漆酶的固定化技术与应用研究进展

酶固定化技术的应用有效提高了漆酶的稳定性和可重复利用性，为其大规模使用提供了条件。载体材料的选择对固定化漆酶的性能至关重要。本文介绍了当前固定化漆酶的3种载体材料（高分子材料、无机纳米材料、有机-无机杂化材料），总结了固定化漆酶在废水处理、固体废物处理、生物传感器制造等方面的研究进展。指出未来的研究方向应集中于：开发新技术或优化现有工艺以降低漆酶生产成本，研发新的载体材料和固定化方法以提高漆酶的长期活性，利用基因工程提高漆酶的稳定性和回收潜力。     

固定化微生物技术在废水处理中的研究进展

介绍了固定化微生物的载体和制备方法，综述了固定化微生物技术近年来在废水处理中的应用现状，并提出今后的研究方向和发展前景。     

白腐菌和红平红球菌共固定化处理增塑剂废水

以赭曲霉死菌丝体为载体,吸附红平红球菌(Rhodococcus erythropo lisNG0402)和白腐菌(Phanerochaete chrysosporiumM E-446)的混合物,用聚乙烯醇作包埋剂进行共固定化。用制备好的共固定化细胞处理增塑剂废水,连续运行19d的结果表明,共固定化处理增塑剂废水的效果远好于单一菌的效果。在pH7.0、溶解氧质量浓度3.0m g/L、水力停留时间25h的条件下,废水中苯酚、COD和色度的去除率连续15d达到了90%以上,对苯酚的去除能力为2.16kg/(m3.d)。     

固定化海带生物吸附剂的制备及其吸附Ni~(2+)的动力学特性

以海藻酸钠、明胶和海带粉为原料制备了固定化海带生物吸附剂。固定化海带生物吸附剂对Ni2+的吸附过程可分为3个阶段:快速吸附阶段、缓慢吸附阶段和吸附平衡阶段。动力学过程可用Lagergren准二级反应动力学方程描述,限速步骤为化学吸附。随Ni2+初始质量浓度的增加,固定化海带生物吸附剂的Ni2+吸附量逐渐增大,Ni2+去除率逐渐降低。吸附过程符合Langmuir和Freundlich吸附等温方程,说明该吸附体系既有物理吸附又有化学吸附,从吸附状态看属于多层吸附,由Langmuir吸附等温方程得出固定化海带生物吸附剂对Ni2+的最大吸附量为39.43mg/g,说明固定化海带生物吸附剂对Ni2+有较好的吸附性能。     

固定化海带生物吸附剂的制备及其吸附Ni2+的动力学特性

以海藻酸钠、明胶和海带粉为原料制备了固定化海带生物吸附剂。固定化海带生物吸附剂对Ni2＋的吸附过程可分为3个阶段：快速吸附阶段、缓慢吸附阶段和吸附平衡阶段。动力学过程可用Lagergren准二级反应动力学方程描述，限速步骤为化学吸附。随Ni2＋初始质量浓度的增加，固定化海带生物吸附剂的Ni2＋吸附量逐渐增大，Ni2＋去除率逐渐降低。吸附过程符合Langmuir和Freundlich吸附等温方程，说明该吸附体系既有物理吸附又有化学吸附，从吸附状态看属于多层吸附，由Langmuir吸附等温方程得出固定化海带生物吸附剂对Ni2＋的最大吸附量为39．43mg／g，说明固定化海带生物吸附剂对Ni2＋有较好的吸附性能。     

氨基介孔磁性载体在柴油生物脱硫中的应用

制备了氨基介孔磁性载体(AMMC),分别采用FTIR,XRD,TEM等技术对AMMC的官能团、磁性、表观形态和沉降性能等进行了表征,并将脱硫菌株固定于AMMC上,以含二苯并噻吩(DBT)的正十六烷为模拟柴油,比较了固定化脱硫菌和游离脱硫菌对柴油的脱硫性能。表征结果显示,AMMC负载了氨基,是具有丰富孔结构的磁性载体(比表面积为61 m~2/g、孔体积为0.131 cm~3/g、平均孔径为11.339 nm),具有悬浮能力强、磁性良好、分离速度快的特点。脱硫实验结果表明:AMMC固定化脱硫菌配合吐温80使用,对DBT的降解率最高,脱硫反应第3天,DBT降解率为75%;AMMC固定化脱硫菌未经活化直接第5次重复使用时,DBT降解率维持在30%左右,游离脱硫菌的DBT降解率不足10%。     

固定化细胞新技术处理废水概况

固定化细胞技术是生物工程内容之一,是七十年代形成的新兴工业,广泛用于医药、食品工业以及环境保护等领域。本文着重介绍了固定化细胞技术处理工业废水的情况,综述了固定化细胞的特性与主要的固定方法。     

改性秸秆制备固定化微生物及对钻井泥浆的处理

将小麦秸秆改性后制备改性秸秆固定化微生物,用于处理钻井泥浆。考察了改性时间、改性剂浓度、改性剂配比对秸秆吸附微生物效果的影响,以及改性秸秆固定化微生物对钻井泥浆的处理效果。实验结果表明:在改性时间为60 min、氢氧化钠溶液浓度为0.1 mol/L、过氧化氢溶液浓度为1.0 mol/L、氢氧化钠溶液与过氧化氢溶液体积比为3∶1的最佳改性条件下,改性秸秆的BET比表面积增大了36.27%,Langmuir比表面积增加了37.63%,微生物吸附量增加了200.77%;在钻井泥浆处理量为1 000 g、改性秸秆固定化微生物加入量为2 g、土壤加入量为1 000 g、处理时间为15 d的条件下,钻井泥浆COD、可溶性盐、石油烃的去除率分别为84.9%,71.6%,90.1%。     

固定化厌氧微生物多孔囊状聚酰胺载体的研制

采用界面聚合方法制备出固定化厌氧微生物多孔囊状聚酰胺载体。该载体壁薄,内外表面粗糙多孔,具有典型的囊状空间、较高的孔体积和比表面积。将该载体用于厌氧法处理人工合成废水,同一时间的沼气产量高于使用基体型多孔聚合物载体和未使用载体时的沼气产量,在3种情况下的36d累积沼气产量分别为1430,1210,875mL。使用电子扫描电镜观察固定化微生物载体,发现有大量的厌氧菌群生长在载体内外表面。实验结果表明,该载体固定厌氧微生物的性能良好。     

专利文摘

降解多/杂环芳烃的仿酶型水处理剂及其制备方法该发明涉及一种降解多/杂环芳烃的仿酶型水处理剂及其制备方法。其技术方案是:将膨润土与去离子水按质量比1:(30～60)混匀,静置,取中间层,得纯化膨润土;再将纯化膨润土与NaCl     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Programs assessing implementation and effectiveness of state forest practice rules and BMPs in the West

The major forest nonpoint source control programs in the West are largely regulatory, either under forest practices acts (California, Idaho, New Mexico, Nevada, Oregon, and Washington) or a streamside management act (Montana). These programs and the specific rules they enforce continue to undergo intensive scrutiny. Still, the questions are the same for these regulatory programs as for states that base nonpoint source control on voluntary BMPs (Arizona, Colorado, Utah, Wyoming). Are the rules or BMPs being applied, and are they effective in reducing nonpoint source pollution to levels that protect beneficial uses of water? The level of debate about forestry in the West has resulted in detailed monitoring and research to answer these questions. In the past, state agencies have assumed levels of BMP compliance based on the percent of operations without enforcement actions. These estimates are being replaced by statistically valid and reproducible monitoring of forest practices rules and BMP compliance levels. BMP effectiveness is being assessed using both qualitative and quantitative methods. This can involve field assessments, process-based research, and control watershed studies. Some trend monitoring is also beginning. With the regional implementation rate for forestry BMPs at about 94% and rising, it is likely that effectiveness testing will continue to be a priority and consume the majority of assessment resources for this region.     

Hysteresis in Reversal of Central European Mountain Lakes from Atmospheric Acidification

Extremely high emissions of S and N compounds in Central Europe (both 280 mmol m^-2 yr^-1) declined by 70and 35%, respectively, during the last decade. Decreaseddeposition rates of SO₄ ^-2, NO₃ ^-, and NH₄ ⁺ in the region paralleled emission declines. The reduction in atmospheric inputs of S and N to mountain ecosystemshas resulted in a pronounced reversal of acidification in the Tatra Mountains and Bohemian Forest lakes. Between the 1987–1990and 1997–1999 periods, concentrations of SO₄ ^-2 and NO₃ ^- decreased (average ± standard deviation) by 22±7 and 12±7 mol L^-1, respectively, in theTatra Mountains, and by 19±7 and 15±10 mol L^-1, respectively, in the Bohemian Forest. Their decrease was compensated in part (1) by a decrease in Ca²⁺ + Mg²⁺ (17±7 mol L^-1) and H⁺ (4±6 mol L^-1), and an increase in HCO₃ ^-(10±10 mol L^-1) in the Tatra Mountains lakes, and (2) by a decrease in Al (7±4 mol L^-1), Ca²⁺ + Mg²⁺ (9±6 mol L^-1), and H⁺ (6±5 mol L^-1), in Bohemian Forest lakes. Despite the rapid decline in lake water concentrations of SO₄ ^-2 and NO₃ ^- in response to reduced S and N emissions, their present concentrations in some lakes are higher than predictionsbased on observed concentrations at comparable emission rates during development of acidification. This hysteresis in chemical reversal from acidification has delayed biological recovery of the lakes. The only unequivocal sign of biological recovery hasbeen observed in erné Lake (Bohemian Forest) where a cladoceran species Ceriodaphnia quadrangular has recentlyreached its pre-acidification abundance.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

Heavy Metals Removal by Biosorption and Flotation

The removal of a mixture of heavy (toxic) metal cations (copper, nickeland zinc) from liquid effluents was investigated in this study at pilotscale, using counter-current contact mode. The innovative processinvolved the abstraction of metal ions onto fungal biosorbents, followedby the application of flotation for the subsequent solid/liquid separationof biomass particles. The ability of microorganisms to remove metal ionsfrom aqueous solutions is a well-known phenomenon. Nevertheless,engineering considerations are very important in decisions, concerningthe commercial future of biosorption and practical solutions are neededfor certain problems, such as the efficient post-separation ofmetal-loaded biomass. The two processes (flotation and biosorption) caneffectively operate in combination, in what it was termed biosorptiveflotation process. The sorbents may be recycled, after appropriate elutionof metals, as well as the treated (clean) water.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

四氮唑废水处理工艺设计

高浓度、高盐分的四氮唑生产废水通过三效蒸发浓缩，馏出液经铁炭氧微电解和混凝预处理，再采用水解酸化一接触氧化一反应二沉主体组合工艺进行处理。研究了该工艺所需构筑物和设备的设计与选型。该工艺在正常运行条件下，处理后出水pH6～9，COD 302mg／L，BOD5 108mg／L，SS30mg／L，色度36倍，水质达到GB8978--1996（污水综合排放标准》三级标准。     

Application of Cellulose Microfibrils in Polymer Nanocomposites

Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were added at low concentrations (2–10% w/w) to polymer gels and films as reinforcing agents. Significant changes in mechanical properties, especially maximum load and tensile strength, were obtained for fibrils derived from several cellulosic sources, including cotton, softwood, and bacterial cellulose. For extruded starch plastics, the addition of cotton-derived microfibrils at 10.3% (w/w) concentration increased Young’s modulus by 5-fold relative to a control sample with no cellulose reinforcement. Preliminary data suggests that shear alignment significantly improves tensile strength. Addition of microfibrils does not always change mechanical properties in a predictable direction. Whereas tensile strength and modulus were shown to increase during addition of microfibrils to an extruded starch thermoplastic and a cast latex film, these parameters decreased when microfibrils were added to a starch–pectin blend, implying that complex interactions are involved in the application of these reinforcing agents.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

Does Soil Acidification Affect Spruce Needle Chemical Composition and Tree Growth?

In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al., 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio.