Life cycle assessment of electricity generation from bagasse in Mauritius

This paper presents the findings of a life cycle assessment (LCA) of electricity generated from the combustion of sugar cane bagasse in Mauritian sugar mills. The study arose from the identification of the need for to provide data for the development of an LCA profile for the electricity mix in Mauritius. The system is limited geographically to the island of Mauritius and is intended to be the representative of current agricultural techniques practiced and current manufacturing processes used by Mauritian sugar mills. The unit operations that make up the system are the growing and harvesting of sugar cane, the transport of the harvested cane to sugar mills, the production of bagasse as a by-product from the sugar milling process, and the combustion of bagasse to generate heat and electricity. The functional unit of the study is the generation of 1 GWh of electricity exported to the national electricity grid. The characterised data for 1 GWh of bagasse-derived electricity were compared with data for 1 GWh of coal-derived electricity, using the same set of characterisation factors. The results of this comparison indicate that bagasse-derived electricity performs well in the areas of greenhouse gas emissions, acidification, and non-renewable energy inputs, but performs poorly in relation to water consumption and eutrophication.     

反渗透处理糖厂二效汽凝水回用锅炉的研究

糖厂以二效汽凝水取代原水回用锅炉是"节能减排"的重要措施,但含糖量过高的二效汽凝水回用锅炉后,将影响锅炉高效、安全使用。故此采用一级反渗透装置对二效汽凝水进行除糖净化处理。实验结果表明:反渗透系统的脱盐率能够稳定在87.82%左右,出水水质完全达到中压锅炉补充给水水质标准。建议拥有中压锅炉的糖厂采用糖厂锅炉补充给水除糖净化新工艺。     

Comparative Life Cycle Assessment of four alternatives for using by-products of cane sugar production

Cane sugar production by-products can be considered either as waste, affecting the environment, or as a resource when an appropriate valorization technology is implemented.This study is made with the objective of identifying and quantifying the aspects which have the largest environmental impact of four alternatives for using by-products and wastes from the cane sugar process and suggest improvements in the systems.For this analysis a cane sugar mill was chosen in Cuba and four alternatives were designed for the by-product valorization. The first alternative represents the conventional sugar production; its main characteristics are the use of synthetic fertilizers, pesticides, the bagasse combustion and the usage of molasses and agricultural wastes as animal food. Other wastes constitute emissions to the environment. Alternatives II, III and IV incorporate more use of by-products and wastes. Alternative II considers the use of wastewater, filter cake and ashes for the substitution of synthetic fertilizers. In Alternative III, the filter cake and wastewater are used for biogas production and Alternative IV integrates alcohol and biogas production into the sugar production process.The assessment is done by means of Life Cycle Assessment, according to the ISO 14040 series by using the SimaPro 6.0 LCA software, Ecoinvent database and the Eco-indicator 99 methodology. As a functional unit the daily sugar production of the mill was defined (216 t/d). The sugar was selected as main product and all the by-products were assumed to substitute other products on the market, avoided products.For the four alternatives, the agricultural stage shows the greatest impact due to land use, fuel and agrochemicals consumption. In the industrial stage, the electricity cogeneration with bagasse has the highest impact as to respiratory effects due to the emission of tiny particle material into the atmosphere. The major difference between the alternatives is found in the resource impact category. The advantage of producing alcohol, biogas, animal food and fertilizers from the by-products is made obvious through the comparative study for resource savings.     

中国水生态分区初探

从生态系统的角度管理自然资源以及进行环境保护,已经成为国际环境保护领域的主流趋势.基于生态分区和地理分类单元开展环境保护与资源管理,已广为世界各国所接受.淡水生态分区是生态分区的一个重要类型,与水文分区和水环境功能分区相比,其在管理、评价和保护河流、溪流和湖泊等淡水水体资源、环境及水生生态系统方面,具有不可比拟的优势.本研究比较了国内外主要水体分区体系,分析各分区体系的优劣,强调在中国开展水生态分区研究的必要性.在此基础上,提出中国水生态分区的目标、范围和指标体系的设想,指出中国水生态分区应根据中国淡水生态系统实际和环境特征,着重突出河流和湖泊等水体的生态服务功能、水生生态系统的敏感性和人类活动的干扰与影响,并就中国水生态分区的范围、分类指标及水生态分区在将来环境管理中与其他现行分区体系的协调做了探讨.     

糖厂酒精废醪液资源化实例

连续运行3个榨季表明采用资源化治理技术"三废",废水和废气达标排放,将原来的污染物全部转化为微生物肥.‘‘资源化治理糖厂污染是一项具有环境效益、社会效益和经济效益的技术.     

Greenhouse gas savings potential of sugar cane bio-energy systems

One of the major justifications for bio-energy systems is their low greenhouse gas (GHG) emissions compared to fossil-energy ones. Transforming a sugar mill into a bio-energy plant would contribute to climate change mitigation via the extraction of renewable electricity and ethanol. This study takes the case of the sugar industry in Thailand and identifies scenario options that offer GHG reduction benefits. Improving efficiency in electricity generation from sugar cane residues e.g. excess bagasse and cane trash is such a beneficial option. Furthermore, extracting ethanol in a so-called bio-refinery, where the co-product stillage is utilized for energy, tends to magnify the potential benefit. The largest savings potential achieved with extracting ethanol from surplus sugar versus current practice in the sugar industry in Thailand amounts to 14 million tonnes CO₂e a year. This cannot be realized in practice until the carbon debt from land conversion is repaid, which takes 4.5–7 years, assuming that the land converted is grassland.     

太子河流域水生态功能Ⅱ级区的划分

流域水生态功能Ⅱ级区是实施流域层面水生生物多样性保护的重要依据. 以太子河流域为研究对象,开展分区指标筛选技术方法研究,通过指标的空间变异性、主导性及其与水生态因子相关性分析,从年均气温、年降水量、年蒸发量、高程、坡度、坡向和NDVI(归一化植被指数)等备选分区指标中筛选出适宜分区指标,在此基础上采用ISODATA(迭代自组织数据分析方法)非监督分类方法划分了太子河水生态功能Ⅱ级区. 结果表明,高程和NDVI具有良好的空间敏感性、主导性以及与水生态因子的相关性,可以反映地貌和植被对太子河水生态系统的影响,是太子河流域水生态功能Ⅱ级区划分的适宜指标. 采用上述指标可将太子河流域划分为3个水生态功能Ⅱ级区:①上游山地森林河流水生态亚区,平均海拔511m,区内以浅水性鱼类和激流性大型底栖动物为主;②中游丘陵森林河流水生态亚区,平均海拔282m,区内以溪流性鱼类和缓流性大型底栖动物为主;③下游平原农业河流水生态亚区,平均海拔65m,区内多受人类活动干扰,以耐污性大型底栖动物为主,少见鱼类.      

Mass-cultivation of carbohydrate rich macroalgae, a possible solution for sustainable biofuel production

Global demand for bio-fuels continues unabated. Rising concerns over environmental pollution and global warming have encouraged the movement to alternate fuels, the world ethanol market is projected to reach 86 billion litres this year. Bioethanol is currently produced from land-based crops such as corn and sugar cane. A continued use of these crops drives the food versus fuel debate. An alternate feed-stock which is abundant and carbohydrate-rich is necessary. The production of such a crop should be sustainable, and, reduce competition with production of food, feed, and industrial crops, and not be dependent on agricultural inputs (pesticides, fertilizer, farmable land, water). Marine biomass could meet these challenges, being an abundant and carbon neutral renewable resource with potential to reduce green house gas (GHG) emissions and the man-made impact on climate change. Here we examine the current cultivation technologies for marine biomass and the environmental and economic aspects of using brown seaweeds for bio-ethanol production.     

A case study on artificial intelligence based cleaner production evaluation system for surface treatment facilities

The metal finishing industry is water intensive. Surveys of South African metal finishing companies indicate that water consumption is as high as 400 L/m² of metal surface treated, whilst best available practice can achieve less than 10 L/m². The industry uses hazardous chemicals such as chrome VI, cadmium, nickel and cyanide. If consumption of these chemicals can be optimized, quantities of heavy metals released into the environment will be reduced. In some cases where cleaner production techniques were applied by local companies, heavy metals have been completely eliminated from effluents discharged to municipal sewers, which represent a significant benefit to the urban environment. This benefit was accompanied by significant reduction in the use of chemicals, with a concomitant cost saving and competitive advantage to the companies concerned.A Danish environmental aid initiative promoted cleaner production in the South African metal finishing industry. Local consultants were trained by Danish experts in this field. The general methodology was to conduct an audit of the chemical, water, human resource and environment aspects of the company and compare it to best available practice. Once the review was completed, a detailed feasibility was performed on systems and equipment required to reduce chemical consumption, water consumption, human resources and environmental impact. Applied to a number of South African companies, these methods have typically achieved reductions of the order of 90% in water use and 50–60% in the use of chemicals.There were difficulties in applying the Danish methodology to South African metal finishing companies, as it makes use of quantitative indices derived from the process operations. The companies are often small and technically unsophisticated, and do not have ready access to the process data that are needed. An alternate system is required to simplify the evaluation and optimization process. This paper proposes a case study on a fuzzy-logic operator based evaluation system that outputs the cleaner production status of the company. The model is compared to an established cleaner production tool.     

石油类污染物淡水短期水质基准研究及其对我国标准修订的意义

环境管理、应急处置和水质标准修订工作亟需石油类污染物淡水水质基准研究作为支撑. 本文筛选整理了大量本土物种毒性数据,利用SSD (物种敏感度分布法)和TPR (毒性百分数排序法)分析了5种典型石油类污染物(原油、苯、甲苯、乙苯和二甲苯)的淡水水生生物急性毒理数据,获得了保护我国淡水水生生物的短期水质基准值. 通过综合对比分析,认为利用SSD获得的基准值可作为石油类污染物的短期水质基准推荐阈值,原油和BTEX(苯系物,包括苯、甲苯、乙苯、二甲苯)的短期水质基准值分别为0.065、2.000、2.340、1.295和1.595 mg/L. 结果表明:①原油的毒性远大于BTEX,这可能是由于毒性的联合作用使得石油的毒性变强. ② 绿水螅对原油最敏感,原因可能是水螅更容易通过摄食或直接摄取获得原油WAF(水溶性组分)的有毒成分;鱼类相较于其他物种对苯更为敏感,而对其他BTEX而言,最敏感物种为节肢动物,原因可能是鱼类和节肢动物器官分化程度以及试验时的龄期选择存在差异,鱼类更易在短时间内将苯代谢为有毒的代谢产物. ③ 不同BTEX的敏感物种虽存在一定差异,但基准值未有数量级的差异. 研究显示,我国现行地表水环境质量标准中石油类标准未单独针对保护水生生物制定,BTEX标准的保护目标是基于人体健康而非水生生物,研究结果对我国石油类污染物环境管理、突发油类污染物对水生生物的危害及风险评估以及淡水水生生物特别是本土物种保护的水质标准制修订工作具有重要的借鉴作用.      

生命周期评价在过程工业用水网络设计中的应用

介绍了考虑环境因素的过程工业用水网络设计研究进展,分析了典型的过程工业水系统的特点,肯定了在整个水系统生命周期内考察用水网络设计方案环境效益的重要性,给出了生命周期评价方法在用水网络设计中应用的技术框架。     

The saccharification–membrane retrieval–hydrolysis (SMRH) process: a novel approach for cleaner production of diosgenin derived from Dioscorea zingiberensis

Diosgenin (CAS number 512-04-9) production from Dioscorea zingiberensis is a very important industry in central-western China. However, treatment of the wastewater with COD up to 50,000 mg/L has been a formidable challenge for the sustainable development of diosgenin industry. A cleaner production process, called the saccharification–membrane retrieval–hydrolysis (SMRH) process, was proposed and pilot-tested by us. The new process combines traditional acid hydrolysis with enzyme hydrolysis and UF/NF technologies. It has two major advantages. (1) The starch in D. zingiberensis is degraded into low molecular weight soluble sugar which is separated and removed before acid hydrolysis of the residue. This prevents the soluble sugar from entering the wastewater; instead it can be utilized as a carbon source in the fermentation industries. (2) UF/NF membrane equipment separates the acid hydrolysis solution into three parts: (a) the colloid phase, (b) the acid solution and (c) the water. All of which can be used in this or in another industry. In this way, the new production process dramatically reduces the wastewater discharge and uses the sugar, acid, water and solid waste in other processes.     

云南蔗糖厂的清洁生产和清洁生产审核

通过对云南蔗糖厂的清洁生产的分析、总结、回顾和对清洁生产审核的成果的介绍,用事实说明了在糖厂认真实施清洁生产的作用和体会。     

流域水生态功能区概念、特点与实施策略

我国正处在从传统的水质管理向水生态管理转变的关键阶段,水生态功能区是实施流域水生态系统管理的基本单元. 结合区划理论的发展,对国内外区划研究进展进行了系统总结,界定了水生态功能区的基本概念,提出了水生态功能区的基本特点及其在环境管理中的主要作用,辨析了水生态功能区与水功能区、生态功能区和主体功能区的关系,提出了水生态功能区实施的政策保障体系. 结果表明,水生态功能区是开展水生态系统健康评估、识别水生态功能和确定水生态保护目标的基本单元,具有基于流域单元进行划分、以水生态系统等级结构为主线、区域区划与类型区划相统一、陆地与水体保持一致性等特点;不同功能区在基本概念、法律和政策依据、分区目的、分区体系、分区指标和方法及其在管理中的作用等方面差异显著,水生态功能区是对上述功能区的发展、补充和完善;作为一个崭新概念,水生态功能区的实施需要从法律、机构、政策和技术等方面全面保障,在此基础上构建流域水环境综合管理技术体系,支撑流域生态文明建设.      

Cleaner production in Mauritian cane-sugar factories

A growing awareness of the impacts of pollution on the environment, coupled with the introduction of sectoral effluent standards by the Mauritian environment authorities, have led to the current situation whereby the sugar factories need to introduce appropriate water and wastewater management systems. The cane-sugar industry has been given 3 years to comply with the legislation on effluent standards. During that 3 year period the industry will have to investigate cleaner production opportunities, select appropriate waste treatment technologies, gain operational experience and confidence with the technology and introduce environmental management systems. The case-study taken from the cane-sugar industry in Mauritius illustrate the extent to which environmental improvements are possible through cleaner production.     

制糖生产零取水零排放的技术方案

针对制糖生产用水存在的问题,提出了制糖生产零取水零排放的技术方案及工艺组成。其核心技术经试验和工程实践证明是合理、有效的,具有技术先进性和推广性。     

The intermediary role of an industry association in policy-making processes: the case of the Dutch paper and board industry

In the policy-making process concerning energy and environmental issues, cooperation between government and firms is a means to create a more efficient energy and environmental policy. Intermediary organizations can play an important role in this policy-making process. Aim of this study is to get insight into the role of one specific intermediary organization: the industry association. In this paper, we focus on the Dutch paper and board industry. Important policy themes for this industry are waste water, waste, and energy efficiency. We distinguished four types of governmental policy instruments: top-down regulation, interactive regulation, negative economic instruments, and positive economic instruments. We analyzed the role of the industry association in the policy-making process for all of these four instruments. The results clearly show different (relative) roles of the industry association in different steps of the policy-making processes and for different types of instruments.     

Eco-efficiency trends of the Flemish industry: decoupling of environmental impact from economic growth

A methodology for eco-efficiency reporting is proposed with eco-efficiency indicators for climate change, acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity, eutrophication, energy consumption and waste generation. The method is applied to emission, consumption and production data of the Flemish industry provided by the Flemish environmental agency for the period 1995–2006. For climate change, acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity and eutrophication, the eco-efficiency improved by 39, 55, 41, 58, 72 and 53%, respectively. For each of these impact categories, the total environmental impact decreased despite an increase in production, indicating absolute decoupling of environmental impact from economic growth. The eco-efficiency indicator for energy consumption and waste generation improved by 16 and 14%, respectively. However, due to the increase in production, the total energy consumption and the amount of waste generated increased: for these two environmental themes decoupling from economic growth was relative. Despite the improved eco-efficiency, industry remains one of the main polluters in Flanders. The application of the method to emission, energy consumption and production data of the Flemish industry resulted in a comprehensive and correct source of information for the general public and the government. Moreover, it can serve as a basis for economically and environmentally sound decisions and for the evaluation of the impact of former decisions.     

无公害农产品土地利用评价体系的研究

土地资源是人类生存最基本的资源，对它的利用与开发必须保持协调的可持续的发展规划。本文以无公害农产品土地利用为例，从环境的角度，构建了产地环境条件子系统、自然条件子系统、经济效益分析子系统和环境影响分析子系统以及各自包含的评价指数集。产地环境条件指标集和自然条件指标集是基于现状的，采用结果指标表达；针对布局规划，环境影响分析和经济效益分析是一种预测评价，对其指标集的构建采用了过程指标的设计。     

Water footprinting at the product brand level: case study and future challenges

Responding to concerns about the unsustainable use of global freshwater resources, especially in agriculture, the concept of water footprinting has recently been developed and applied to a wide range of commodities. In this paper, water footprints were calculated for two complex agrifood products, 250 g Peanut M&M's^® and 575 g Dolmio^® pasta sauce, in order to evaluate the usefulness of the concept when applied at the product brand level. The process LCA-based methodology took account of blue water appropriated from surface and groundwater resources, green water appropriated from the root zone by plants, and dilution water, being the volume of freshwater needed to assimilate emissions to freshwater. These case studies revealed several issues, namely the lack of correspondence between water footprints and the availability of water for alternative uses in the absence of production, and the difficulty in relating water footprints to potential social and environmental harm. As such, the water footprinting concept requires further development to be useful for promoting sustainable production and consumption.