on the 1993 International Electrotechnical Commission 1131-3 standards are now used extensively;
• Personal computers operate even faster, have more capacity, are less expensive, and, along with their related software, dominate the automation market;
• Shrink-wrapped, personal computer-based, supervisory control and data acquisition (SCADA) software is now readily available and relatively inexpensive (although it requires extensive configuration);
• Supervisory control and data aquisition systems now typically include monitoring, control, trend, and data features that most users need, and many also include historical data archiving, reporting, fuzzy control (a formal methodology for representing, manipulating, and implementing a human’s heuristic knowledge about how to control a system), artificial neural networks, and model predictive control (a class of controllers that use a model of the process to compute a sequence of manipulated variable adjustments to optimize the future behavior of the process);
• The Internet plays an important role in dispersing information and is evolving into a platform for wide-area control systems; and
• Physical and cyber security have become important issues.
In addition, the following changes have come about since the 2006 edition of this MOP:
• The Department of Homeland Security and other organizations published useful and practical guidelines on cyber security;
• The American National Standards Institute and the International Society of Automation (2009) published excellent guidelines on best practices for alarming;
• Hollifield et al. (2008) provided excellent recommendations on best practices for the HMI;
• Many utilities have developed or plan to develop energy management plans that use their SCADA systems to control energy more effectively; and
• The use of Web-based interfaces has become more common for controllers, individual instruments, and final control elements. In some instances, it is technically possible to access a Web-enabled PLC or instrument via a Web browser (perhaps on a smartphone) from any place on earth that has Internet access. The judicious application of cyber security measures, however, typically precludes such access.
Thirty-four years ago, the authors of the first edition noted that, because automation is a rapidly changing field, the manual would need frequent updates. This is still true today.
3.0 TECHNOLOGY AS A STRATEGY, NOT A LIMITATION
Because automation technology has matured, instruments, control elements, and strategies can handle most processes and problems today, and water resource recovery facility (WRRF) owners, managers, and operators simply expect every part of an automation system to work and to work well. Now, most of the keys to a successful project are organizational and managerial issues rather than technical ones.
Admittedly, some challenges such as automation of solids treatment and dewatering processes remain. However, researchers, manufacturers, and practitioners have recently made tremendous progress in addressing them. Moreover, further research is being conducted in North America, Europe, and Asia.
4.0 WHAT THIS MANUAL DOES AND DOES NOT INCLUDE
When Water Environment Federation’s (WEF’s) Automation of Water Resource Recovery Facilities Task Force first defined the scope of this update, they estimated that the manual would be approximately 600 pages (about 10% longer than the 2006 edition’s 576 pages) to accommodate new developments in the field.
After considerable discussion on what to keep, add, and leave out, the task force decided to update much of the material in the previous editions, except for obsolete technologies and technologies for which considerable written material was already available. The task force also incorporated much of the content of WEF’s now out-of-print 1997 Special Publication, Automated Process Control Strategies, which is the latest guidance document on specific process control strategies for wastewater treatment systems. The task force did not discuss the important issue of data quality. Fortunately, Olsson and Newell (1999) present an excellent discussion of the topic. The task force also decided not to debate the relative merits of traditional design–bid–build and design–build contracts or to address construction management issues. The task force did not address the issue of contract vs in-house programming. In addition, the task force did not address collection system controls in this edition because that topic was covered thoroughly in Design of Urban Stormwater Controls (WEF et al., 2012).
5.0 INTENDED AUDIENCE
This manual primarily focuses on the automation system designer and the design process. However, this manual will also show WRRF owners, managers, and operators what types of design documents to expect when undertaking an automation project and the standards used to evaluate them.
6.0 MANUAL OF PRACTICE CHAPTER CONTENTS
Each chapter in this MOP is written to stand alone; therefore, readers looking for specific information can simply turn to the appropriate chapter. For more information on a particular topic, see the references or suggested readings sections included in most chapters.
In Chapter 2, a business case for automation is made, stressing that control systems can help utilities be more effective and efficient. Investments in automation can and should reduce labor, chemical, and power needs while improving performance and reliability. Both tangible and intangible costs and benefits are discussed. Several methodologies for financial analysis and the incorporation of risk and intangible benefits are presented.
In Chapter 3, elements of a complete automation design project are introduced. Each type of document (drawings, lists, and written material) is briefly discussed, and standards and references are delineated. Detailed descriptions of each element are provided.
Because of its importance to the design process, process and instrumentation diagrams (P&IDs) are described in depth in Chapter 4. Process and instrumentation diagrams are typically one of the first design documents developed for a project. Design elements of P&IDs are described and their interactions with other design documents are discussed. Recent developments in intelligent P&IDs are also introduced.
In Chapter 5, the process control narrative, a text-based method of describing a process control strategy, is discussed. Chapter 6 presents an introduction to writing specifications. It describes the Construction Specifications Institute format and provides details on what the various sections are and what content they contain.
Chapter 7 combines a tutorial on process-control basics, from feedback controllers to advanced model-based controls, with an updated version of the material from WEF’s (1997) Automated Process Control Strategies. It contains written descriptions of successful control strategies on a unit process basis for many of the most common wastewater treatment processes. The sections on control of dewatering, anaerobic digestion, and incineration have been updated and expanded.
