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Instrumentation, control and automation progress in the United States in the last 24 years
e:>
Pergamon
Wal. Sci
T~ch.
Vol. 37. No. 12. pp. 21-25. 1998.
IAWQ ~ 1998 Published by Elsevier Science Ltd. Printed in GreatBritain. Allrightsreserved 0273-1223/98 $19'00 + 0'00
PU: S0273-1223(98)OO366-7
INSTRUMENTATION, CONTROL AND AUTOMATION PROGRESS IN THE UNITED STATES IN THE LAST 24 YEARS M. Truett Garrett, Jr. Espey, Hustonand Associates. Inc.• 3200 Wi/crest. Suite 200. Houston, TX 77042-3366. USA
ABSTRACf A historical overview is presented of instrumentation control and automation as applied in US wastewater treatment plants. A description is given how computer equipment has progressed through direct digital control. distributed control. programmable logic controllers. to the use of personal computers along with PLC's or 110 boards in minimum systems. Software developments have brought systems analysis. expert systems. fuzzy logic control. and artificial neural network control. An instrumentation test house has been organized in the US to improve the odds of purchasing reliable instruments. Technical Conferences on lCA are presented regularly by the American Water Works Association and the Water Environment Association. There is still need for designers to consider a complete system that includes a data base for automatic preparation of reports on the plant for use at other levels as was called for by delegates to the early workshops. © 1998 Published by Elsevier Science Ltd. All rights reserved
KEYWORDS Instrumentation; control; automation; USA. INTRODUCfION When one contemplates the great variations in geography, climate, and types of receiving water bodies, and the authority of the individual states, it is clear that a report on the progress of ICA in the United States of America may not be totally comprehensive. Moreover this progress has not been accomplished without outside influence, instead it has been greatly influenced by workshops of this specialty group, and particularly by the two that have been in North America: Houston and Denver in 1985 and Hamilton and Banff in 1993. At the 1971 IAWPR Workshop in Vienna, it was realized that designers had been working on wastewater treatment plant automation without complete awareness of what had been going on elsewhere. The first workshop on Instrumentation, Control and Automation was organized by committees from the UK and the US and held in 1973 to present a complete view of the state of the art. (Guarino and Drake, 1973). The US committee was chaired by Carmen Guarino and the UK committee was chaired by the late R. A. R. (Tony) Drake. Two hundred twenty five participants attended the technical sessions in London and Paris. Five countries besides the US and the UK were represented on the technical program.
21
22
M. TRUElT GARRE1T. lR
ROLEOFICA At the 1977 Workshop, held in London and Stockholm, there were invited comments on the deterrents and problems perceived as hindering progress in automation. Guarino and Radziul (1977) cited the following as deterrents: public ownership, lack of sensors, inadequate knowledge of process kinetics, and funding. In the U.S., passage of PL92500, The Federal Water Pollution Control Act Ammendments of 1972, and its grant program began to encourage instrumentation and automation of large and medium sized plants. The fast pace of construction, without time for evolutionary development, was predicted by Guarino to result in some BIG mistakes. The need for adaptive tuning of control loops was noted as well as the need for improved communication for management of collection systems. Dennis Clifford (1977) pointed out that sensors were available, but maintenance and quality assurance were problems. Bill Garber (1977) cited the need for continued work on process dynamic equations, the inadequacy of "canned software", and the need for "dirty water" sensors with auto calibration. D. H. Newsome (1977) pointed out that the data obtained should be stored for the following uses: a. for reports to higher levels b. for direct use by higher levels c. for processing and archival storage. He also noted the need for research on methods of data acquisition, definition of the requirements for operational information at all levels, and the consideration of needs beyond that for plant operation . PROGRESS OF COMPUTER SYSTEMS In the early 70's many agencies planned to install systems to provide remote monitoring of plant conditions, logging of data, and displaying the status of the plant on large mimic boards. Next came reports on the reliability of the computer systems and control loops. This led to CRT displays instead of mimic boards, and the inclusion of the essential motor operated valves and other control equipment in plant designs. Remote operation was particularly helpful in very large plants as process changes often were required during storms when travel to the various processes was difficult. Distributed control systems replaced many direct digital control systems. Programmable logic controllers with ladder logic language that was readily understood by electricians gained in popularity. The personal computer has been used in many installations as I/O cards and software became available. Because of mass production, these are inexpensive to repair and/or replace, and their speed and memory capacity now challenge the mini- computer. This development is world wide as the manufacturers are multi-national companies. Garber and Anderson (1985) observed that during this period, some computer systems failed to perform or failed to function after seemingly short time periods. The owners found that repair parts were not available, or that the people who did the original programming were not to be found. After being scrapped, often the systems were not readily replaced. They describe the use of PLC's and personal computers for wastewater treatment plant control. Now, after years of having to do a real selling job to fiscal managers, they are beginning to ask if computer components don't need to be budgeted for replacement. Although the plant wiring may last for many decades. it is now better understood that instruments and computer components have a life of only five to ten years. It has been learned that it is prudent to regularly update the operating system and to anticipate obsolescence of data storage systems and transfer archived data to modem storage media. Regulatory agencies have taken advantage of the progress in computer technology and equipment. This is satisfying as it is the desire of this specialty group that all stakeholders should take advantage of the technology. Most states require that pumping stations and treatment plants not manned 24 hours per day have monitoring of essential equipment and processes along with telemetry to a station attended 24 hours
Instrumentation. control and automation in the United Stales
23
per day. This has opened the door for data logging and automatic or remote process control with minimum extra investment. The requirement for dechlorination has meant that chlorination must be automatically controlled with on-line analyzers. This is very economical in contrast to the cost of staffing two more shifts per day. MODELS, SIMULATION AND EXPERT SYSTEMS Process modeling and simulation had its beginning with researchers at universities, using main-frame computers. With time, the models have been tested and improved. Computer cost has been reduced by a factor of over 200. Thus today many simulation packages are available for the modem PC. Since the market is small, the cost of these packages remains high, from 5 to 20 times the cost of the PC. Nevertheless, their development has contributed to the understanding and development of Biological Nutrient Removal, Sequencing Batch Reactors, improved aeration efficiency through denitrification, and better understanding of activated sludge settling tanks. A series of Workshops by the specialist group on Systems Analysis in Water Quality Management was begun in London in 1987 (Beck, 1987). The group considered modeling of broader systems than a treatment plant. This is illustrated by two papers: (I) Schilling and Petersen (1987), "Real time operation of urban drainage systems - validity and sensitivity of optimization techniques", and (2) Vitasovic, Sandaas and Nitz (1987), "Application of systems engineering concepts to combined sewer overflow control at Seattle Metro." Automatic control systems and expert systems not only provide improvement in operating quality and economy, but they provide stability in plants as personnel turnover occurs. INSTRUMENT TEST HOUSE ITA, the Instrumentation Testing Association of North America is an organization of user agencies in Canada and the US intent upon improving the odds of success in the purchase of instrumentation for water and wastewater control. Through funding from its members, ITA conducts tests of on-line analyzers using a carefully prepared protocol that has been reviewed by the manufacturers of the instruments to be tested. While the tests do not identify which instrument is best, they do identify equipment that can be expected to work satisfactorily in a water or wastewater treatment plant. On the basis of the ITA tests, the City of Houston purchased 78 on-line chlorine analyzers to provide automatic control of chlorination and dechlorination at 26 wastewater treatment plants. Garrett, Ahmad and Young (1993) used the new Astrom-Hagglund (1988) relay feedback procedure for tuning the controllers used with the on-line chlorine analyzers for chlorination control at Houston. In contrast to older controller tuning procedures, the relay feedback procedure is adaptable to slow processes and the process is under control while the procedure is in use. RECENT DEVELOPMENTS The Water Environment Federation has produced Manuals of Practice on Instrumentation in Wastewater Treatment Facilities and Strategies for Automatic Control of Wastewater Treatment Plants. The WEF and the American Water Works Association both hold yearly workshops on computer control. Mention of some of the presentations at the 1997 WEF Specialty Conference. "Computer Technologies for the Competitive Utility", June 16-19, will illustrate the status of ICA in the US at the present time. Thomas J. McGovern, "On-Line Remote Billing Meters" describes how concerns of the communities that were billed for service was satisfied by modifying the instrumentation to capture the "registered digits" of the primary meter. This eliminated the question of calibration when an analogue signal is transmitted. They also put the meter readings on the INTERNET to allow users to monitor their own flow.
24
M. TRUETI GARRETf.lR
John A. Nye and William L. Overbeck, "Distributed Intelligence Maximizes SCADA CSO Efficiency:" Lima, Ohio has a CSO control system that meets regulatory requirements. It predicts wet weather events and uses the sewer system volume to prevent "wash-outs" at the wastewater treatment plant. This is an example of progress in the use of systemanalysis. Larry Chubb, "Use of Packet Radio Network for Primary SCADA. Communication: The Promise and the Reality." No license is required for this new radio network. Michael W. Heitz, Biju George, and James E. Welp, "Neural Network Applications in Municipal Wastewater Collection and Treatment Facilities." Cincinnati, Ohio uses a new control procedure that is presented in the sense of "you can do it." Michael Barnett, "Adaptive Neural Network for Intelligent Operation of Activated Sludge Process: Modeling". A mechanistic model was used to train the neural network. The above discussion presents some of the things that have been achieved. In presenting some thoughts of what may not have been achieved - I must modify that to not totallyachievedyet. NEEDS The river associations in Germany and the water authorities in the UK have had regional authority and responsibility and a built-in association with national environmental control agencies. Thus their planning and implementation of ICA has been system wide and pursued both vertically and horizontally . We are grateful and indebted to them for the papers describing their systems that have been presented at these workshops. In the USA it has been more likely that systems would evolve sequentially: process monitoring and control, computer control at the laboratory bench and LIMS, data logging and report generation, computer based maintenance management, computer based time and personnel record keeping, and computer based industry control (prompt automatic generation of violation notices from laboratory reports via a network). However all of the above are occurring, but in different orders and on different time tables throughout the great number of different cities, authorities, and unincorporated utility districts. Considering the great number of individuals that will be responsible for making decisions on the best way to coordinate their water and wastewater systems, there appears to be a need for continued development and updating of curricula in trade schools and universities. In universities, education is needed at both the undergraduate and graduate student levels. John Andrews (1997), Professor Emeritus at Rice University, has often said "The traditional senior course, which is usually titled Design of Water and Wastewater Treatment Plants should instead be titled Design and Operation of Water and Wastewater Treatment Plants with it being understood that operations includes the quantitative description of dynamic behavior and the use of control systems to convert unsatisfactory dynamic behavior to satisfactory behavior." While we have been enthralled with using ICA to provide least cost, but elegant solutions to our water and wastewater problems, the counsel of Newsome (1977) above, in regard to data acquisition and management has fallen out of our tool kit. An example. that will remain unnamed, illustrates the situation and may not be that unusual. In a 60 MGD plant with distributed control by PLC's and a supervisory computer the operators fill out eleven daily report forms by hand. Some items are the record of manual measurements such as DO and settling tests while another is the reading of the plant flow meter register digits. The data is kept in file cabinets and is manually copied to provide monthly reports for use at higher levels. While the multi-million dollar computer system provides excellent control of the plant, important requirements of plant management have been left out, so we must conclude that our job is not finished yet!
Instrumentation.control and automationin the UnitedSlates
25
FUTURE DEVELOPMENTS AND PRACflCES Two aspects of ICA can be safely predicted: I. the need for optimally controlled plants will increase due to tightening permit requirements and the ever present need to reduce cost ; 2. the quality of the instrumentation and the control systems will improve. A third important item is the attitude and technical skill of the personnel involved in system projects . Through experience and exchange of information at technical meetings, they will become better informed on the performance and cost of various systems. The goal will be excellence in total plant performance, and ICA will playa strong supportive role. The workshops such as this and those sponsored by the WEF and AWWA serve to allow for practitioners to catch up and for specialists to advance the envelope of knowledge. Moreover, the workshops and proceedings are available to managers as well. This task has been made easier by the attraction of the PC and available entertainment software. Most elementary school students are already adept at using the computer. REFERENCES Andrews. J. F. (\997). Personal communication. May 26,1997. Astrom, K. J. and Hagglund.T. (\988). Automatic Tuning of PIDControllers. InstrumentSociety of America, Research Triangle Park. NC. pp. 40-42. Beck. M. B. (ed) (1987). Systems Analysis in Water Quality Management (Ady. Wat. Pollut, Control no. 3). Pergamon Press. Oxford. Clifford,D. (1977). Discussionof Guarinoand Radziul(1977). Progress in WaterTech., 9(5/6). 11-12. Garber. W. F. (1977). Practical problems in the application of control systems in large scale wastewater treatment programmes. Progress in WaterTech.• 9(5/6).11-12. Garber, W. F. and Anderson. J. J. (1985). From the Slandpoint of an operator - what is really needed in the automation of a wastewater treatment plant Instrumentation and Control of Waterand Wastewater Treatment and Transport Systems (Ady. Wat. Pollut. Controlno. 2). R. A. R. Drake. ed. PergamonPress, Oxford. pp. 429-442. Garrett, M. T.• Ahmad. Z. and Young. S. (1993). Experiencewith the relay procedurefor tuning controllers in automatic control of chlorination. Wat. Sci. Tech., 28(11-12).257-261. Guarino. C. and Radziul, J. W. (1977). Water-Wastewater.I & A, U. S. A. Progress in WaterTech.. 9(5/6),35-39. Guarino. C. and Drake. R. A. R. (1973). Forward. Instrumentation Control and Automation for Waste-waterTreatment Systems. Progress in WaterTecb; 6{5/6), viii. Newsome.D. H. (1977). Changingconcepts of water data acquisition. Progress in WaterTech; 9(5/6), 21. Schilling. W. and Petersen. S. O. (1987). Real time operation of urban drainage systems- validity and sensitivity of optimization techniques. Systems Analysis in Water Quality Management (AdY. Wat. Pollut. Control no. 3). M. B. Beck (ed). Pergamon Press. Oxford. pp. 259-270. Vitasovic, z., Sandaas. R. and Nitz, B. (1987). Applicationof systems engineeringconcepts to combined sewer overflow control at Seattle Metro. Systems Analysirin Water Quality Management (Ady. War. Pollut. Control no. 3). M. B. Beck (ed). Pergamon Press, Oxford. pp. 271-282.
Pergamon
Wal. Sci
T~ch.
Vol. 37. No. 12. pp. 21-25. 1998.
IAWQ ~ 1998 Published by Elsevier Science Ltd. Printed in GreatBritain. Allrightsreserved 0273-1223/98 $19'00 + 0'00
PU: S0273-1223(98)OO366-7
INSTRUMENTATION, CONTROL AND AUTOMATION PROGRESS IN THE UNITED STATES IN THE LAST 24 YEARS M. Truett Garrett, Jr. Espey, Hustonand Associates. Inc.• 3200 Wi/crest. Suite 200. Houston, TX 77042-3366. USA
ABSTRACf A historical overview is presented of instrumentation control and automation as applied in US wastewater treatment plants. A description is given how computer equipment has progressed through direct digital control. distributed control. programmable logic controllers. to the use of personal computers along with PLC's or 110 boards in minimum systems. Software developments have brought systems analysis. expert systems. fuzzy logic control. and artificial neural network control. An instrumentation test house has been organized in the US to improve the odds of purchasing reliable instruments. Technical Conferences on lCA are presented regularly by the American Water Works Association and the Water Environment Association. There is still need for designers to consider a complete system that includes a data base for automatic preparation of reports on the plant for use at other levels as was called for by delegates to the early workshops. © 1998 Published by Elsevier Science Ltd. All rights reserved
KEYWORDS Instrumentation; control; automation; USA. INTRODUCfION When one contemplates the great variations in geography, climate, and types of receiving water bodies, and the authority of the individual states, it is clear that a report on the progress of ICA in the United States of America may not be totally comprehensive. Moreover this progress has not been accomplished without outside influence, instead it has been greatly influenced by workshops of this specialty group, and particularly by the two that have been in North America: Houston and Denver in 1985 and Hamilton and Banff in 1993. At the 1971 IAWPR Workshop in Vienna, it was realized that designers had been working on wastewater treatment plant automation without complete awareness of what had been going on elsewhere. The first workshop on Instrumentation, Control and Automation was organized by committees from the UK and the US and held in 1973 to present a complete view of the state of the art. (Guarino and Drake, 1973). The US committee was chaired by Carmen Guarino and the UK committee was chaired by the late R. A. R. (Tony) Drake. Two hundred twenty five participants attended the technical sessions in London and Paris. Five countries besides the US and the UK were represented on the technical program.
21
22
M. TRUElT GARRE1T. lR
ROLEOFICA At the 1977 Workshop, held in London and Stockholm, there were invited comments on the deterrents and problems perceived as hindering progress in automation. Guarino and Radziul (1977) cited the following as deterrents: public ownership, lack of sensors, inadequate knowledge of process kinetics, and funding. In the U.S., passage of PL92500, The Federal Water Pollution Control Act Ammendments of 1972, and its grant program began to encourage instrumentation and automation of large and medium sized plants. The fast pace of construction, without time for evolutionary development, was predicted by Guarino to result in some BIG mistakes. The need for adaptive tuning of control loops was noted as well as the need for improved communication for management of collection systems. Dennis Clifford (1977) pointed out that sensors were available, but maintenance and quality assurance were problems. Bill Garber (1977) cited the need for continued work on process dynamic equations, the inadequacy of "canned software", and the need for "dirty water" sensors with auto calibration. D. H. Newsome (1977) pointed out that the data obtained should be stored for the following uses: a. for reports to higher levels b. for direct use by higher levels c. for processing and archival storage. He also noted the need for research on methods of data acquisition, definition of the requirements for operational information at all levels, and the consideration of needs beyond that for plant operation . PROGRESS OF COMPUTER SYSTEMS In the early 70's many agencies planned to install systems to provide remote monitoring of plant conditions, logging of data, and displaying the status of the plant on large mimic boards. Next came reports on the reliability of the computer systems and control loops. This led to CRT displays instead of mimic boards, and the inclusion of the essential motor operated valves and other control equipment in plant designs. Remote operation was particularly helpful in very large plants as process changes often were required during storms when travel to the various processes was difficult. Distributed control systems replaced many direct digital control systems. Programmable logic controllers with ladder logic language that was readily understood by electricians gained in popularity. The personal computer has been used in many installations as I/O cards and software became available. Because of mass production, these are inexpensive to repair and/or replace, and their speed and memory capacity now challenge the mini- computer. This development is world wide as the manufacturers are multi-national companies. Garber and Anderson (1985) observed that during this period, some computer systems failed to perform or failed to function after seemingly short time periods. The owners found that repair parts were not available, or that the people who did the original programming were not to be found. After being scrapped, often the systems were not readily replaced. They describe the use of PLC's and personal computers for wastewater treatment plant control. Now, after years of having to do a real selling job to fiscal managers, they are beginning to ask if computer components don't need to be budgeted for replacement. Although the plant wiring may last for many decades. it is now better understood that instruments and computer components have a life of only five to ten years. It has been learned that it is prudent to regularly update the operating system and to anticipate obsolescence of data storage systems and transfer archived data to modem storage media. Regulatory agencies have taken advantage of the progress in computer technology and equipment. This is satisfying as it is the desire of this specialty group that all stakeholders should take advantage of the technology. Most states require that pumping stations and treatment plants not manned 24 hours per day have monitoring of essential equipment and processes along with telemetry to a station attended 24 hours
Instrumentation. control and automation in the United Stales
23
per day. This has opened the door for data logging and automatic or remote process control with minimum extra investment. The requirement for dechlorination has meant that chlorination must be automatically controlled with on-line analyzers. This is very economical in contrast to the cost of staffing two more shifts per day. MODELS, SIMULATION AND EXPERT SYSTEMS Process modeling and simulation had its beginning with researchers at universities, using main-frame computers. With time, the models have been tested and improved. Computer cost has been reduced by a factor of over 200. Thus today many simulation packages are available for the modem PC. Since the market is small, the cost of these packages remains high, from 5 to 20 times the cost of the PC. Nevertheless, their development has contributed to the understanding and development of Biological Nutrient Removal, Sequencing Batch Reactors, improved aeration efficiency through denitrification, and better understanding of activated sludge settling tanks. A series of Workshops by the specialist group on Systems Analysis in Water Quality Management was begun in London in 1987 (Beck, 1987). The group considered modeling of broader systems than a treatment plant. This is illustrated by two papers: (I) Schilling and Petersen (1987), "Real time operation of urban drainage systems - validity and sensitivity of optimization techniques", and (2) Vitasovic, Sandaas and Nitz (1987), "Application of systems engineering concepts to combined sewer overflow control at Seattle Metro." Automatic control systems and expert systems not only provide improvement in operating quality and economy, but they provide stability in plants as personnel turnover occurs. INSTRUMENT TEST HOUSE ITA, the Instrumentation Testing Association of North America is an organization of user agencies in Canada and the US intent upon improving the odds of success in the purchase of instrumentation for water and wastewater control. Through funding from its members, ITA conducts tests of on-line analyzers using a carefully prepared protocol that has been reviewed by the manufacturers of the instruments to be tested. While the tests do not identify which instrument is best, they do identify equipment that can be expected to work satisfactorily in a water or wastewater treatment plant. On the basis of the ITA tests, the City of Houston purchased 78 on-line chlorine analyzers to provide automatic control of chlorination and dechlorination at 26 wastewater treatment plants. Garrett, Ahmad and Young (1993) used the new Astrom-Hagglund (1988) relay feedback procedure for tuning the controllers used with the on-line chlorine analyzers for chlorination control at Houston. In contrast to older controller tuning procedures, the relay feedback procedure is adaptable to slow processes and the process is under control while the procedure is in use. RECENT DEVELOPMENTS The Water Environment Federation has produced Manuals of Practice on Instrumentation in Wastewater Treatment Facilities and Strategies for Automatic Control of Wastewater Treatment Plants. The WEF and the American Water Works Association both hold yearly workshops on computer control. Mention of some of the presentations at the 1997 WEF Specialty Conference. "Computer Technologies for the Competitive Utility", June 16-19, will illustrate the status of ICA in the US at the present time. Thomas J. McGovern, "On-Line Remote Billing Meters" describes how concerns of the communities that were billed for service was satisfied by modifying the instrumentation to capture the "registered digits" of the primary meter. This eliminated the question of calibration when an analogue signal is transmitted. They also put the meter readings on the INTERNET to allow users to monitor their own flow.
24
M. TRUETI GARRETf.lR
John A. Nye and William L. Overbeck, "Distributed Intelligence Maximizes SCADA CSO Efficiency:" Lima, Ohio has a CSO control system that meets regulatory requirements. It predicts wet weather events and uses the sewer system volume to prevent "wash-outs" at the wastewater treatment plant. This is an example of progress in the use of systemanalysis. Larry Chubb, "Use of Packet Radio Network for Primary SCADA. Communication: The Promise and the Reality." No license is required for this new radio network. Michael W. Heitz, Biju George, and James E. Welp, "Neural Network Applications in Municipal Wastewater Collection and Treatment Facilities." Cincinnati, Ohio uses a new control procedure that is presented in the sense of "you can do it." Michael Barnett, "Adaptive Neural Network for Intelligent Operation of Activated Sludge Process: Modeling". A mechanistic model was used to train the neural network. The above discussion presents some of the things that have been achieved. In presenting some thoughts of what may not have been achieved - I must modify that to not totallyachievedyet. NEEDS The river associations in Germany and the water authorities in the UK have had regional authority and responsibility and a built-in association with national environmental control agencies. Thus their planning and implementation of ICA has been system wide and pursued both vertically and horizontally . We are grateful and indebted to them for the papers describing their systems that have been presented at these workshops. In the USA it has been more likely that systems would evolve sequentially: process monitoring and control, computer control at the laboratory bench and LIMS, data logging and report generation, computer based maintenance management, computer based time and personnel record keeping, and computer based industry control (prompt automatic generation of violation notices from laboratory reports via a network). However all of the above are occurring, but in different orders and on different time tables throughout the great number of different cities, authorities, and unincorporated utility districts. Considering the great number of individuals that will be responsible for making decisions on the best way to coordinate their water and wastewater systems, there appears to be a need for continued development and updating of curricula in trade schools and universities. In universities, education is needed at both the undergraduate and graduate student levels. John Andrews (1997), Professor Emeritus at Rice University, has often said "The traditional senior course, which is usually titled Design of Water and Wastewater Treatment Plants should instead be titled Design and Operation of Water and Wastewater Treatment Plants with it being understood that operations includes the quantitative description of dynamic behavior and the use of control systems to convert unsatisfactory dynamic behavior to satisfactory behavior." While we have been enthralled with using ICA to provide least cost, but elegant solutions to our water and wastewater problems, the counsel of Newsome (1977) above, in regard to data acquisition and management has fallen out of our tool kit. An example. that will remain unnamed, illustrates the situation and may not be that unusual. In a 60 MGD plant with distributed control by PLC's and a supervisory computer the operators fill out eleven daily report forms by hand. Some items are the record of manual measurements such as DO and settling tests while another is the reading of the plant flow meter register digits. The data is kept in file cabinets and is manually copied to provide monthly reports for use at higher levels. While the multi-million dollar computer system provides excellent control of the plant, important requirements of plant management have been left out, so we must conclude that our job is not finished yet!
Instrumentation.control and automationin the UnitedSlates
25
FUTURE DEVELOPMENTS AND PRACflCES Two aspects of ICA can be safely predicted: I. the need for optimally controlled plants will increase due to tightening permit requirements and the ever present need to reduce cost ; 2. the quality of the instrumentation and the control systems will improve. A third important item is the attitude and technical skill of the personnel involved in system projects . Through experience and exchange of information at technical meetings, they will become better informed on the performance and cost of various systems. The goal will be excellence in total plant performance, and ICA will playa strong supportive role. The workshops such as this and those sponsored by the WEF and AWWA serve to allow for practitioners to catch up and for specialists to advance the envelope of knowledge. Moreover, the workshops and proceedings are available to managers as well. This task has been made easier by the attraction of the PC and available entertainment software. Most elementary school students are already adept at using the computer. REFERENCES Andrews. J. F. (\997). Personal communication. May 26,1997. Astrom, K. J. and Hagglund.T. (\988). Automatic Tuning of PIDControllers. InstrumentSociety of America, Research Triangle Park. NC. pp. 40-42. Beck. M. B. (ed) (1987). Systems Analysis in Water Quality Management (Ady. Wat. Pollut, Control no. 3). Pergamon Press. Oxford. Clifford,D. (1977). Discussionof Guarinoand Radziul(1977). Progress in WaterTech., 9(5/6). 11-12. Garber. W. F. (1977). Practical problems in the application of control systems in large scale wastewater treatment programmes. Progress in WaterTech.• 9(5/6).11-12. Garber, W. F. and Anderson. J. J. (1985). From the Slandpoint of an operator - what is really needed in the automation of a wastewater treatment plant Instrumentation and Control of Waterand Wastewater Treatment and Transport Systems (Ady. Wat. Pollut. Controlno. 2). R. A. R. Drake. ed. PergamonPress, Oxford. pp. 429-442. Garrett, M. T.• Ahmad. Z. and Young. S. (1993). Experiencewith the relay procedurefor tuning controllers in automatic control of chlorination. Wat. Sci. Tech., 28(11-12).257-261. Guarino. C. and Radziul, J. W. (1977). Water-Wastewater.I & A, U. S. A. Progress in WaterTech.. 9(5/6),35-39. Guarino. C. and Drake. R. A. R. (1973). Forward. Instrumentation Control and Automation for Waste-waterTreatment Systems. Progress in WaterTecb; 6{5/6), viii. Newsome.D. H. (1977). Changingconcepts of water data acquisition. Progress in WaterTech; 9(5/6), 21. Schilling. W. and Petersen. S. O. (1987). Real time operation of urban drainage systems- validity and sensitivity of optimization techniques. Systems Analysis in Water Quality Management (AdY. Wat. Pollut. Control no. 3). M. B. Beck (ed). Pergamon Press. Oxford. pp. 259-270. Vitasovic, z., Sandaas. R. and Nitz, B. (1987). Applicationof systems engineeringconcepts to combined sewer overflow control at Seattle Metro. Systems Analysirin Water Quality Management (Ady. War. Pollut. Control no. 3). M. B. Beck (ed). Pergamon Press, Oxford. pp. 271-282.