Ultrafiltration is an advance method of filtering un-dissolved solids from water with filtration between 0.01 – 0.5 micron. In this membrane filtration process, hydrostatic pressure forces liquid against a semipermeable membrane, which uses hollow fibers of membrane material, and the feed water flows either inside the shell, or in the lumen of the fibers.
This is how the suspended solids and solutes of high molecular weight are retained leaving the low molecular weight solute particles (the nutrients) pass through the membrane. Water is filtered removing all the particles from the water and hence no waste water is produced. The primary perk of using ultrafiltration is that it requires low pressure for filtration, hence it is energy efficient.