Application of Ozone in Hospital Wastewater Treatment

1. Core Advantages of Ozone for Hospital Sewage

Hospital wastewater contains pathogenic bacteria, viruses, antibiotics, disinfectant residues, pharmaceutical micro-pollutants and radioactive trace substances, with strict disinfection requirements. Ozone is an ideal advanced oxidant for this scenario:

1. Powerful broad-spectrum sterilization Ozone rapidly destroys the cell wall, nucleic acid and enzyme system of bacteria (E. coli, Salmonella), viruses (COVID, hepatitis virus, norovirus), fungi and spores. It achieves 99.99% disinfection efficiency within a short contact time, far better than traditional chlorine disinfection. It avoids virus mutation and drug-resistant strains caused by insufficient disinfection.
2. No residual toxic by-products Unlike sodium hypochlorite and liquid chlorine which produce carcinogenic trihalomethanes (THMs), ozone only decomposes into oxygen after oxidation. No secondary pollution to water bodies, no residual chlorine to harm aquatic organisms.
3. Dual functions: disinfection + pollutant degradation Besides sterilization, ozone oxidizes and breaks down residual antibiotics, hormones, anesthetics, organic solvents and medical dye waste in hospital wastewater. It effectively reduces COD, BOD and chroma of wastewater.
4. Decolorization & deodorization It oxidizes malodorous substances such as hydrogen sulfide, amines produced by the decay of patient excreta and biological waste, eliminating black color and stench of sewage.
5. Automatic, safe operation Ozone is generated on-site via ozone generators, no storage, transportation risks of chemical disinfectants. Matched with ORP/redox online monitoring system, it can automatically adjust ozone dosage according to water quality load.

2. Main Application Scenarios in Hospitals

2.1 Terminal disinfection of comprehensive hospital total wastewater

Whole hospital mixed sewage (wards, operating rooms, laboratories, canteens) flows into the sewage station after sedimentation, anaerobic/aerobic biochemical treatment. Ozone advanced oxidation tank is set at the final process:

• Online ORP sensor controls ozone injection; standard control value 650–800mV to meet national medical sewage discharge standards.
• Kill residual pathogenic microorganisms after biochemical treatment, degrade refractory pharmaceutical residues.

2.2 Independent disinfection for high-risk wastewater branches

Separate ozone treatment systems are deployed for high-pollution sewage to prevent cross-contamination of total wastewater:

1. Laboratory & pathology wastewater: Contains chemical reagents, formalin, tissue fixatives, cytotoxic drugs. Ozone oxidizes toxic organic chemicals and inactivates biological specimens.
2. Dialysis room wastewater: High microbial content, easy biofilm breeding; ozone eliminates biofilm and prevents pipeline blockage.
3. Infectious disease ward sewage (fever ward, isolation ward): Independent ozone pre-disinfection tank before merging into main pipeline to cut off virus transmission risk.
4. Operating room & dental wastewater: Blood residue, disinfectant waste, heavy metal organic complexes, ozone degrades organic binders and decolorizes blood wastewater.

2.3 Reuse of hospital reclaimed water

After ozone disinfection and filtration, treated wastewater can be recycled for non-contact domestic water: toilet flushing, green irrigation, ground cleaning, cooling circulating water of air conditioning units. It cuts hospital tap water consumption and operation costs.

2.4 Auxiliary application: Pipeline & sewage tank biofilm cleaning

Similar to the ozone nanobubble mixing system in your drawing: micro-nano ozone bubbles circulate inside sewage storage tanks and pipelines, continuously peel off biofilm and kill hidden bacteria, solving long-term pipeline sludge, odor and bacterial reproduction problems.

3. Standard Process Flow of Ozone Hospital Wastewater Treatment

    Grid → Sedimentation Tank → Biochemical Aeration Tank → Secondary Sedimentation → Ozone Advanced Oxidation Mixing Tank
    (with nano-bubble circulation + ORP automatic control) → Filtration → Discharge / Reuse

1. Sewage enters mixing tank, ozone gas dissolves into water through nano-bubble circulation pump to improve dissolution efficiency;
2. Online redox sensor detects water oxidation value, feeds signal back to ozone generator to automatically increase/decrease ozone output;
3. After sufficient oxidation and sterilization, water is filtered and discharged up to standard.

4. Limitations & Matching Optimization Measures

1. High energy consumption cost Ozone production consumes electricity. Solution: Combine with UV synergistic oxidation (O₃/UV) to reduce ozone dosage and lower power consumption.
2. Weak removal effect on ammonia nitrogen Ozone cannot efficiently remove ammonia nitrogen. Solution: Complete nitrification and denitrification in the front biochemical section first.
3. Short half-life in water Ozone decomposes quickly. Solution: Adopt micro-nano bubble mixing tank with internal circulation to extend gas-water contact time, improve utilization rate of ozone.
4. Corrosion to equipment Ozone is corrosive to carbon steel. Solution: All pipelines, mixing tanks, sensors use stainless steel 316L or PTFE anti-corrosion materials.

5. Environmental & Compliance Value

1. Meet strict national discharge standards for medical wastewater (limits on intestinal pathogens, viral load, COD, drug residues).
2. Eliminate hidden dangers of chlorine disinfection by-products, protect river and underground water environment around the hospital.
3. Reclaimed water reuse reduces urban water supply pressure, conforms to hospital green energy-saving transformation policies.
4. On-site ozone generation avoids hazardous chemical storage, reducing hospital safety management risks of disinfectants.