The average household may not think twice about the water it sends down the drain, but a new review by Igor Kogut of Hohenstein Innovations gGmbH in Germany is forcing the sector to confront an uncomfortable truth: the very chemicals that make modern life convenient are quietly accumulating in the environment, often slipping through treatment systems designed for an older generation of pollutants.
Kogut’s research, published in *Clean Technologies* (translated from the German *Kreislaufwirtschaft und Technologien*), reveals that while 56% of global wastewater is now treated, the systems in place were not built for the cocktail of sodium chloride from water softeners, microplastics from synthetic fabrics, antibiotics from flushed medications, or PFAS from non-stick pans. “We’ve designed our water infrastructure around bulk organic matter and nutrients,” Kogut notes. “But the real challenge today isn’t volume—it’s persistence.”
What makes this review particularly compelling is its quantitative lens. By converting pollutant loads into per capita annual emissions, Kogut and his team show that everyday products—detergents, toilet paper, personal-care items—contribute disproportionately to chloride and organic loads, while trace contaminants like pharmaceuticals and microplastics linger due to their resistance to conventional treatment. The findings underscore a growing mismatch: treatment plants optimized for biochemical oxygen demand (BOD) are ill-equipped to remove trace organics or engineered nanomaterials.
The implications for the energy sector are significant. Advanced technologies like reverse osmosis, nanofiltration, and electrochemical oxidation promise higher removal rates but come with steep energy and cost demands. Reverse osmosis, for instance, can demand up to 10 times more energy than activated sludge systems per cubic meter of treated water. “The transition from conventional to advanced treatment isn’t just a technical upgrade—it’s an energy transition in miniature,” Kogut observes. “And without targeted policy or incentives, the financial burden will fall unevenly across municipalities and industries.”
The review also highlights a paradox in decentralized systems, where small-scale solutions often lack the resilience to handle persistent contaminants. Hybrid systems—combining membrane bioreactors with adsorption or photocatalysis—are emerging as a compromise, offering improved performance without the full energy penalty of full-scale reverse osmosis.
For water utilities, technology providers, and energy planners, the message is clear: the next generation of wastewater infrastructure must balance environmental performance with energy efficiency. As Kogut puts it, “We can’t keep treating wastewater as a waste problem to solve cheaply. It’s a resource challenge—and one that demands integrated thinking across water, energy, and materials.”