased with increasing NaCl concentration. These results indicated that a shock loading of NaCl significantly reduced methane generation. In addition, the methane generation rates could be recovered up to 64-72% using water dilution as a remedial measure. Further investigation using 16S rRNA analysis revealed that the predominant genus of the methanogens shifted from Methanoculleus to Methanosarcina after the removal of the osmotic stress using water dilution.
Methane Recovery from NaCl Inhibition of Food Waste Anaerobic Digestion
( Jae Hac Ko ),( Danling Xia ),( Qiyong Xu ) 한국폐기물자원순환학회(구 한국폐기물학회) 2020 한국폐기물자원순환학회 추계학술발표논문집 Vol.2020 No.-
One of the big challenges of food waste anaerobic digestion is the inhibition of high NaCl concentrations. This study investigated the effects of NaCl fluctuation on the methane generation of food waste anaerobic digestion under both thermophilic and mesophilic conditions, especially focusing on shock loading of high NaCl concentration with/without water dilution treatment. In general, methane generation decreased with increasing the concentration of NaCl concentrations. Thermophilic AD was more sensitive to NaCl concentration change at the range of 5-10 g/L. When NaCl concentration increased from 0 g/L to 30 g/L, the accumulative methane volumes of thermophilic and mesophilic reactors decreased from 420 mL to 133 mL and from 529 mL to 133 mL, respectively. With increasing NaCl concentration, pH of digestate decreased while COD and VFA concentrations increased. Results indicated that a shock-loading of NaCl significantly reduced methane generation. Using water dilution as a remedial measure, the methane generation rates could be recovered up to 64% - 72%. Further investigation with 16S rRNA analysis showed that the predominant genus of methanogens shifted from Methanoculleus to Methanosarcina after removal of osmotic stress by water dilution.
Municipal Solid Waste Degradation and Compaction
( Jae Hac Ko ),( Mingying Li ),( Fan Yang ),( Qiyong Xu ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
This study investigated the impact of compaction on anaerobic degradation of municipal solid waste (MSW) during the phase of methane formation. Two stainless steel lysimeters were constructed with equipped a hydraulic cylinder to apply pressure load on the MSW. When methane production rates decreased from the peak rate of each column, pressure load was applied at different degrees of decomposition (DOD). When pressure load was applied, chemical oxygen demand (COD) showed temporary increases, Methane production rate also increased by the compaction. However, the impact of compaction on methane production rate varied with different degrees of decomposition. MSW compaction reduced pore space of MSW resulting in increasing the contact surface area of among MSW particles. It was thought that the mass transfer of volatile fatty acids could be enhanced by increased contact surface area and degree of saturation as the consequence of the compaction.
Metabolism Characteristics of Mycoplasma pneumoniae Infection in Asthmatic Children
Luo Jiaying,Chen Huian,Zhang Qiyong,Huang Xinyun,Qin Xu,Li Jing,Chen Siyi,Xiao Yongxin,Sun Lihong,Sun Baoqing 대한천식알레르기학회 2022 Allergy, Asthma & Immunology Research Vol.14 No.6
Purpose: Studies have shown that Mycoplasma pneumoniae (Mp) infection can aggravate symptoms in asthmatics. However, the mechanism by which Mp infection exacerbates asthma remains unclear. Metabolomics can help identify the mechanism of Mp aggravating asthma in children, thereby providing more a potential target for improving clinical treatment programs. In this article, we analyzed the metabolic level of patients to explain how Mp aggravates asthma in children. Methods: We divided the subjects into the asthma, Mp infection, asthma combined with Mp infection and healthy groups. Patients’ peripheral blood was collected for metabolic and interaction analysis. Cytokine levels were measured via serum and exhaled breath condensate (EBC). Results: A total of 150 participating subjects were divided into four groups after exclusion. We found out that there were different metabolic pathways between the healthy and disease groups. The major pathways of both asthma and asthma combined with Mp infection were valine, leucine and isoleucine biosynthesis; malate-aspartate shuttle was the main differential pathway for Mp infection. Moreover, even though three disease groups involved 81 metabolites at the same time, compared with asthma combined with Mp infection, 2 single disease groups still involved different amino acid pathways (phenylalanine, tyrosine and tryptophan biosynthesis; valine, leucine and isoleucine biosynthesis). Interaction analysis showed that Mp infection in asthmatic patients not only activated cytokines, but also activated Toll-like receptors (TLRs) 2 and 6. Finally, the levels of interleukin (IL)-4, IL-8, IL-13 and tumor necrosis factor-α in EBC with asthma combined with Mp infection were significantly higher than the 2 single disease groups. Conclusions: Mp infection in asthmatic children can cause changes in the levels of various amino acids in the body, which were enriched in the pathways such as valine, leucine and isoleucine biosynthesis. Palmitic acid can activate TLR2, and iloprost reduces IL-10 levels, ultimately leading to the increased airway inflammation.