A Refresher on Water Recovery Engineering
Posted on September 23, 2025
It might be easy for those who live near the Great Lakes to forget, but freshwater is a finite and precious resource on our planet. And it’s up to water recovery engineers to keep clean water flowing from our watercourses as much as possible.
According to Ishin Kaya, a Senior Water and Wastewater Engineer at Anderson, Eckstein & Westrick, Inc., the goal of wastewater treatment and water recovery engineering is to collect wastewater and — through treatment plants — treat the water so that it can safely go back into the environment or be used by nature or humans again.
“Water recovery engineering focuses on collecting, treating, and safely returning used water from homes, businesses, and industries back into the environment,” Kaya said. “Wastewater engineers design and operate treatment plants, manage sewer networks, control odor and corrosion, and solve issues like removing pollutants including harmful chemicals, nutrients, and pathogens.”
Polluted water often contains excess organic matter and nutrients. As these materials break down, they consume oxygen, and once oxygen is depleted, anaerobic conditions develop. In these conditions, microorganisms release gases like methane and hydrogen sulfide. Excess nutrients can also cause algal blooms; when these blooms die and decompose, they further reduce oxygen levels, sometimes creating fish kills. Untreated sewage may also carry pathogens that spread disease and make water unsafe for people and wildlife.
The wastewater treatment process involves removing pollutants including metals, nutrients such as nitrogen and phosphorus, and trace organic compounds. Kaya said water recovery engineers are experts in designing facilities that contain networks of pumps, aeration systems, clarifiers that settle biomass (sludge), and filtration/membrane steps through a process known as polishing.
Water that’s flushed or goes down a drain in an urban environment makes its way through the sewer system until it reaches a centralized treatment facility, which screens out larger debris. Afterward, the wastewater goes into a treatment facility’s sedimentation tanks to further separate solid materials from the water.
Next, the water enters large aeration tanks — a critical step in further pollutant removal. Oxygen is introduced to stimulate beneficial microorganisms that metabolize organic contaminants. While pathogens are already present in the incoming wastewater, they are not directly affected during aeration. After this stage, the microbial biomass settles out as biosolids (also known as waste sludge). However, the treated effluent may still contain pathogens, which are eliminated in a final disinfection step.
An extra step can involve more filtration, or the use of ozone or UV light to disinfect the water.
“After biological treatment to separate the microorganisms, the water enters a tertiary stage to polish it, further removing fine particles, nutrients, odors, and trace chemicals,” Kaya explained. “Finally, after disinfection, the clean water is discharged into a lake or river, or reused for irrigation or industrial processes.”
Wastewater is more than just dirty water. Its hidden value lies in how its organics can be converted into biogas and generate electricity.
“And even after the energy is recovered, the leftover biosolids still hold nutrients like phosphorus and nitrogen that can be made into eco-friendly fertilizer for farms, with proper biosolids treatment and stabilization,” he said, adding that biosolids reuse depends on regulatory standards and local rules.
Without this proper wastewater treatment process, Kaya explained, wastewater could contaminate bodies of water and groundwater, sickening wildlife and the public by exposing them to toxins. He added that while around 2.5% of the earth’s water is freshwater, only less than 0.2% of the earth’s water is accessible freshwater from lakes, rivers, or shallow groundwater that is fit for drinking, growing food, supporting livestock, and running industries.
“Therefore, protecting this tiny fraction through proper treatment is essential,” Kaya said. “It keeps our limited supply safe from contamination, safeguards public health, and preserves ecosystems for future generations.”