The aging of pit mud in long fermented grains pits might be induced by inappropriate maintenance and serious deficiency of nutrients.A series of rejuvenation approaches was adopted in the experiments.As a result,pit mud moisture content and Bacillus sp.numberin pit mud in-creased greatly and pit mud quality got improved evidently.The quality of aged pit mud reached up to the standards of quality pit mud quickly and its quality product rate in the production could achieve 85%,as high as the production level in old workshop.(Tran.by YUE Yang)
Mechanical refining (MR) is a cost-effective pretreatment in biochemical conversion processes that is employed to overcome biomass recalcitrance. This work studied the effects of MR on biogas and methane produced by the anaerobic digestion (AD) of dairy manure. The cumulative gas volume and yield from the AD of manure refined at 6k revolutions increased by 33.7 and 7.7% for methane and by 32.0 and 6.4% for biogas, respectively, compared to the unrefined manure. This enhancement was reached by increasing manure solubilization, reducing particle size, and achieving external fibrillation and internal delamination of fibers in manure. However, the highly refined manure (subjected to 60k revolutions) exhibited methane and biogas yields that were reduced by 9.5 and 1.5%, respectively. This decrease was observed because the pore structure was ruptured, and finely ground manure particles were aggregated together at high revolutions (60k), thereby inhibiting the release of organic matter from the manure. Therefore, this study indicates that the MR for pretreatment of dairy manure could have great potential for significantly enhancing AD of dairy manure. Further studies will include optimization of conditions of mechanical refining (i.e., mechanical intensity, process time), a continuous AD of dairy manure pretreated by the MR, and scale-up with cost evaluation.
Although various studies have investigated biochar (BC) soil amendments for improving soil microbial abundance, functions, and community structure, a comparison of dairy manure biochar (MBC) to wood biochar (WBC) is warranted given the large volume of manure produced in high-intensity dairy production. Additionally, the synergistic effects of different BC sources and loading percentages on microbial functions and community composition using massively parallel 16S DNA sequencing in BC-amended soils with different types of crops are limited. In this study, the synergistic effects of BC type, BC loading percentage, and crop types on soil fertility, prokaryote community diversity, and functions were investigated in a greenhouse study. The MBC and WBC were used to amend sandy loam soils at increasing BC loading percentages (0, 5, and 10%) to grow the cool-season forages crimson clover (Trifolium incarnatum; an annual legume) and Italian ryegrass (Lolium multiflorum Lam.; an annual forage grass) for 120 days. High nutrient concentrations in MBC shifted microbial communities towards r-strategists and alkaliphiles, potentially increasing the rate of nutrient bioremediation from high nitrogen- and phosphorus-containing soil amendments. This study enables emerging biochar agronomic use recommendations with different crops.
Biochemical methane potential (BMP) tests were conducted for investigating the effects of alfalfa-derived biochar (AF-BC) on anaerobic digestion (AD) of dairy manure under various loading of AF-BC (0–10 g/L). BMP tests were performed at mesophilic temperature (37 °C) with the addition of AF-BC. Biogas and methane volumes and concentrations, water quality parameters (i.e., COD (chemical oxygen demand)), and volatile fatty acids (VFAs) were measured during the AD process. The addition of 1 and 5 g/L of AF-BC increased the biogas yields by 15.51% and 26.09% and methane yields by 14.61% and 26.88% compared with the control without addition of AF-BC. Additionally, the addition of AF-BC (1–10 g/L) decreased the lag phase by 7.14–22.45% and the CO2 content of biogas by 13.60–32.48%, while increasing the COD removal efficiency by 19.19–35.94% in the AD of dairy manure. Moreover, the addition of AF-BC also decreased total VFAs and acetic acid concentrations in the AD process. The increase in AD performance was mainly owing to the improvement of buffering ability of the AD system and direct interspecies electron transfer (DIET) among AD microorganisms resulting from the addition of AF-BC. In contrast, the addition of 10 g/L AF-BC did not show any obvious improvement in biogas and methane yields in the AD of dairy manure, possibly because of toxic effects from excessive addition of AF-BC toward the AD microorganisms. Therefore, this study supported practical feasibility of AF-BC-enhanced AD of dairy manure.
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