Search

With the advantages of high treatment capacity and low operational cost, large-scale trough composting has become one of the mainstream composting patterns in composting plants in China. This study measured concentrations of O 2 , CO 2 , CH 4 and NH 3 on-site to investigate the spatial and temporal distribution of pore gas concentrations during mainstream large-scale trough composting in China. The results showed that the temperature in the center of the pile was obviously higher than that in the side of the pile. Pore O 2 concentration rapidly decreased and maintained <5% (in volume) for 38 days or more in both the center and side of the pile and effective O 2 diffusion occurred at most in every two contiguous layers. Pore CO 2 and CH 4 concentrations at each measurement point were positively correlated ( 0.436 ≤ r ≤ 0.570, P < 0.01 ) and the concentrations in the side of the pile were obviously lower than those in the center. The top layer exhibited highest pore O 2 concentration and lowest CO 2 and CH 4 concentrations, and the bottom layer was on the contrary. No significant differences in pore NH 3 concentrations between different layers or between different measurement points in the same layer were found. Therefore, mixing the center and the side of the pile when mechanical turning and adjusting the height of the pile according to the physical properties of bulking agents are suggested to optimize the oxygen distribution and promote the composting process during large-scale trough composting when the pile was naturally aerated, which will contribute to improving the current undesirable atmosphere environment in China. [ABSTRACT FROM AUTHOR]

In this study, 838 representative animal manure samples were collected from 552 sites across China. Chemical analyses of 19 parameters, including the proximate analysis, ultimate analysis, heating values and some essential mineral elements, were conducted on the samples. The energy potential of animal manure in China was quantified based on the chemical analysis. The results showed that the chemical characteristics of the different types of animal manure were highly variable. Principal component analysis results demonstrated that the closest compositional characteristics were between dairy manure and beef manure. Several strong and important associations, namely phosphorus–magnesium, phosphorus–copper, phosphorus–zinc, copper–zinc, calcium–potassium, fixed carbon–calcium, volatile matter–iron and ash–volatile matter–fixed carbon–carbon–hydrogen–higher heating value–lower heating value, were identified. The calculated outputs of total potential annual thermal energy, syngas and methane yields from the five types of animal manure in China were 4400.63 TJ, 983.40 × 10 9 m 3 and 188.89 × 10 9 m 3 , respectively. The air gasifier energy conversion efficiency ( t = 850 °C, equivalence ratio (ER) = 0.3) for different animal manures was in the range of 66.80–83.22%. [ABSTRACT FROM AUTHOR]