The utilisation potential of urban greening waste: Tartu case study

In light of climate change and the increasingly limited availability of energy resources, any form of renewable raw materials that can be used for energy production should be accounted for. One of the most promising renewable sources is considered to be that of lignocellulosic feedstock. In urban forestry and greening, millions of tons of lignocellulosic waste is produced every year but that biomass mostly goes unused. The aim of this research project was to investigate the utilisation potential of this very form of waste biomass using a medium-sized town as a sample for the work (Tartu in Estonia, with a population circa 100,000). Woody and non-woody vegetation representing greening waste from different seasons was investigated: spring and autumn leaves, and mixed waste from urban greening which contained grass, twigs, and leaves. BMP assays were conducted to estimate the biogas production potential and the three step bio-ethanol production process was used to estimate the bio-ethanol production potential. In the bio-ethanol production process, an N₂ explosion pre-treatment was used, followed by enzymatic hydrolysis and fermentation. Map analysis was used to assess the area that was manageable by urban forestry and greening in the city of Tartu in order to estimate the amount of greening and forestry waste that was available for bioconversion and the volumes of biofuel that could be produced.     

速生杨硫酸盐浆中木素的存在对纤维素水解反应性能及其产物结构的影响(英文)

对木素含量为0.9％～8.3％的速生杨硫酸盐浆进行了X-射线分析研究。利用多相水解方法测定了其反应性能。研究确定,浆中结晶纤维素含量取决于木素脱出程度并随着木素含量的降低而增加。木屑和浆中的纤维素结晶度相当高,而在脱木素过程中只呈微小变化。木素存在于多相水解反应过程中起着阻碍纤维素水解的作用,降低其反应速度常数。基于研究结果还提出了木素与纤维素结晶部分外表面联结的结论,并探讨了这种联结键的可能方式.     

Fungal growth on a common wood substrate across a tropical elevation gradient: Temperature sensitivity, community composition, and potential for above-ground decomposition

Fungal breakdown of plant material rich in lignin and cellulose (i.e. lignocellulose) is of central importance to terrestrial carbon (C) cycling due to the abundance of lignocellulose above and below-ground. Fungal growth on lignocellulose is particularly influential in tropical forests, as woody debris and plant litter contain between 50% and 75% lignocellulose by weight, and can account for 20% of the C stored in these ecosystems. In this study, we evaluated factors affecting fungal growth on a common wood substrate along a wet tropical elevation gradient in the Peruvian Andes. We had three objectives: 1) to determine the temperature sensitivity of fungal growth - i.e. Q₁₀, the factor by which fungal biomass increases given a 10 °C temperature increase; 2) to assess the potential for above-ground fungal colonization and growth on lignocellulose in a wet tropical forest; and 3) to characterize the community composition of fungal wood decomposers across the elevation gradient. We found that fungal growth had a Q₁₀ of 3.93 (95% CI of 2.76-5.61), indicating that fungal biomass accumulation on the wood substrate nearly quadrupled with a 10 °C increase in temperature. The Q₁₀ for fungal growth on wood at our site is higher than Q₁₀ values reported for litter decomposition in other tropical forests. Moreover, we found that above-ground fungal growth on the wood substrate ranged between 37% and 50% of that measured in the soil, suggesting above-ground breakdown of lignocellulose represents an unexplored component of the C cycle in wet tropical forests. Fungal community composition also changed significantly along the elevation gradient, and Ascomycota were the dominant wood decomposers at all elevations. Fungal richness did not change significantly with elevation, directly contrasting with diversity patterns observed for plant and animal taxa across this gradient. Significant variation in fungal community composition across the gradient suggests that the characteristics of fungal decomposer communities are, directly or indirectly, influenced by temperature.     

废菌糠及其辅料对香菇培养料中木质纤维素降解的影响

香菇培养料中含有２０％的废菌糠。在营养生长阶段可以加速木质纤维素复合体的解体，并将木质纤维素的降解率提高７％以上，辅料中还原糖和氮素的含量水平不同，木质纤维素率也不同，从１７．５０％到２０．１２％不等，辅料２＃对木质纤维素降解促进作用最明显，辅料３＃次之，辅料１＃和辅料４＃相近，为最低。     

Energy Productivity Potential Assessment of Saccharum spontaneum L.Germplasm Resources

[Objective]The energy productivity potential of Saccharum spontaneum L.germplasm resources as energy plants was discussed in this paper.[Method]The energy productivity potential of Saccharum spontaneum L.germplasm resources collected from the wild was assessed from the aspects of cellulose,semicellulose,lignin and crude ash contents and caloric value.[Result]The total content of cellulose and semicellulose ranged from 41.75%to 69.13%,the lignin content ranged from 2.16%to 11.75%,the crude ash content ranged from 4.79%to 9.34%and the caloric value ranged from 16.00 to 17.69 MJ/kg among the 30 Saccharum spontaneum L.germplasms.Compared to other plants,Saccharum spontaneum L.had higher contents of cellulose and semicellulose,a higher caloric value but lower contents of lignin and crude ash.[Conclusion]From the perspective of producing fuel ethanol with lignocellulose,Saccharum spontaneum L.has a great potential for development as an energy plant.     

木质纤维素预处理技术发展现状及展望

木质纤维素来源广泛,是最丰富的可再生资源,但木质纤维素结构致密、难降解,需要进行预处理。木质纤维素预处理在很大程度上决定了工艺可行性、经济可行性和环境可持续性。讨论了预处理在木质纤维素生物能源回收方面的应用进展,旨在为相关行业实现高效木质纤维素生物转化提供参考。      

木质纤维素原料厌氧生物降解研究进展

分析了木质纤维素原料生物降解特性的分析,重点从两个方面介绍了利用这种原料进行厌氧生物降解产沼气的研究进展:原料预处理技术,包括物理处理、化学处理、生物处理以及热处理技术;厌氧发酵工艺,包括单相发酵和两相发酵工艺,以及混合原料发酵工艺,并简要探讨了木质纤维素原料厌氧生物降解进一步的研究和发展方向。     

高效木质纤维素分解菌群筛选及其酸碱调节能力研究

为获得能够改良土壤酸碱性的微生物群体, 以混合堆放牛粪、鸡粪的储粪池外围土样为材料, 采用限制培养技术筛选了一组木质纤维素分解菌群, 并对该菌群在不同初始pH下的适应能力和纤维材料的分解能力及其耐盐特性进行了研究。结果表明: 以不同碳源(滤纸、玉米秸秆、稻草秸秆和小麦秸秆)制作不同初始pH(5.0~11.0)的培养基, 接种木质纤维素分解菌群后培养基pH均迅速向中性变化, 第3 d集中至8.0左右, 6 d后稳定至7.8~8.6; 7 d内滤纸、玉米秸秆、稻草秸秆和小麦秸秆失重率分别超过93.15%、50.53%、44.29%和42.60%; 以滤纸为惟一碳源、NaCl浓度2.0%的培养基接种, 7 d滤纸失重率达84.82%。木质纤维素分解菌群具有较强的适应及调节pH能力, 且能够高效分解木质纤维材料, 并具有一定的耐盐特性, 可见该菌群在酸碱土壤酸碱性改良领域具有一定开发潜力。     

14C Cycling in lignocellulose-amended soils: predicting long-term C fate from short-term indicators

We compared lignocellulose (the second most abundant component of plant material) degradation over 8 months in contrasting soils from each of five sites across the United States with the aim of assessing which soils are likely to store more C. The soils were collected from a tallgrass prairie restoration (farmland, and plots restored in 1993 and 1979), the semiarid shrub-steppe (cool, moist upper slope and warm, dry lower slope soils), long-term farmland (no-till and conventional-till), and from two forest soils (loblolly pine and Douglas fir; fertilized and nonfertilized). Soils that rapidly metabolized freshly added C exploited endogenous and newly transformed C to a lesser degree over the course of the incubation (lower slope shrub-steppe, nonfertilized Douglas fir, and tallgrass prairie farmed and 1993 restorations). We also pooled the data to find a strong relationship between sand content and lignocellulose C remaining in the soil after 8 months (R=0.68) and also between short-term storage of lignocellulose C (at 7 days) and lignocellulose C remaining after 8 months (R=0.94). To predict C storage, models of C and soil properties must be modified to reflect the structure and function of microbial communities. Communities in richer soils may be more competent to use native C following fresh C additions when compared with communities in poorer soils.     

对新一代生物燃料丁醇的概述

首先介绍了生物丁醇的发展历程,然后介绍了生物丁醇发酵菌种及丁醇的生物合成途径,最后总结了对目前生产生物丁醇存在的问题和解决方案,以期为燃料丁醇的工业化生产提供参考。