By Steve C. Green and Mitch C. Matthews
Research studies, empirical evidence, and the march of time all suggest that the implementation of next-generation technologies at wastewater utilities is profoundly important, if not imperative, for efficient operations.
Climate change, urbanization, aging infrastructure, spiraling energy costs, and an evolving regulatory environment — these are just some of the challenges facing the global water sector. When it comes to wastewater treatment, plant operators are required to cope with growing demand and increasingly stringent environmental standards while lowering operating costs. Although the challenges are many and complex, they present a compelling opportunity. Accelerating the adoption of high-efficiency wastewater treatment technologies will not only result in greater productivity of wastewater operations, but also unlock significant emissions abatement, representing a meaningful step forward in tackling the impacts of climate change. And importantly, these advanced, sustainable wastewater treatment technologies are readily available today.
The Energy Efficiency Opportunity
Inefficient wastewater operations result in excessive energy consumption, high operating costs, and harmful greenhouse gas emissions related to electricity generation. Global carbon dioxide (CO2) emissions have increased by almost 50 percent since 1990, and, as many countries enact legislation to decrease CO2 emissions, there is growing pressure on municipalities and governments to show leadership in addressing global warming. Improving energy efficiency is a key tool for reducing greenhouse gases.
Xylem’s Powering the Wastewater Renaissance report found that investment in currently available high-efficiency technologies could reduce electricityrelated greenhouse gas emissions from the global wastewater sector by up to 50 percent. The analysis also suggests that much of this reduction in electricity-related emissions can be achieved at a negative or neutral cost. Adopting these technologies would have a significant impact on the greenhouse gas emissions responsible for fueling climate change — equivalent to removing 11.4 million cars from the road, according to American Forests, a nonprofit organization based in the U.S.
In addition to regulatory and environmental considerations, reducing operating costs remains a top concern for wastewater managers. Since energy is consumed from the primary treatment stage to the digestion of sludge products, energy costs often represent the largest portion of operating expenditures in a wastewater treatment plant. With world energy consumption expected to grow by 28 percent between 2015 and 2040 , demand for high-efficiency, intelligent wastewater technologies is growing. This is coupled with a shift in focus from the energy efficiency of single components or products to optimizing efficiency throughout an entire system with the correct combination of technologies, resulting in reduced carbon emissions and lower lifecycle costs.
Advanced, Intelligent Technologies Supporting The Drive For Efficiency
Intelligent technologies are transforming the wastewater landscape, reducing the requirement for human intervention and delivering energy and reliability benefits, as well as enhanced asset management capabilities.
Pump technology, for example, is becoming smarter and supports increased efficiency and enhanced lifecycle costs. According to a report by Frost & Sullivan, the deployment of IoT technologies and Industry 4.0 will increase operational efficiency in the global pump industry by nearly 45 percent, escalate return on investment for manufacturers, and widen application scope.
Similarly, high-efficiency, low-speed submersible mixers with integrated speed control are engineered to use only the energy required at a given time and quickly change to meet seasonal fluctuations or changing operational requirements, while having the mixing power to handle future demand. The result is superior mixing and energy efficiency, with energy costs reduced by up to 50 percent. Collectively, these advanced technologies enable treatment plant operators to extract actionable insights from data to optimize their operations and enhance productivity and sustainability.
Maximizing Resources With Advanced Automation And Simplified Maintenance
The automation of a growing number of processes within the treatment plant is delivering greater reliability and efficiency, and helping plant operators to achieve a higher quality of treated water. Automated technologies self-diagnose and recommend interventions, enabling plant managers to take preventive action, either directly or by calling on a local water technology partner to provide support on a contract basis. The automation of processes facilitates more-effective resource management as personnel typically required to oversee pipe leaks and valves, electrical systems, and instrumentation equipment are freed up for other critical activities.
This is particularly important at a time when some regions are experiencing a decline in trained operators due to an aging workforce and a large number of industry employees nearing or currently eligible for retirement. Furthermore, training of new operators tends to focus largely on familiarity with device interfaces, rather than diagnosis of mechanical equipment issues.
Customizable, integrated biological control software and hardware systems are available that can be used with existing treatment technologies to enhance the efficiency of operations. Process performance optimizers with real-time monitoring and control mean that operators always know actual treatment process conditions, rather than relying on a “best guess.” This stabilizes the process and helps to avoid the common pitfall of excess treatment and the significant energy consumption associated with this process. Process performance optimizers dynamically adapt to changing conditions to optimize contaminant removal for guaranteed effluent quality at the lowest energy demand.
Making The Most Out Of Data For Smarter Wastewater Management
Laboratory measurement of grab or composite samples is the dominant method of compliance monitoring. However, process monitoring is increasingly being done with measurements from online analytical instrumentation in order to provide continuous control of the process, minimize inputs of chemicals and energy, and avoid conditions leading to process upsets. Continuous monitoring improves decision making and reduces the burden on staff for sampling and measuring process parameters multiple times per day. Furthermore, by leveraging these systems’ advanced reporting capabilities, operators can achieve further optimization through trend analysis. Ultimately, these smart water technologies facilitate the collection, delivery, management, and analysis of data more frequently, supporting smarter operations at every point in the wastewater treatment process.
Ensuring Compliance In An Evolving Regulatory Environment
In addition to supporting the drive for lower operational costs, sustainable, reliable technologies are supporting wastewater managers to meet increasingly stringent environmental regulations to address effluent quality, while ensuring optimal efficiency.
For example, nutrients such as nitrogen and phosphorus are the primary cause of eutrophication in surface waters, resulting in algal blooms, low dissolved oxygen, and fish kills. Next-generation denitrification systems reduce the nutrients in the effluent stream by converting nitrate nitrogen to nitrogen gas. These systems convert the filters to become biologically active so that the effluent meets the mandated nitrate and phosphorus levels.
Efforts to reduce nutrient impairment have brought about more stringent effluent limits for wastewater treatment plants, often necessitating biological nutrient removal (BNR) systems to ensure compliance. BNR processes can be both effective and economical; however, many conventional treatment systems try to achieve BNR using dissolved oxygen (DO) levels alone to control the process, resulting in unnecessary energy consumption. Process performance optimizers with ammonia-based aeration control are a smarter and more flexible option. With continuous monitoring of the effluent ammonia level, the air supply can be adjusted to match the actual oxygen requirement at all times, providing energy savings and keeping the plant compliant. Advanced controls for aerobic sludge digestion offer a similarly high potential for energy savings during the aeration process.
Proper mixing within anoxic and anaerobic zones can help ensure lower effluent nutrients and improved treatment efficiency. Effective mixing is often accomplished with submersible, low-speed submersible, or impeller mixers such as top-entry agitators. The right mixing technology works within the plant’s BNR system design to maintain optimum conditions for nutrient removal. In addition to efficient mixing, the right mixer should also provide low maintenance and low operating costs, ultimately resulting in a low lifecycle cost.
The Role Of The Wastewater Treatment Plant In Resource Recovery
Wastewater treatment plants are a vital link in paving the way to a secure water future. One-third of the world’s population experiences water scarcity at least one month per year. In the face of growing needs and increasingly variable supply, communities must turn to innovative solutions to ensure water security. Communities are responding to this challenge through storage, conservation, public outreach, groundwater management, and water reuse. The latter is a proven approach that can help meet growing water demands while safeguarding existing water supplies.
Reuse technologies such as ozone-enhanced biologically active filtration processes (O3-BAF), advanced oxidation processes (AOP), and UV and ozone disinfection solutions are designed to provide the highest level of treatment. These solutions, engineered to ensure protection of human health and the environment while meeting the most stringent regulations, are being used at wastewater treatment sites around the world.
Embracing The Challenge, Realizing The Opportunity
The challenges facing the wastewater sector are undoubtedly complex. With smart investment and innovative financing through public- or private-sector structures, however, the burning issues on the minds of wastewater managers and policymakers alike can be addressed, and the full potential of lowcarbon technologies unleashed. Ensuring optimum efficiency in wastewater treatment operations will support the drive to meet global emissions reduction targets, while also delivering considerable cost savings for plant operators. The good news is that achieving this goal is not solely dependent on technology development, but is also a matter of accelerating adoption of existing high-efficiency technologies. Let’s work together to embrace the opportunity and enhance the productivity of this crucial sector.
About The Authors
Steve Green is the municipal market manager for Xylem Inc., covering the western U.S. and Canada. Steve holds a B.S. in Civil Engineering from Montana State University, and an MBA from the University of Washington. He began his career as a civil engineering consultant, designing water and wastewater treatment plants and conveyance systems, before transitioning into business development, sales, and marketing. Green also serves as an advisor member to the Water Design-Build Council, furthering best practices for technology deployment in collaborative delivery projects. He has over 18 years of experience in the water industry.
Mitch C. Matthews is the municipal marketing manager for Xylem covering the southeast region of the U.S. and has been working with Xylem for more than three years. Mitch’s role involves working with customers in the municipal sector and Xylem’s broad portfolio of water and wastewater treatment and transport solutions. He holds a B.S. in Industrial Engineering from Southern College of Technology and began his career as an application engineer in the oil, refinery, and exploration industry. Matthews has more than 20 years of experience in the water sector.