Desulphurization of dibenzothiophene by bacteria

Four out of 187 strains, from enrichment cultures of dibenzothiophene (DBT), grew on DBT or thiophene 2-carboxylate as S sources. The four isolates, presumptively identified as Agrobacterium sp., Xanthomonas sp. and Corynebacterium spp., individually and together desulphurized DBT, producing 2-hydroxybiphenyl and sulphate.M. Constanti and A. Bordons are with the Departament de Bioquímica i Biotecnologia, and J. Giralt is with the Departament d'Enginyeria Química, both of the Universitat Rovira i Virgili, Pl. Imperial Tarraco 1, 43005 Tarragona, Catatonia, Spain     

Removal of H2S by the purple sulphur bacterium Ectothiorhodospira shaposhnikovii

When Ectothiorhodospira shaposhnikovii VKM B-1525 was used for desuphurization of biogas in the laboratory and in a pilot plant, there was complete oxidation of H₂S, the main product being elemental sulphur. The advatage of this culture over green bacteria is discussed.M.B. Vainshtein, G.I. Gogotova and N.-J. Heinritz are with the Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia     

Environmental biotechnology in India: prospects and case studies

The emergence and acceptance of the concept of sustainable development warrants that the scope of environmental biotechnology be enlarged to address issues like environmental monitoring, restoration of environmental quality, resource/residue/waste-recovery/utilization/treatment, and substitution of the non-renewable resource base with renewable resources. This paper delineates the current and prospective applications in these sub-areas of environmental biotechnology, and documents case studies on environmental monitoring (enteric viruses), restoration of environmental quality (oil spill remediation), resource recovery (hydrocarbon recovery from oily sludges, biosurfactants from distillery spentwash, desulphurization of coal & sour gases), and substitution of non-renewable resources with renewables (conversion of lignocellulisics into value added chemicals).The author is with the National Environmental Engineering Research Institute, Nagpur: 440 020, India     

台湾海峡离岛工业区海域浮游生物丰度之长期变化

本研究利用1993-2010年在云林县台西乡沿岸的8个站位所进行的一年四季近岸10 m及离岸20 m水深的浮游生物调查资料及同步的水质资料, 分析了发电厂建成后对浮游生物的影响。本海域18年内浮游生物各类群丰度/密度的各季节平均值, 皆以第四季(10-12月)为最低, 而各个类群的最高平均值出现的季别并不一致。其中浮游动物出现于第一和第二季(1-6月), 浮游植物和虾、蟹幼体在第二季(4-6月), 而鱼卵和仔鱼则是在第一至第三季(1-9月)。自2000年第三季起, 测线5的测站经常有pH值低于7.8的情形。当该海域水体测得pH值低于7.8时, 浮游动物(75±69 ind./m³)﹑浮游植物((1.60±2.28)×10³ cell/L)﹑虾幼体(2.4±5.8 ind./m³)﹑蟹幼体(1.9±5.0 ind./m³)及鱼卵(0.88±1.10 ind./m³)和仔鱼(0.16±0.32 ind./m³)的丰度/密度值皆偏低, 仅为历年总平均值的1/2。据此建议将发电厂排入海洋之水体pH值控制在7.8以上, 以降低对浮游生物多样性及丰度的冲击。     

Microbiological coal desulphurization

Sulphur compounds present in coal impose severe limitations on its utilization since sulphur-containing gases emitted into the atmosphere upon direct combustion of coal cause serious environmental pollution problems. Removal of sulphur compounds from coal by microbial action has many advantages over physical and chemical desulphurization methods. The potential use of various microorganisms for the removal of sulphur compounds from coal is presented. Environmental conditions and major process variables affecting the process performance are identified and their possible effects are discussed. Various process schemes for microbial desulphurization (MDS) of coal are suggested. It is concluded that microbial methods have a high potential in removing sulphur compounds from coal. However, more research and development work is needed in this field to overcome present technological problems.     

Influence of oxygen adsorption on the dynamic K(L)a measurement in three-phase slurry reactors

To check for possible mass transfer limitations of oxygen and/or carbon dioxide in kinetic experiments on microbial desulphurization of coal, it is important to properly measure the volumetric mass transfer coefficient (k(L)a) especially at high slurry densities. Volumetric mass transfer coefficients of oxygen, at different solid hold-up values (epsilon(s) = 0 to 0.28) of coal slurries (d(par) < 100 * 10(-6) m), were measured in a lab scale fermentor and in a lab scale pachuca tank, using the dynamic gas-liquid absorption method. It was shown that serious errors could occur due to oxygen adsorption at the coal surface. Using the data of an independently measured adsorption isotherm, the real k(L)a could be calculated from the measured apparent k(L)a. The results show a k(L)a decrease of 40% to 50% at a volumetric solid hold-up of 28%. Estimation of the oxygen and carbon dioxide transfer rates, from the measured mass transfer coefficients, indicates that the stirred fermentor is suitable for kinetic experiments at high slurry densities, whereas the pachuca tank and shake flask are not. (c) 1992 John Wiley & Sons, Inc.     

半胱氨酸的代谢与免疫功能研究进展

半胱氨酸(Cys)是一种半必需氨基酸,是构成体内重要抗氧化物质谷胱甘肽(GSH)的主要成分,对机体抗氧化和自由基消除功能十分重要。组织中Cys的浓度通过调节Cys生成和有效移除巯基维持在较低水平。Cys和蛋氨酸(Met)新陈代谢调节可以在维持Cys低水平的同时,保证巯基作为它们基本功能的充足供应。Cys是多种合成和分解代谢酶的底物,主要被肝Cys二氧酶(CDO)调节。CDO以Cys敏感方式被上调,主要是通过降低蛋白泛素化比率,从而降低26S蛋白酶体介导的蛋白降解。该文对Cys的摄入、新陈代谢途径以及免疫与抗氧化功能作一简要综述。     

Biotechnological possibilities for waste tyre-rubber treatment

Every year large amounts of spent rubber material, mainly from rubber tyres, are discarded. Of the annual total global production of rubber material, which amounts to 16–17 million tonnes, approximately 65% is used for the production of tyres. About 250 millions spent car tyres are generated yearly in USA only. This huge amount of waste rubber material is an environmental problem of great concern. Various ways to remediate the problem have been proposed. Among these are road fillings and combustion in kilns. Spent tyres, however, comprise valuable material that could be recycled if a proper technique can be developed. One way of recycling old tyres is to blend ground spent rubber with virgin material followed by vulcanization. The main obstacle to this recycling is bad adhesion between the crumb and matrix of virgin rubber material due to little formation of interfacial sulphur crosslinks. Micro-organisms able to break sulphur-sulphur and sulphur-carbon bonds can be used to devulcanize waste rubber in order to make polymer chains on the surface more flexible and facilitate increased binding upon vulcanization. Several species belonging to both Bacteria and Archaea have this ability. Mainly sulphur oxidizing species, such as different species of the genus Thiobacillus and thermoacidophiles of the order of Sulfolobales, have been studied in this context. The present paper will give a background to the problem and an overview of the biotechnological possibilities for solutions of waste rubber as an environmental problem, focusing on microbial desulphurization.     

Life cycle considerations of the flue gas desulphurization system at a lignite-fired power plant in Thailand

Goal, Scope and Background  The Flue Gas Desulphurization (FGD) system has been installed at the biggest lignite-fired power generation plant in Thailand to reduce the large amount of SO₂ emission. In order to understand the costs and benefits, both in ecological and economic terms, the lignite-fired plant was studied both before and after the installation of the FGD system. The focus of this study is to consider not only the Life Cycle Assessment (LCA) outcome but also the Life Cycle Costing (LCC) factors. The results can provide valuable information when selecting appropriate technologies to minimize the negative impact that lignite-fired power plants have on the environment. Methods  The Life Cycle Assessment - Numerical Eco-load Total Standardization (LCA-NETS) system was used to evaluate the impact on the environment of both the lignite-fired plant and the FGD system. Life Cycle Costing (LCC) was used to provide a comparison between alternative before and after installation of FGD. LCC, a powerful analytical tool, examines the total cost, in net present value terms, of a FGD system over its entire service lifetime. Results and Discussion  The results of the study are shown in the eco-load values over the entire life cycle of the lignite-fired plant. Comparative models of the power plant, before and after the installation of the FGD system, are evaluated using the LCA-NETS system. The results indicate that the installation of the FGD system can reduce the acidification problem associated with lignite-fired plants by approximately 97%. The LCC estimation shows the major costs of the FGD system: capital investment, operating and maintenance, and miscellaneous costs. The LCC provides the decision-making information when considering the cost of the FGD system in terms of protecting the environment. Conclusion and Outlook  LCA is an important decision-making tool for environmental policies, especially with regard to the selection of pollution control equipment for lignite-fired plants. Green coal technologies and strategies to reduce the negative impact on the environment are essential to produce more environmentally-friendly power plants with a sustainable future.