Design of Mass Exchange Network and Effluent Distribution System for effective water management

The environmental impact of industrial wastewater and higher cost of fresh water are the serious challenges faced by the process industries. It has led to the development of many new techniques to minimize fresh water consumption. Of the many approaches, which have been developed, the Water Source Diagram (WSD) is a flexible and dynamic alternative for the generation of different scenarios for the management of water networks with reduction in total consumption. In the present study WSD concept was coupled with water mains concept to mains simplify the piping network and reduce the cost. A new procedure was developed for integrating the effluent treatment processes to evolve Effluent Treatment Network. Example from literature having multi contaminants was considered. This simple procedure involving hand calculations will be a useful tool for process engineers to design water and effluent treatment networks. Also the WSD and ETN were combined to form an evolutionary WAMEN (Water Allocation and Mass Exchange Network) and the proposed WAMEN aims for minimum fresh water consumption.     

Environmental performance optimization using process water integration and Sustainable Process Index

Water integration studies have focused on reducing the amount of water used by a process on the assumption that environmental impact is reduced through efficient water reuse. However, the environmental impact of retrofitting the water network through the installation of pumps and pipes and energy for their utilization which may even lead to a network with a higher environmental cost as measured using a more comprehensive metric, is rarely, if at all, considered. Using the Sustainable Process Index (SPI) as a means of measuring environmental impact, this study addresses the question on water integration and environmental impact and shows that there is a balance that must be struck between water savings and water network modifications.     

A simultaneous optimization approach for the design of wastewater and heat exchange networks based on cost estimation

A new systematic methodology for designing wastewater and heat exchange networks for process industries involving effluent streams containing multiple contaminants is proposed. A simultaneous optimization approach mathematically combines the problems of wastewater and heat exchanger network optimization into a single step. This process includes two global iterations of a similar two-stage approach and optimizes networks for water and heat exchange simultaneously based on cost estimation. The objective function is to minimize the total annual cost of the wastewater and heat exchange network design which is subject to the mass and energy balance constraints on all the pertinent flows and to constraints related to the concentrations of contaminants. The proposed method employs a strategy to address a mixed integer non-linear programming (MINLP) formulation. Cost estimates for optimized wastewater and heat exchange networks for an oil refinery process are generated, illustrating the effectiveness of the proposed methodology.     

Optimization of water networks in industrial processes

Industry is responsible for high water consumption and it has become one of the main sources of water resource deterioration. However, industries are seeking alternatives that minimize the impact of using these natural resources. Some of the alternatives for reducing water consumption involve the reuse and/or recycling of wastewater. This study aims to seek alternatives to optimize water networks, minimize freshwater consumption and/or reduce costs. A non-linear program (NLP) model targeting the minimization of freshwater consumption and/or operating costs was developed. The model is based on the conservation equations of chemical species (contaminants) and mass (water). Options to reduce the cost and consumption of networks with and without regeneration processes are presented. The solutions are identified using a two-step procedure in which cost is optimized while the previously obtained minimum freshwater consumption remains fixed. The results showed excellent agreement with results reported by other authors.     

基于动态剪枝的城市供水管网优化调度算法

城市供水管网的优化调度模型,需要反复调度水力学模型来计算目标函数和约束条件,从而产生巨大的计算和时间成本。在优化迭代过程中,为了获得更优秀的优化结果,通常在搜索空间中约束条件的边界进行搜索,产生了大量不满足约束的样本和较低的优化效率。为解决这一问题,提出了一种高效的基于约束条件的动态剪枝方法,在运行水力学模型前,利用优化计算过程中积累的数据来判断样本是否符合约束条件,从而剔除不满足约束的样本,提高优化效率。模型分别在1个案例管网和1个真实管网上进行测试,结果表明:使用朴素贝叶斯、决策树和支持向量机作为动态剪枝算法,在获得和原始优化模型几乎相同结果的同时,分别减少56.4%、58.5%和56.8%的计算次数。     

Integrating purifiers in refinery hydrogen networks: a retrofit case study

Hydrogen is an important utility in the production of clean fuels such as low-sulfur gasoline and diesel. The shortage of hydrogen resource motivates the integrated management of hydrogen networks with purifiers. In this paper, we propose a systematic approach for the retrofit design of these hydrogen networks. By establishing a state-space superstructure, all possible placements of existing compressors and purifiers are incorporated in the proposed MINLP model. Total annual cost (TAC) is employed as the optimizing object to understand the trade-offs between operating cost and capital cost. A real refinery system near Shanghai of China city is used to illustrate the applicability of the approach.     

ECO-design of reuse and recycling networks by multi-objective optimization

An ECO-optimized reuse of process liquors addresses the financial gain and the effective use of resources. In processes that have a potential for process liquor recovery, the minimization of both economic and environmental burdens can be realised by an ECO-optimal design of reuse and recycling network (RRN).In this paper, a procedure for synthesizing such an RRN for a metal finishing process is investigated. The simultaneous analysis of environmental impact sensitivity (SAEIS) based on a superstructure approach, combined with multi-objective optimization is performed by mixed-integer nonlinear programming (MINLP). This allows an “eco–eco” trade-off i.e. total annualized cost and environmental impacts are minimized simultaneously. By varying the weighting factor, different RRN alternatives were generated. A replacement of the standard and closed-loop system by these solutions, even for the environmentally friendliest case, yielded a reasonable cost saving on raw material's inputs.     

资源型城市绿色GDP核算研究——以陕西省榆林市为例

根据联合国制定的SEEA2003核算体系的方法,对我国城市社会经济核算体系进行纠正,提出了榆林市的绿色GDP(GGDP)核算模式。对2001-2006年榆林市传统GDP及GGDP核算结果进行对比分析,结果表明：①2001年以来,榆林市GDP分别在129.31×10⁸～439.48×10⁸元之间,GGDP则分别在55.02×10⁸～329.90×10⁸元之间,各年度GGDP/GDP(%)分别在42.55%～75.07%之间;②自2001年以来,榆林市的土壤资源、林木资源、水资源以及矿产资源的变化,致使GGDP/GDP产生了较大的变化,其中资源消耗账户中土壤资源的耗减成本是GGDP核算的最大贡献因子;同时,资源消耗账户占GDP比重处于24.74%～57.20%之间。③环境质量退化账户主要是由水体污染、大气污染、工业固体废弃物污染以及环保人员支出等构成,自2001年以来除工业固体废物污染持续保持较高比例外,其它污染成本基本保持均衡,其占GDP的百分比处于0.20%～0.29%之间。     

基于地理分区及神经网络的湖泊水库富营养化研究

构建了一个基于地理分区及神经网络的湖泊水库富营养化综合评价体系.以美国环境保护署Nutrient Criteria Database数据库为参照对象,有针对性地研究我国湖泊水库的情况,首次提出了基于地理分区的简易评价标准,对不同地理特征的水体富营养化临界值进行了定量研究.同时本研究还建立了基于神经网络的富营养化评价模型...     

绿色水资源利用效率的测度和收敛性分析

为实现水资源的高效利用和生态环境价值,必须把非合意产出纳入水资源利用效率的研究范畴。使用2003-2013年中国30个省市的面板数据,选取Malmquist-Luenberger生产率指数测算了考虑环境污染的绿色水资源利用效率,在此基础上,进行了各地区水资源利用效率的收敛性检验,研究结果表明：1）针对全国而言,环境约束下的动态绿色水资源利用效率低于无环境约束得到的水资源利用效率,即忽视非合意产出时水资源利用效率被高估,这也表明传统的水资源利用效率数值的“虚高”是以水生态破坏为代价的。2）全国绿色水资源利用效率增长3.3%,其中,技术进步对水资源利用效率增长起到了正向作用,但技术效率却对改善水资源利用效率起了阻碍作用。3）全国、东部和中部区域绿色水资源利用效率增长率趋向于稳态,但西部区域的增长率虽存在条件β收敛,但不存在绝对β收敛。最后根据研究结果,提出高度重视水资源的经济价值和生态环境功能;紧扣自主创新和产业结构调整主线,通过技术进步大幅提升绿色水资源利用效率及建立节水减排的内在动力机制,缩小绿色水资源利用率的地区差距等建议。     

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。     

天津市再生水利用现状的调查与研究

天津是一个资源性缺水城市,文章通过对天津市供排水需求与现状进行分析.论述了再生水在农田水利、工业、景观河道、民用等各方面的使用现状和发展前景,阐明了再生水在天津水资源利用领域的重要性.从技术角度分析了再生水处理的几种途径以及天津再生水利用规划、现状与存在的问题,提出天津市再生水利用的总体设想与建议.     

天津市不同后备水资源对比评价研究

为了缓解天津水资源严重短缺的困境,利用层次分析法,从水资源保证程度、调水协调难度、可供水量、工程成本、供水管网改造成本、水质、水处理成本、污水处理难度、生态环境风险等角度对天津市主要后备水源进行了综合对比评价。评价结果认为海水淡化、南水北调中线调水、地下咸水开发、海水直接利用可以作为天津市理想的后备水资源开发方案;上游水库调水、南水北调东线调水、引黄调水可以作为应急后备水源方案;污水处理后主要用作灌溉、生态、景观用水。     

MBR工艺在牛仔布水洗废水处理中的应用

以某服装洗涤厂牛仔布水洗废水处理工程为例,介绍了混凝沉淀＋水解酸化＋MBR处理的工艺,并对处理后水质及回用情况进行了技术经济分析。表明用MBR作为主体工艺处理牛仔布水洗废水,可以减少废水处理占地面积,吨水成本小于4元,而且MBR出水80%以上可以满足回用要求,减少新鲜水的消耗。     

Clean technology for the tapioca starch industry in Thailand

The tapioca processing industry is considered to be one of the largest food processing industrial sectors in Thailand. However, the growth of the tapioca starch industry has resulted in heavy water pollution as it generates large amount of solid waste and wastewater with high organic content. This study explores the applicability of clean technology options to improve the environmental performance of tapioca starch-processing plants in Thailand. Eight Tapioca starch plants were selected for an exclusive analysis of the dynamics of clean technology development and adoption. Proposed options mainly involve water reduction and energy conservation. These include reuse and recycling of water, technology modification in the production process, and use of biogas to substitute fuel oil for burners. Implementation of these proposed alternatives to real companies shows that the reduction of starch loss, and water and fuel cost savings can be achieved.     

Synthesis of batch water network for a brewery plant

This paper presents an industrial application of mixed-integer nonlinear programming (MINLP) models for the optimisation of a water network, which was initiated by an integral need for cleaner production within a brewery. Several mathematical models were developed in order to reduce the use of freshwater, whilst considering the specific requirements of each particular production section. These models are based on the design method developed by Kim and Smith [1]. The original formulation is modified to enable efficient integration of discontinuous and semi-continuous water-using processes in the packaging area. Semi-continuous processes are treated as water sources of limited capacity. The option of installing storage tanks for semi-continuous water streams is included in the model, in order to re-use these streams during the shutdown periods of semi-continuous operations. The original model is additionally extended with the option of installing local (on-site) wastewater treatment units operating either in batch or semi-continuous modes. This enables the analysing of opportunities for regeneration re-use within the production area, i.e. the brewhouse with a cellar, because of high contaminant concentrations at these sites. The scheduling of batch wastewater treatment units is performed simultaneously in order to adjust the treatment schedule to a fixed schedule of batch processes.     

水夹点技术用于石化行业水网络优化研究

运用水夹点技术,对某石化企业进行用水网络优化研究。在流量恒定和流量改变两种条件下,对某石化企业13个用水操作原有用水网络进行初始设计和优化改进。结果表明,在流量恒定和流量改变条件下,通过用水网络初始设计节约新鲜水用量分别为17.17%和13.72%,对初始设计用水网络的优化设计可简化用水网络,回用管路数分别由14条和16条减少为11条和8条,优化后的用水网络分别节约新鲜水用量17.25%和14.81%。水夹点技术在工业用水节约和废水减量方面具有实用价值和较好的应用前景。     

草甘膦生产工艺水资源代谢分析与优化建议

以某农药集团草甘膦生产工艺为例,运用工业代谢分析方法对其水资源代谢过程进行量化分析,建立了水代谢平衡账户并绘制了水代谢图,在此基础上,识别和筛选出草甘膦生产过程中的主要用水单元及废水排放单元,并据此提出优化建议. 结果表明,草甘膦生产过程中的主要用水类别为蒸汽,其蒸汽消耗单元多且用汽量大,而换热网络单一,冷凝水浪费较严重,系统中水资源重复利用水平较差.针对该问题,从系统优化和节水管理等方面提出了工艺废水的重复利用及主要用汽单元之间的换热网络优化等建议,以期提高生产过程中的水资源利用效率.      

Decision support in disinfection technologies for treated wastewater reuse

The environmental and social impact derived from treated wastewater reuse is an intrinsically complex multidimensional process, which involves multiple criteria and multiple stakeholders. This paper presents the use of multicriteria decision through the TOPSIS method, applied to six different methodologies concerning the disinfection of treated wastewater before reusing. Results have shown that the best disinfection technique for treated wastewater has been chlorination with 4 ppm, if this water is to be destined to an urban, agricultural or industrial use, due to a large weight given to cost and environmental criteria. Conversely, in recreational and environmental uses, the alternative of ultraviolet light disinfection was the chosen alternative. Economic criteria showed priority in the most entrepreneurial uses of the water, although social and political cost had a greater weight in the case of environmental or recreational uses. The inclusion of environmental and social assessment in the disinfection technique decision support clearly provides a cleaner and more sustainable production.     

京津冀钢铁行业节能、SO2、NOx、PM2.5和水协同控制

建立自下而上的综合动态优化模型,在节能、大气污染物（SO₂、NO_x和PM_2.5）减排和节水的综合约束下,研究京津冀地区2015~2030年钢铁行业48项节能减排技术优化发展路径,并预测该地区钢铁行业能耗、大气污染物排放和水耗.结果表明,国家应优先鼓励推广干熄焦,小球烧结技术等22项技术,此类技术可以有效协同控制能耗、大气污染物排放和水耗.京津冀地区钢铁行业具有很大的节能、大气污染物减排和节水潜力,到2030年在实现大量节能、大气污染物减排潜力的同时可以实现节水10.08亿m³.虽然计算得到的购水成本仅约占总成本的2%,但是京津冀地区面临着严重大气污染和极度的水资源短缺问题,仍然需要兼顾节能减排技术对水资源的影响.