Knowledge-based supervision and control of wastewater treatment plant: a real-time implementation

The hardware architecture and the software development of a real-time knowledge-based distributed control system for the supervision of a wastewater treatment pilot plant are presented. The operation scheme is based on an A²/O system (anaerobic, anoxic, oxic) and includes organic matter removal, nitrification/denitrification, and Enhanced Biological Phosphorous Removal (EBPR). The hardware architecture involves different supervision levels, including two autonomous process computers (plant control and analysers control) and a PLC. The software architecture includes a Knowledge-Based Expert System (KBES) as the top control system. The KBES has been developed in G2, an expert system development environment based on object-oriented structural design. This system is fed with data obtained from the plant monitoring (in-line, on-line and off-line data) and with actuation data of the lower control levels. Using this information, the KBES supervises the pilot plant in order to help with fault detection and plant maintenance, but also modifies setpoints and other variables of the local control level to adapt the system to the different influent conditions. The overall system has been implemented and validated at pilot scale.Spanish Inter-Ministry Commission of Science and Technology (C.I.C.Y.T.) - BIO94-0679-C02, AMB97-0889-c03-01.Fundação Calouste Gulbenkian (FCG).Generalitat de Catalunya. Consell Interdepartamental de Recerca i Innovació Tecnològica (CIRIT)

Wastewater treatment improvement through an intelligent integrated supervisory system

This paper shows the result of years of work by a cooperative research group including chemical engineers, environmental scientists and computer scientists. This research has been focused on the development and implementation of new techniques for the optimisation of complex process management, mainly related to wastewater treatment plants (WWTP). The experience obtained indicates that the best approach is a Supervisory System that combines and integrates classical control of WWTP (automatic controller for maintaining a fixed dissolved oxygen level in the aeration tank, use of mathematical models to describe the process...) with the application of knowledge-based systems (mainly expert systems and case-based systems). The first part is an introduction to wastewater treatment processes and an explanation of the complexity of the management and control of such complex processes. The next section illustrates the architecture of the supervisory system and the work carried out to develop and build the expert system, the casebased system and the simulation model for implementation in a real plant (the Granollers WWTP). Finally, some results of the field validation phase of the Supervisory System when dealing with real situations in the plant are described.Aquest article mostra el resultat de la col·laboració portada a terme durant els darrers anys entre grups d'enginyeria química, enginyeria ambiental i intel·ligència artificial. El treball se centra en el desenvolupament de tècniques per a la millora i supervisió de processos complexos, especialment del tractament biològic d'aigües residuals. L'experiència demostra que la millor opció requereix desenvolupar un sistema supervisor que combini i integri tècniques de control clàssic (controlador automàtic del nivell d'oxigen dissolt en el reactor biològic, ús de models descriptius del procés, etc.) amb sistemes basats en el coneixement (concretament sistemes experts i sistemes basats en casos). El present article descriu la complexitat de la gestió del procés de tractament de les aigües residuals, l'arquitectura integrada que es proposa i el desenvolupament i la construcció de cadascun dels mòduls d'aquesta proposta per a la implementació real a l'estació depuradora d'aigües residuals de Granollers. Finalment, es detallen alguns resultats del procés de validació del seu funcionament enfront de situacions quotidianes de la planta

Wastewater treatment improvement through an intelligent integrated supervisory system

Aquest article mostra el resultat de la col·laboració portada a terme durant els darrers anys entre grups d'enginyeria química, enginyeria ambiental i intel·ligència artificial. El treball se centra en el desenvolupament de tècniques per a la millora i supervisió de processos complexos, especialment del tractament biològic d'aigües residuals. L'experiència demostra que la millor opció requereix desenvolupar un sistema supervisor que combini i integri tècniques de control clàssic (controlador automàtic del nivell d'oxigen dissolt en el reactor biològic, ús de models descriptius del procés, etc.) amb sistemes basats en el coneixement (concretament sistemes experts i sistemes basats en casos). El present article descriu la complexitat de la gestió del procés de tractament de les aigües residuals, l'arquitectura integrada que es proposa i el desenvolupament i la construcció de cadascun dels mòduls d'aquesta proposta per a la implementació real a l'estació depuradora d'aigües residuals de Granollers. Finalment, es detallen alguns resultats del procés de validació del seu funcionament enfront de situacions quotidianes de la planta.This paper shows the result of years of work by a cooperative research group including chemical engineers, environmental scientists and computer scientists. This research has been focused on the development and implementation of new techniques for the optimisation of complex process management, mainly related to wastewater treatment plants (WWTP). The experience obtained indicates that the best approach is a Supervisory System that combines and integrates classical control of WWTP (automatic controller for maintaining a fixed dissolved oxygen level in the aeration tank, use of mathematical models to describe the process...) with the application of knowledge-based systems (mainly expert systems and case-based systems). The first part is an introduction to wastewater treatment processes and an explanation of the complexity of the management and control of such complex processes. The next section illustrates the architecture of the supervisory system and the work carried out to develop and build the expert system, the casebased system and the simulation model for implementation in a real plant (the Granollers WWTP). Finally, some results of the field validation phase of the Supervisory System when dealing with real situations in the plant are described

A Multi-Agent System framework to support the decision-making in complex real-world domains

The aim of this work was to develop a framework capable of supporting the decision-making process in complex real-world domains, such as environmental, industrial or medical domains using a Multi-Agent approach with Rule-based Reasoning. The validation of the framework was done in the environmental domain, particularly in the area of river basins

An Agent Architecture for Supervising a Pilot WWTP

Abstract: This paper describes the development and implementation of a real-time Knowledge-Based System (KBS) for the supervision and control of a wastewater treatment pilot plant (WWTPP) with biological removal of organic matter and nutrients. The hardware architecture contains different supervision levels, including two autonomous process computers (plant control and analyzers control) and a PLC, being the KBS the top supervisory level. The KBS has been developed using the G2 expert systems shell, and it is implemented for real-time operation. The implementation of the different components of the KBS is done under the Intelligent Agents paradigm. The knowledge is organized in several distributed agents, representing the available knowledge for every sub-process of the WWTPP. In addition to these independent agents, a Supervisor Agent acts as the master of the independent agents. The implementation of the KBS in the pilot plant has supposed the transformation of a classical control system with a fixed behavior in a system adaptable to different problems that could appear in a WWTP. The main achievement of this prototype is a versatile framework able to deal with different plant configurations, based on the object-oriented paradigm and on rule-based reasoning

ProCLAIM: an argument-based model for deliberating over safety critical actions

In this Thesis we present an argument-based model – ProCLAIM – intended to provide a setting for heterogeneous agents to deliberate on whether a proposed action is safe. That is, whether or not a proposed action is expected to cause some undesirable side effect that will justify not to undertake the proposed action. This is particularly relevant in safetycritical environments where the consequences ensuing from an inappropriate action may be catastrophic. For the practical realisation of the deliberations the model features a mediator agent with three main tasks: 1) guide the participating agents in what their valid argumentation moves are at each stage of the deliberation; 2) decide whether submitted arguments should be accepted on the basis of their relevance; and finally, 3) evaluate the accepted arguments in order to provide an assessment on whether the proposed action should or should not be undertaken, where the argument evaluation is based on domain consented knowledge (e.g guidelines and regulations), evidence and the decision makers’ expertise. To motivate ProCLAIM’s practical value and generality the model is applied in two scenarios: human organ transplantation and industrial wastewater. In the former scenario, ProCLAIM is used to facilitate the deliberation between two medical doctors on whether an available organ for transplantation is or is not suitable for a particular potential recipient (i.e. whether it is safe to transplant the organ). In the later scenario, a number of agents deliberate on whether an industrial discharge is environmentally safe.En esta tesis se presenta un modelo basado en la Argumentación –ProCLAIM– cuyo n es proporcionar un entorno para la deliberación sobre acciones críticas para la seguridad entre agentes heterogéneos. En particular, el propósito de la deliberación es decidir si los efectos secundario indeseables de una acción justi can no llevarla a cabo. Esto es particularmente relevante en entornos críticos para la seguridad, donde las consecuencias que se derivan de una acción inadecuada puede ser catastró cas. Para la realización práctica de las deliberaciones propuestas, el modelo cuenta con un agente mediador con tres tareas principales: 1) guiar a los agentes participantes indicando cuales son las líneas argumentación válidas en cada etapa de la deliberación; 2) decidir si los argumentos presentados deben ser aceptadas sobre la base de su relevancia y, por último, 3) evaluar los argumentos aceptados con el n de proporcionar una valoración sobre la seguridad de la acción propuesta. Esta valoración se basa en guías y regulaciones del dominio de aplicación, en evidencia y en la opinión de los expertos responsables de la decisión. Para motivar el valor práctico y la generalidad de ProCLAIM, este modelo se aplica en dos escenarios distintos: el trasplante de órganos y la gestión de aguas residuales. En el primer escenario el modelo se utiliza para facilitar la deliberación entre dos médicos sobre la viabilidad del transplante de un órgano para un receptor potencial (es decir, si el transplante es seguro). En el segundo escenario varios agentes deliberan sobre si los efectos de un vertido industrial con el propósito de minimizar su impacto medioambiental

Optimisation of a water company’s waste pumping asset base with a focus on energy reduction

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonWater companies use a significant quantity of electricity for the operation of their clean and wastewater assets. Rising energy prices have led to higher energy bills within the water companies, which has increased operating costs. Thus, improvements in demand side energy management are needed to increase efficiency and reduce costs, which forms the premise for this research project. Thames Water Utilities Ltd has identified that improvements in demand side energy management is required and is currently researching various methods to reduce energy consumption. One initiative included the upgrade of a variety of site telemetry assets. By deploying these new telemetry assets, Thames Water Utilities Ltd are more able to liberate the asset data and as such, be able to make informed decisions on how better to control and optimise the target sites, which is where this research project has seen further opportunities. This enhanced telemetry and SCADA infrastructure will enable successful research to further develop an intelligent integrated system that tackles pump scheduling and process control with the emphasis on energy management. The use of modern techniques, such as artificial intelligence, to optimise the network operation is gradually gaining traction. The balance between implementing new technology (with the benefits it may bring) and reluctance to change from the incumbent operating model will always provide challenges in the technology adoption agenda. The main work of this research project included the physical surveying of a wastewater hydraulic catchment, inclusive of all wet well dimensions, lidar overlays, and pump electrical power characteristics. These survey results where then able to be programmed by the research into the company’s' hydraulic model to enable a higher degree of accuracy in the modelling, as well as enabling electrical power as a measurable output. From here, the model was then able to be optimised, focussing on electrical energy as an output variable for reduction. The research concluded that electrical energy consumption over time can be reduced using the aforementioned strategies and as such recommends further work to move from the model environment to physical architecture. It does so with the key message that risk tolerances on water levels must be pre-agreed with hydraulic specialists prior to deployment

Institutional arrangements for resource recovery and reuse in the wastewater sector

As populations grow and urban centres expand, meeting water demand and wastewater management requirements will become increasingly difficult. Goal 6 of the Sustainable Development Goals is to: ‘Ensure availability and sustainable management of water and sanitation for all’. Part of the approach to achieving this will be reusing wastewater and will require a greater understanding of the institutional arrangements that support or obstruct reuse. This research was designed to achieve this and aimed to develop a set of factors that investors could use to assess the institutional feasibility of reuse in a given setting. The methodology combined a case study approach, focusing on wastewater systems in Bangalore, India and Hanoi, Vietnam, with triangle analysis to assess: the content of policies and laws; the structures (formal and informal) to implement laws and reuse projects; and the culture around acceptance and engagement in reuse. The reuse practices observed in Bangalore were treatment and use within apartments, centralized treatment and sale to industries, use in agriculture after natural attenuation, groundwater recharge and lake regeneration. In Hanoi the only reuse was indirect use from rivers feeding fish ponds and fields, although formal treatment and use is planned. Critically, both cities have environmental and water resources policies and laws that advocate reuse, as well as related local legislation. However, support for reuse is not reciprocated in industrial, agricultural or fisheries law, the result being that reuse does not always take place as planned. Legislation is required along the whole sanitation chain to the point of wastewater use. Structures to implement reuse are also vital. In Bangalore the water board has initiated reuse projects and established the New Initiatives Division but resources are a limiting factor. Effective institutions include expertise, manpower and financing mechanisms, which are lacking in both cities. The environment agency is also engaged in reuse though legislation on recycling in residential and commercial complexes but guidance for users is inadequate, expectations are perceived to be excessive and monitoring is almost impossible. The driver for reuse is increasingly the benefits observed by users. In the case of apartments this is a reliable water source and reduced costs of water supply. As a result, a private sector in wastewater treatment is becoming established. The active civil society and strong, independent media are instrumental in providing information to potential users and holding authorities to account in Bangalore. Their absence in Hanoi is notable. In summary, institutional elements to be considered are: supportive legislation across all sectors; details of acceptable reuse, deterrents and inducements; budget allocation; structures to enable reuse; strong civil society, NGOs, courts, media and universities providing evidence of suitability and safety; donors and finance mechanisms; and stakeholders willing to use the products. Encumbrances are inconsistent or uncoordinated legislation, lack of cooperation and insufficient benefit sharing or perceptions of benefits along the reuse chain

Bibliographical review on cyber attacks from a control oriented perspective

This paper presents a bibliographical review of definitions, classifications and applications concerning cyber attacks in networked control systems (NCSs) and cyber-physical systems (CPSs). This review tackles the topic from a control-oriented perspective, which is complementary to information or communication ones. After motivating the importance of developing new methods for attack detection and secure control, this review presents security objectives, attack modeling, and a characterization of considered attacks and threats presenting the detection mechanisms and remedial actions. In order to show the properties of each attack, as well as to provide some deeper insight into possible defense mechanisms, examples available in the literature are discussed. Finally, open research issues and paths are presented.Peer ReviewedPostprint (author's final draft