A review on the production of fermentable sugars from lignocellulosic biomass through conventional and enzymatic route—a comparison

The scarcity of fossil fuels has urged the economically developed countries to find the resources for an alternative energy sources. In apprehension to this, biofuels, like bioethanol and biobutanol, produced from lignocellulosic biomass were considered as potential alternative. There are several methods for the pretreatment of biomass before it is being used as a feedstock for the production of fermentable sugars. However, one of the crucial concerns here is to enumerate an economic pretreatment scheme that can be implemented in large scale for the production of mostly exposed cellulosic part from biomass. This will ensure an effective hydrolysis of cellulose for the production of fermentable sugars and the production of biobutanol from these derived sugars. Moreover, the keynote understanding of an effective fermentation is the production of less inhibitory compounds like furfural, hydroxymethyl furfural during the hydrolysis of cellulose. Enzymatic hydrolysis of cellulose was reported as the most efficient method is this aspect. Trichoderma sp. was found the mostly used resources for the enzyme called cellulase and Aspergillus sp. for hemicellulase enzymes. The most crucial part here is the isolation of proper enzyme that will increase the rate of hydrolysis. Moreover, selection of proper pretreatment process will be a key benefit to the production of fermentable sugars through enzymatic hydrolysis. Based on the biomass nature, the evaluated hot water pretreatment followed by enzymatic hydrolysis with a provision of enzyme reusability (like encapsulated or enzyme separation with membrane) seems to be promising for enhanced biofuel-production.     

Comparative study of solar-powered water production from atmospheric air using different desiccant materials

In this paper, experiments have been performed in order to determine the quantity of water produced from the atmospheric air using different desiccant materials named Silica gel, Activated alumina and Molecular sieve 13 X. On the bases of experimental results, a correlation is derived among the different temperatures and water production using Central Composite Design (CCD) of Response Surface Methodology. A newly designed solar glass desiccant box type system (SGDBS), three in number, has been used. Design parameters for the production of water has been taken as depth of material from the glass is 0.22 m, inclination in angle as 30°, effective thickness of glass as 3 mm and number of glazing as single. It has been found experimentally that the maximum quantity of water produced by Silica gel, Activated alumina and Molecular sieve 13 X is 160, 20 and 35 ml/kg/day, respectively. Whereas theoretically, value of water produced by the Silica gel, Activated alumina and Molecular sieve 13 X is 600, 28 and 60 ml/kg/day, respectively.     

分子生态技术对厌氧脱氮除磷微生物优势菌群的鉴定

应用分子生态克隆技术,直接对A/O反应器所驯化培养的厌氧脱氮除磷微生物样品进行主要功能菌群的分子生态学鉴定。通过克隆文库的序列分析,发现驯化培养后厌氧污泥样品中的优势菌群主要是Azospirillum和Selenomonas两个属。这一结果表明,厌氧反应器中的某些红螺菌科和氨基酸球菌科的微生物,可能是在厌氧条件下对氮磷同时降解起关键作用的功能菌群。     

印染废水生化出水中各类有机物在小型活性炭床吸附过程中的去除效果

采用连续流活性炭炭床处理印染废水生化出水,通过XAD-8/XAD-4吸附树脂将印染废水生化出水中的溶解性有机物分为4类:疏水酸、非酸疏水物质、弱疏水物质和亲水物质,采用超滤膜法测定水样的分子量分布,对印染废水生化出水中不同种类以及不同分子量大小的有机物在煤质炭、椰壳炭2种活性炭动态实验处理过程中的去除特性进行研究。实验结果表明,2种活性炭对该水样中的有机物均有明显的去除效果,其中以煤质炭的处理效果较优。煤质炭吸附疏水性和亲水性有机物均有明显的处理效果,对非酸疏水物质和弱疏水有机物的吸附效果较差。煤质炭对分子量<10 k的小分子有机物的吸附效果对实验结果的贡献较大。     

自制ZSM-5分子筛对甲苯气体的吸附-脱附性能

考察了自制ZSM-5分子筛对甲苯气体的吸附-脱附性能,并与市售MCM-22分子筛进行了对比实验。实验结果表明:在吸附温度为25℃、进口甲苯质量浓度为840mg/m3、吸附气体流速为0.016m/s、床层高度为15cm的条件下,出口甲苯质量浓度达到0.8mg/m3时的穿透时间为82min,吸附效率为4.26mg/g;在脱附温度为80℃、脱附气体流速为0.016m/s的条件下,脱附35min时出口甲苯质量浓度达到最大,为1220mg/m3。自制ZSM-5分子筛的吸附-脱附性能优于市售MCM-22分子筛。     

微孔分子筛的合成及其去除水中氨氮的实验研究

以廉价的天然矿物岩石作为主要原料,采用水热晶化法合成了微孔分子筛。分子筛有效孔径约为0.9 nm,BET比表面积583m2/g,阳离子交换容量(CEC)316 meq/100 g。将其用于水体中氨氮的去除,实验结果表明,分子筛对氨氮的吸附速率较快,吸附时间为20 min时,吸附基本达饱和;分子筛对氨氮的最大吸附量可达11.6 mg/g,其吸附规律很好地符合Fruendlich吸附等温式;在有干扰离子如Ca2+、Mg2+、Al3+和Fe3+等存在的情况下,仍能优先选择吸附NH4+,且吸附率几乎没有变化。动态吸附柱实验的效果好于静态实验,出水12 h内去除率均>85％;饱和了氨氮的分子筛,用氢氧化钠溶液洗脱再生,解吸率达92％,再生后的分子筛与原分子筛相比吸附率几乎没有降低。     

炼油厂达标废水中溶解性有机物的表征

采用超滤和凝胶色谱法调查了炼油厂达标废水中溶解性有机物 (DOM)的分子量分布 ,并用树脂吸附和离子交换技术研究了该废水DOM中疏水性酸 (HoA)、碱 (HoB)及中性物 (HoN)和亲水性酸 (HiA)、碱 (HiB)及中性物 (HiN)的比例 ,用气相色谱 质谱法 (GC MS)定性分析了疏水性有机物的组成 .结果表明 ,某炼油厂达标废水的TOC为 12 0 6～ 16 80mg·L-1,其中溶解性有机碳 (DOC)为 10 15～ 14 4 4mg·L-1;分子量 <1k的DOM约为 80 % (以TOC计 ) ;DOM中HiN、HoN、HoA、HiB、HoB及HiA的含量分别为 2 9 7% ,2 6 5 % ,2 1 1% ,13 4 % ,5 1%及 4 2 % .鉴定出的HoN包括脂肪烃、苯系物、含硫化合物及邻苯二甲酸酯类化合物等 ,其中C10和C11脂肪烃、甲基亚硫酰苯及邻苯二甲酸二丁脂化合物的含量相对较高 .根据表征结果提出了回用处理建议.     

Genetic diversity and IUCN Red List status

The International Union for Conservation of Nature (IUCN) Red List is an important and widely used tool for conservation assessment. The IUCN uses information about a species’ range, population size, habitat quality and fragmentation levels, and trends in abundance to assess extinction risk. Genetic diversity is not considered, although it affects extinction risk. Declining populations are more strongly affected by genetic drift and higher rates of inbreeding, which can reduce the efficiency of selection, lead to fitness declines, and hinder species’ capacities to adapt to environmental change. Given the importance of conserving genetic diversity, attempts have been made to find relationships between red-list status and genetic diversity. Yet, there is still no consensus on whether genetic diversity is captured by the current IUCN Red List categories in a way that is informative for conservation. To assess the predictive power of correlations between genetic diversity and IUCN Red List status in vertebrates, we synthesized previous work and reanalyzed data sets based on 3 types of genetic data: mitochondrial DNA, microsatellites, and whole genomes. Consistent with previous work, species with higher extinction risk status tended to have lower genetic diversity for all marker types, but these relationships were weak and varied across taxa. Regardless of marker type, genetic diversity did not accurately identify threatened species for any taxonomic group. Our results indicate that red-list status is not a useful metric for informing species-specific decisions about the protection of genetic diversity and that genetic data cannot be used to identify threat status in the absence of demographic data. Thus, there is a need to develop and assess metrics specifically designed to assess genetic diversity and inform conservation policy, including policies recently adopted by the UN's Convention on Biological Diversity Kunming-Montreal Global Biodiversity Framework.     

Comparing results of cultured and uncultured biological methods used in biological phosphorus removal

Increasing attention has been paid to phosphate-accumulating organisms(PAOs)for their important role in biological phosphorus removal.In this study,microbial communities of PAOs cultivated under different carbon sources(sewage,glucose,and sodium acetate) were investigated and compared through culture-dependent and culture-independent methods,respectively.The results obtained using denaturing gradient gel electrophoresis(DGGE)of polymerase chain reaction-amplified 16S rDNA fragments revealed that the diversity of bacteria in a sewage-fed reactor(1#)was much higher than in a glucose-fed one(2#)and a sodium acetate-fed one(3#);there were common PAOs in three reactors fed by different carbon sources.Five strains were separated from three systems by using a phosphate- rich medium;they were from common bacteria isolated and three isolates could not be found in DGGE profile at all.Two isolates had good phosphorus removal ability.When the microbial diversity was studied,the molecular biological method was better than the culture-dependent one.When phosphorus removal characteristics were investigated,culture-dependent approach was more effective. Thus a combination of two methods is necessary to have a comprehensive view of PAOs.     

低分子环保型压裂液技术的开发及应用

通过对低分子环保型压裂液体系(LMF)与传统瓜尔胶压裂液体系的性能进行对比分析,得出低分子环保型压裂液体系,无论在工程还是在环保方面,都有明显的优势。它的推广应用,将产生明显的经济和社会效益,为我国绿色环保压裂液的发展,提供了新的思路。