Funding body: European Commission (Framework 5)

Wastewater reuse presents a feasible solution to the growing pressure on Europe's water resources. However, wastewater reuse implementation faces obstacles that include insufficient public acceptance, technical, economic and hygienic risks and further uncertainties caused by a lack of awareness, accepted standards, guidelines and uniform European legislation.

Funding body: Engineering and Physical Sciences Research Council (EPSRC)

The network project is half-way through its three year grant period. It has made good progress in developing and maintaining contact between academic groups researching into computer technology for the design and management of underground infrastructure for the water industry, on both the clean and wastewater sides. Contacts with industry have been strengthened with new industrial members joining, and an increased awareness of the needs of industry conveyed to the academic members.

Funding body: Engineering and Physical Sciences Research Council (EPSRC)

Funding body: Ewan Optimal Solutions Ltd.

Development work resulted in the software programs, GAnet and GAcal, which have been used on commercial projects involving hydraulic model calibration, design of water distribution network reinforcement and rehabilitation schemes and the optimization of level controlled pumping station operation. GAcal has also been sold commercially. Current development work is aimed at integrating GAnet with OpenNet, a library of C++ classes that provide the facilities for modelling water networks.

Funding body: Engineering and Physical Sciences Research Council (EPSRC)

The joint project between the Exeter University's Centre for Water Systems and Imperial College is aimed at developing an integrated, inverse-transient approach to leakage detection and model calibration.

Funding body: Engineering and Physical Sciences Research Council (EPSRC)

An EPSRC project titled 'Inverse Transient Analysis in Pipe Networks for Leakage Detection, Quantification and Roughness Calibration' was executed jointly by Exeter University (EU, GR/M66981/01) and Imperial College (IC). The project was initiated around the idea of detecting leaks in water distribution systems (WDS) by calibrating the transient simulation model for unknown nodal leaks (Liggett et al., 1994). During the project, EU's part of the research work was to concentrate on the improvement of existing methodologies for WDS model calibration and sampling design.

Funding body: Engineering and Physical Sciences Research Council (EPSRC)

To promote the efficient use of resources there is a recognised need to make best use of existing infrastructure. Whole Life Costing (WLC) in combination with computational optimisation techniques has been used to satisfy this need. WLC methodologies consider all the costs (private & social) that accrue to initiation, provision, operation, maintenance, servicing and decommissioning, over the useful life of a service facility. Application of WLC to (capital and operational) management of water distribution networks has been based on detailed consideration of holistic performance and explicit linking of costs to their drivers. Decision Modelling links the Costs and Performance frameworks via WLC Scenario Management Software called WiLCO.

Funding body: Commonwealth Commission

Operational energy costs make up a substantial proportion of the annual expenses of water supply utilities. It is thus important that the operational control of water distribution systems is optimized to ensure that appropriate levels of service and reliability are met at minimum cost. The operational optimization problem is complicated by a number of factors: vast numbers of possible operational solutions; variations in demands and electricity tariffs through a typical operating cycle; minimum reservoir level requirements; and limitations on the number of pump switches. An additional complication is the non-linear hydraulic behaviour of water distribution systems, which makes computer modelling of these systems computationally expensive. One of the most effective ways of optimizing the operation of water distribution systems is through the application of genetic algorithms (GAs).

Calibration of computer models for network analysis is a regular component of the model building process. The process generally first involves a series of field tests during which pressures and flows are recorded at strategic locations in the system. This is followed by a desk exercise during which adjustments are made to the roughness values used in modelling the system until a satisfactory match is obtained between modelled and observed values. The selection of a satisfactory set of roughness values can be a tedious business when undertaken by the traditional trial and error approach. In this work, several methodologies were proposed to assist the modeller in the following two tasks: firstly in the selection of sensitive sampling locations in a water distribution system and secondly in the derivation of a good calibrated hydraulic network model. A new calibration approach which consists of adjusting the pipe roughness, the pipe diameter and the nodal demand which certain limits, is proposed by using a genetic algorithm search method.

Funding body: ERASMUS scheme (European Community)

The water industry in the United Kingdom spends approximately £70,000,000 per annum on electricity for pumping water supply. Similarly, almost 7% of the electricity consumed in the United States is used by the municipal water utilities. Since treated water pumping compromises the major fraction of the total energy budget, optimised operational schedules can improve the energy efficiency of a water distribution system. System operators make these operational schedules with the aid of special decision support software. This software is based on mathematical models, which can comprise several thousand components. During the search for an optimal operational schedule, those water network models are run many times for different input and operating conditions. However, only a few key results are normally necessary, so a simplified model which provides those outputs could be adequate.

Funding body: British Council

The problem of choosing the best possible set of network improvements to make with a limited budget is presented as a large optimisation problem to which conventional optimisation techniques are poorly suited. A multi-objective approach is developed, using capital cost and benefit as dual objectives, enabling a range of non-inferior solutions of varying cost to be derived. A Structured Messy Genetic Algorithm is developed, incorporating some of the principles of the Messy Genetic Algorithm, such as strings which increase in length during the evolution of designs. The algorithm is shown to be an effective tool for the current optimisation problem, being particularly suited both to the multi-objective approach and to problems which involve the selection of small sets of variables from large numbers of possibilities.

Funding body: ERASMUS scheme (European Community)

Cost minimisation is the main issue for water companies when establishing pumping regimes for water distribution. Energy consumption and pump maintenance represent by far the biggest expenditure, accounting for around 90% of the lifetime cost of a water pump. This work explores the development and use of multiobjective Genetic Algorithms for pump scheduling in water supply systems. The two objectives considered are minimisation of energy and maintenance costs. Pump switching is introduced as a surrogate measure of maintenance cost. The multiobjective algorithm is compared to the single objective GA, with both techniques improved by using hybridisation with a local-search method.