Advanced SCADA: 6 essential upgrades to optimize your wastewater treatment

Many wastewater treatment plants (WWTPs) are looking at supervisory control and data acquisition (SCADA) systems and other new technology to optimize performance. What are the drivers behind this and where can SCADA really perform? Simon Baker, our global wastewater market sector lead, and Mike Karl, our water global digital lead, discuss when the time is right to upgrade and how a state-of-the-art SCADA system can fundamentally transform the efficiency of today’s WWTPs.

A troublesome legacy

Most WWTPs already use a SCADA system in one form or another. Many of these were installed when the plant was first built and since then, the demands on WWTPs have evolved substantially. Far more complex to operate and requiring increasingly stringent permit compliance, legacy technology and systems are struggling to keep up with these changes and often can’t guarantee optimal WWTP operations anymore. Plant operators are faced with one of two paths, depending on the state of their current system:

1. Is there life left in the SCADA system? In which case, operators can incorporate more advanced control strategies and user interface elements to extend its effectiveness and longevity.

Or

2. Is the current technology obsolete? It may be time for a full SCADA replacement.

Another major challenge facing WWTPs is an aging workforce. According to the U.S. EPA, nearly one-third of current operators will be eligible for retirement within the next decade, leaving the industry with a significant loss of institutional knowledge. WWTPs are complex facilities involving a mix of mechanical, electrical, and control systems, alongside chemical and biological processes. Becoming a fully certified operator requires years of specialized training. As veteran operators retire, the shortage of skilled professionals could leave plants understaffed, impacting the ability to monitor and manage operations effectively. The scarcity of recruitment and trained talent though, is a problem that can be overcome with more intuitive tools like SCADA.

No time to waste

SCADA modernization is an important consideration for all providers of wastewater services. There are many challenges and benefits involved in the modernization process, but automated systems like SCADA play an essential role in our wastewater systems by maintaining public health, ensuring compliance and optimizing operations. Like any technology though, it’s only as strong as its weakest point.

Whether starting out on the journey to SCADA replacement or looking to add to existing systems, this is an essential investment in the future. For WWTPs to withstand population growth, aging infrastructure, tighter regulations, and the need to reduce their carbon footprint, they will lean ever more heavily on modern SCADA technology.

Accelerating plant optimization

Combining SCADA advances with those of today’s sensor and process technologies provides WWTPs with a range of areas for operational optimization.
Here are six that will make the greatest difference:

1.Solids retention time (SRT). If the SRT is too long, energy is wasted as the biology in the aeration tanks starts to aerobically digest. If it’s too short, the wastewater won’t be sufficiently treated and will risk permit violations. Wastewater testing is traditionally done manually, perhaps once a day, to check when optimum SRT is reached. SCADA, on the other hand, can deliver ammonia-based control, where sensors continually monitor the residual ammonia, allowing precise control of the SRT for maximum effectiveness.

2.Aeration. Nozzles at the bottom of the tank diffuse oxygen through the liquid to provide an ideal environment for bacteria to break down the organic matter and ammonia. Operators use set points in the control system throughout the tank to measure the dissolved oxygen. These are infrequently reviewed and optimized, often leading to over-aeration of the tank and wasted energy.

Aeration accounts for up to 50 percent of a WWTP’s total energy costs. SCADA can optimize this process using either dynamic-based control (within the SCADA system) or a digital twin (an online model of the biology that can be run to precisely inform the set point). These advanced technologies and sensors can achieve the required levels of effluent organics and ammonia with significant energy savings.

3.Solids dewatering. This process uses mechanical separation with the aid of chemicals so less solids can be trucked off site. The process may involve sensors and traditionally the set point is adjusted manually by looking at the output.

By using new sensor technologies and tuning methods, SCADA can do this pre-emptively. It monitors the dewatering system including the inputs and outputs and machine conditions, and dynamically adjusts the set point. This can save on chemicals, reduce the energy needed to run equipment and lower the weight and costs of hauling.

4.Chemical dosing. Disinfection is typically carried out by adding chlorine – though, sometimes, plants use ultraviolet light. The dosing amount is usually based on the flow rate of the effluent and is often over-dosed for safety. However, new sensors and technology can add information about input quality and use feedback from chlorine residual meters, so you can alter the dose depending on what is needed. This more nuanced system cuts the peaks and troughs of traditional dosing and saves money by reducing the amount of chemicals used.

5.Operator time efficiency. If there’s one thing operators lament regarding control systems, it’s inefficient alarms. At any one time the control room may have dozens of alarms going off. Often, it’s because equipment has been shut off or is out of service, so operators may not address it. However, this can lead to issues where alarms have been ignored and plants have been in overflow conditions, causing permit violations. New technology and advanced algorithms rationalize these alarms, eliminating the wasted time spent working out which alarms need attention and which can be safely ignored.

6.Maintenance schedules. New sensor technology and SCADA systems can enable a shift from periodic, to predictive-based maintenance. For instance, where a pump had traditionally been lubricated every quarter (whether necessary or not), algorithms can spot if that pump is using more energy than it should, making it a candidate for immediate maintenance. Issues can be dealt with before they cause downtime and costly, unnecessary maintenance can be eliminated.

Where could a leading SCADA implementation take WWTPs?

WWTP operators are pulling live and historical data from multiple sources to monitor and control the treatment processes effectively. However, a deluge of data can make it difficult for operators to process effectively. Modern SCADA systems take this data in stride, analyzing it to determine trends that inform enhanced plant operations, and pre-emptively making recommendations on adjustments to ensure there are no operational hiccups.

An optimal SCADA system can:

• Reduce risk to the public, the environment and the plant’s operations and maintenance staff
• Optimize energy efficiency
• Refine chemical dosing
• Complete routine tasks automatically
• Extend asset life through condition monitoring / assessment
• Predict issues and prioritize preventive maintenance
• Enable a safe working environment for operators
• Mitigate workforce challenges by empowering less experienced staff to make informed decisions

Deephams sewage treatment works upgrade is a prime example of SCADA optimization in action. One of London’s largest wastewater treatment plants, Deephams required a major upgrade. We deployed innovative Integrated Fixed Activated Sludge technology that enabled Thames Water to intensify its treatment process, delivering cleaner water without having to expand its site.

We’ve developed the above maturity curve to help those considering SCADA modernization assess where they are currently and where their future efforts can be best placed. With an awareness of the ideal timing for undertaking modernization, WWTP operators and decision-makers can appropriately plan resources and training for this fundamental transformation.

If you’d like to find out more about how SCADA can optimize your WWTP processes, please get in touch with our Digital Water team or the authors Mike Karl and Simon Baker.