PREFACE

These proceedings comprise a selection of manuscripts originally presented as papers or posters at the 7thIAWQ Workshop on Instrumentation, Control and Automation (lEA) for use in the management and controlof Water and Wastewater Treatment and Transport Systems held in Brighton, UK, in July 1997.

This workshop was the seventh in a series organised by IAWQ's Specialist Group on Instrumentation ,Control and Automation; the first was held in London and Paris in 1973. Subsequently, the event was held atfour yearly intervals as follows: London and Stockholm 1977, Munich and Rome 1981, Houston and Denver1985, Yokohama and Kyoto 1990, Banff and Hamilton 1993. The 8th Workshop will be held in Denmarkand Sweden during 2001 and will be organised by the Specialist Group's new Chairman, Professor GustafOlsson.

In the opening session of this Workshop the Group invited speakers to review past practices and previewfuture developments in ICA. Included in these proceedings are the papers of G. Olsson (Sweden), T. Ohto(Japan), T. Garrett (USA) and R. Huntingdon (UK). The major points made are summarised below.

Gustaf Olsson stated that the major driving forces in Scandinavia leading to improvements in the use of ICAwere both regulatory and technical, nutrient removal being a major requirement in both Sweden andDenmark. On the technical side, the use of computers for on-line data acquisition and to some extent controlis now commonplace and moves are afoot to deploy integrated operation such as combined sewer and plantcontrol. Full-scale experiences have been obtained and a reduced need for large equalisation volumesdemonstrated.

In his presentation Professor Tohru Ohto of Iwake Meisei University, Japan emphasised the need to buildsecure water supply systems, which can withstand natural disasters such as earthquakes. He also emphasisedthat wastewater systems require substantial improvement to ensure an effluent quality that maintains rawwastewater quality: this is necessary since most water supply systems depend on surface water resources. Tothis end systems have been upgraded by integration of electric, instrumentation and control systems. Thenew computer systems have international standard open architecture, are downsized, operate in real time, arehighly reliable and networked. Ultra high-speed, reliable digital communication systems are deployed andcontrol systems utilise advanced mathematical models, fuzzy logic controls and also neuro and knowledge­based models integrated into a single system. He stated that these systems are used in advanced watertreatment, broad-based management and control of water distribution systems. Further a database has beendeveloped for area topography, maps, pipelines, plant facilities and equipment management andmaintenance, including automatic reading of meters which can easily be accessed. Perhaps the most novel ofthe systems he described was one based on the use of optical fibre cable networks laid in sewers and utilisedfor, amongst other purposes, remote supervising control of a pumping station, supervising control of asludge treatment facility at a wastewater treatment plant as well as information transmission betweentreatment plants.

The presentation made by Truett Garrett reviewed progress in ICA in the USA during the last 24 years.Major points made were the advances in hardware and software leading to the use of personal computersalong with PLCs an I/O boards in minimum systems, and the use of systems analysis, expert systems, fuzzylogic and artificial neural network control. In addition much effort has been expended in the setting up andoperation of an instrumentation test house to improve the odds of purchasing reliable equipment.

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The presentation by Ron Huntingdon (UK) comprised an account of 20 years' development of ICA in awater utility and indicated that the major impetus was economically driven; this had led to the setting up ofan integrated computerised telemetry system for core data gathering and information transfer for use inimproved management of the water utility. The philosophy adopted, improvements made, disappointmentsthat occured and human aspects were all discussed, and progress in the development of off-line systemsindicated. Desirable future improvements were highlighted and human aspects explored.

The papers and posters which, following peer review, have been selected for publication are grouped intofour themes. The first of these, entitled Management and Operational Systems, comprises six papers, startingwith the report of a system for the management of serial aeration basins controlled automatically to removeboth carbon and nitrogen.

In the second paper the characterisation of bioreactor mixing by means of residence time distribution tests(RID) was discussed and shown to be of value for determining effectiveness and volume utilisation. Themethod also proved valuable for determining appropriate hydraulic topology for dynamic models for use insimulation and model based control.

In paper three the benchmarking of water treatment process control against other processing industry sectorsin Australia was discussed and a quantitative statistical tool which can be used for performing a benefitsanalysis was presented.

Paper four gave an interesting approach to process audit and asset assessment utilising on-lineinstrumentation linked via modems both to personnel operating the plant and consultants undertaking thestudy. Two examples were given and the approach appeared to be both novel and useful.

In the fifth paper a new operational support system for the oxidation ditch process was described in whichthe operational index was calculated from the DO concentration, the operator deciding the aerationconditions to keep the index within target range.

The final paper in the session was also concerned with real time control of the sewer system utilised as ameasure for the abatement of the pollution caused by urban run-off in the receiving water. However thestudy indicated the reduction of combined sewer overflow (CSO) which has been deployed as an artificialperformance criterion does not correlate well with DO levels in the receiving stream because of other factorssuch as photosynthesis in the water.

By far the largest number of papers and posters submitted were concerned one way or another with controlaspects, with 16 of these papers and posters being selected for publication. These covered a wide range ofapplications and control technologies ranging from comparatively simple hardwired systems to thosedeploying fuzzy logic and/or artifiical neural networks. Some examples are given below.

Ohtshuki et al. described an intelligent control system based on a "blackboard" concept and its application tothe control of wastewater treatment processes. A framework of an intelligent control system was in factconstructed using the blackboard concept to overcome the difficulties of multiple modelling organisationand successfully used to control a high-rate activated sludge system.

Bechmann et al. presented a paper on the control of sewer systems and wastewater treatment plants usingpollutant concentration profiles obtained from on-Ioine measurements of UV absorption and turbidity (fromwhich actual values of COD and SS could be determined) coupled with grey-box modelling to estimate theamount of deposits in the sewer system.

Chou et al. described the application of an optical monitor to evaluate the coagulation of pulp wastewater.This demonstrated a relatively simple instrumental method of control of coagulation.

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Lindberg described a system in which a linear multivariable time-variant state-space model. developed froma simulation study using the IAWQ model, could be used to predict the ammonium and nitrate concentrationin the last aeration zone in a pre-nitrifiying ASP and further utilised this model to develop a multivariablelinear device to control the concentration of ammonia and nitrate ions.

Hayes et al. described on-line nitrification inhibition monitoring using immobilised bacteria. A culture ofimmobilised nitrifying bacteria in a system maintained at 30°C was utilised since this enhances the rate ofnitrification and hence gives an early warning of toxicity. A prototype on-line version has been developedand is undergoing field trials.

The third group of manuscripts discussed was entitled Respirometry and other Instrumentation andcomprises twelve articles: the first four, which provoked excellent discussion. follow on from the work ofthe IAWQ Task Group on Respirometry in the control of the activated sludge process and showed acontinuing great interest in the subject.

The subsequent papers on instrumentation were mainly optically based and in general concerned with themonitoring of water quality (colour, turbidity, nitrate and ammonia). Novel techniques were described andimproved performance compared with that of existing instruments indicated. A particularly useful technique(Meredith) was the use of a simple electrochemical cell to adjust the pH value of the sample prior todetermining very low levels of total ammonia as NH3 using an optrode. Also likely to be of considerablevalue in the future is the development of a liquid core fibre optic device for use in the far UV: this enabledlow levels of nitrate ion to be monitored successfully (Belz et al.).

Also of interest was the remote sensing approach to the monitoring of turbidity (Johnson). Finally one mustnot ignore the value of and need for reliable sampling techniques (Haider & Haider).

Ten articles concerned with aspects of mathematical modelling have been selected. Much of the workdiscussed was concerned with model reduction with a view to their use in on-line control applications and itis evident that significant progress has been made in this area. Also discussed was an optimisation algorithmfor selection of design and operation parameters in complex activated sludge processes and once again theneed for validation of the models was stressed although it was suggested that the more complex the systems.the more useful optimisation algorithms could be.

Other papers were largely concerned with prediction aspects. Carstensen et al. for example were concernedwith the reduction of hydraulic load for urban storm control of a municipal plant. In general it wasconcluded that models for model-based predictive control should be kept simple and identifiable frommeasured data.

Hall et al. described a mathematical filter backwash model which determines the volume of deposit detachedinto suspension at any point during the backwash. It also determines the change in concentration both withinand emerging from the filter bed. Output concentration during backwashing predicted by the model showsgood correlation with turbidity recordings obtained from experimental columns. Experimental work iscurrently underway to verify the model on full-scale plant.

A paper relating to distribution reservoir control (Oshima et al.) described demand predictions using adeterministic chaos method. and it was claimed that the method provided automatic and stable control bydecreasing the number of pump start-stop operations, making full use of the demand regulating function ofthe reservoir, maintaining a high storage rate according to the demand pattern and minimising variations inwater distribution rate.

It can be seen from the above that mathematical modelling activities have not only diversified and increasedin the last four years but are now moving closer to an ability to solve real life problems.

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The above indicates the wide variety of techniques and application areas currently being investigated. Wecan confidently expect that there will be good progress in the near future.

The Workshop concluded with a stimulating and novel presentation by Olsson and Newell whichsummarised the proceedings and analysed the audience in terms of interest and origin as well as providing abreakdown of the technical content, an assessment of impact and speculation on future trends.

Finally I would like to thank the members of the Organizing and Programme Committees, the staff on theIAWQ Secretariat and the many expert reviewers for their respective contributions to the organisation of theWorkshop and the editing of these proceedings.

Ron BriggsChairman, Specialist Group and Programme Committee