The clean room is designed to keep the airborne particles in the air below the defined cleanliness level and also maintain the required cleanliness for the materials, chemicals, and water supplied in the space. It can manage the environmental conditions such as temperature, humidity, pressure and so on, if necessary.
The cleanliness standard of the clean room is generally applied to the KS standard
- Industrial clean room : U.S FEDERAL STANDARD 209E
- Biological clean room : NASA standard, NHB5340.2 but now the above is standard

●Five principles of clean room
These are the five principles that must be adhered to safely and efficiently maintain a clean room. It prevents and suppresses the generation of dust in the room and prevents the infiltration of dust from the outside. Once dust is generated and infiltrated, the clean room keeps the infiltrated dust not to accumulate and removes the dust and maintains constant temperature, humidity and pressure in the room at all times.

●Clean Room Standard
- [KS I ISO 14644-1] Clean room and related control environment - Air cleanliness classification
- [KS I ISO 14644-2] Clean room and related control environment - Test and monitoring standard for maintaining continuous rating
- [KS I ISO 14644-3] Clean room and related control environment - Test method
- [KS I ISO 14644-4] Clean room and related control environment ? Design, construction, beginning of operation
- [KS I ISO 14644-5] Clean room and related control environment - Operation
- [KS I ISO 14644-6] Clean room and related control environment - Terminology
- [KS I ISO 14644-7] Clean room and related control environment - Separator
- [KS I ISO 14644-8] Clean room and related control environment - Classification of air cleanliness according to

concentration of chemicals
- [KS I ISO 14644-9] Clean room and related control environment - Classification of surface cleanliness according to attached particle concentration
- [KS I ISO 14644-10] Clean room and related control environment ? Classification of surface cleanliness according to concentration of chemicals
- [U.S FEDERAL STANDARD 209E] Standard Practice for Design and Construction of Aerospace Clean rooms and Contamination Controlled Areas
- [ISO DIS 14644-1] Clean rooms and associated controlled environments
- [NASA NHB 5340.2] Clean Rooms & Work Stations for the Microbially Controlled Environment +Cancelled, No

Contact oxidation	Direct aeration
Forms biofilm on Media	Improves water shearing force
Surface of biofilm - decomposition of organic materials	Prevents attachment of microbe
Inside of biofilm - nitrogen removal	Maintains processing efficiency
High capacity of retaining microbe	Maintains specific surface area of materials

 

Processing efficiency	Maintenance	Economic efficiency
High efficiency for increased quantity of retaining microbe Strong against flux and change of water quality Deals with high.low density Continuous processing efficiency (direct aeration)	No blockade of Media aperture Small quantity of generated sludge Easy maintenance for Biobridge (Media apparatus) Attenuated operation	Small necessary site for building Low costs for construction Short period of construction Low maintenance cost