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The patented cartridge ensure that all of the urine is collected and stored in the cartridge with an airtight seal. Urine is 3% waste and 97% water, the cartridge acts like a filter and removes the sediment before the urine is passed into the waste pipe, leaving what is essentially grey water.
The cartridge is locked into the waterless urinal using a key which creates and airtight barrier between the waste pipe and the washroom which ensures that no bad odours can come back into the wash room from the waste pipe. Inside the cartridge, a biodegradable oil floats on top of the fluid as it is less dense than water or urine, this forms an airtight barrier between the cartridge and the wash room, locking in urine, smells and bacteria that may be inside the waterless urinal cartridge.
The cartridges tells you when they need to be changed as there will be traces of the blue seal inside the urinal bowl. The you simply replace the cartridge with a new one. The cartridges will need to be changed after around 7,000 uses, but Camp Nou in Barcelona only have to change theirs once a year due to having so many waterless urinals installed.