Production of volatile fatty acid from fruit waste by anaerobic digestion at high organic loading rates: Performance and microbial community characteristics.

This study examined the performance and microbial community dynamics of an anaerobic volatile fatty acid (VFA) production reactor for treating fruit waste by stepwise increasing organic loading rates (OLRs) from 8 to 24 g volatile total solids (VTS)/(L·d). Results showed that higher VFA concentrations of 52.25-61.90 g chemical oxygen demand (COD)/L can be maintained at each OLR, thereby resulting to a production of 0.70-0.76 g chemical oxygen demand (COD)VFA/g VTS. Notably, an increase in OLR from 8 to 14 g VTS/(L·d) was beneficial for achieving higher VFA concentrations and yields. Moreover, an increase in OLR affected the VFA distribution significantly; acetate and butyrate became dominant in the fermentation liquid at OLRs ≥ 14 g VTS/(L·d). Microbial community dynamics analysis revealed that phyla Firmicutes and Actinobacteriota were predominant at each OLR, and the genera Lactobacillus, Clostridium_sensu_stricto_12, and Caproiciproducens were closely related to anaerobic VFA production.

Biogas Production from Distilled Grain Waste by Thermophilic Dry Anaerobic Digestion: Pretreatment of Feedstock and Dynamics of Microbial Community.

Distilled grain waste (DGW) eluted from the Chinese liquor making process poses potential serious environmental problems. The objective of this study is to evaluate the feasibility of converting DGW to biogas by thermophilic dry anaerobic digestion. To improve biogas production, the effects of dilute H2SO4 and thermal pretreatment on DGW were evaluated by biochemical methane potential (BMP) tests. The results indicate that 90 °C thermal pretreatment provided the highest methane production at 212.7 mL/g-VTSadd. The long-term thermophilic dry anaerobic digestion process was conducted in a 5-L separable flask for more than 3 years at a volatile total solid (VTS) loading rate of 1 g/kg-sludge/d, using synthetic waste, untreated and 90 °C thermal pretreated DGW as the feedstock, respectively. A higher methane production, 451.6 mL/g-VTSadd, was obtained when synthetic waste was used; the methane production decreased to 139.4 mL/g-VTSadd when the untreated DGW was used. The 90 °C thermal pretreated DGW increased the methane production to 190.5 mL/g-VTSadd, showing an increase of 36.7% in methane production compared with that using untreated DGW. The microbial community structure analysis indicates that the microbial community in the thermophilic dry anaerobic digestion system maintained a similar structure when untreated or pretreated DGW was used, whereas the structure differed significantly when synthetic waste was used as the feedstock.

Aerobic composting of digested residue eluted from dry methane fermentation to develop a zero-emission process.

Digested residue remained at the end of a process for the production of fuel ethanol and methane from kitchen garbage. To develop a zero-emission process, the compostability of the digested residue was assessed to obtain an added-value fertilizer. Composting of the digested residue by adding matured compost and a bulking agent was performed using a lab-scale composting reactor. The composting process showed that volatile total solid (VTS) degradation mainly occurred during the first 13days, and the highest VTS degradation efficiency was about 27% at the end. The raw material was not suitable as a fertilizer due to its high NH4+ and volatile fatty acids (VFAs) concentration. However, the composting process produced remarkable results; the physicochemical properties indicated that highly matured compost was obtained within 62days of the composting process, and the final N concentration, NO3- concentration, and the germination index (GI) at the end of the composting process was 16.4gkg-1-TS, 9.7gkg-1-TS, and 151%, respectively. Real-time quantitative PCR (qPCR) analysis of ammonia oxidizers indicated that the occurrence of nitrification during the composting of digested residue was attributed to the activity of ammonia-oxidizing bacteria (AOB).

Thermophilic Dry Methane Fermentation of Distillation Residue Eluted from Ethanol Fermentation of Kitchen Waste and Dynamics of Microbial Communities.

Thermophilic dry methane fermentation is advantageous for feedstock with high solid content. Distillation residue with 65.1 % moisture content was eluted from ethanol fermentation of kitchen waste and subjected to thermophilic dry methane fermentation, after adjusting the moisture content to 75 %. The effect of carbon to nitrogen (C/N) ratio on thermophilic dry methane fermentation was investigated. Results showed that thermophilic dry methane fermentation could not be stably performed for >10 weeks at a C/N ratio of 12.6 and a volatile total solid (VTS) loading rate of 1 g/kg sludge/d; however, it was stably performed at a C/N ratio of 19.8 and a VTS loading rate of 3 g/kg sludge/d with 83.4 % energy recovery efficiency. Quantitative PCR analysis revealed that the number of bacteria and archaea decreased by two orders of magnitude at a C/N ratio of 12.6, whereas they were not influenced at a C/N ratio of 19.8. Microbial community analysis revealed that the relative abundance of protein-degrading bacteria increased and that of organic acid-oxidizing bacteria and acetic acid-oxidizing bacteria decreased at a C/N ratio of 12.6. Therefore, there was accumulation of NH4+ and acetic acid, which inhibited thermophilic dry methane fermentation.

Prevalence and Predictors of Hypertension in the Labor Force Population in China: Results from a Cross-sectional Survey in Xinjiang Uygur Autonomous Region.

The objective of this study was to examine the prevalence of hypertension and identify its contributory factors in the labor force population in Karamay. A total of 2819 adults (55.9% male adults) were interviewed and examined. The overall crude prevalence of hypertension was 32.4%. Among 914 hypertensive patients, 34.8% were aware of their diagnosis, 22.1% received treatment, and 5.6% achieved blood pressure control. Hypertension was significantly correlated with age, overweight/obesity, central obesity, diabetes, and dyslipidemia in both men and women. In addition, less education, alcohol consumption, and less walking were risk factors for men. Effective hypertension prevention and control programs are urgently needed to decrease the burden of hypertension in this region.