The present invention teaches, that the removal of particles of any charge
from liquid stream is possible by mechanisms other than sieving with good
flow and low pressure drop. The use of a weakly charged or neutral
surface on the one or more filters within a pre-selected pH range is
used. Consequently, particles that are much smaller than the filter pore
size are captured with high efficiency. The essentially neutral or weakly
charged material filter surface in the filtration liquid may be formed
through the proper selection of filter material or a surface modification
of the base filters(s) to create the essentially neutral or weakly
charged surface.