Start up of biological sequencing batch reactor (SBR) and short‐term biomass acclimation for polyhydroxyalkanoates production

BACKGROUND: The adaptation/selection of mixed microbial cultures under feast/famine conditions is an essential step for polyhydroxyalkanoates (PHA) production. This study investigated the short‐term adaptation of a mixed microbial culture (activated sludge) during the start up of a sequencing batch reactor (SBR). RESULTS: Four different SBR runs were performed starting from different inocula and operated at the same organic load rate (8.5 gCOD L^?1 d^?1) and hydraulic retention time (1 day). At 3–7 days from SBR start up, the selected biomass was able to store PHA at comparable rate and yield with those obtained after long‐term acclimation. Independently from the time passed, a short feast phase was the key parameter to obtain PHA storage at high rate and yield in the following accumulation stage (244 mgCOD g^?1CODnonPolym h^?1 for specific storage rate and 48% COD COD^?1 as PHA content in the biomass). The DGGE profiles showed that the good storage performance and the structure of the microbial community were not fully correlated. CONCLUSIONS: The results suggest a new strategy for operating the PHA accumulation stage directly in the SBR, after very short biomass adaptation, instead of using two separate reactors for biomass enrichment and PHA accumulation, respectively. © 2012 Society of Chemical Industry     

Microalgal biomass as a fermentation feedstock for bioethanol production

BACKGROUND: The increasing cost of fossil fuels as well as the escalating social and industrial awareness of the environmental impacts associated with the use of fossil fuels has created the need for more sustainable fuel options. Bioethanol, produced from renewable biomass such as sugar and starch materials, is believed to be one of these options, and it is currently being harnessed extensively. However, the utilization of sugar and starch materials as feedstocks for bioethanol production creates a major competition with the food market in terms of land for cultivation, and this makes bioethanol from these sources economically less attractive. RESULT: This study explores the suitability of microalgae (Chlorococum sp.) as a substrate for bioethanol production via yeast (Saccharomyces bayanus) under different fermentation conditions. Results show a maximum ethanol concentration of 3.83 g L^?1 obtained from 10 g L^?1 of lipid‐extracted microalgae debris. CONCLUSION: This productivity level (～38% w/w), which is in keeping with that of current production systems endorses microalgae as a promising substrate for bioethanol production. Copyright © 2009 Society of Chemical Industry     

Waste paper sludge as a potential biomass for bio-ethanol production

This review describes the utilization of paper sludge (PS), which is waste from the pulp and paper industry. Its advantages make PS the cellulosic biomass with the most potential for bio-refinery research and applicable for industrial scale. Some of the grain based biofuels and chemicals have already been in commercial operation, including fuel ethanol or biochemical products. Unfortunately, research and application of PS are yet in their infancy and suffer from large scale because of low productivity. Reviewing the many researches that are working at the utilization of PS for bio-refineries could encourage the utilization of PS from laboratory research to be applied in industry. For this reason, PS usage as industrial raw material will be effective in solving the environmental problems caused by PS with clean technology. In addition, its conversion to bio-ethanol could offer an alternative solution to the energy crisis from fossil fuel. Two methods of PS utilization as raw material for bio-ethanol production are introduced. The simultaneous saccharification and fermentation (SSF) using cellulase produced by A. cellulolyticus and thermotolerant S. cerevisiae TJ14 gave ethanol yield 0.208 (g ethanol/g PS organic material) or 0.051 (g ethanol/g PS). One pot bioethanol production as a modified consolidated biomass processing (CBP) technology gave ethanol yield 0.19 (g ethanol/g Solka floc) and is considered to be the practical CBP technology for its minimizing process.     

In vitro production of polyhydroxyalkanoates: achievements and applications

The mechanisms of polyhydroxyalkanoate (PHA) production have been studied for over half a century. However, despite numerous improvements in the control of monomer composition, genetically‐engineered host organisms, fermentation strategies and polymer recovery processes they remain uncompetitive compared with petrochemical plastics. Recently, interest has developed in the enzyme‐catalysed production of PHAs in vitro. This has allowed the study of enzyme kinetics and properties, and represents another strategy for the economic production of PHAs on the industrial scale. It also presents an opportunity to coat other materials in thin films of PHA so as to modify the surface properties. In vitro production offers advantages over in vivo methods as it enables greater control over monomer composition and molecular weight, does not require a biomass‐accumulation phase, simplifies downstream processing and can utilise a wider range of monomeric subunits. Copyright © 2009 Society of Chemical Industry     

Study on the possibility of waste mushroom medium as a biomass resource for biorefinery

In order to investigate the possibility of waste mushroom medium as a biomass resource for biorefinery, characteristics of hydrolysate and pretreated biomass obtained from oxalic acid pretreatment were examined. The hydrolysate contained high glucose and low concentrations of inhibitors. The glucose concentration in the hydrolysate particularly increased when temperature gradient was used during pretreatment, compared with that of isocratic condition. The highest increase rate of glucose was 63.16% when pretreatment was performed at 140 °C for 25 min with 0.032 oxalic acid (g/g), and increased temperature to 170 °C. At the same time, ethanol production of Scheffersomyces stipitis using hydrolysate was 15.72 g/L after 48 h, which correspond to an ethanol volumetric productivity of 0.33 g L^?1 h^?1. Most of the lignin and some of the cellulose remained in the pretreated biomass. The total lignin content of the pretreated biomass, represent between 31.81 and 45.05%, compared to 28.8% of the raw material. The calorific value of the pretreated biomass ranged from 4940 to 5111 kcal/kg which represent increase of 3–6% compared to the raw material, due to higher contents of lignin in the pretreated biomass.     

Catalytic pyrolysis of biomass for biofuels production

Fast pyrolysis bio-oils currently produced in demonstration and semi-commercial plants have potential as a fuel for stationary power production using boilers or turbines but they require significant modification to become an acceptable transportation fuel. Catalytic upgrading of pyrolysis vapors using zeolites is a potentially promising method for removing oxygen from organic compounds and converting them to hydrocarbons. This work evaluated a set of commercial and laboratory-synthesized catalysts for their hydrocarbon production performance via the pyrolysis/catalytic cracking route. Three types of biomass feedstocks; cellulose, lignin, and wood were pyrolyzed (batch experiments) in quartz boats in physical contact with the catalysts at temperature ranging from 400 °C to 600 °C and catalyst-to-biomass ratios of 5-10 by weight. Molecular-beam mass spectrometry (MBMS) was used to analyze the product vapor and gas composition. The highest yield of hydrocarbons (approximately 16 wt.%, including 3.5 wt.% of toluene) was achieved using nickel, cobalt, iron, and gallium-substituted ZSM-5. Tests performed using a semi-continuous flow reactor allowed us to observe the change in the composition of the volatiles produced by the pyrolysis/catalytic vapor cracking reactions as a function of the catalyst time-on-stream. The deoxygenation activity decreased with time because of coke deposits formed on the catalyst.     

Optimal mode of operation for biomass production

The rate of biomass production is optimised for a predefined feed exhaustion using the residue ratio as a degree of freedom. Three modes of operation are considered: continuous, repeated batch, and repeated fed-batch operation. By means of the Production Curve, the transition points of the optimal modes of operation are derived. The analytical expressions of these transitions for variable bioreaction kinetic parameters are determined. The key measures “degree of difficulty of conversion” and “degree of exhaustion” are introduced to define the optimal modes in more general terms. The “degree of difficulty” describes the effect of the kinetic parameters and the feed substrate concentration on the conversion; the “degree of exhaustion” describes the desired final condition. In fed-batch operation, the proposed constant feed policy approximates the optimal feed policy closely.     

Lignocellulosic biomass for the preparation of cellulose‐based hydrogel and its use for optimizing water resources in agriculture

Recently, efforts have been devoted to find ways in utilizing biomass as feedstocks for the production of organic chemicals. This is because of its abundance, renewability and worldwide distribution. Lignocellulosic agricultural waste materials are regarded as abundant, inexpensive, and readily available natural resources for both chemical and paper industries. Hydrogels are polymeric materials that vary in their origin and composition and can absorb large amount of water without dissolving. In our study, cellulose‐based acrylic acid hydrogel was synthesized starting from rice straw as a source for the lignocellulosic material, where cellulose was first isolated after alkaline‐acid pulping treatment followed by bleaching step with sodium hypochlorite resulting of 90.8% holocellulose. The cellulose‐based acrylic acid hydrogel was synthesized applying heterogeneous reaction and shows a swelling ratio more than 3000%. The resulting hydrogel was further characterized with FT‐IR and SEM. On the other hand, comparison between the rice straw‐based hydrogel and the commercially available acrylamide hydrogel was studied for improving maize production in salt affected soil as well as in the growth promoters of maize under water stress. The experimental results demonstrated that the yield parameters were increased with increasing irrigation rates. Both types of hydrogels introduce positive and significant effect compared to the one without adding hydrogels. Also, acrylamide hydrogel was effective for improving almost yield parameters more than applying rice straw‐based hydrogel. Generally, the addition of hydrogel increases the nutrient concentration, uptake, and both of water and nutrients use efficiency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42652.     

Municipal Solid Waste as a Source of Lignocellulosic Fiber and Plastic for Composite Industries

Municipal solid wastes (MSWs) generated each year contain potentially useful and recyclable materials for composites. Interest is high for the use of MSWs in composites, thus providing cost and environmental benefits. The main objective of this study was to show the potential of municipal solid waste materials for making wood plastic composites. The possibility of using recycled materials in the development of composites is very attractive, especially with respect to the large quantity of wood and plastic waste generated daily. Waste wood and paper can meet all the requirements in order to replace inorganic fillers in thermoplastic composites. Advantages associated with biocomposite products include lighter weight and improved acoustic, impact, and heat reformability properties—all at a cost less than that of comparable products made from plastics alone. In addition, these composites can possibly be reclaimed and recycled for the production of second-generation composites.     

煤炭行业清洁生产与矿井水资源化利用

介绍了推行清洁生产的意义和主要措施,清洁生产要治理废弃物、污染源,综合利用煤矸石、矿井水、瓦斯等采煤伴生物,复垦采煤沉陷区土地,对煤炭进行洗选加工;简述了我国煤矿矿井水处理利用现状以及矿井水资源化的重要意义与任务,处理后的矿井水可用于矿区生产、生态、生活用水,矿井回灌、商品水等多方面,可获得较高的经济效益。     

Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass

Furfural is a natural precursor to furan‐based chemicals and has the potential to become a major renewable platform chemical for the production of biochemicals and biofuels. However, current industrial furfural production relies on relatively old and inefficient strategies that have hindered its capacity, and low production yields have strongly diminished its competitiveness with petroleum‐based alternatives in the global market. This mini‐review provides a critical analysis of past and current progress to enhance furfural production from lignocellulosic biomass. First, important chemical and fuel products derived from the catalytic conversion of furfural are outlined. We then discuss the importance of developing integrated production strategies to co‐produce furfural with other valuable chemicals. Furfural formation and loss chemistries are explored to understand effective methods to improve furfural yields from pentosans. Finally, selected relevant commercial and academic technologies that promise to improve lignocellulosic furfural production are discussed. © 2013 Society of Chemical Industry     

The technical feasibility of biomass gasification for hydrogen production

Biomass gasification for energy or hydrogen production is a field in continuous evolution, due to the fact that biomass is a renewable and CO₂ neutral source. The ability to produce biomass-derived vehicle fuel on a large scale will help to reduce greenhouse gas and pollution, increase the security of European energy supplies, and enhance the use of renewable energy. The Värnamo Biomass Gassification Centre in Sweden is a unique plant and an important site for the development of innovative technologies for biomass transformation. At the moment, the Värnamo plant is the heart of the CHRISGAS European project, that aims to convert the produced gas for further upgrading to liquid fuels as dimethyl ether (DME), methanol or Fischer–Tropsch (F–T) derived diesel. The present work is an attempt to highlight the conditions for the reforming unit and the problems related to working with streams having high contents of sulphur and alkali metals.     

Hydrothermal catalytic conversion of biomass for lactic acid production

The production of lactic acid has increased owing to growing polymer markets, increased demand in the chemical sector and many applications in the food industry. Biomass hydrothermal decomposition is potentially a method for lactic acid production. To obtain a higher yield of lactic acid, the influence of metal ions (Zn(II), Ni(II),Co(II) and Cr(III)) on biomass decomposition in sub‐critical water (T = 300 °C) was investigated and the catalyst function in the complex reaction network of biomass degradation was discussed. In comparison with a non‐catalytic process, the addition of 400 ppm Ni(II) catalyst increased the yield of lactic acid from 3.25% to 6.62% at 300 °C and 120 s for microcrystalline cellulose. The lactic acid yield for glucose was 9.51% for 400 ppm Co(II) catalyst at 300 °C and 120 s. In the case of Cr(III) and Ni(II), the conversion of maize straw, sawdust and rice husk first increased, and then decreased from 0 to 800 ppm. For catalyst Cr(III), Zn(II) and Ni(II), the conversion of wheat bran indicated a decreasing trend. Transition metal ions have a great influence on raw materials conversion to lactic acid. In the conversion of pyruvaldehyde to lactic acid, the ionic catalyzed Cannizzaro‐type reaction would take place. Copyright © 2007 Society of Chemical Industry     

植物纤维原料液化新技术

介绍了植物纤维原料液化的几种新技术。植物纤维在微波作用下可以有效地液化,反应时间也显著缩短,即使是结晶度较高的纤维素也可充分降解;固体酸催化剂有较高的催化活性和选择性,而且可以循环利用;离子液体能使液化反应在近似均相的反应体系中进行,能高效地溶解纤维素、木质素和半纤维素,提高液化效率。超临界流体具有高扩散性和低表面张力,能够很好地渗透到固体内部,是植物纤维原料液化的优异溶剂。     

生物质制芳烃技术进展与发展前景

对目前利用生物质生产芳烃几种路线以及研究进展进行评述。介绍了前景较好的代表性工艺,如：Anellotech公司开发的生物质热解制芳烃（Bio-AromaticsTM）工艺、Virent公司开发的生物基氢解糖类经过催化转化制PX（Bio-FormingTM）工艺以及Gevo公司开发的生物质异丁醇制芳烃工艺,并详细分析了各工艺的原料来源、工艺流程、工艺条件等特点。分析几种生物质芳烃工艺生产成本,并对照传统石脑油裂解重整制芳烃生产成本,分析各工艺经济性后,得出结论：Anellotech公司开发的生物质热解制芳烃工艺经济性成本与经济性最佳。在此基础上,提出今后生物质制芳烃的研究应当以提高原料利用效率、增加芳烃产率和选择性为重点,开发适合生物质转化反应的催化剂和反应器。     

薯蓣皂素清洁化生产工艺及资源化利用研究进展

现有的薯蓣皂素传统生产工艺具有工艺简单、易操作的优点, 但在产率、能耗及环境污染等方面存在较大问题。本文综述了国内外薯蓣皂素清洁化生产工艺的研究进展, 介绍了两类清洁化生产工艺--传统无机酸水解改进工艺和非无机酸水解工艺, 着重概述了发展前景较好的非无机酸水解工艺, 包括离子交换树脂催化法、离子液体催化法、生物转化法以及热分解处理法, 并比较了不同工艺的优缺点。指出传统无机酸水解改进工艺虽能减少无机酸对环境的污染, 大部分还能提高皂素产率, 但废水废渣的问题仍然没有解决;非无机酸水解工艺几乎零污染排放, 但存在产率低、成本高等不足。本文同时简述了从黄姜提取皂素过程中废水废渣的综合利用方法, 总结了清洁化生产工艺和废渣利用中存在的问题, 提出未来应以提高非无机酸水解工艺的皂素产率为研究重点, 并对废渣的资源化利用不断进行探索和开发。     

Modelling of a biomass fired furnace for production of lime

This paper deals with the mathematical modelling of a furnace devoted to the limestone processing. The novelty of this reactor is that the energy required by the endothermic reaction of calcination is provided by the combustion of biomass, making it compatible with sustainable development. The model is based on balance equations completed with phenomenological relations for the estimation of heat and mass transfer inside the reactor and for the estimation of the kinetics of the reaction. In a first section, the equations describing the behaviour of a single reacting particle of limestone are derived. The model relies on the assumption that the reacting particle obeys the shrinking core model. Then this model of a single particle is introduced in a more general one-dimensional model describing the whole furnace, where the different relevant properties depend upon the location within the reactor. Some industrial information is compared to numerical predictions, thus validating the model. Also the results provided by the numerical model allow for a better comprehension of the different phenomena occurring within the reactor.     

Progress in the hydrolysis of lignocellulosic biomass for fuel-thanol production

以木质纤维素生产燃料乙醇具有原料可再生性和环境友好的优点而备受重视。本文介绍了国内外木质纤维素制取燃料乙醇中的水解工艺过程,包括浓酸水解、稀酸水解和酶水解工艺,分析了各工艺的技术特点,同时指出稀酸预处理-酶水解工艺将成为近几年国内外研究和开发的重点。