Water Sterilisation Techniques Flashcards
What is product water?
Treated water that requires sterilisation to prevent microbiological contamination
Product water refers to water that has undergone treatment but still needs to be sterilised to ensure safety.
What is the main chemical sterilisation method used by municipal water supply companies?
Chlorination
Chlorination is a common practice for sterilising drinking water and is often increased during hot months to combat higher microbiological levels.
Why is chlorine not a viable option for sterilisation on the brewery site?
It is removed via an activated carbon filter
Activated carbon filters are used to eliminate chlorine before water is used in brewing to avoid undesirable flavours.
How powerful is chlorine dioxide compared to chlorine?
2.5 times more powerful
Chlorine dioxide is a more effective oxidising agent than chlorine, making it a suitable alternative for water treatment.
What is a key characteristic of chlorine dioxide?
It does not produce associated flavour taints
Unlike chlorine, chlorine dioxide does not impart an unpleasant taste to treated water.
What is the typical concentration level of chlorine dioxide used in water treatment?
Up to 1.5 mg/L
This concentration is effective for sterilisation purposes in water treatment.
What reaction produces ozone for water sterilisation?
Oxygen is passed through a high voltage field
This method generates ozone, which is then injected into the water for disinfection.
What is the dissolved ozone concentration typically achieved in water treatment?
0.5 mg/L
This level is sufficient to exert bactericidal activity through oxidation.
What is a major advantage of using ozone for water sterilisation?
It is unaffected by pH and works very rapidly
Ozone’s effectiveness is consistent across varying pH levels and provides quick disinfection.
What is a significant disadvantage of ozone sterilisation?
High running cost compared to other methods
The operational expenses associated with ozone generation can be a limiting factor for its use.
What wavelength range is effective for UV light sterilisation?
200-280 nm
This specific range of UV light is effective in destroying the DNA of microbiological contaminants in water.
What is a drawback of using UV light for sterilisation?
Lack of residual killing potential
Sterilisation occurs only at the point of irradiation, meaning any contaminants introduced after treatment could survive.
What is sterile filtration?
Using a porous membrane to retain microbiological contaminants
This method involves passing water through a membrane with a specific pore size, typically between 0.2-0.45 μm.
What is the main advantage of sterile filtration?
No flavour taint
Sterile filtration does not affect the taste of the treated water.
What is a drawback of sterile filtration?
Filters can easily become blocked
To maintain effectiveness, pre-filtration is often necessary to remove larger contaminants.
What type of paper from the WHO covers the disinfection process of water?
Inactivation (disinfection) process
This paper provides comprehensive details on various disinfection methods for water treatment.
