Nitrogen transformation and its microbial mechanism under co-composting of biogas slurry with garden waste.

Large amount of garden waste is consecutively produced in China every year. The composting with urea and microbial inoculum makes it possible to dispose garden waste in large quantities. However, composting accompanies with serious nitrogen loss and environmental problems. The biogas slurry contains considerable nitrogen nutrients and microorganisms, which theoretically could be used as alternative to urea and bacteria to reduce nitrogen loss, respectively. We set up three treatments of biogas slurry + garden waste (GB), biogas slurry + garden waste + urea (GBU), and biogas slurry + garden waste + urea + microbial inoculum (GBUM) to investigate the decomposition, nitrogen conversion and nitrogen loss in the co-composting process. The results showed that the high tempe-rature period of GB treatment was longer and more stable compared to that of GBU and GBUM treatments. The pH and EC value of GB treatment would benefit composting process and generated products with the highest germination index (GI) (221.8%). In addition, NH3 and N2O emission rates in the GB treatment were 2.59 mg·kg-1·d-1 and 3.65 µg·kg-1·d-1, respectively, being 99.0% and 50.0% lower than that in the GBU treatment and 99.4% and 40.7% lower than that in the GBUM treatment. The results of δ18O vs. δ15NSP dual isotopocule plots approach analysis showed that the GB and GBU treatments were dominated by denitrification, and that the contribution of denitrification was higher in the GB treatment. In contrast, the GBUM treatment was dominated by nitrification. The degree of N2O reduction in GB treatment (83.7%) was higher than the other two treatments. It was clear that GB treatment had the best maturity and lowest nitrogen loss in all treatments by enhancing the N2O reduction process during denitrification to reduce N2O emission. In conclusion, the biogas slurry and garden wastes could be directly co-composted without the limitation of C/N and microbial addition. The co-composting method could protect the environment and save resources leading to the recycling of waste in actual production.

Extraction of Oil from Flaxseed (Linum usitatissimum L.) Using Enzyme-Assisted Three-Phase Partitioning.

In this study, enzyme-assisted three-phase partitioning (EATPP) was used to extract oil from flaxseed. The whole procedure is composed of two parts: the enzymolysis procedure in which the flaxseed was hydrolyzed using an enzyme solution (the influencing parameters such as the type and concentration of enzyme, temperature, and pH were optimized) and three-phase partitioning (TPP), which was conducted by adding salt and t-butanol to the crude flaxseed slurry, resulting in the extraction of flaxseed oil into alcohol-rich upper phase. The concentration of t-butanol, concentration of salt, and the temperature were optimized to maximize the extraction yield. Under optimized conditions of a 49.29 % t-butanol concentration, 30.43 % ammonium sulfate concentration, and 35 °C extraction temperature, a maximum extraction yield of 71.68 % was obtained. This simple and effective EATPP can be used to achieve high extraction yields and oil quality, and thus, it is potential for large-scale oil production.

Ionic Liquid-Based Ultrasonic-Assisted Extraction of Secoisolariciresinol Diglucoside from Flaxseed (Linum usitatissimum L.) with Further Purification by an Aqueous Two-Phase System.

In this work, a two-step extraction methodology of ionic liquid-based ultrasonic-assisted extraction (IL-UAE) and ionic liquid-based aqueous two-phase system (IL-ATPS) was developed for the extraction and purification of secoisolariciresinol diglucoside (SDG) from flaxseed. In the IL-UAE step, several kinds of ILs were investigated as the extractants, to identify the IL that affords the optimum extraction yield. The extraction conditions such as IL concentration, ultrasonic irradiation time, and liquid-solid ratio were optimized using response surface methodology (RSM). In the IL-ATPS step, ATPS formed by adding kosmotropic salts to the IL extract was used for further separation and purification of SDG. The most influential parameters (type and concentration of salt, temperature, and pH) were investigated to obtain the optimum extraction efficiency. The maximum extraction efficiency was 93.35% under the optimal conditions of 45.86% (w/w) IL and 8.27% (w/w) Na2SO4 at 22 °C and pH 11.0. Thus, the combination of IL-UAE and IL-ATPS makes up a simple and effective methodology for the extraction and purification of SDG. This process is also expected to be highly useful for the extraction and purification of bioactive compounds from other important medicinal plants.