Hospitals heal the sick, but their wastewater tells a different story—one of chemical and biological contamination that threatens ecosystems and public health.
Imagine a hidden stream flowing from our hospitals, carrying a complex mixture of life-saving medicines, disinfectants, and infectious agents directly into our environment. This is not a scene from a science fiction novel, but the reality of hospital wastewater, an underestimated environmental threat that conventional sewage treatment plants are often ill-equipped to handle 1 . This article unveils the composition of this masked threat and explores the innovative solutions scientists are developing to neutralize it.
Advanced treatments like ozonation and UV-LED light show promise in neutralizing these contaminants 7 .
Hospital wastewater (HWW) is far more polluted and complex than typical urban sewage. This effluent is a concentrated brew of diverse and hazardous pollutants.
Recognizing the inadequacy of conventional treatment, researchers are pioneering advanced methods. A compelling 2025 study implemented a continuous-flow treatment system at a hospital in Tokyo, Japan, to test the effectiveness of combining ozonation and ultraviolet (UV-LED) light 7 .
Untreated hospital wastewater was pumped into a cylindrical ozonation tank at a flow rate of 20 liters per minute 7 .
Ozone gas was generated and injected into the tank as microbubbles and ultrafine bubbles, maximizing its contact with the wastewater. A key innovation was the re-circulation of excess ozone gas back into the system, improving efficiency 7 .
After ozonation, the water was subjected to further disinfection using ultraviolet light-emitting diodes (UV-LEDs) 7 .
The team measured the system's effectiveness by analyzing the water before and after treatment for levels of antimicrobial-resistant bacteria (ARB) and the concentration of various antimicrobial drugs 7 .
The results demonstrated the powerful synergy of the combined treatment.
The study proved that this combined system could successfully and continuously inactivate ARB to undetectable levels 7 .
The system effectively removed most of the targeted antimicrobials, though the persistence of some drugs like ampicillin highlights the need for ongoing optimization 7 .
This experiment provides a robust model for a scalable, effective treatment technology that could drastically reduce the environmental footprint of hospitals 7 .
Tackling the complex challenge of HWW requires a diverse arsenal of technologies.
A biological treatment where microbes grow on plastic carriers, degrading organic matter. It's valued for its high impact load resistance and flexibility 2 .
Injects ozone gas, a strong oxidant, into wastewater. It inactivates pathogens and degrades a wide range of micropollutants, leaving no chemical residue 7 .
Uses UV light to damage the DNA of microorganisms, preventing their replication and rendering them harmless. It is often used as a final polishing step 7 .
Uses microorganisms to break down pollutants in the absence of oxygen. Specific microbial communities can degrade antibiotic classes like fluoroquinolones and sulfonamides 8 .
An emerging advanced oxidation technology where liquid is forced through a constriction, creating bubbles that implode. This generates extreme local conditions and free radicals that destroy recalcitrant organic pollutants and sterilize the water 6 .
The threat posed by hospital effluents is clear and urgent. From altering aquatic ecosystems to fueling the rise of untreatable superbugs, the consequences of inaction are severe 1 7 .
Reduction of ARB with advanced treatment 7
Removal of some antimicrobials with ozonation 7
While innovative technologies like ozonation, UV disinfection, and advanced oxidation processes show great promise, their widespread adoption is critical.
Addressing this masked environmental threat requires a concerted effort from healthcare professionals, hospital administrators, policymakers, and scientists. The path forward involves stricter regulations, increased investment in advanced on-site treatment infrastructure, and continued research into more efficient and cost-effective purification technologies 1 9 .