JWWA S102 Antibacterial Test (Japan Water Works Association)

Antibacterial test

Filtrating conditions

Filter cartridge:【containing silver-carrying activated carbon fibers (J15) 7%=210mg-Ag/kg】made by other companies
Core size: (OD) 110 mm/(ID) 56.1 mm x 300 mm (L)
Filter flow: 15 L/min.
Testing water: running water
Water temperature: 20±3oC

Testing method

• Install the cartridge into the water filter.
• Filtrating water for 10 minutes using the above conditions and collect samples from the filtered water using a sterilized vial.
• After water samples are collected, stop filtering and keep the samples in a temperature & humidity chamber for 24 hours at 25 oC.
• After remaining still for 24 hours, filter the water again (for 30 seconds) and collect the filtrated water using the sterilized vial.
• After water samples are collected, stop filtering again and keep the samples for 2 days (3 days after the filtrating starts).
• Perform the same operation after 7 days.

Results

General bacterial count (quantity of bacteria /mL) (standard for running water: below 100/mL)

Received an award from the MOEA as an excellent water-saving technological equipment manufacturer in 2008

The antibacterial performance of the Japanese silver-carrying activated carbon fiber filter cores

Once combined with fibers containing silver ions, the filter cartridge obtain antibacterial properties.
Definition of silver-carrying activated carbon (according to the Japanese Association of Water Cleaners) : Possesses the same qualities of activated carbon set forth in provisions on food additives and contains 0.01-5% of silver ions.

• Fine silver (Ag) particles scattered throughout the silver-carrying activated carbon fibers.
• To achieve antibacterial performance, trace components of silver (Ag) must be released into water as positive ions. Insoluble silver in water also has antibacterial performance, but the high antibacterial performance that is immediately shown against intruding bacteria largely depends upon the silver ions (Ag+) that are soluble in water.
• During filtration by the cartridge, silver is released to the filtered water, but it mostly remains in the cartridge by attaching onto the activated carbon fibers to prevent growth of bacteria in the cartridge.

(For reference) The amount of silver ions released from the filter cartridge is less than 0.1 mg/L under normal use conditions according to the standards of the Japanese Association of Water Cleaners.

It is more appropriate to term “bacterial-killing effects” as bacteria-inhibiting (antibacterial) effects.

JIS L1902: 2002 method for absorbing bacterial liquid

An approximately 18 mm-thick testing piece weighing 0.4 g is used as a specimen, and six specimens are used according to the standards. Each of the three antibacterial processing test specimens is placed into the glass vial and sterilized in a high pressure sterilizing pot using high pressure vapor. Then 0.2mL of the testing bacterial liquid is taken, contact is made with multiple positions on the specimen, and incubate in the glass vial is carried out at 37±1℃ for 18±1 hours.
The test results are two-digit numbers of valid bacteriostatic values or bactericidal activity values obtained from the average value of the logarithm value of viable count.
(The antibacterial standard is that the Bactereostatic activity value is >=2.2)

Bacteriostatic activity can be improved by changing the silver-carrying activated carbon fibers 【J15(Ag-ACF)】. Effects are determined by using a silver content of 150 mg-Ag/kg.

Received an award from the MOEA as an excellent water-saving technological equipment manufacturer in 2008