Read the wastewater article by Patrick Dorn, sales engineer at Mills-Winfield Engineering Sales, Inc., on the Pumps & Systems website.
Historically, the wastewater treatment industry has taken longer to innovate than other business sectors. Overall, wastewater treatment processes have consisted of three basic phases for decades with improvements in technology and equipment being incremental. With a future of uncertainties—perhaps as many as in years past but now more pressing due to new challenges—treatment technologies must continue to evolve but at a rapid pace.
These new challenges make immediate and long-term planning more difficult with increasing energy costs, finite resources and more rigorous regulations in response to climate change. The future is never certain, but these challenges are likely to escalate rather than diminish over time. For this reason, many are working to address four current trends in wastewater treatment improvement: nutrient removal and recovery, trace organic compounds, energy conservation and production and sustainability.
New innovations are already here, and others are on the way, complete with artificial intelligence (AI) and machine learning options, which can provide detailed wastewater sample reports for water plants in a matter of minutes. It is important to note current equipment may be used for many of the necessary trends. All it takes is a shift in mindset with an eye toward the future.
Equipment sales and leasing organizations can encourage change within the wastewater treatment industry by providing the pumps, systems, agitators and vibrating fluid beds that deliver efficient, effective and environmentally friendly performance.
Nutrient Removal
While several areas throughout the country have focused on nutrient removal for decades, one example being Florida’s efforts to reduce nitrogen and phosphorous, all wastewater treatment plants are expected to provide nutrient removal or reduction in the near future.
The current treatment phases target removal from the first steps of the process—in other words, when sewage enters the plant through a screen to remove large items that might damage equipment. These items could be leaves, sticks, paper, rags, plastic, etc. Further removal occurs for smaller items in a grit chamber. This is where sand, pebbles and any other small items will settle to the bottom. Pumps then slow the flow of water through the tanks so any further suspended solids, those lighter than the stones and sand, can settle to the bottom.
Water treatment plants that already work to remove nutrients from wastewater begin during the activated sludge process throughout the secondary phase. This is accomplished by using various chemicals and reactions to convert the elements into substances that can be broken down or removed in the next phase. For instance, non-settling particles may be recaptured through the introduction of coagulant chemicals using a flash mixer, such as a surface aerator impeller or a dynamic inline mixer. The mixer ensures rapid, uniform distribution of the coagulant throughout the tested wastewater, causing the smaller particles to form a flocculent mass (or floc), which can then be removed from the water.
In Florida, nitrogen is removed by oxidizing ammonia into nitrite, which is then converted into a nitrate. During the aerating process in the second phase, heterotrophic bacteria reduce the nitrate to a benign nitrogen gas, thereby using less oxygen and carbon. Expect to see more wastewater plants use this and similar techniques for the removal of nitrogen and other nutrients.
The activated sludge can be retained for additional uses, which could lead to the recovery of more nutrients. Whatever does not provide useful elements for recovery can then be converted into fuel or fertilizer, ensuring all wastewater that flows in finds some future purpose.
Energy Management
In the near future, if not already, wastewater plants will focus on energy management in response to rising energy costs and climate change. The goal of becoming energy neutral or even energy positive—where energy is recovered for reuse—will be a priority for all. These initiatives can be achieved through several different processes that could involve equipment already in use for the plant.
Incremental improvements to wastewater plants will set many on course with goals, such as maximizing efficiency, achieving more treatment with less power, reducing and producing energy and generating renewable power. All of these will work together to decrease a plant’s carbon footprint.
Perhaps the most common inclusion in energy management initiatives will be increased anaerobic processes to remove pollutants. The benefits would be many, beginning with the elimination of higher costs associated with aeration and sludge handling. New equipment, such as an anaerobic membrane bioreactor, may be necessary at some point to make new processes that produce energy, rather than consume it, a reality.
Sustainability
The focus on energy management will also include measures for sustainability. Lowering emissions, reducing the energy needed for nutrient removal and maximizing efficiency in processes are just the first steps toward sustainability. The future of wastewater management will also involve discovering new ways to create energy rather than use it. The anaerobic denitritation process previously mentioned is just one way wastewater plants can begin to turn the tide.
Other nutrients recovered from wastewater can also work to increase sustainability, particularly phosphorus. Currently, the earth has enough phosphorus reserves to last the next 100 to 300 years. With the ability to recover phosphate from wastewater, those reserves could be stretched endlessly. Though not currently economical, the process will be tested and improved over the coming years. The processes used for phosphate recovery may then be used to design and develop other nutrient recovery systems.
The ability to recapture nutrients from wastewater could go a long way toward conserving energy and potentially using these elements in the creation of new energy, which are both key factors in increasing sustainability. Sludge from water treatment may also be used in a variety of ways, such as fertilizer or combustible fuel. Fine sieves, which are currently undergoing innovation and improvement, could make collecting more solids, such as cellulose fibers from toilet paper, a reality. Upon collection of these fibers, the material can be compacted, and perhaps recycled, to make more paper.
The purpose of wastewater treatment is to make water reusable. Through improved technology, faster processes and innovation, the ability to reuse more water than ever before may be captured. Despite facing an uncertain future, there is still excitement around the innovation and improved strategies that emerge every day. These innovations and new strategies can be used to create near- and long-term plans to tackle energy efficiency and sustainability in steps both small and large. These plans for the future will help to increase flexibility and agility so that pivots are possible when the industry is faced with new challenges.
There is a lot to be said about current technology. New is not always better. Where possible, current equipment can and should be used to achieve new outcomes, with replacements only coming for those strategies and equipment that will not keep up with tomorrow’s needs.