EAWAG System

In gravity-driven membrane (GDM) technology, no backflushing or cleaning is used. Pressure necessary to press water through the membranes is generated by gravity, which is generated by difference of water levels between two storage tanks. As a feed, natural water (river, spring, well or rainwater) can be used without pre- or post-treatment. BIO-CEL® membrane sheets with a pore size of 40 nm are placed vertically inside the membrane tank. The sheets are manufactured by Microdyn-Nadir  and are usually employed in membrane bioreactors for wastewater treatment. Although turbid waters can also be used, a pretreatment is required if the water becomes extremely turbid (> 500 NTU). The clean water tank has dimensions for a total volume of 10 liters, the membrane tank has dimensions for 20 liters.

Minimal training is needed, but programs don’t exist as yet. Maintenance of the filter unit comprises regular cleaning of the tap in order to avoid contamination. Also, a regular surveillance of the clean water tank is needed in order to avoid overflow.

Expected life span 5-8 years (This has not yet been tested)

Unknown

Field observations  are strongly indicating high recontamination factors linked with maintenance and unsanitary conditions.