Process Control: Optimization verses Troubleshooting

 

The goal of this article is threefold:

1. Encourage operators to learn as much as possible about the foundational concepts of their discipline (water or wastewater).
2. Encourage operators to continuously work on developing a robust, proactive and reactive process control program.
3. Encourage operators to reach out to the Georgia Rural Water Association (GRWA) for assistance with any issues you may have with regards to compliance, setting up a process control program, training, etc.

Learn Theory! Learn Theory! Learn Theory! If you know theory you can use it! If you don’t know theory you can’t use it!

Thinking in terms of complex systems is difficult. Many people, even after studying for years, do not understand basic principles. Systems thinking is often counterintuitive at many points. It takes many years to gain any degree of skill, and it still often eludes us. (Extraordinary Leadership: Thinking Systems, Making a Difference, 2009, Reberta M. Gilbert, M.D, pg 5)

I have been introducing most of my courses with above quote since I first read it in 2008. Dr. Gilbert used this quote to introduce her book Extraordinary Leadership. The book’s focus is on leadership that recognizes that organizations are groups of people formed into emotional units and effective leadership is about understanding the emotional functioning of groups, individual’s and oneself. Her perspective is derived from Family Systems Theory and is very similar to that of conflict resolution and conflict transformation theories used by practitioners that work with large group (organizational, regional, national and international) conflicts.

The American Manufacturing Sector learned a long time ago that controlling product quality at the end of the assembly line is inefficient, costly and produces a product with highly variable quality characteristics. Process control describes an activity or group of activities that identifies and monitors multiple inputs and outputs throughout a manufacturing or production process to determine their character and quality and modify them if necessary to ensure conformity, limit waste and increase efficiency, thereby guaranteeing a high quality final product. Process control, then, requires both frequent monitoring to maintain a high degree of optimization and troubleshooting the process when things go awry.

Optimization: The process or methodology of making something operate as efficient as possible.

Troubleshooting: The process of identifying and solving process upsets and problems

Theoretically, in a closed system or a closely monitored system, the process should never become unbalanced to the point where the it veers off course and troubleshooting should be necessary. The good thing is, when things do go amiss, the same concepts apply and the same skills are used in both optimization and troubleshooting.  All one has to do is review the monitoring data, pinpoint where the system began to become unstable and make adjustments. In an open system, however, it may require additional investigation, testing, and monitoring to determine where the system strayed from the path.

The primary focus of traditional certification training programs is on helping people pass the certification exams. The aim is to provide individuals enough information (data) to enable them to obtain their certification so they can begin to operate a water or wastewater plant. This is a very important role. The number of licensed water and wastewater operators continues to dwindle every year. Those of us who entered the field in the 1960’s and 1970’s and even the 1980’s are entering retirement age and there have not been enough new recruits to replace us.

There are some deficiencies in the above model. The first, certification training is, of necessity, very broad. All one has to do is conduct a survey of the different types of water treatment or wastewater treatment plants that are being constructed today. Let’s consider water treatment: since the 1990’s new approaches and processes began to be applied and continue to evolve to address a variety of concerns. These approaches include renewed emphasis on source water protection, enhanced chemical treatment options throughout the plant, optimizing coagulation and filtration performance, enhanced filtration technology, recycle stream management, plus consideration of new technologies, such as new disinfection technologies and membrane treatment. All one has to do is look at the number of membrane types on the market to see the complexity in the industry.

Added to the above, new classes of constituents emanating from modern human life has been discovered in trace amounts in water supplies. These include pharmaceutical compounds, personal hygiene products and a host of “forever chemicals,” the most prominent being PFAS and PFOS. Additionally, new "emerging" pathogens are being discovered and their potential occurrence and treatability in water supplies evaluated. The potential impacts of these developments will eventually show up in permit requirements and will place additional demands on the design requirements for water treatment facilities that have yet to be determined. The issues affecting wastewater treatment are similar.

The problem with the current training model comes after one has received one’s license. Many operators work in small systems and wear multiple hats. They enter an existing system with an established history and must work within that context. The training they receive for that specific, preexisting system is dependent upon the current management and is often a matter of “this is the way it has always we’ve always done it”. In very small cities they may be the only licensed operator in the city and are thrust into the operation of a plant with no training whatsoever.

The ideal scenario is to modify our training programs to focus more on concepts and less on data. One example comes from a question on one of the Georgia certification exams. From what I have been told, the multiple-choice question is something along the lines of “What is the Modified Ludzak-Ettinger Process?”.  Approaching training from this direction requires one to memorize every patented wastewater treatment process on the market, of which there are dozens. A better approach would be to have one memorize the foundational concepts of the nutrient removal process along with the major alterations, of which there are only a handful. For example, once one understands that, if an anoxic reactor is placed before an aerobic reactor, one needs to recycle the aerobic reactor nitrate-rich effluent back to the anoxic reactor for reducing the nitrates, this concept applies to any patent which places the anoxic tank before the aerobic tank. Learning theory eliminates the need for memorizing all the existing and future iterations of nutrient removal processes. It also provides one with the basic foundation for entering and quickly evaluating any wastewater treatment system and developing an effective treatment optimization program.

A second, related scenario is to integrate optimization/troubleshooting concepts into certification training programs. For example, dual media filtration is common in both water and wastewater treatment. Our training programs often offer generic descriptions of their construction and operation, but offer little regarding process control or troubleshooting. Much of what takes place in a filter occurs out of sight. An in-depth investigation into the internal physical/chemical processes that transpires in a filter is complex and requires taking the filter offline at regular intervals for a thorough inspection. A comprehensive review of an individual filter assessment as described in CHAPTER 5 – INDIVIDUAL FILTER SELF-ASSESSMENT of the EPA Guidance Manual for Compliance with the Surface Water Treatment Rules: Turbidity Provisions would provide a good foundation for both troubleshooting and process control of filters regardless of whether they are in a water or wastewater plant, and is a good example of how the same metrics that apply to troubleshooting also apply to process control.

A second example is related to the nutrient removal topic introduced earlier. A modern Basic Wastewater Treatment Course, after discussing wastewater lagoons and fixed film devices could include an Activated Sludge Concepts section that begins with an in-depth introduction into Sequencing Batch Reactor (SBR) technology. SBR’s do it all: carbonaceous BOD removal, nitrogenous BOD removal, nitrate removal and phosphorous removal. It does so in a natural, logical sequence that does not require any internal recycle, but might, under certain conditions, require some substrate addition in either the aerobic phase or anoxic phase. Once one understands the SBR process, one can rapidly progress on to the other configurations (ex. anoxic, aerobic, anaerobic, aerobic with internal recycle from the aerobic back to the anoxic) as well as advanced concepts such as Integrated Fixed-Film Activated Sludge (IFAS) process or Moving Bed Bio-Reactors (MBBR’s) for enhanced nitrogen removal. These discussions can also be integrated into an introduction into Wastewater Lagoon Technology, since many of these concepts can also be use there as well.

Process control/troubleshooting concepts will be integrated as natural part of the discussion of SBR technology and will be reviewed with each subsequent discussion of the various alternatives. This will equip the trainee with the basic conceptual knowledge needed to operate a plant from day one.

Of course, the Georgia Rural Water Association is always available to assist with any process control, troubleshooting, training, and any other compliance and operational issues that may crop up.

The next few posts will focus on Activated Sludge Concepts. After that, I will focus on some water related topics of interest.  

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Regards

Dennis Brown, dbrown.grwa@gmail.com; 678.750.3886