Gaining control of effluent residual (Part 2)

Gaining control of effluent residual (Part 2)

This guest post is authored by Narciso Santiago, a project engineer at EMA, Inc. in Orlando, Fla.  Narciso was a presenter at the 2013 ISA Water/Wastewater Symposium.

In Part 1 of this post,  I explained the difference between being “in control” versus being “out of control” of effluent residual, and indicated that unless the process has long and variable dead time advance process control technology is not a requirement for gaining control of effluent residual. The consequences of being “in” or “out” of control were explained and several important factors for effective residual control were mentioned.Waste Water Treatment

In this post, a list of important factors is given and specific trim controller configuration is discussed. Before gaining control of effluent residual, these key factors must be addressed. The following checklist will help you determine which factors will enable the ability to gain automatic control of effluent residual.

1. Chlorine feed system working correctly. Metering pumps or chlorinators working correctly.

2. Chlorine feed flowmeters (if any) are working correctly for the entire operating range and are calibrated properly. If the flowmeter is unable to give accurate measurement during low flow conditions it should not be utilized for flow control, and the metering pump (or chlorinator) must be controlled by volumetric command (%).

3. Chlorine analyzer is installed according to manufacturer specifications. Sample transport time should be less than 30 seconds whenever possible. Sample lines should be cleaned and flushed on a periodic basis based on experience.

4. All chlorine analyzers require periodic maintenance. Implement a maintenance program (if not already in place) to follow the manufacturer’s maintenance recommendations. Perform conformance sampling by taking a grab sample, running a standard laboratory analysis, and comparing the answers on a periodic basis based on experience.

5. If redundant analyzers are utilized, perform redundancy validation on a periodic basis based on experience. Although not required to gain control of effluent residual, analyzer redundancy is recommended to increase reliability.

6. Mixing done at or near the point of chemical injection. Poor mixing may result in a non-representative of the stream as a whole. Achieving good control without a representative sample is not possible.

7. The control measuring point is near point of injection. The immediate chlorine demand must be satisfied to gain control of effluent residual. The residual measurement used for control must be taken shortly after chlorine addition and mixing.

8. Process dead time. Best residual control is achieved with small process dead time. To measure process dead time while the process is in a steady state and control set to flow pace mode only, increase the dosage setpoint (large increase) and record the time it takes the measured residual start to increase.  When performing a test to determine the process dead time, a historical trend is recommended to be able to also determine the system time constant, the CV delta change (%) and the PV delta change (%). These data are required to calculate initial tuning parameters. Note that advance process control (APC) technology may be required to gain control of a process with long and variable process dead time.

9. Current control algorithm. Knowing the control algorithm enables operators to determine if the control system is working correctly. The fundamental control algorithm is simply a flow pace formula multiplied by a correction factor. [Feed Rate = Flow Pace Rate * (Trim Controller Output)].  The “flow pace rate” portion of the formula calculates a desired feed rate based on dosage setpoint. The “trim controller output” portion of the formula calculates a correction factor based on the error between the setpoint and the residual measured.

10. Control strategy. Is the influent residual measured used for control? In automatic control, is the operator able to set the automatic control for flow pace only and also able to set the system to flow pace plus trim control? Is the operator able to change the dosage (mg/l)? If using bleach, is the operator able to change concentration (%) and specific weight (lbs./gal)?

Once all items in the checklist above have been checked off, the trim controller PID must be configured and initial tuning parameters calculated.

The initial cycle time (time between executions, also known as task period) must be set to equal or greater than twice the influent residual analyzer sampling time. This means that the trim controller output, which is also the correction factor, updates once every time the cycle time elapses. The scale factor shown provides a bump-less transfer to trim mode functionality (Figure 1).

Figure 1, Trim Controller

Figure 1, Trim Controller

A process response graph is shown in Figure 2 as an example. The actual process response trend and initial tuning parameters are determined utilizing the data collected during the process dead time test, checklist item No. 8.

Figure 2, Process Response Graph

Figure 2, Process Response Graph

The process gain:
G = (delta PV %) / (delta CV %)
System time constant:
T = (t1 – t2) * 1.5
Process dead time = t0
Initial PID parameters:
K = 1.5T/Gt0
Ti = 2.5t0
Td = 0.4t0

Set the initial dead band to 0.5PPM, and turn off the PID zero crossing functionality. Since chlorine addition based on effluent residual measured will be out of phase with incoming flow due to detention time, the immediate chlorine demand (shortly after adding it) must be satisfied to gain control of effluent residual.

For effluent processes without excessive dead time, implementing the fundamental considerations discussed in part 1 of this post, addressing the important factors outlined in the checklist above, and proper configuration of the trim controller result in gaining control of effluent residual.

What a historical trend of effluent residual at your plant would depict? The residual measured consistently tracking the setpoint? Or a residual measured not tracking the setpoint? A 24 hour historical trend of the effluent residual will answer the question.

Narciso Santiago

About the Author
Narciso Santiago, CAP, is a project engineer at EMA, Inc. in Orlando, Fla., a company dedicated to the design, development, and implementation of control systems and automation for water and wastewater facilities. Prior to joining EMA, Narciso spent over 12 years at Gencor Industries, a manufacturer of asphalt plants, soil remediation plants, combustion systems and control systems. Narciso is an adjunct instructor for the School of Electronics Technology at ITT Technical Institute in Lake Mary, Fla. He earned a bachelor’s degree in electronics engineering technology from the University of Puerto Rico, and an associate of instrumentation engineering technology from the Technological Institute of Puerto Rico. Narciso has been a certified automation professional since April 2009. Contact Narciso at: nsantiago@ema-inc.com.
Gaining control of effluent residual (Part 1)

Gaining control of effluent residual (Part 1)

This guest post is authored by Narciso Santiago, a project engineer at EMA, Inc. in Orlando, Fla.  Narciso was a presenter at the 2013 ISA Water/Wastewater Symposium.

Many times I have walked into different wastewater facilities control rooms and looked at the effluent residual trend, which to me looks like it is out of control. When I ask for the first time how the effluent residual control is performing, most likely I will get the same answer, it’s doing ok.Effluent Residual

But in reality, there is a big difference between a trend depicting “in control” of effluent residual (Figure 1, below) and a trend depicting “no control” (Figure 2, below). Good control can simply be determined by the fact that the process variable will track the setpoint (in this case the residual measured). A lack of understanding of effluent residual control fundamental considerations results in higher operational and chemical costs.

A trend depicting a small deviation from setpoint demonstrates excellent process tuning. But in wastewater effluent facilities not having good control of residual results in chemical waste, and therefore, gaining effluent residual control is more important than having an excellent process tuning. The immediate result of gaining control of effluent residual is chemical savings.

Figure 1

Figure 1, in control

Figure 2

Figure 2, no control

Advance process control (APC) technologies can provide ultimate optimization for effluent residual control and should be utilized when process conditions demand process modeling and predicting capabilities such as processes with long and variable dead times. But since not all programmable logic controllers are APC capable, and gaining control of the effluent residual is more important than optimizing process tuning, APC technology is not a requirement to gain control of effluent residual.

Important factors for effective effluent residual control include correctly sized control elements; installation and maintenance practices; types of chlorine analyzers; and analyzer redundancy. But more important factors are fundamental considerations that include mixing at the point of injection and how it affects the flow stream; the measuring point location and why it matters; the process dead time and how it relates to choosing a more advanced control method or not; the processing algorithm which is an industry standard; and how a correction factor based on error between setpoint and process variable is implemented.

When there is no effective control of effluent residual, operational activities include time spent daily verifying the effluent residual will not go out of compliance, and taking multiple samples daily to determine the actual value of the effluent residual. Also, the operator is more likely to set the system to manual control, and set the chemical feed rate for enough chemical feed to guarantee the effluent residual will not go out of compliance. The result of these activities will show up in the effluent residual trend depicting a process variable not tracking the setpoint. Worse, a residual trend indicating the residual measured at full scale does not represent the actual value of the residual measured; it’s higher.

In contrast, when the effluent residual is under control, the time spent verifying if the residual is in compliance is now a matter of checking the influent and effluent residual trends for consistency; and a dosage adjustment is now based on the knowledge of actual process disturbances.

In wastewater facilities with no effective control of effluent residual, addressing the important factors and implementing fundamental considerations mentioned above results in gaining control of effluent residual and reduction of operational time and chemical consumption. Upgrading the programmable logic controller and software is most likely not required. Implementation and initial tuning can be completed in a few days. Additional tuning time may be required, but the overall implementation cost will most likely prove to be affordable with immediate cost savings in chemicals.

In Part 2 of this post, I will offer a checklist to help you assess factors that must be considered to achieve automatic control of effluent residual.

Narciso Santiago

About the Author
Narciso Santiago, CAP, is a project engineer at EMA, Inc. in Orlando, Fla., a company dedicated to the design, development, and implementation of control systems and automation for water and wastewater facilities. Prior to joining EMA, Narciso spent over 12 years at Gencor Industries, a manufacturer of asphalt plants, soil remediation plants, combustion systems and control systems. Narciso is an adjunct instructor for the School of Electronics Technology at ITT Technical Institute in Lake Mary, Fla. He earned a bachelor’s degree in electronics engineering technology from the University of Puerto Rico, and an associate of instrumentation engineering technology from the Technological Institute of Puerto Rico. Narciso has been a certified automation professional since April 2009. Contact Narciso at: nsantiago@ema-inc.com.
Using smarter technology to solve the municipal water conundrum

Using smarter technology to solve the municipal water conundrum

This guest post is authored by Carey Hidaka, an IBM worldwide client solutions professional.  Carey was the keynote speaker at the 2013 ISA Water/Wastewater Symposium.

Do you think about where your water comes from and if it will be there tomorrow?  Do you think about where water goes after you’ve used it and how it’s reused as a part of the earth’s water cycle?  Did you know that the amount of fresh water on earth is about the same now as when the dinosaurs walked the planet, and that more and more people are using it now at an ever faster rate?Water in glass

Clean, fresh water is a basic human need that is rapidly becoming a scarce resource.  South Africa even states that access to “sufficient water” is a constitutional right.

Water isn’t just for personal consumption.  Seventy percent of the world’s fresh water is used for irrigation, producing about 40 percent of the world’s food.  Water also generates the world’s electricity by producing steam, powering turbines, cooling equipment and conveying power generation by-products.  Our way of life is inextricably tied to water in many ways.

Population growth stresses our fresh water supplies.  According to the United Nations, water use has been growing at more than twice the rate of population growth in the last century.

Unchecked urbanization and industrialization are contaminating the fresh water we have, making the problem even worse.  In rapidly industrialized China in 2012, up to 40 percent of the rivers were seriously polluted and 20 percent were so bad that their water quality was rated too toxic for human contact.

And the infrastructure that delivers clean water and collects and treats dirty water is falling apart.  The American Society of Civil Engineers in 2009 assigned a report card GPA of D to the U.S. infrastructure, with drinking water and wastewater both achieving grades of D-.  This “improved” in a 2013 update to grades of D.  The World Health Organization estimates that by 2050 70 percent of the world’s population will live in cities; this will further stress an already fragile infrastructure.

Water is one of the most abundant resources on earth, but usable fresh water only makes up less than 1 percent of the total.  Unless we do something differently about how we source clean water and treat wastewater, there won’t be enough fresh water for current and future generations.

Cities don’t have the funding to repair disintegrating infrastructure, install new infrastructure and desalinate to produce enough “new” fresh water to avoid the impending crisis.  Traditional engineering solutions alone can’t solve these problems.

The Way Forward Starts With Data

Lots of data is generated when clean water is produced and wastewater is collected and treated.  How can we analyze that data and combine it with new data sources like crowd sourcing and social media, to create new insights and make better and timelier decisions about water?

For example, the City of South Bend, Indiana is using data from its wastewater collection system to help eliminate combined sewer overflows that contaminate the St. Joseph River with untreated wastewater.  This saves the city from spending millions of dollars in traditional engineering solutions (sewer separation, storage facilities, etc.).

Miami-Dade Parks, Recreation and Opens Spaces is using water meter data to determine where water is leaking and being wasted, reducing water consumption by 20 percent and saving $860,000 per year.

Data doesn’t create more fresh water, but it feeds analysis and decision making about where to source water, when to desalinate, how to stop pollution and what pipes to fix before they break.

What Can We Do?

It’s been said that the world’s next wars will be fought over water, not oil.  How do we take a scarce resource like water and use it in the wisest way possible to support life?  With today’s new technologies, the economic uncertainties in our cities, the challenges of drought, climate change, and failing infrastructure, what else can we be doing?  In what ways can we use data to make better decisions?  What kinds of problems can we solve?  Can we use data and technology to unleash innovation and creativity to leap from reacting to problems to proactively solving them?

OLYMPUS DIGITAL CAMERA

About the Author
Carey Hidaka is an IBM worldwide client solutions professional in the IBM Software Group, with experience as a consultant in the smarter water management business development team and mobile/wireless services. He has 29 years of information technology experience and practiced for nine years as a consulting environmental engineer and registered professional engineer where he focused on water resource planning and water and wastewater treatment plant designs and implementations for public and industrial sector clients. Carey has a master’s degree in business administration with finance specialization from the University of Chicago, a master’s degree in environmental engineering from the University of Illinois at Urbana-Champaign, and a bachelor’s degree, with honors, in civil engineering from the University of Colorado at Boulder. He is also a member of the American Water Works Association.
How to Protect Water and Wastewater Facilities from Cyberattack

How to Protect Water and Wastewater Facilities from Cyberattack

This guest post is authored by David Mattes, founder of Asguard Networks of Seattle, Wash. 

“If you aren’t scared yet, you haven’t been paying attention.”  So goes the aphorism for modern times, and it applies equally well to industrial cybersecurity.  Conclusive proof is hard to come by, but consider the supporting evidence: U.S. presidential executive orders, vulnerabilities markets for ICS, U.S. Secretary of Defense warnings of a “cyber Pearl Harbor”, extremely low patch uptake for ICS/IT automation components, vast and varied ICS CERT warnings, Internet census reports of huge populations of exposed ICS systems.  Before Stuxnet, stories like this just didn’t get any attention if they were even published.  All industries are affected.  Water and wastewater environments are no different, and in fact are particularly attractive to threat actors not only because they are the foundation of advanced societies, but because they are easy targets.

Security with Lock

Because water and wastewater environments are critical infrastructure that have stringent availability and quality requirements, operators have a duty to protect these systems from cyberattack.  When trying to balance the surety with the risk, there are many challenges that have opposing forces, and network connectivity is a classic example of trying to make progress in one domain (e.g. reduced downtime), while backsliding in another (e.g. cyber risk exposure).

Despite the cybersecurity challenges associated with increasing connectivity, industry and government organizations are making steady progress.  How do you get caught up on the progress on security standards and best practices?  How does this progress turn into actionable steps you can take at your utility to strengthen the cybersecurity and increase the robustness of your industrial systems?  These are tough questions to answer, but ultimately this is where the rubber meets the road.  This is a big responsibility.  Are you up for it?  I hope so, because we all depend on you for our high quality of life.

To stay current, you have to get involved in the discussions that are happening.  The hardest step is the first step.  Beyond this, simply keep going.  The ISA participates in the cybersecurity discussion with ISA 99, ISA Secure, and ISA 100.  The U.S. government has some great resources, including ICS-CERT, ICSJWG, NIST Special Publications (SP 800-82 focuses on ICS Security).  If you work for a water utility, DHS offers free ICS Security trainingSANS also provides training and resources (20 critical security controls).  Most large North American electric utilities are regulated by FERC, and the CIP standards published by NERC are worthwhile reading, at least from the perspective of what may eventually happen in the water industry.  Finally, there are various LinkedIn groups with active discussions about ICS security.

My cybersecurity focus is on standards and solutions for network segmentation, which seeks to minimize network connectivity to the absolute minimum.  As Ralph Langner, the researcher who cracked the Stuxnet code, discusses in his book Robust Control System Networks, automation systems are not well-suited to large, flat and open networks.  Network segmentation is about applying the principle of least privilege to network communications, and when implemented in automation networks, you can achieve environments that are more robust, resilient and secure.

The ISA TR100.15.01 document presents an architecture model that describes how to segment, secure, and manage communications over trusted and untrusted networks.  When combined with the IF-MAP and ICS Security standards from the Trusted Computing Group (TCG) and the Host Identity Protocol (HIP) from the Internet Engineering Task Force (IETF), a picture emerges of how to create scalable, manageable, industrial cybersecurity products that are a natural fit for water utilities.

What makes a good fit?  A security solution must be “secure by default,” easy to use, flexible to changing environments, self-documenting and integrate well with other defensive layers.  Most importantly, a security solution must support and enhance the availability, robustness and resiliency of the automation systems.  By supporting our water resources, you play a vital role in our great society.  As part of this responsibility, I challenge you to stay abreast of the cybersecurity issues and challenges facing your industry, and standards-based solutions that can make a real difference.  Together we can rise to the occasion.

David Mattes

About the Author
David Mattes founded Asguard Networks to create products that address the challenge of managing connectivity and information security for industrial control systems (ICS). Prior to Asguard Networks, David spent 13 years in Boeing’s R&D organization. At Boeing, David focused on ICS security issues, particularly on the challenge of segmenting connectivity for ICS devices into private networks and securely connecting them to and through Boeing’s enterprise networks. David was the co-creator and technical and implementation lead on an architecture that not only satisfied Boeing’s InfoSec governance and security requirements, but also met the needs of the end users. He received a master’s degree in electrical engineering from the University of Washington and a bachelor’s degree in electrical engineering from the University of New Mexico. Contact David at mattes@asguardnetworks.com.
Big Data Focus at 2013 ISA Water/Wastewater Symposium

Big Data Focus at 2013 ISA Water/Wastewater Symposium

This guest post is authored by Graham Nasby, general symposium chair of the 2013 ISA Water/Wastewater and Automatic Controls Symposium.

Big Data is Big News in just about every corner of our digitally connected world.  Leveraging massive amounts of process data archives is a game changer for practically any industrial process, enabling greater levels of agility, efficiency and competitiveness.  This year’s 2013 ISA Water/Wastewater and Automatic Controls Symposium will deliver the most current information on Big Data with a keynoteWaste Water system presentation by Carey E. Hidaka of IBM Software Group.  Carey’s speech, “Using Data from Municipal Water/Wastewater SCADA Systems (and Other Sources) to Make Smarter Operational, Maintenance, and Infrastructure Investment Decisions” focuses on how Big Data approaches to plant optimization can reap real rewards.

The ISA water/wastewater symposium, to be held 6-8 August in Orlando, Fla., also will showcase “smart water,” or the intelligent application of application automation technology to municipal water and wastewater plants.  The modern municipal water treatment plant now includes a sophisticated automated control system, carefully designed operator interfaces and advanced data analytics for process automation.  All of this infrastructure must be designed, built, operated and maintained by a highly skilled workforce.  The ISA symposium serves as an ideal venue for professionals from operations, maintenance, design and integration to share ideas, network and learn about new technologies.

In addition to the Big Data keynote, the 2013 ISA water/wastewater symposium also features  37 technical speakers, three invited speakers and guest speakers from the Water Environment Federation (WEF) and the Florida Section of the American Water Works Association (AWWA).

Other notable symposium presentations include:

  • Smart Water Networks for Operational Efficiency Gains
    – Brian Heimbigner and Mark Bitto, ABB
  • Risks of Smart Water Applications – Rigorous Risk Assessment of the Adoption of Smart Water Applications
    – Andreas Hauser, Thomas Stoertkuhl, Klaus Estenfeld amd E. Earl Eiland -TÜV SÜD AG
  • Using Procedural Automation to Improve Operational Efficiency with ISA106
    – Marcus Tennant and Leila Myers, Yokogawa
  • SCADA Control and Monitoring Of Groundwater Remediation Facilities: Past, Present And Planning For The Future
    – Obadiah Kilonzo and Kevin Flemming, Carolina Automation Systems
  • Simulate Your Way out of a Difficult Real Time Control Problem: Automatically Controlling Gates to Reduce Combined Sewer Overflows (CSOs)
    – Maxym Lachance,TetraTech and Sid Lodewyk, City of Edmonton (Alberta, Canada)

To view a complete list presentations for the 2013 ISA Water/Wastewater and Automatic Controls Symposium, visit:  www.isawwsymposium.com/technical-speakers-list.

Registration for the three-day symposium is now open at: www.isawwsymposium.com/register.  Discounts are available for ISA, WEF and AWWA members.  Register by July 2 to receive early-bird pricing.

About thGraham Nasby_100pe Author
Graham Nasby, PE, PMP is the general symposium chair of the 2013 ISA Water/Wastewater and Automatic Controls Symposium, which is being held 6-8 August in Orlando, Fla. at the Crowne Plaza Orlando-Universal Hotel.  Nasby is a senior member of the ISA and a voting member of the ISA18 alarm management standards committee.  He works as a senior instrumentation & control engineer with Eramosa Engineering Inc. Contact: graham.nasby@eramosa.com.
2013 Water/Wastewater Symposium Focuses on “Smart Water” Technology

2013 Water/Wastewater Symposium Focuses on “Smart Water” Technology

This post is authored by Graham Nasby, general symposium chair of the 2013 ISA Water/Wastewater and Automatic Controls Symposium.

Plant reliability, safety and cost-efficiency are among the common goals of professionals working in the municipal water and wastewater sectors.  The Water/Wastewater Industries Division (WWID) of the ISA, which serves as a key educational, technical, professional development and networking resource for the sector, is gearing up for the 2013Water/Wastewater Wastewater Plantand Automatic Controls (WWAC) Symposium, to be held 6-8 August 2013 in Orlando, Florida.

The fall/winter WWID newsletter features complete details on the August symposium, designed for professionals focused on water and wastewater instrumentation, automation and SCADA technology.  “Smart Water” has been selected as the central theme for the event.  SCADA (supervisory control and data acquisition) systems typically gather a vast array of process data – the symposium will be looking at smarter ways to use this data. Topics to be explored will include using process data to drive better plant visualization, improve situational awareness, optimize operations and maintenance, and reduce energy costs.  Additional topics will include using data to enable online process optimization and improved asset management, along with several general SCADA topics unique to the municipal water/wastewater sector.

The 2013 ISA Water/Wastewater and Automatic Controls Symposium will feature two days of expert presentations on instrumentation, system integration, automation, plant case studies, new technologies, optimization, SCADA, HMI, human factors and alarm management.  In addition, specialty training courses at the symposium will be of particular interest.  The symposium is sponsoring a two-day, in-depth cybersecurity course and one-day course on flow meter selection/sizing.  Attendees can earn continuing education units (CEU) and professional development hours (PDH) by participating in educational sessions and ISA training courses.  To register for the summer symposium, click this link.

The 2013 WWAC Symposium extends an open invitation for the submission of abstracts for presentations, papers and posters at the Orlando event.  Abstracts should be a maximum of 250 words and must be submitted electronically to the program committee.  Deadline for abstract submission has been extended to Jan. 31.  Click this link for abstract submission details.

Also of note is the WWID Student Scholarship Program, which is designed to promote careers in the water/wastewater industry.  Open to WWID members and their children who are pursuing higher education, the scholarship offers up to $2,000 in educational support.  The scholarship application, which is available on Page 5 of the newsletter, is due by Jan. 31 and can be submitted via email.

The WWAC symposium is joint collaboration of ISA members and staff, as well as industry sponsors and partnerships.  WWID volunteers have solidified relationships with a wide range of supporting organizations, including the Water Environment Federation, the Florida section of the American Water Works Association, the Florida Water Environment Association and the National Rural Water Association.

More information about the 6-8 August 2013 symposium can be found at www.isawwsymposium.com

About thGraham Nasby_100pe Author
Graham Nasby, PE, PMP is the general symposium chair of the 2013 ISA Water/Wastewater and Automatic Controls Symposium, which is being held 6-8 August in Orlando, Florida at the Crowne Plaza Orlando-Universal Hotel.  Nasby is a senior member of the ISA and a voting member of the ISA18 alarm management standards committee.  He works as a system integrator with Eramosa Engineering Inc. Contact: graham.nasby@eramosa.com

Pin It on Pinterest