Demonstration of a tool for automatic learning and re-use of knowledge in the activated sludge process.

Wastewater treatment plant operators encounter complex operational problems related to the activated sludge process and usually respond to these by applying their own intuition and by taking advantage of what they have learnt from past experiences of similar problems. However, previous process experiences are not easy to integrate in numerical control, and new tools must be developed to enable re-use of plant operating experience. The aim of this paper is to investigate the usefulness of a case-based reasoning (CBR) approach to apply learning and re-use of knowledge gained during past incidents to confront actual complex problems through the IWA/COST Benchmark protocol. A case study shows that the proposed CBR system achieves a significant improvement of the benchmark plant performance when facing a high-flow event disturbance.     

Dynamic reasoning to solve complex problems in activated sludge processes: a step further in decision support systems.

Decision support systems (DSS) have generated high expectations as a tool to support activated sludge operation because of their ability to represent heuristic reasoning and to handle large amounts of qualitative, uncertain and low-accuracy data. Previous applications have been satisfactory to control simple problems, when static reasoning and literature-based solutions were enough. However to face complex operational problems with biological origin and slow dynamics (e.g. solids separation problems), it is necessary to use dynamic reasoning and apply long-term control strategies, monitoring the evolution of the process and adjusting the action plan according to the feed back of the process. This paper presents a dynamic reasoning DSS to face solids separation problems in the activated sludge system. The DSS is capable of identifying the complex problem affecting the process, determining if the current situation is new or a continuation from the previous one, assessing what is the specific cause of the situation, and recommending a long-term control strategy, which is daily adjusted according to the evolution of the process.     

Water management: some personal reflections

In recent years, books, papers and media coverage of the global water crisis due to physical scarcities of water have become a growth industry. Is this widely accepted hypothesis correct? It is argued in this paper that the world is not facing a water crisis because of physical scarcities of water, as people with linear and compartmentalized thinking are forecasting, but is facing a crisis because of the inefficient way water has been managed in the past and is being managed in nearly all countries of the world. There is at present enough knowledge, experience, technology and even funds to solve the world's water problems for all uses. In addition, the world's future water problems will be very different compared to past and current problems. A new mindset is needed, first to identify the emerging water and water-related problems of the world, and then to find and implement appropriate solutions. Based on the current evidence, there is every reason to be cautiously optimistic of the world's water future.     

Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters.

Anaerobic digestion of concentrated domestic wastewater streams--black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR--decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations were extensively studied; accumulation system (AC) and UASB septic tank at 15, 20 and 25 degrees C. Due to long retention times in an AC reactor, far stabilisation of treated medium can be accomplished with methanisation up to 60%. The AC systems are the most suitable to apply when the volume of waste to be treated is minimal and when a direct reuse of a treated medium in agriculture is possible. Digested effluent contains both liquid and solids. In a UASB septic tank, efficient separation of solids and liquid is accomplished. The total COD removal was above 80% at 25 degrees C. The effluent contains COD and nutrients, mainly in a soluble form. The frequency of excess sludge removal is low and sludge is well stabilised due to a long accumulation time.     

Nutrient minimisation in the pulp and paper industry: an overview.

This paper reviews nutrient issues within the pulp and paper industry summarising: nitrogen and phosphorus cycles within treatment systems; sources of nutrients within pulping and papermaking processes; minimising nutrient discharge; new approaches to nutrient minimisation; and the impact of nutrients in the environment. Pulp and paper industry wastewaters generally contain insufficient nitrogen and phosphorus to satisfy bacterial growth requirements. Nutrient limitation has been linked to operational problems such as sludge bulking and poor solids separation. Nutrients have been added in conventional wastewater treatment processes to ensure optimum treatment performance. Minimising the discharge of total nitrogen and phosphorus from a nutrient limited wastewater requires both optimised nutrient supplementation and effective removal of suspended solids from the treated wastewater. In an efficiently operated wastewater treatment system, the majority of the discharged nutrients are contained within the biomass. Effective solids separation then becomes the controlling step, and optimisation of secondary clarification is crucial. Conventional practice is being challenged by the regulatory requirement to reduce nitrogen and phosphorus discharge. Two recent developments in pulp and paper wastewater treatment technologies can produce discharges low in nitrogen and phosphorus whilst operating under conventionally nutrient limited conditions: i) the nutrient limited BAS process (Biofilm-Activated Sludge) which combines biofilm and activated sludge technologies under nutrient limited conditions and ii) an activated sludge process based on the use of nitrogen-fixing bacteria. Aerated stabilisation basins often operate without nutrient addition, relying on settled biomass in the benthal zone feeding back soluble nutrients, or the fixation of atmospheric nitrogen. Thus effective nutrient minimisation strategies require a more detailed understanding of nutrient cycling and utilisation. Where it is not possible to meet discharge constraints with biological treatment alone, a tertiary treatment step may be required. In setting nutrient control guidelines, consideration should be given to the nutrient limitations of the receiving environment, including other cumulative nutrient impacts on that environment. Whether an ecosystem is N or P limited should be integrated with wastewater treatment considerations in the further design and development of treatment technology and regulatory guidelines. End-of-pipe legislation alone cannot predict environmental effects related to nutrients and must be supplemented by an effects-based approach.     

梁的独立覆盖分析方法

采用前期提出的独立覆盖流形法,提出梁的独立覆盖分析方法。该方法的特点是:与实体分析采用同一模式,可以应用完全多项式的覆盖函数进行梁的实体分析,或使多项式中的某些项不参与计算来模拟梁的基本假设,从而实现Timoshenko梁和Euler-Bernoulli梁的计算;仅要求近似场函数的C₀连续性;避免了Timoshenko梁在求解细长梁时的剪切自锁;即使对于实体分析而言,通常情况下也不存在由于梁高远小于梁长而导致的数值病态。为体现梁结构的特点,以二维的矩形截面梁为例,给出了局部坐标系下的独立覆盖流形法公式,以及“先截面、后轴向”的积分方式,并用几个算例验证了方法的有效性。本思路可以直接推广到求解三维问题,为梁板壳分析提供全新的途径。     

Enhancement of microbubble generation in a pressurized dissolution process by packing the nozzle with porous ceramics

The pressurized dissolution method is often used for microbubble generation. However, the main disadvantage of this method is that a large amount of energy (more than 0.3 MPa) is required to generate many microbubbles, each of which have a diameter of several dozen μm. To overcome this problem, we investigated the effectiveness of porous ceramic when used as the packing material in the pressurized dissolution method. The results showed that when compared with the control (no porous ceramics), use of porous ceramics resulted in a 39% increase in the number of microbubbles. Furthermore, when this system was used for the flotation separation of artificial suspended solids and activated sludge, the level of separation achieved with porous ceramics at 0.15 MPa was the same as that achieved using no porous ceramics at 0.25 MPa. It was estimated that the use of porous ceramics led to a 40% reduction in the energy required for the dissolved air flotation, with subsequent decreases in the operating cost.     

基于文化粒子群算法的水库防洪优化调度

针对水库防洪调度具有多约束、高维、非线性和不易求解的特点,在粒子群算法(PSO)的进化机制中引入文化算法(CA),利用文化算法的信仰空间对粒子群的进化进行指导,建立了文化粒子群算法(PSO-CA)。该算法在种群空间中采用PSO算法,在信仰空间中利用从种群空间中提炼出来的群体经验所形成的形势知识对群体的"早熟"现象进行监视,利用规范化知识对粒子加以限定,提高了算法计算效率。实例验证,该算法能较好地克服粒子群算法易陷入局部最优的缺点,并加快其收敛速度,可以有效解决水库防洪调度问题。     

基于CBR的防汛知识获取研究

随着知识管理和计算机信息技术的不断发展，知识获取的应用越来越广泛，并促使有效地管理组织的现行知识，大量的实现隐性知识转换为显性知识，从而实现知识共享和传播。在分析了知识获取的研究现状后，基于CBR方法在事例的检索过程中采用关键词匹配和最相邻检索相结合的检索策略和方法对防汛知识进行获取，说明了CBR方法在知识获取中的重大作用。     

离心试验技术在土石坝工程中的应用

本文系统地分析了土石坝离心模型试验中存在的几个关键技术问题,并结合国内外一些工程试验实例,研究了解决这些问题的途径,最后还提出了一些有待改进的建议。     

一种气垫式调压室防漏新方法

气垫式调压室具有良好的水击波反射功能,能有效降低水电站负荷急剧变化时压力管道的水击压力,但运行过程中的漏气现象制约了气垫式调压室的推广应用。提出了一种防止气垫式调压室漏气的新方法,即在传统气垫式调压室内放置橡胶芯袋作为盛气装置,实现调压室盛气和结构承载功能的分离,利用橡胶材料柔软、弹性模量小、密封性好等特点,从根本上解决了盛气密封薄壳容易开裂渗漏的问题。根据力学平衡原理、材料的应力应变关系和调压室结构的变形协调条件,结合流体力学理论和调压室内水位波动的变化规律,构建了橡胶芯袋变形与受力本构关系,并分别推导出了单个、多个橡胶芯袋预灌气压的计算式,为调压室结构设计与工程控制提供了理论依据。     

龙滩水电站进水口坝段混凝土施工的重点技术

龙滩左岸大坝工程是龙滩水电站实现蓄水发电的关键项目,场地狭窄、坝体结构复杂、工序繁多、技术要求高、质量要求严是该项目的施工特点,施工单位针对这些问题进行了认真细致的研究,在借鉴其他工程成功经验的基础上,引进并推广应用多项适用于该工程的新技术、新材料和新工艺,成功解决了进水口坝段施工技术难题,为今后类似工程施工提供了宝贵经验。     

基于云模型的单沟泥石流危险性模糊综合评价

针对泥石流孕育和发生过程中的不确定性,为解决传统单沟泥石流危险性评价过程中指标权重和隶属度确定易受到个人经验和主观偏好的影响,以及定性概念和定量描述之间转换的限制问题,以单沟泥石流沟为研究对象,应用云模型对模糊综合评价进行改进。评价结果表明:(1)通过改进的评价方法得到11条泥石流沟中处于中度危险的有3条,其余8条处于高度危险,与泥石流灾害防治工程勘察规范(DZ/T0220-2006)所计算的结果较为一致;(2)改进方法考虑了传统模糊综合评价结果用单一的数字表示定性概念所带来的局限性,且综合考虑了评价结果的中心值、模糊性和随机性,用云模型表示单沟泥石流评价结果极大地提高了评价结果的可靠性和可视化。     

水泥固化东湖淤泥的工程性质试验研究

利用将水泥、化学固化剂和机械力脱水三种方法相结合的方式对东湖淤泥进行固化处理,通过界限含水率、强度试验(包括CBR和直剪试验)以及渗透试验研究了在使用水泥固化过程中水泥掺量、养护龄期以及压实度对固化土工程性质的影响。结果发现:仅使用化学固化剂和机械脱水固化处理后的淤泥属于高液限粉土,CBR强度低,不能满足路基填料的要求。使用水泥能够有效提高一次改性固化土的CBR强度和直剪黏聚力,养护龄期对CBR强度影响很小,而水泥掺量、养护龄期和压实度对内摩擦角的影响均不大。此外,在水泥掺量从0%增大到8%的过程中,渗透系数呈现出先增大后减小的趋势,在水泥掺量为2%时达到最大值。综合分析,在水泥二次改性过程中,为符合路基填筑要求,水泥掺量宜为8%,压实度宜大于92%。     

砒砂岩区侵蚀治理技术研究进展

黄河流域砒砂岩区是我国北方生态严重退化的地区,其土壤侵蚀治理长期以来是我国水土保持学界所面临的难题之一,其难点在于砒砂岩区水力、风力、冻融、重力等多动力复合侵蚀交替发生且时空分异性强、侵蚀岩性机理及侵蚀动力过程复杂、干旱缺水而暴雨集中,以及人们对于砒砂岩区土壤侵蚀规律性认知水平的局限性。本文从砒砂岩区土壤侵蚀特征、治理措施及其作用与效益,以及砒砂岩治理技术研究新成果等方面综述了砒砂岩区土壤侵蚀治理技术的研究与实践进展,并提出了存在的问题。阻控侵蚀与植被恢复一体化、砒砂岩资源利用与生态衍生产业发展相结合,以及实现生态综合治理将成为砒砂岩区土壤侵蚀治理技术研究的未来主要发展方向。     

对县域污水处理回用现状的调查

污水再生利用,实现污水资源化,是目前解决节水治污两大问题最有效的途径,在水资源严重短缺的当今社会有着重要的现实意义,县域城市受资金等条件的约束,在污水处理回用中存在的诸多问题急需解决。文中介绍了闻喜县废污水排放及处理回用情况、存在问题,并提出了加强县城污水回用的几点建议。     

SMW工法围护的基坑开挖对周围环境的影响

ＳＭＷ工法制作的地下连续墙集挡土止水两大功能于一体，是基坑围护的新方法。本文结合南京地铁某明挖基坑工程，分析ＳＭＷ工法围护的基坑开挖对邻近建筑物和周围环境的影响，为ＳＭＷ工法在南京地区推广应用积累经验。     

减少蒸压砂加气混凝土砌块墙体裂缝

安徽水安亮亮QC小组,在"来安中学公寓楼工程"建设中,为了解决"蒸压砂加气混凝土砌块墙体裂缝问题"而开展了QC小组活动。QC小组通过现状调查找出了主要问题为"竖直贯穿裂缝",经过分析,确认了三个要因,小组根据这三个要因分别制定了对策、措施,确保了目标的实现,取得了一定的经济效益和社会效益。QC小组活动的经验可以在该企业今后的类似工程中借鉴和参考。与此同时,QC小组的QC知识得到增长,质量意识、团队精神及分析和处理问题的能力得到了提高。     

内梅罗指数法在水质评价中存在问题及修正

根据内梅罗指数评价公式,分析了内梅罗指数法进行水质评价存在的问题并进行了修正,解决了原方法在水质评价中的数值不连续的局限性,地下水综合评分值仅受极大值的影响而与Fave关系甚微的弊端,以及原内梅罗指数计算值因相对集中而缺失"较好"水质级别的问题。应用修正前后的内梅罗指数法,对研究区地下水水质评价结果表明,修正后的内梅罗指数法在评价的水质状况时,更能反映真实情况。