Case-based reasoning, a promising tool to face solids separation problems in the activated sludge process.

Classical control has serious limitations when faced with solids separation problems in the activated sludge process. Lack of knowledge about the mechanisms involved in the imbalance within the different microbiological communities implies that a general solution to these undesirable situations has not yet been provided. However, operators have to make decisions based on their experience and intuition to solve the problem (or at least to minimise the effects). The acquisition and registration of the knowledge learnt from each new experience can be decisive when solving similar problems in the future. Case-based reasoning (CBR) is an advanced technique for knowledge management in complex systems that uses past experiences to solve brand new situations. Previous simplified proposals in this field have exposed limitations, but this paper describes a new approach to CBR, considering the dynamics and the complexity of solids separation problems.     

The influence of operating experiences in the design of the IVAR thermal drying plant expansion in Stavanger, Norway.

The Regional Wastewater Treatment Plant of North Jaeren (IVAR IKS) serves the Stavanger conurbation with a population equivalence of 240,000. The site was the first in Norway to operate a thermal drying and a pelletising plant for municipal sludge. Since the start up in 1992, IVAR has encountered most of the operational problems typically associated with thermal drying processes. Considerable modifications have been made and lessons learnt resulting in the plant being one of the few thermal drying facilities in Norway which continues to operate successfully. In general, thermal drying is often considered as a costly, energy demanding and complex process requiring careful attention to safety aspects such as risks of self-combustion, fires and dust explosions. The paper presents general considerations of operating experiences influencing the procurement and design stage of the new extended IVAR thermal drying plant. Furthermore, topical issues important for resolution of thermal drying problems are also discussed. Mass and energy balances for the Stavanger plant are presented.     

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%。     

Re-use of winery wastewaters for biological nutrient removal.

The aim of this study was to evaluate the feasibility of the re-use of the winery wastewater to enhance the biological nutrient removal (BNR) process. In batch experiments it was observed that the addition of winery wastewater mainly enhanced the nitrogen removal process because of the high denitrification potential (DNP), of about 130 mg N/g COD, of the contained substrates. This value is very similar to that obtained by using pure organic substrates such as acetate. The addition of winery wastewater did not significantly affect either phosphorus or COD removal processes. Based on the experimental results obtained, the optimum dosage to remove each mg of N-NO3 was determined, being a value of 6.7 mg COD/mg N-NO3. Because of the good properties of the winery wastewater to enhance the nitrogen removal, the viability of its continuous addition in an activated sludge pilot-scale plant for BNR was studied. Dosing the winery wastewater to the pilot plant a significant increase in the nitrogen removal was detected, from 58 to 75%. The COD removal was slightly increased, from 89 to 95%, and the phosphorus removal remained constant.     

Simulation and optimization of an experimental membrane wastewater treatment plant using computational intelligence methods

The optimization of relaxation and filtration times of submerged microfiltration flat modules in membrane bioreactors used for municipal wastewater treatment is essential for efficient plant operation. However, the optimization and control of such plants and their filtration processes is a challenging problem due to the underlying highly nonlinear and complex processes. This paper presents the use of genetic algorithms for this optimization problem in conjunction with a fully calibrated simulation model, as computational intelligence methods are perfectly suited to the nonconvex multi-objective nature of the optimization problems posed by these complex systems. The simulation model is developed and calibrated using membrane modules from the wastewater simulation software GPS-X based on the Activated Sludge Model No.1 (ASM1). Simulation results have been validated at a technical reference plant. They clearly show that filtration process costs for cleaning and energy can be reduced significantly by intelligent process optimization.     

Water shortage and needs for wastewater re-use in the north China.

This paper analyses the present condition of the water shortage in north China where annual rainfall is low and per capita water resource is below the line of regular water stress, or even the line of absolute water scarcity. Of the available water resources, the percentge of water withdrawal in all the north basins is high--the Yellow River and Huai River basins being greater than 80% and the Hai River basin mainly depending on interbasin water transfer. Over-withdrawal of water also results in serious water environmental problems including "flow cut-off" of the Yellow River main channel and water pollution of many rivers. The paper also analyses the potential of wastewater as a resource and the demand for treated wastewater re-use. In north China, due to low rainfall and high potential evaporation environmental re-use, gardening, afforestation, etc. is considered as the main usage of the treated wastewater. Considering the economic restrictions in the less developed area, a decentralised system can be taken as an important option in formulating water re-use strategies.     

河道采砂管理的难点及对策

河道采砂管理是一项复杂的社会事务管理工作，经过几年的实践，各地水行政主管部门在管理河道采砂方面逐步积累了宝贵的经验。但目前还存在思想观念上的不适应、机构队伍上的不适应以及装备经费的紧缺、法律制度的缺位等诸多问题。维护河道的健康安澜，实现河道采砂的长效管理需要进一步提高认识．建立和落实地方行政首长负责制，加强“四个专门”建设，加快立法进程。     

An overview of the integration of ozone systems in biological treatment steps.

Despite the well-known potential and performance of combined biological and ozonation processes for wastewater treatment, only few full-scale applications are published. Beside the synergistic effects of such process combination, which lead to oxidation of recalcitrant and inhibitory compounds or intermediates by enhancement of their biodegradability, the key for raising applicability is the improvement of the ozonation efficiency. An overview about the history and progress of full-scale applications, which deals with combined ozonation and biological treatment is given. Recently more than 40 applications exist, but many of them are not published. Therefore, a couple of selected not yet published applications have been mentioned in this paper. Landfill leachate and industrial wastewater treatment were mostly applicated, while treatment of municial wastewater treatment plant (WWTP) effluents are of increasing interest due to several advantages such as disinfection, decolourisation and removal of persistent dissolved organic carbon (DOC) for water re-use and groundwater recharge.     

Selection of operational strategies in activated sludge processes based on optimization algorithms

This paper presents a new optimization algorithm for the selection of design and operation parameters in complex Activated Sludge (AS) processes. The algorithm estimates automatically the dimensions and operating point of the plant that minimize a global penalty function combining effluent requirements and costs. The mathematical optimization is based on a direct search algorithm integrated in a previously developed simulation package.Some illustrative examples concerning the design and operation of the Alpha process have been included to show the potential of this kind of mathematical tool when the complexity of plant configuration increases. The results obtained by the optimization procedure generate useful guidelines for the design and operation and suggest a great potential in the application for solving more complex problems when additional objectives and costs are included.     

Application of a membrane bioreactor for the treatment of low loaded domestic wastewater for water re-use.

This paper describes the demonstrative scale application of a membrane biological reactor (MBR) for low loaded domestic wastewater with low attitude to biological treatment (carbon/nitrogen approximately 5). The biological process was managed by the automatically controlled alternate cycles allowing for re-use purposes with a remarkable reduction of the operational costs. The global process evaluation revealed the system capability of obtaining high nitrogen removal (effective nitrogen removal of 69%) thanks to its high flexibility related to the hourly loading fluctuation. Moreover, high removal of heavy metals and polycyclic aromatic hydrocarbons (PAH) was obtained due to the perfect retention capability of the membranes. In-depth studies were conducted to determine the process behaviour for activated sludge over aeration and with addition of exogenous carbon. Limitation of sludge over aeration and energy savings were observed with a gradient air supplying method. The addition of exogenous carbon (acetic acid up to carbon/nitrogen approximately 9) led to complete nitrogen removal (Ed = 96%) and permitted biological phosphorus uptake. In conclusion, it was been found that the coupled process alternated cycles-MBR had the capacity to remove COD, BOD, N, P and suspended solids, as well as heavy metals and organic micropollutants, resulting in high quality effluent suitable for re-use purposes.     

10 years of operation of an integrated nutrient removal treatment plant: ups and downs. Background and water treatment.

Water retention times less than 3 h from inlet to outlet were necessary to meet new effluent requirements without extending the footprint of the existing plant. Nitrogen removal was required at the existing, high loaded, direct precipitation plant and space was not readily available. The staff at the VEAS WWTP took on the task to design a new process at their own risk. Selected solutions and ups and downs in the water treatment during the past 10 years of operations and further developments are presented in this paper. Always asking for well-proven solutions might make life easy. The intent of this paper is to encourage some of our colleagues to be more daring in their approach to new challenges. However, expect sleepless nights in order to solve the unexpected problems along the way.     

Optimization analysis of decentralised sanitation and re-use system.

With the application of system dynamics, a dynamic nonlinear model reflecting the relationship between decentralised water use and reclaimed water supply and demand has been established. Through a system analysis, the model has been applied to a small residential district to predict and analyse the situation of future use of fresh water, demand and supply of re-used water, and treatment scale of reclaimed water. It is illustrated in this paper that wastewater decentralised treatment and re-use can decrease the consumption of fresh water without lowering the standard of living water for the district residents. On this basis, a rational scale and construction time of the decentralised sanitation and re-use system have been determined. Also, the paper predicts the influencing factors of the increasing water cost and changes in consumers' acceptability to re-use water in the decentralised sanitation and re-use system.     

积极推进水务管理体制改革深入开展水利政策法规研究

总结3年来广西水务管理体制改革和水利政策法规研究取得的经验与存在的一些问题。提出了以新《水法》颁布实施为契机,认真贯彻中央新时期的治水方针,积极稳妥地推进水务体制改革,深入开展水利政策法规的研究,努力开创广西水利事业的新局面。     

贝雷法在级配碎石基层级配检验中的应用

引进贝雷法矿料级配检验手段,结合碎石力学指标CBR,对级配碎石规范范围内选取的12个典型的级配进行检验,分析了CA比、FAc比、FAf比和K值对CBR的影响。试验结果表明:CA和CBR的相关系数为0.6901,K值和CBR的相关系数为0.8178,FAc比和FAf比对CBR的影响不明显。因此,用CBR、CA比和K值这三项指标评价级配碎石性能是可行的。CA在0.58左右的级配碎石混合料有较高的强度,并建议其K值在92.99～104.58之间。     

水泥稳定三峡库区风化砂CBR值试验研究

以宜昌市三峡库区风化砂为研究对象,采用水泥对其进行稳定改良,拟用作公路路面基层。在风化砂中分别掺入3%,5%,7%,9%的水泥,在标准养护条件下,分别养护了7,14,21,28 d,然后进行加州承载比(CBR)值试验。试验结果表明水泥可以有效提高风化砂的CBR值,且水泥掺量和养护龄期均对风化砂的CBR值有很大影响;在养护龄期一定时,水泥稳定风化砂的CBR值随水泥掺量的增加逐渐增大,CBR值与水泥掺量之间呈良好的对数关系;在相同的水泥掺量下,水泥稳定风化砂的CBR值随养护龄期的增长稳步提高,CBR值与养护龄期之间基本呈线性关系。综合考虑经济性和风化砂的力学特性,风化砂中掺入7%的水泥能使CBR值达到最大值。     

The use of modelling and reuse techniques in the development of water management systems in basins with limited water resources.

Drawing on experiences in New South Wales from 1950 to 1980 in modeling and re-use techniques in the development of desalination technology and its application in fresh water production for potable use, the paper describes how Australia realized its responsibilities in developing participative and sustainable approaches to land use and water resources management. An analysis of the lessons from the operation of the Bayswater zero-discharge power station significantly contributed to the debate on sustainable approaches, highlighting that no management policy of a water basin can be implemented without a model based on reliable data from all sectors (including the environment), and no management model can be implemented without the participation of all stakeholders. These ideals were reflected in the conception and establishment of the Murray-Darling Basin Commission. The Commission succeeded in bringing together all major stakeholders in this huge basin, though it took more than 15 years to do so. While widely recognized as one of the most advanced and successful experiences in integrated management of a drainage basin, it has still not achieved the reversal of many unsustainable agricultural practices, giving a clear indication of the difficulties and time required for producing sustainable solutions.     

火/核电厂冷却水试验研究50 年的进展和体验

本文对我院50年持续对火/核电厂冷却水问题试验研究作了一个专业性的历史回顾。共分3部分。第1部分简述了此专业研究从无到有的大致发展过程。第2部分是本文的主体,分(1)模型试验相似性;(2)工程布置优化;(3)数模及一些重要参数的基本研究;(4)冷却塔,概述了历年提出的一些创新性概念、方法,以及其在工程研究中的实际应用。第3部分是多年研究和社会实践的一些体验,包括对专业今后发展的期望。     

千枚状板岩CBR特征及影响因素分析

路基填料的承载比（CBR值）是土体抗局部剪切力（潜在强度）的反映,是评价其路用性能的重要指标。为了研究千枚状板岩CBR值的特征和影响CBR值的主要因素,结合武广客运专线的工程实际,对沿线的千枚状板岩进行了室内CBR值试验。从颗粒组成、矿物成分以及泡水时间、最大颗粒粒径和击实次数几方面研究了其对填料CBR值的影响,并对影响因素采用无重复双因素方差分析方法进行了显著性分析。结果表明：影响CBR值的主要因素是填料中的颗粒矿物组成和泡水时间与击实次数,颗粒大小影响不是很大。在此需要强调的是风化软岩不能直接用于浸水地区路基的填筑,必须对填料进一步改良,同时加强路基、路面的防护与排水措施。