Which organism can be effectively removed by sub-micron filtration?

Sub-micron filtration is particularly effective at removing parasites and organisms that are small in size and not visible to the naked eye. Giardia lamblia, a protozoan that can cause gastrointestinal illness, has a size that typically ranges from 10 to 20 micrometers, which is considerably larger than sub-micron filter capabilities. However, the cysts of Giardia, which are the resistant forms responsible for survival in water, can be efficiently captured by these filters.

Sub-micron filters can effectively remove particles and microns-sized organisms, making them an important method for ensuring safe drinking water by preventing potential pathogens such as Giardia from passing through the filtration system. This ability is crucial in water treatment applications, as the removal of such contaminants is vital for protecting public health.

In the context of the other organisms listed, while E. coli can also be removed by such filtration methods, it does not match the specific focus on protozoan cyst removal. Legionella and Cryptococcus present different challenges due to their size and nature, making sub-micron filtration less targeted toward those specific pathogens compared to the well-established capabilities against Giardia lamblia.