Integrated operation of sewer system and WWTP by simulation-based control of the WWTP inflow.

In recent years numerical modelling became a standard procedure to optimise urban wastewater systems design and operation by integration. For dynamic control of the wastewater teatment plant (WWTP) inflow, a model-based predictive concept is introduced aiming at improving the receiving water quality. An on-line simulator running parallel to the real WWTP operation reflects the actual state of operation and provides this model information to a prognosis tool which determines the best option for the WWTP inflow. The investigations showed that it is possible to reduce the NH4-N peak concentrations in the receiving water by dynamic WWTP inflow control based on predictive scenario analysis.     

Aerobic granulation in a sequencing batch reactor (SBR) for industrial wastewater treatment.

Aerobic granulation seems to be an a attractive process for COD removal from industrial wastewater, characterised by a high content of soluble organic compounds. In order to evaluate the practical aspects of the process, comparative experimental tests are performed on synthetic and on industrial wastewater, originating from pharmaceutical industry. Two pilot plants are operated as sequencing batch bubble columns. Focus was put on the feasibility of the process for high COD removal and on its operational procedure. For both wastewaters, a rapid formation of aerobic granules is observed along with a high COD removal rate. Granule characteristics are quite similar with respect to the two types of wastewater. It seems that filamentous bacteria are part of the granule structure and that phosphorus precipitation can play an important role in granule formation. For both wastewaters similar removal performances for dissolved biodegradable COD are observed (> 95%). However, a relatively high concentration of suspended solids in the outlet deteriorates the performance with regard to total COD removal. Biomass detachment seems to play a non-negligible role in the current set-up. After a stable operational phase the variation of the pharmaceutical wastewater caused a destabilisation and loss of the granules, despite the control for balanced nutrient supply. The first results with real industrial wastewater demonstrate the feasibility of this innovative process. However, special attention has to be paid to the critical aspects such as granule stability as well as the economic competitiveness, which both will need further investigation and evaluation.     

Enhanced nitrogen removal using C/N load adjustment and real-time control strategy in sequencing batch reactors for swine wastewater treatment.

The laboratory-scale sequencing batch reactor (SBR) was used to study the effectiveness of an integrated strategy of real time control with C/N ratio adjustment for practical swine wastewater treatment. Swine waste was used as the external carbon source for continuous treatment in the SBR reactors. Oxidation-reduction potential and pH were used as parameters to control the continuous denitrification and nitrification process, respectively. A constant effluent quality could be obtained, despite drastic variations in the characteristics of influent wastewater. Also, a relatively complete removal of nutrients was always ensured, since the optimum quantity of the external carbon source could be provided for complete denitrification, and a flexible hydraulic retention time was achieved by the successful real-time control strategy. The average removal efficiencies of total organic carbon and nitrogen were over 94% and 95%, respectively.     

Temperature and conductivity as control parameters for pollution-based real-time control.

Most sewer system performance indicators are not easily measurable online at high frequencies in wastewater systems, which hampers real-time control with those parameters. Instead of using a constituent of wastewater, an alternative could be to use characteristics of wastewater that are relatively easily measurable in sewer systems and could serve as indicator parameters for the dilution process of wastewater. This paper focuses on the possibility to use the parameters of temperature and conductivity. It shows a good relation of temperature and conductivity with the dilution of DWF (dry weather flow) during WWF (wet weather flow) a monitoring station in Graz, Austria, as an example. The simultaneous monitoring of both parameters leads to valuable back-up information in case one parameter (temperature) shows no reaction to a storm event. However, for various reasons, anomalies occur in the typical behaviour of both parameters. The frequency and extent of these anomalies will determine the usefulness of the proposed parameters in a system for pollution-based real-time control. Both the normal behaviour and the anomalies will be studied further by means of trend and correlation analyses of data to be obtained from a monitoring network for the parameters of interest that is currently being set up in the Netherlands.     

Model-Based Operation of Multi-Purpose River and Reservoir Systems

The optimal management of multi-objective river and reservoir systems is particularly challenging for event-driven real-time operation to ensure predictive planning and to determine the best possible operation strategy. The best flow forecast possible for the river basin as well as knowledge of the effects of control instructions on flow dynamics and on the achievement of operation objectives must therefore be used. This paper presents a decision support tool for the management of a multi-objective river and reservoir system in Germany. In this context model-based predictive control is an appropriate method for optimizing the value to be controlled over a short forecast period. The future system status is simulated with a forecast-based hydraulic process model. In this way the most effective solutions for the required reservoir release which will fulfil the pre-specified multi-purpose operation objectives can be identified. These results can be used for the efficient analysis of upcoming conflicts of objectives. In combination with the users’ practical experience a realizable control instruction may be derived.

     

Innovations in wastewater treatment: the moving bed biofilm process.

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 degrees C), while denitrification rates were as high as 3.5g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.     

城镇污水处理厂的氮负荷分析

阐述了污水处理厂进水、生物系统进水氮负荷的分析和除氮过程中氮平衡分析的方法,通过举例说明了氮负荷的不同对除氮设施的影响。对污水处理厂除氯设计和污水处理厂除氮能力分析有一定的参考作用。     

On-line nitrification inhibition monitoring using immobilised bacteria

As wastewater treatment plant managers are required to meet increasingly stringent standards the focus on processes has shifted more and more towards assessing the treatability of a waste. Many substances discharged to effluent treatment plants may inhibit the process of nitrification. Traditional testing methods are costly and cannot be used for real time control which has led to the development of the Amtox™ system.Amtox™ uses a culture of immobilised nitrifying bacteria in a system maintained at 30°C. This enhances the rate of nitrification and gives an early warning of toxicity. This paper presents data comparing Amtox with the conventional nitrification inhibition test method and describes the instrument designed for laboratory use. Preliminary data for the on-line Amtox system are also included: these data provide the first, direct, continuous measure of nitrification inhibition on an effluent treatment plant.     

小城镇污泥处理方法

随着城镇化进程的加快.城镇污水排放量也不断增加,污水处理迫在眉睫.污水处理过程中必然产生大量成分复杂的污泥如处理不当会对环境造成严重污染.污泥的处理、处置在污水处理中是不可或缺的,如何将产量巨大、成分复杂的污泥进行妥善安全地处理,已成为深受关注的重大课题.针对小城镇污泥的特征,提出了几种宜在小城镇实施的污泥处理与处置方法.     

Monitoring systems and real-time data analysis

This paper describes a system used for the real-time handling of hydrological data. The system, which aims at evaluating hydrogeological risk, allows the integration of both historical and real-time data with geographic and cartographic information concerning the region being monitored.The second part of the paper describes an application of the system whose object is real-time forecast of landslide.     

An integrated approach for improving the wastewater discharge and treatment systems

Since treatment plants have been built all over Germany during the last decades, the water quality of receiving streams has been improved remarkably. But there are still a lot of quality problems left, which are caused e.g. by combined sewer overflows (CSO), treatment plant effluents or rainwater discharges from separate sewer systems. At present different efforts are undertaken to control sewer systems in order to improve the operation of urban drainage systems or more generally, design processes. The Emschergenossenschaft and Lippeverband (EG/LV) are carrying out research studies, which are focusing on a minimization of total emissions from sewer systems both from wastewater treatment plant (WWTP) effluents and from CSO. They consider dynamic interactions between rainfall, resultant wastewater, combined sewers, WWTP and receiving streams. Therefore, in an advanced wastewater treatment, a model-based improvement of WWTP operation becomes more and more essential, and consequently a highly qualified operational staff is needed. Some aspects of the current research studies are presented in this report. The need and the use of an integrated approach to combine existing model components in order to optimize dynamic management of combined sewer systems (CSS) with a benefit for nature are outlined.     

Implementing Pollution Source Control—Learning from the Innovation Process in English and Welsh Water Companies

Improving the stimulation and management of innovation by water utilities is a key mechanism through which the challenges of securing sustainable water and wastewater services will be achieved. This paper describes the process of adopting source control interventions (SCIs) by water and sewerage companies (WaSCs) in England and Wales. SCIs can be defined as efforts by water suppliers to control agricultural pollution where it arises. To investigate differences in the extent to which SCIs have and are being adopted across all ten WaSCs in England and Wales, Rogers’ five stage innovation model is used to structure and interpret results from a series of semi-structured interviews with raw water quality and catchment management personnel. Results suggest that to promote SCI innovation by WaSCs, regulation should be designed in two interdependent ways. First, regulation must generate awareness of a performance gap so as to set an agenda for change and initiate innovation. This can be achieved either through direct regulation or regulation which raises the awareness of an organisations performance gap, for example through additional monitoring. Simultaneously, regulation needs to create possibilities for implementation of innovation through enabling WaSCs to utilise SCIs where appropriate. Evidence from the research suggests that appropriate intermediary organisations can assist in this process by providing a resource of relevant and local knowledge and data. Future research should seek to characterise the factors affecting each stage in the WaSC innovation process both to confirm the conclusions of this study and to reveal more detail about various influences on innovation outcomes.     

Process control automation and remote on-line supervision: the strategy for wastewater treatment in an Italian piedmont

The paper deals with the real application of a strategy, based on process control automation and remote on-line supervision, for the wastewater treatment in a piedmont. Seven existing small wastewater treatment plants were selected to be upgraded and to be included into a network remotely supervised. A consolidated bending point based alternating process was applied for the biological treatment. Further, the potentialities of the process control automation were enhanced by the appropriate design of the whole plant. The examination of a case study included into the network shows the real stable high performances of the plant in terms of total nitrogen removal. Moreover, the power requirements are significantly reduced according to a correct energy policy.     

Exploring the Gap Between Water Managers and Researchers: Difficulties of Model-Based Tools to Support Practical Water Management

Supported by EU funds, the European research community has been putting much effort into providing model-based tools to support water resource managers in implementing water management as well as the implementation of the Water Framework Directive. This paper presents the results of a two-year long elicitation phase which aimed to explain why the use of tools in water management is not as great as the corresponding investment in applied research in this area might suggest it should be. The paper identifies a gap between water managers and research community that is evidence of a mutual misunderstanding of the fundamental activities of both communities. We elaborate on these misunderstandings between these two communities by focussing on their attitudes towards seven assumptions that derived from an elicitation phase carried out between 2003 and 2004. These misunderstandings appear to revolve around the issues of the role and importance of model-based tools in water management; the transferability of models to new target sites; the role of participatory modelling in water management; how to solve lack of confidence in model-based tools; the development of computer user interfaces to improve tool usability; and the nature of model integration. Based on these insights, recommendations for improving research, development and ultimately the use of model-based tools in river basin management processes are proposed. The recommendations include improving researchers’ understanding of water management processes and the role their tools play within such a process; identifying for both communities the importance that such tools can play as part of social learning-oriented management processes; improving the role of software consultancies as carriers of research results; considering new methods of model transferability between target basins; and expanding the structure of funding for academic research and development projects to allow the greater provision of non-technical requirements such as post-development tool maintenance and transferability, required by water managers.     

实时洪水预报中基于岭估计的AR修正模型研究

为提高实时洪水预报精度,经常将水文模型与误差修正模型相结合,AR模型因其结构简单广泛应用于实时洪水预报误差修正。然而,实际应用显示,AR模型时常出现修正结果不稳定现象,表现为流量修正幅度过大,甚至出现“震荡”现象,严重影响修正效果。鉴于此,本文从矩阵特征值角度解释了AR模型出现不稳定现象的原因,并引入岭估计方法选择性利用流量信息更新自回归系数,使其更满足真实流量的涨落过程,增强该模型的稳健性。将新方法应用于蔺河口流域,结果显示岭估计方法显著提高了AR模型的稳健性,从而改善了模型修正效果,进一步提高了洪水预报精度。     

Technical-economical evaluation of the operation of oxidation ditches.

The optimisation of the economic performance is a central aspect in the management of wastewater treatment plants. A model-based procedure was developed that could provide a clearly enunciated and concise way of reporting to the stakeholders on how well the assets are performing and can perform, separating the firm inefficiency from the effect of the treatment. The applied modelling method is conventional considering current modelling research practice, but very good from practical point of view in that it is applicable utilising existing plant data, i.e. without the use of additional measuring campaigns. This paper illustrates the validity of the developed procedures through the evaluation of the performance of oxidation ditches.     

Semi-quantitative analysis of a specific database on priority and emerging substances in wastewater and sludge

The Water Framework Directive (WFD) has drawn attention to a series of metals and organic compounds because of their demonstrated or potential harmfulness for aquatic environments. The aim of our work was to build and to process a "practical" database focused on the role of wastewater treatment plants for the removal of the 37 priority compounds that have to be reduced or stopped by 2015, and of 34 additional relevant contaminants. About 11,000 concentration values in raw and treated wastewater and sludge, from more than 100 peer-reviewed articles and six French national screening programs, were integrated. A systematic approach showed the global low quality of data for most of the compounds, with missing information about the treatment process, sampling and analysis, leading to 10% of the data available for removal efficiency calculations. A semi-quantitative analysis allowed the identification of 20 priority and 10 additional relevant substances more frequently quantified at significant concentrations in raw wastewater and treated wastewater. Conventional activated sludge was able to remove more than 70% of half of the studied compounds, leaving only 10% of them with less than 50% removal. Physical-chemical treatments appeared to be about 30% less efficient than biological treatments. In addition, very few data are available concerning some compounds and some processes, especially sludge treatment and tertiary wastewater treatment processes. Therefore, complementary on-site measurements and modeling are required to propose adapted solutions for the treatment of priority and emerging substances in wastewater treatment plants.     

Fuzzy control of nitrogen removal in predenitrification process using ORP.

In order to meet increasingly stringent discharge standards, new applications and control strategies for the sustainable removal of nitrogen from wastewater have to be implemented. In the past years, numerous studies have been carried out dealing with the application of fuzzy logic to improve the control of the activated sludge process. In this paper, fuzzy control strategies of predenitrification systems are presented that could lead to better effluent quality and, in parallel, to a reduction of chemicals consumption. Extensive experimental investigations on lab scale plant studies have shown that there was excellent correlation between nitrate concentration and ORP value at the end of the anoxic zone. Results indicated that ORP could be used as an on-line fuzzy control parameter of nitrate recirculation and external carbon addition. The optimal value of ORP to control nitrate recirculation and external carbon addition was - 86 +/- 2 mV and - 90 +/- 2 mV, respectively. The results obtained with real wastewater also showed the good performance and stability of the fuzzy controllers independently from external disturbances. The integrated control structure of nitrate recirculation and external carbon addition in the predenitrification system is also presented.     

滑坡区域的真三维数字仿真

介绍了一种滑坡区域的真三维数字模型仿真方法.通过已知的滑坡区地形数据,结合地质工作人员提供的剖面图,可以重建该区域的地下不同岩层属性及滑动面等与地质灾害紧密相关的地质结构.模型采用了基于三棱柱体体元的建模方法.实验结果证明该方法能较好地解决基于层状地质结构的三维仿真,能有效地将采样所获得的各种空间数据相融合,实现滑坡区域的真三维模拟,为地质灾害区域的防治提供可视化手段.     

Model-based control of the substrate concentration in an aeration basin using the wastewater level

This paper deals with the minimal-cost control of the modified activated sludge process with varying level of wastewater in the aerator tank. The model-based adaptive controller of the effluent substrate concentration, basing on the substrate consumption rate and manipulating the effluent flow rate outcoming from the aerator tank, is proposed and its performance is compared with conventional PI controller and open loop behavior. Since the substrate consumption rate is not measurable on-line, the estimation procedure on the basis of the least-square method is suggested. Finally, it is proved that cooperation of the DO concentration controller with the adaptive controller of the effluent substrate concentration allows the process to be operated at minimum costs (low consumption of aeration energy).