A concept of water usage efficiency to support water reduction in manufacturing industry

Increasing pressures on freshwater supplies, continuity of supply uncertainties, and costs linked to legislative compliance, such as for wastewater treatment, are driving water use reduction up the agenda of manufacturing businesses. A survey is presented of current analysis methods and tools generally available to industry to analyze environmental impact of, and to manage, water use. These include life cycle analysis, water footprinting, strategic planning, water auditing, and process integration. It is identified that the methods surveyed do not provide insight into the operational requirements from individual process steps for water, instead taking such requirements as a given. We argue that such understanding is required for a proactive approach to long-term water usage reduction, in which sustainability is taken into account at the design stage for both process and product. As a first step to achieving this, we propose a concept of water usage efficiency which can be used to evaluate current and proposed processes and products. Three measures of efficiency are defined, supported by a framework of a detailed categorization and representation of water flows within a production system. The calculation of the efficiency measures is illustrated using the example of a tomato sauce production line. Finally, the elements required to create a useable tool based on the efficiency measures are discussed

Cost-Effective Water Quality Management Strategies in Central and Eastern Europe

Many countries in Central and Eastern Europe will be formulating new environmental regulations within the next few years. Among the many topics which these are likely to address is the development of control policies for waste-water dischargers, including municipal sewage treatment plants. In Western Europe and North America, standards have relied heavily upon so-called "best available technology" control policies, which require dischargers to use treatment processes that reduce emissions of BOD, phosphorus, and nitrogen as much as is technically feasible. However, these technologies are often very expensive. Given the state of Central and Eastern European economies, less expensive methods to improve water quality should be seriously considered. In this paper, we investigate control policies, alternative sewage treatment possibilities, water quality models, and optimization methods required to identify least-cost strategies to improve the region's ambient water quality. We survey the costs and technical capacities of a variety of treatment techniques, ranging from simple primary or mechanical treatment to advanced technology to remove nutrients. We also survey existing water quality models and show how they can be adapted to the policy analysis problem. Finally, we characterize a number of potential policies in terms that are amenable to analysis of their costs and ambient quality impacts. Focussing on municipal waste-water treatment plants and water quality in rivers and streams, we show how these techniques can be integrated and applied. We conclude with an empirical example based on the Nitra, a small, heavily contaminated river in Slovakia

Doctor of Philosophy

dissertationControlling combined sewer overflows (CSOs) is one of the greatest urban drainage challenges in more than 700 communities in the United States. Traditional drainage design typically leads to centralized, costly and energy-intensive infrastructure solutions. Recently, however, application of decentralized techniques to reduce the costs and environmental impacts is gaining popularity. Rainwater harvesting (RWH) is a decentralized technique being used more often today, but its sustainability evaluation has been limited to a building scale, without considering hydrologic implications at the watershed scale. Therefore, the goal of this research is to study watershed-scale life cycle effects of RWH on controlling CSOs. To achieve this goal, (i) the life cycle costs (LCC) and long-term hydrologic performance are combined to evaluate the cost-effectiveness of control plans, (ii) the life cycle assessment (LCA) and hydrologic analysis were integrated into a framework to evaluate environmental sustainability of control plans, and (iii) the major sources of uncertainty in the integrated framework with relative impacts were identified and quantified, respectively. A case study of the City of Toledo, Ohio serves as the platform to investigate these approaches and to compare RWH with centralized infrastructure strategies. LCC evaluation shows that incorporating RWH into centralized control plans could noticeably improve the cost-effectiveness over the life cycle of drainage infrastructure. According to the results of the integrated framework, incorporating RWH could reduce Eco-toxicity Water (ETW) impacts, but caused an increase in the Global Warming Potential (GWP). In fact, incorporating RWH contributes to avoidance of untreated discharges into water bodies (thus reducing ETW) and additional combined sewage delivered to treatment facilities (thus increasing GWP). The uncertainty analysis suggests that rainfall data (as a hydrologic parameter) could be a significant source of the uncertainty in outputs of the integrated framework. Conversely, parameters of LCIA (life cycle impact assessment) could have trivial impacts on the outputs. This supports the need for robust hydrologic data and associated analyses to increase the reliability of LCA-based urban drainage design. In addition, results suggest that such an uncertainty analysis is capable of rendering optimal RWH system capacity as a function of annual rainfall depth to lead to minimized life cycle impacts. Capacities smaller than the optimal size would likely result in loss of RWH potable water savings and CSO control benefits, while capacities larger than optimal would probably incur excessive wastewater treatment burden and construction phase impacts

Comparison of control strategies for multi-objective control of urban wastewater systems

In recent years much attention has been paid to integrated management and control of urban wastewater systems. With the application of integrated system modelling tools, overall system performance can be improved to a great extent in terms of receiving water quality, through development of optimal control strategies. Most studies to date, however, have used a single objective to demonstrate the potential benefits. Control of urban wastewater systems is actually a multiple objective optimisation problem, involving balancing different, possibly conflicting objectives required by stakeholders with different interests. This paper compares three different control strategies for multi-objective optimal control of the urban wastewater system, including one global control strategy and two integrated control strategies. A popular multiple objective evolutionary algorithm, NSGA II, is applied to derive the Pareto optimal solutions for the three strategies. The comparative results show the benefits of application of integrated control in achieving an improved system performance in terms of dissolved oxygen and ammonium concentrations in the receiving river. The simulation results also illustrate the effectiveness of NSGA II in deriving the optimal control strategies with different complexities

Optimizing the design of an estuarine water quality monitoring network by optimal control techniques

In this work, we propose a novel methodology in order to automatically optimize the location of the sampling points for a water quality monitoring network in an estuary, in such a way that any unknown pollution source can be identified (both in intensity and location) from the data supplied by those sampling points. In the central part of the article, after a rigorous mathematical formulation of the environmental problem, the full details of its numerical implementation are given. Finally, we present and analyze the results when applying the above proposed technique to study a real case in Ría of Vigo (northwestern Spain).Agencia Estatal de Investigación | Ref. TED2021-129324B-I00Universidade de Vigo/CISU

Optimisation-based methodology for the design and operation of sustainable wastewater treatment facilities

The treatment of municipal and industrial wastewaters in conventional wastewater treatment plants (WWTPs) requires a significant amount of energy in order to meet ever more stringent discharge regulations. However, the wastewater treatment industry is undergoing a paradigm shift from a focus on waste-stream treatment and contaminant removal to a proactive interest in energy and resource recovery facilities, driven by both economic and environmental incentives. The main objective of this thesis is the development of a decision-making tool in order to identify improvement opportunities in existing WWTPs and to develop new concepts of sustainable wastewater treatment/recovery facilities. The first part of the thesis presents the application of a model-based methodology based on systematic optimisation for improved understanding of the tight interplay between effluent quality, energy use, and fugitive emissions in existing WWTPs. Plant-wide models are developed and calibrated in an objective to predict the performance of two conventional activated sludge plants owned and operated by Sydney Water, Australia. In the first plant, a simulation-based approach is applied to quantify the effect of key operating variables on the effluent quality, energy use, and fugitive emissions. The results show potential for reduced consumption of energy (up to 10-20%) through operational changes only, without compromising effluent quality. It is also found that nitrate (and hence total nitrogen) discharge could be signficantly reduced from its current level with a small increase in energy consumption. These results are also compared to an upgraded plant with reverse osmosis in terms of energy consumption and greenhouse gas emissions. In the second plant, a systematic model-based optimisation approach is applied to investigate the effect of key discharge constraints on the net power consumption. The results show a potential for reduction of energy (20-25%), without compromising the current effluent quality. The nitrate discharge could be reduced from its current level to less than 15 mg/L with no increase in net power consumption and could be further reduced to <5 mg/L subject to a 18% increase in net power consumption upon the addition of an external carbon source. This improved understanding of the relationship between nutrient removal and energy use for these two plants will feed into discussions with environmental regulators regarding nutrient discharge licensing.The second part of the thesis deals with the application of a systematic, model-based methodology for the development of wastewater treatment/resource recovery systems that are both economically and environmentally sustainable. With the array of available treatment and recovery options growing steadily, a superstructure modeling approach based on rigorous mathematical optimisation provides a natural approach for tackling these problems. The development of reliable, yet simple, performance and cost models is a key issue with this approach in order to allow for a reliable solution based on global optimisation. it is argued that commercial wastewater simulators can be used to derive such models. The superstructure modeling framework is also able to account for wastewater and sludge treatment in an integrated system and to incorporate LCA with multi-objective optimisation to identify the inherent trade-off between multiple economic and environmental objectives. This approach is illustrated with two case studies of resource recovery from industrial and municipal wastewaters. The results establish that the proposed methodology is computationally tractable, thereby supporting its application as a decision support system for selection of promising wastewater treatment/resource recovery systems whose development is worth pursuing. Our analysis also suggests that accounting for LCA considerations early on in the design process may lead to dramatic changes in the configuration of future wastewater treatment/recovery facilities.Open Acces

Assessing the Viability of Heuristic Predictive Control for Integrated Urban Drainage Systems

The implementation of real time control (RTC) in integrated urban drainage systems (IUDS) has been extensively explored in numerous studies, with the purpose of improving its performance, particularly, during storm occurrences. This approach frequently focuses on volume-based control, to minimize combined sewer overflows (CSOs) volume and investment costs in CSO controlling and new infrastructures intended to manage these incidents and mitigate polluted discharges into the receiving watercourses. Among the different RTC strategies, heuristic and optimization-based control can be distinguished from the research work available, such as rule based RTC (RB-RTC) and model predictive control (MPC), respectively. To enhance the viability of RTC, rainfall forecasting has been introduced in the IUDS, to assess the possible combination with RTC and the benefits and risks that derive from it, considering these forecasts are associated with uncertainties. Despite the reasonable results obtained for both control strategies in CSO controlling, only optimization-based control has been combined with rainfall forecasts. This dissertation assesses the potential of heuristic predictive control in IUDS, by combining RB RTC with real radar rainfall forecast and applying it to a case study in the Netherlands. An existent full-integrated catchment model built for the IUDS selected for this study was used and sufficiently calibrated to deliver reasonable results compared with monitoring data. The accuracy of the real radar rainfall forecast was evaluated and, when compared with observed rainfall data, it correctly predicts a considerable amount of storm occurrences. One of the two heuristic control strategies developed proved to be beneficial for the performance of the IUDS, contributing for CSO volume reduction and avoiding the overcharge of the wastewater treatment plant (WWTP). This can potentially increase the quality of the receiving watercourses, prevent urban flooding and maximize the efficiency of the WWTP operation. Finally, recommendations, to further improve and explore heuristic predictive control, are provided.A implementação de controlo em tempo real (RTC) nos sistemas de drenagem urbanos integrados (IUDS) tem sido investigada com o propósito de melhorar o seu desempenho, particularmente, durante eventos de precipitação. Esta abordagem baseia-se maioritariamente na minimização do volume das descargas de emergência (CSOs) e dos custos de investimento no controlo de CSO e em novas infraestruturas projetadas para mitigar estas ocorrências e a deterioração dos emissários. As estratégias de RTC podem ser fundamentalmente baseadas em controlo heurístico e de otimização, distinguindo-se o RTC baseado em regras (RB-RTC) e modelo de controlo preditivo (MPC), respetivamente. Embora esteja associada a incertezas, a previsão de precipitação foi introduzida em IUDS para investigar a sua combinação com o RTC, nomeadamente os benefícios e os riscos. Estas estratégias apresentam resultados razoáveis relativamente ao controlo de CSO, mas, apenas as de otimização foram aplicadas com previsões. Esta dissertação avalia o potencial do controlo preditivo heurístico em IUDS, através da aplicação de RB-RTC com previsão de precipitação por radar num estudo de caso nos Países Baixos. Para isso, um modelo de drenagem urbana desenvolvido para o IUDS selecionado para este estudo foi utilizado e suficientemente calibrado para produzir resultados razoáveis, comparativamente a medições de monitorização. A precisão da previsão também foi avaliada e comparada com medições, e a mesma prevê corretamente um número considerável de eventos de precipitação. Uma das duas estratégias de controlo heurístico desenvolvidas demonstrou constituir um benefício para um melhor desempenho dos IUDS, uma vez que contribui para a redução do volume de CSO e evita a sobrecarga da estação de tratamento de águas residuais (WWTP). Esta estratégia pode também contribuir para um aumento da qualidade dos emissários, prevenir inundações urbanas e maximizar a eficiência da operação das WWTP. Por fim, são disponibilizadas recomendações para investigar e melhorar o controlo preditivo heurístico

NoMoDEI : A framework for Norm Monitoring on Dynamic Electronic Institutions

With the growth of the Internet, computational systems have become more and more complex, often including complicate interconnected networks of autonomous components. The need to bring some organisational structure into autonomous systems becomes urgent, as this allows regulating the behaviour of the different autonomous components to ensure their objectives are aligned with the holistic objectives of the system. Normative Systems are one of the mechanisms that can be applied to define and enforce acceptable behaviour within distributed electronic systems which should comply with some (human) regulations. One of the requirements to effectively implement Normative Systems is to be able to assess, at runtime, the state of the normative environment. Existing lines of research have already tried to tackle this issue on some simple scenarios. However, more complex scenarios may appear, for instance, scenarios where the normative context is not static, but it expands and contracts as new norms are added to the institution and removed from it respectively. As in human legal systems, it is easy to foresee that some of these electronic normative environments will not be static. They should be able to evolve through time as regulations change, effectively adapting to new situations and behaviours. Under these conditions, a monitoring system must be able to continue computing the state of the normative environment at runtime, as often we can not afford to perform the changes on the normative context off-line. Furthermore, it must be guaranteed the monitoring system can keep producing states of the normative environment that are consistent with the changes performed on the normative context. For instance, if a norm has been removed from the normative context, it does not make sense anymore to compute normative states where the norm has been violated. In this thesis we present NoMoDEI, a normative monitoring framework for dynamic Electronic Institutions. We formalize and develop an extended normative framework and architecture to cope with scenarios where the normative context is dynamic, therefore norms can be added, removed and updated. The operations are to be performed at run-time, without having to stop computing the normative state. The normative states computed are consistent with the expansion and contraction operations. NoMoDEI is introduced in three steps. First, we formally define the operations to be supported in order to allow for expanding and contracting the normative context. Then, we instantiate the formal operations, providing implementation details. Finally, we demonstrate our framework by applying it to two use cases: E-health systems and waste-water management on a river basin.Amb l'expansió d'Internet els sistemes computacionals han esdevingut més complexos, sovint incorporant complicades xarxes interconnectades de components autònoms. Es per això que la necessitat d'incorporar estructures organitzacionals en el sistemes autònoms s 'accentua, donat que aquestes estructures permeten regular el comportament dels diferents components autònoms, tot assegurant que els seus objectius es troben alineats amb els objectius generals del sistema. Els Sistemes Normatius (i.e. Normative Systems) són un dels mecanismes que podem aplicar per definir i imposar patrons acceptables de comportament dintre de sistemes electrònics distribuïts. Això esdevé especialment important quan el sistema es troba regimentat per regulacions (normalment humanes). Un dels requeriments per implementar Sistemes Normatius és ser capaços de determinar, en temps d'execució, l'estat de l'entorn normatiu. Existeixen línies de recerca que ja han tractat aquest problema en alguns escenaris simples. El món real però ens ofereix escenaris més complexes, com per exemple, escenaris on el context normatiu no és estàtic, si no que s'expandeix i contrau a mesura que noves normes són afegides o eliminades de la institució. Tal com passa als sistemes legals humans, és fàcil preveure que alguns contextos normatius electrònics no seran estàtics. Aquests contextos haurien de ser capaços d'evolucionar a través del temps a mesura que les regulacions canvien, adaptant-se a noves situacions i comportaments. Sota aquestes condicions, un sistema de monitorització ha de ser capaç de continuar calculant l'estat de l'entorn normatiu en temps d'execució, ja que sovint no ens podem permetre realitzar els canvis a l'entorn normatiu aturant el procés de monitorització. És més s'ha de garantir que el sistema de monitorització sigui capaç de continuar produint es tats de l’entorn normatiu de forma consistent amb els canvis realitzats. Per exemple, el fet d'eliminar una norma fa que no tingui gaire sentit continuar calculant es tats normatius on aquesta norma ha es tat violada. A aquesta Tesi presentem NoMoDEI, una infraestructura de monitorització normativa per institucions electròniques dinàmiques. Formalitzem i desenvolupem una infraestructura de monitorització normativa estesa capaç d'operar en escenaris on el context normatiu es dinàmic. Es a dir, diverses normes poden ser introduïdes, eliminades o actualitzades del context normatiu en qualsevol moment. Aquestes operacions s'han de poder realitzar en temps d'execució, es a dir, sense deixar de calcular l'estat normatiu. Es més, els estats normatius calculats han de ser consistents amb les respectives operacions d'extensió o contracció del context. Durant la Tesi presentem NoMoDEI en tres passos. Primer proporcionem una definició formal de les operacions que la infraestructura ha de suportar per permetre expandir i contraure el context normatiu. A continuació instanciem aquestes operacions proporcionant detalls d'implementació. Finalment demostrem que la nostra infraestructura pot ser aplicada a casos d'ús del món real introduint dos casos: sistemes de salut electrònics (i.e. E-health) i sistemes de tractament d’aigües residuals a la conca d’un riuPostprint (published version

Water Quality Management in the Nitra River Basin

The Nitra River is a tributary of the Vih which enters the Danube downstream of Bratislava. The watershed area is slightly larger than 5000 km2, and more than 650000 inhabitants live there. The quality of the river is one of the poorest in Slovakia due to numerous municipal and industrial discharges and the low level of wastewater treatment. The ongoing economic transition and shortage of financial resources for environmental management call for the development of regional short-run, least-cost policies. The development of such policies was the main objective of this joint study with the participation of IIASA, the Water Research Institute (VUVH, Bratislava) and the Vih River Basin Authority. The present state of emissions and water quality was evaluated on the basis of available, routine types of information (including observations from the basin-wide water quality monitoring network) and additional data collection. It was found that industrial discharges form problems which can be handled mostly locally with a straight-forward strategy. In contrast, the management of municipal discharges -- representing about 70% of the total BOD5 emission in the catchment -- is a more complex issue requiring the development of a regional policy. The definition of ambient water quality criteria (or the usage of a combination of ambient and effluent criteria) reflecting water use is a pre-requisite of the establishment of a least-cost policy. Thus, the application of water quality models is necessary to relate emissions to receiving water quality (as well as their changes). Due to the nature of the problem, a number of oxygen and nutrient balance models were used, ranging from the traditional Streeter-Phelps model to the latest version of U.S. EPA's QUAL model family. The models were calibrated and validated on the basis of two comprehensive longitudinal water quality profile observations. These observations were gathered under low-flow conditions to correspond with the design requirements of the strategy development. Due to the presence of uncertainties of different origins, the methodology of Hornberger, Spear, and Young (based on the so-called "behavior definition") was applied for parameter estimation of simpler models which then were directly incorporated into an optimization model. This optimization model was based on dynamic programming, utilizing structural features of river basin water pollution problems. Elements of the water quality control policy model or decision support system (including the linked hydraulic and water quality model(s), the parameter estimation and uncertainty analysis routines, the dynamic programming, the database, the graphical user-interface, etc.) were developed in a rather generic fashion to allow a transfer from one watershed to another. This philosophy corresponds to the broader goals of IIASA's Water Resources Project dealing with issues of the management of degraded river basins in Central and Eastern Europe and the development of associated methodologies for which the Nitra River served as a case study. Starting from the existing municipal wastewater treatment facilities, a number of alternatives were developed for each site on the basis of various combinations of well-proven physical, biological, and chemical processes to which different effluent quality (BOD-5, TP, NH4-N, NO3-N, etc.) as well as investment, operation, maintenance, and repair costs belong. The technological alternatives (and their major parameters) serve as input to the management optimization model. A special focus was devoted to phased plant development and innovative, cost-effective upgrading of highly overloaded plants by adding chemicals in low dosage. The issue of upgrading was also experimentally analyzed by jar tests at different treatment plants. The objectives of the policy model were formulated in terms of minimizing the total annual cost or the investment cost. Constraints might incorporate ambient water quality (characterized by DO, BOD-5 and NH4-N), effluent criteria, and/or minimum level of treatment. The derived least-cost policies were compared to policies based strictly on effluent criteria and to those based on the application of "best available technology." The effluent criteria based policy stems from the new Slovakian legislation if its ambient criteria element was excluded (the legislation defines the simultaneous usage of effluent and ambient criteria and an eleven-year long transition period after which more stringent standards should be met). The role of industrial emissions was demonstrated in a sensitivity fashion, while the influence of parameter uncertainty on the developed policies was analyzed by an a posteriori Monte Carlo simulation and a multi-objective assessment. The study shows that significant cost savings are possible in comparison to uniform, effluent standard policies. They also suggest that a long-term strategy should be realized on the basis of a sequence of properly phased least-cost policies corresponding to ambient (or regionally variable) standards to be tightened gradually as financial resources become available