Why is hospital wastewater more difficult to treat than regular wastewater?

Hospital wastewater is one of the most strictly regulated types of wastewater today because it contains many specific pollutants such as organic matter, pathogenic microorganisms, grease, Nitrogen compounds, and chemicals generated during medical examination and treatment activities. If not treated properly, medical wastewater can affect the receiving environment and increase the risk of spreading harmful microorganisms to the outside environment. Therefore, hospital wastewater treatment systems must ensure stable operation and comply with current environmental regulations before discharge.

1. Characteristics of Hospital Wastewater

Hospital wastewater is generated from many different areas such as medical examination zones, laboratories, treatment rooms, kitchens, and residential areas. The wastewater often contains organic matter, grease, suspended solids, pathogenic microorganisms, and Nitrogen compounds generated during medical activities.

Hospital wastewater commonly contains:

• Organic matter (BOD, COD)
• Suspended solids (TSS)
• Grease and oil
• Nitrogen and Phosphorus compounds
• Pathogenic microorganisms
• Coliform
• Cleaning chemicals and medical chemicals

In particular, hospital wastewater often fluctuates depending on hospital operating schedules, with unstable flow rates and stricter microorganism control requirements compared to many other wastewater types.

Composition of wastewater in hospitals

2. Why Is Hospital Wastewater More Difficult to Treat Than Conventional Wastewater?

Compared to conventional domestic wastewater, hospital wastewater has more complex pollution characteristics and requires stricter treatment control. In addition to organic pollutants, medical wastewater also contains pathogenic microorganisms, chemicals, and continuously fluctuating pollution loads depending on hospital operations.

2.1 Contains Many Pathogenic Microorganisms and Coliform

One of the most important characteristics of hospital wastewater is the presence of bacteria, viruses, Coliform, and disease-causing agents generated during medical treatment activities.

Therefore, the treatment system must not only reduce BOD and COD but also ensure effective disinfection and microorganism control before discharge into the environment.

2.2 Complex Pollutant Composition

Besides conventional organic pollutants, hospital wastewater may also contain laboratory chemicals, detergents, pharmaceuticals, grease, and many compounds that are difficult to biodegrade.

This increases treatment complexity and requires the system to operate stably to avoid affecting microbial activity.

2.3 Continuously Fluctuating Wastewater Loads

Wastewater flow rates in hospitals often vary depending on daily operating periods. Areas such as treatment rooms, kitchens, laundry rooms, and laboratories can cause large fluctuations in pollution loads within a short time.

If the system does not have a suitable equalization tank, microorganisms in the biological treatment tank can easily experience shock loading, reducing treatment efficiency.

2.4 Strict Nitrogen and Microorganism Treatment Requirements

Compared to many conventional wastewater types, hospital wastewater usually requires stricter control of Nitrogen, Ammonia, and Coliform to comply with QCVN 28:2010/BTNMT.

Therefore, treatment systems often combine multiple biological treatment stages such as Anoxic, aerobic treatment, and disinfection to improve overall treatment efficiency.

2.5 Stable Operation and Odor Control Requirements

Hospitals operate continuously and require high standards of hygiene and environmental quality. Therefore, wastewater treatment systems must minimize odor generation, reduce noise, and maintain stable long-term operation.

Why is hospital wastewater so difficult to treat?

3. What Risks Can Occur If Wastewater Is Not Properly Treated?

If hospital wastewater is not treated properly, many environmental and operational problems may occur, such as:

• Effluent not meeting QCVN 28:2010/BTNMT
• Odor generation during operation
• Coliform exceeding allowable limits
• Impact on receiving water sources
• Increased risk of spreading pathogenic microorganisms
• Shock loading affecting microorganisms in biological tanks
• Increased operating and maintenance costs

In addition to technical problems, businesses or medical facilities may also face difficulties in environmental management if the treatment system operates unstably over a long period.

4. Which Technologies Are Suitable for Hospital Wastewater Treatment Today?

MBBR Technology (Moving Bed Biofilm Reactor) uses moving biofilm carriers inside the tank to increase the attachment area for microorganisms.

Thanks to high biomass density, the system can improve the treatment efficiency of BOD, COD, and Nitrogen in hospital wastewater while minimizing the impact of fluctuating wastewater loads.

MBR Membrane Technology (Membrane Bioreactor) is a technology combining biological treatment with membrane filtration using extremely small membrane pores.

This technology helps:

• Effectively remove suspended solids
• Reduce Coliform and many small-sized microorganisms
• Improve effluent quality
• Reduce the need for secondary settling tanks

This is why many hospitals today prioritize applying MBR technology in wastewater treatment systems.

5. Reference Hospital Wastewater Treatment Process

Hospital wastewater treatment systems are usually designed with multiple treatment stages to remove organic pollutants, Nitrogen, and pathogenic microorganisms before discharge into the environment.

Step 1: Collection and Preliminary Treatment

Wastewater is collected and preliminarily treated through:

• Collection tank: Collects all wastewater generated in the hospital.
• Bar screen: Removes coarse waste and large impurities before further treatment.
• Grease trap tank: Separates grease and floating substances to minimize impacts on downstream microorganisms.

Step 2: Equalization and Biological Treatment

After preliminary treatment, wastewater continues through:

• Equalization tank: Stabilizes wastewater flow and pollutant concentration.
• Anaerobic tank: Partially decomposes organic matter under anaerobic conditions.
• Anoxic tank: Supports nitrate removal and Nitrogen treatment.
• MBBR aerobic tank: Treats organic compounds using aerobic microorganisms combined with biofilm carriers.
• MBR membrane tank: Filters suspended solids and small microorganisms using membrane technology.

At this stage, microorganisms decompose pollutants and support Nitrogen treatment in wastewater.

Step 3: Disinfection and Sludge Treatment

After biological treatment, wastewater continues through:

• Intermediate tank: Stores membrane-filtered water and supports MBR membrane backwashing.
• Disinfection tank: Eliminates Coliform and pathogenic microorganisms before discharge.

In addition, the system also includes:

• Sludge storage tank: Stores excess sludge generated from the system.
• Sludge dewatering machine: Reduces sludge volume and moisture before disposal.
• Odor treatment system: Collects and treats odors generated during operation.

These processes help stabilize sludge, reduce odors, and ensure treated wastewater meets current environmental standards.

Hospital wastewater treatment process

6. Hospital Wastewater Treatment Solutions from Dai Nam

With many years of experience in the wastewater treatment field, Dai Nam supports site surveys, design, and construction of hospital wastewater treatment systems suitable for each capacity and actual operational requirements.

The solutions are optimized toward:

• Stable operation
• Space-saving design
• Reduced operating costs
• Effective odor and microorganism control
• Compliance with QCVN 28:2010/BTNMT before discharge

Dai Nam has implemented many wastewater treatment systems for hospitals, residential areas, and medical facilities with the goal of optimizing treatment efficiency and ensuring long-term operational stability for businesses.