Sustainable biofuels from algae

There is currently great interest in microalgae as sources of renewable energy and biofuels. Many algae species have a high lipid content and can be grown on non-arable land using alternate water sources such as seawater. This paper discusses in detail the issue of sustainability of commercial-scale microalgae production of biofuels with particular focus on land, water, nutrients (N and P) and CO₂ requirements and highlights some of the key issues in the very large scale culture of microalgae which is required for biofuels. The use of genetically modified algae is also considered.     

Microalgae cultivation using an aquaculture wastewater as growth medium for biomass and biofuel production

Microalgae as a main feedstock has attracted much attention in recent years but is still not economically feasible due to high algal culture cost. The objective of this study was to develop a comprehensive eco-friendly technology for cultivating microalgae Platymonas subcordiformis using aquaculture wastewater as growth medium for biomass and biofuel production. Platymonas subcordiformis was grown in pretreated flounder aquaculture wastewaters taken from different stages. Each of wastewater contained different levels of nutrients. The biomass yield of microalgae and associated nitrogen and phosphorous removal were investigated. The results showed that algal cell density increased 8.9 times than the initial level. Platymonas subcordiformis removed nitrogen and phosphorus from wastewater with an average removal efficiency of 87%–95% for nitrogen and 98%–99% for phosphorus. It was feasible to couple the removal of nitrogen and phosphorus from wastewater to algal biomass and biofuel production. However, further studies are required to make this technologies economically viable for algae biofuel production.     

International trade in biofuels: an introduction to the special issue

Currently, many countries are establishing goals for substituting biofuels for fossil fuels. These goals usually foresee 5–10% substitution while today's production, in most countries, is far below 2%. Evidently, many countries will seek to meet their ambitious biofuel targets through imports. This global trade in biofuels, which is to some extent already taking place, will have a major impact not only on other commodity markets like vegetable oils or animal fodder but also on the global land use change and on environmental impacts. This special issue focuses on the relation between trading, policy making and sustainability impacts of biofuels. It demonstrates the strong but complex link between biofuels production and the global food market, it unveils policy measures as the main drivers for production and use of biofuels and it analyzes various sustainability indicators and certification schemes for biofuels with respect to minimizing the adverse effects of biofuels while maximizing the benefits of the future use of biofuels.     

Microalgae cultivation using an aquaculture wastewater as growth medium for biomass and biofuel production

Microalgae as a main feedstock has attracted much attention in recent years but is still not economically feasible due to high algal culture cost. The objective of this study was to develop a comprehensive eco-friendly technology for cultivating microalgae Platymonas subcordiformis using aquaculture wastewater as growth medium for biomass and biofuel production. Platymonas subcordiformis was grown in pretreated flounder aquaculture wastewaters taken from different stages. Each of wastewater contained different levels of nutrients. The biomass yield of microalgae and associated nitrogen and phosphorous removal were investigated. The results showed that algal cell density increased 8.9 times than the initial level. Platymonas subcordiformis removed nitrogen and phosphorus from wastewater with an average removal efficiency of 87%-95% for nitrogen and 98%-99% for phosphorus. It was feasible to couple the removal of nitrogen and phosphorus from wastewater to algal biomass and biofuel production. However, further studies are required to make this technologies economically viable for algae biofuel production.     

剩余污泥焚烧灰分磷回收及其技术进展

焚烧渐渐成为剩余污泥终极处理、处置方式,而焚烧产生的污泥灰分中又包括了污水中绝大部分(>90%)的磷.因此,从焚烧灰分中回收磷也为污水磷回收提供了最佳位点.从污泥灰分中回收磷已存在一些适用技术,但灰分中重金属含量对工艺选择有重要影响,这可能会限制灰分直接用作农作物肥料的可行性与价值.因此,磷提取并纯化是灰分磷回收的重要技术步骤,同时也需兼顾工艺经济成本与环境影响.为此,本文从磷提取与磷纯化角度总结了目前灰分磷回收技术的国际研发进展,涵盖生物法、湿式化学法和热化学法;分析比较了不同方法在技术经济、环境影响及适用灰分方面的差别.生物法行之有效、环境影响小,但完成磷回收时间漫长;湿式化学法研发、应用最为广泛,但对环境影响较大;与污泥焚烧统筹合建可使热化学法更具经济性.然而,3类不同技术工艺并不具有相互替代性,需根据灰分成分进行合理选择.此外,前端污水处理以及中端污泥前处理也应与末端灰分磷回收相结合,尽量避免过多化学药剂投加带来的污泥灰分金属含量增加.污泥单独焚烧亦是决定灰分磷回收效率的关键.欧洲政策已明显支持污泥焚烧并从灰分中回收磷,政策和做法值得我国借鉴、学习.     

中肋骨条藻与锥状斯氏藻藻际细菌溶藻效应研究

通过向对数生长期的中肋骨条藻和锥状斯氏藻培养体系中分别加入体积分数1%和10%的2216E培养基,以未加入培养基的对照组和10%无菌组作为对照,研究藻际细菌的溶藻效应.结果表明,对照组、1%组及10%无菌组的中肋骨条藻和锥状斯氏藻生长未受抑制,而10%组的中肋骨条藻和锥状斯氏藻生长则受到显著的抑制(p0.001),在第96h时,藻细胞几乎都被裂解,藻细胞数、叶绿素a含量及叶绿素荧光效率(Fv/Fm)显著低于对照组、1%组及10%无菌组(p0.001),表明藻际细菌具有抑制微藻生长的作用.在整个溶藻过程中,中肋骨条藻10%组细菌丰度增加了约250倍,锥状斯氏藻10%组藻际细菌丰度增加了约300倍,藻际细菌丰度的剧增可能是溶藻的主要原因.作为溶藻效果的评价指标,叶绿素荧光效率要优于细胞形态的改变、藻细胞数量的变化及叶绿素a含量,是较理想的溶藻检验指标.     

微藻生物富集重金属的研究进展

环境中的重金属来源广泛,在环境中有稳定、迁移、累积的特性,已严重危胁到人类健康。控制和消除重金属污染是当今世界环境面临的紧迫问题和巨大挑战。以水环境中的重金属修复为要点,介绍了利用微藻作为吸附材料的创新型生物修复技术在污水修复领域的可行性和优势,根据微藻富集重金属的主要机制,详述了生物富集的过程以及影响吸附行为的主要因素(pH、温度、离子强度、溶解性有机质),并指出了现阶段微藻生物富集重金属的研究重点和趋势。     

微藻型微生物燃料电池的研究进展

在石油资源日趋紧张以及环境恶化日趋严重的今天,微生物燃料电池(MFC)因其可同时实现污水处理和能源回收而受到广泛关注。微藻技术与MFC技术结合产生的微藻型MFC系统得到证实并随之兴起,其中尤以微藻生物阴极型MFC因可实现污水处理、零碳排放、CO2捕捉、太阳能捕获及电能、生物柴油、藻体残渣有价回收等多重功能,成为研究热点。文章根据其中微藻所起的不同作用将微藻型MFC系统分成三类,在参阅大量文献的基础上进行了全面综述,并由此对构建高效微藻生物阴极型MFC进行了探讨,提出了计算机辅助菌种选择技术等相关设想,最后对微藻型MFC的发展提出了展望。     

久效磷对海洋微藻毒性机理的初步研究Ⅲ.超氧化物歧化酶和过氧化物酶活性的变化

报道了久效磷对３种海洋微藻细胞内２种清除活性氧的关键性酶－超氧化物歧化酶和过氧化酶活性的影响。结果显示：１．在久效磷的胁迫下，扁藻和三角褐指藻细胞的超化物歧化酶活性均表现出下降的总变化趋势，而叉鞭金藻细胞的ＳＯＤ活性时而上升，时而下降，在整个胁迫过程中呈现出无规律性的变化。２．随着久铲磷胁迫时间的延长，３种微藻细胞的过氧化酶活性均逐渐下降，表现出相同的变化规律性。     

久效磷对海洋微藻毒性机理的初步研究Ⅲ.超氧化物歧化酶和过氧化物酶活性的变化

报道了久效磷对３种海洋微藻细胞内２种清除活性氧的关键性酶———超氧化物歧化酶和过氧化物酶活性的影响．结果显示：１在久效磷的胁迫下，扁藻和三角褐指藻细胞的超氧化物歧化酶（ＳＯＤ）活性均表现出下降的总变化趋势，而叉鞭金藻细胞的ＳＯＤ活性时而上升，时而下降，在整个胁迫过程中呈现出无规律性的变化．２随着久效磷胁迫时间的延长，３种微藻细胞的过氧化物酶活性均逐渐下降，表现出相同的变化规律性．这说明不同的藻种，久效磷对其细胞内酶活性的影响不尽相同．推测超氧化物歧化酶和过氧化物酶（ＰＯＤ）活性的降低是微藻细胞内过量产生活性氧，进而引起藻细胞膜脂过氧化伤害的主要原因之一．     

Brazilian biofuels and social exclusion: established and concentrated ethanol versus emerging and dispersed biodiesel

Increasing interest in biofuels trade between developed and developing countries has spurred worldwide discussions on issues such as subsidies and the ‘food for fuel’ crisis. One issue missing in recent discourse is the pressure exerted on developing countries to adopt large-scale mechanized farming practices to increase economic efficiencies. Such approaches often exclude small-scale farmers from participating in the emerging biofuels market, thus exacerbating poverty and social exclusion. Drawing on both qualitative and technical data, we discuss such pressures using Brazilian ethanol and biodiesel production. Pressure from international markets to become more economically efficient may contribute towards the erosion of recent schemes to encourage social benefits for small farmers in biodiesel production. We conclude with trade and policy implications.     

丙溴磷影响海洋微藻生长机理的初步研究

研究了丙溴磷对三角褐指藻和青岛大扁藻生长的影响及其可能的机理。结果显示，低浓度的丙溴磷可以刺激它们的生长，高浓度的丙溴磷则对其生长产生抑制作用；低浓度丙溴磷还使藻细胞的脂质过氧化程度在低水平增高，ＳＯＤ活性有所降低；高浓度时则使其指质过氧化程度过量升高，ＳＯＤ活性显著下降，加入抗氧化剂不仅可抑制低浓度丙溴磷对微藻生长的刺激效应，而且能缓解高浓度丙溴磷对微藻的毒害作用，因此，丙溴磷作用于微灌的抗氧化     

Agro-ecological engineering in China: a way towards sustainableagriculture

ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｈｉｇｈｒａｔｅｏｆｔｈｅｗｏｒｌｄｅｃｏｎｏｍｉｃｇｒｏｗｔｈｉｎｔｈｉｓｃｅｎｔｕｒｙ ,ｍａｎｙｕｎｐｒｅｃｅｄｅｎｔｅｄ“ｅｃｏｌｏｇｉｃａｌｃｒｉｓｅｓ” ,ｓｕｃｈａｓｄｅｐｌｅｔｉｏｎｏｆｎａｔｕｒａｌｒｅｓｏｕｒｃｅｓ,ｅｎｖｉｒｏｎｍｅｎｔａｌｄｅｔｅｒｉｏｒａｔｉｏｎ ,ｓｏｉｌｅｒｏｓｉｏｎ ,ｄｅｃｅｒｔｉｆｉｃａｔｉｏｎ,ａｎｄｇｌｏｂａｌｃｈａｎｇｅ,ｈａｖｅｂｒｏｋｅｎｏｕｔａｌｌｏｖｅｒｔｈｅｗｏｒｌｄ .Ｍａｎｙｅｖｉｄｅｎｃｅｓｉｎｄｉｃａ…     

Constructing sustainable palm oil: how actors define sustainability

Biofuels as a renewable source of energy have gained considerable importance in recent years. The use of biofuels is expected to rise since national governments of developed nations like the US and European countries see it as one of the ways to fulfill climate targets and increase the security in their energy supply. Production of biofuels is also expected to rise as developing nations see in biofuels the opportunity for connecting to international markets through supplying a new demand in the energy market.Several studies report on the environmental, social and economic gains and detriments that can arise from increased biofuel production and consumption. However, research that provides insight into the way in which such issues are defined by actors within the product chain is scarce. In this article we analyse how the strategies and value definitions of actors involved in the production and consumption of biofuels lead to specific definitions of sustainability. The empirical material concerns the chain of palm oil production in Colombia and electricity generation in the Netherlands. It is analysed using the method of action-in-context, which allows us to uncover the level and source of diversity of sustainability definitions in the product chain.While the current growth in production of palm oil is definitely buyer driven, the analysis of various activities in the chain shows that several aspects of sustainability are defined in more complex actor fields throughout the product chain.     

四种饵料微藻对海水养殖水体N、P的去除研究

为了探索采用微藻处理与综合利用技术净化工厂化海水养殖水体的可行性,研究测定了一些常用饵料微藻对水体N、P的去除能力.主要以绿色巴夫藻(Pavlova viridis)、青岛大扁藻(Platymonas sp.)、三角褐指藻(Phaeodactylum tricornutum)和塔胞藻(Pyramimonas sp.)为...     

我国机动车排放标准的阶段跨越及其相关因素

汽车工业的未来发展将在社会经济可持续发展的总体战略之下计划和进行.本文从我国目前机动车的生产规模、我国未来机动车的市场、国民收入和城市道路等方面讨论了我国机动车未来发展趋势.以广州市为例,定量地分析了广州市机动车排放NOX的削减目标及控制措施的削减潜力和费用,结果表明,在广州市实现2010年的NO_X环境目标,必须提前实施EURO3标准.讨论了机动车标准阶段跨越的技术可行性及燃油质量的影响因素.     

Standardized and simplified life-cycle assessment (LCA) as a driver for more sustainable biofuels

The assessment of environmental impacts along the life cycle of biofuels is a complex and resource-demanding task that cannot be afforded by small producers in developing countries. Therefore, certification schemes bear the risk that small and independent producers will be locked out and the market for sustainable biofuels will be dominated by international investors and large-scale plantations. However, many environmental impacts of various production chains of biofuels and feedstocks are already known. This knowledge has been used to create a web-based questionnaire for a “Sustainability Quick Check for Biofuels” (SQCB, http://www.sqcb.org). SQCB reduces the need for user entries to the most relevant and best-known parameters of the biofuel production chain. Based on this user input, a specific inventory is automatically modelled and linked to background data. SQCB then calculates the environmental impact assessment and checks the results against sustainability criteria. Since the results are calculated immediately, key environmental factors can be interactively analyzed. One major goal of the SQCB is to support the market entrance for local biofuel producers, given that strengthening local stakeholders is a key driver for empowering rural communities in development countries.     

含氧生物质燃料的生命周期评价

为公正评价汽车代用燃料的能耗与环境效益,运用生命周期评价方法,研究了在燃料中分别添加不同比例的乙醇和甲酯2种生物质,带来的生命周期能耗和污染物排放变化,并对含氧生物质燃料的未来情景进行了预测分析.结果表明:乙醇代用燃料未降低化石燃料消耗,甲酯代用燃料可降低约20%的化石燃料消耗;几种配比的代用燃料均可降低石油消耗,甲酯代用燃料降低的趋势更加明显;各种代用燃料的温室气体排放都比较严重;乙醇代用燃料增加了NO_x排放,而甲酯代用燃料可降低约50%的NO_x排放;乙醇和甲酯的加入均能降低车用阶段的PM₁₀排放;燃料生产阶段的SO₂排放在整个生命周期中约占80%,必须严格控制;甲酯代用燃料可降低VOC排放.     

Effect of TiO2 nanoparticle aggregation on marine microalgae Isochrysis galbana

TiO_2 nanoparticles(NPs) could adversely impact aquatic ecosystems. However, the aggregation of these NPs could attenuate this effect. In this work, the biological effects of TiO_2 NPs on a marine microalgae Isochrysis galbana were investigated. The aggregation kinetics of TiO_2 NPs under different conditions was also investigated to determine and understand these effects. Results showed that, though TiO_2 NPs had no obvious impact on the size and reproducibility of algal cells under testing conditions, they caused a negative effect on algal chlorophyll, which led to a reduction in photosynthesis. Furthermore, fast aggregation of TiO_2 NPs occurred under all conditions, especially at the pH close to the p Hzpc. Increasing ionic strength and NP concentration also enhanced the aggregation rate.The aggregation and the following sedimentation of TiO_2 NPs reduced their adverse effects on I. galbana.