MBR Membranes

Ultrafiltration is a process that uses organic polymer membranes to filter particles by size and is typically used to separate or remove bacteria and macromolecules with molecular weights greater than approximately 300,000 daltons from wastewater in both municipal and industrial applications; the configuration in which the membrane is used within a biological process is defined as MBR, an acronym for the English “Membrane BioReactor” which indicates the activated sludge water purification process (BioReactor) in which the liquid-solid separation phase is performed by membrane filtration (Membrane) instead of sedimentation as in conventional activated sludge plants.

MBR is the acronym of the English “Membrane BioReactor” which indicates the activated sludge water purification process (BioReactor) in which the liquid-solid separation phase is carried out by membrane filtration instead of by sedimentation as in sludge plants conventional actives. The ZeeWeed membrane is a supported hollow fiber PVDF membrane. The PVDF membrane, characterized by high porosity, acts as an impassable physical barrier for the microorganisms that make up the activated sludge but is easily permeable by water molecules. ZeeWeed membrane devices are immersed in the mixture to be filtered and work in an OUT-IN configuration, i.e. the direction of filtration goes from the outside of the hollow fiber towards the inside in such a way that the suspended solids remain outside the membrane while only the permeate (clarified water) reaches the internal channel of the fiber (lumen) from where it is then collected and conveyed towards the final discharge.

To control and minimize the natural loss of permeability due to the filtration process, these filtration devices are equipped with an air insufflation system which hinders, through greater turbulence near the fibres, the formation of areas with a greater concentration of solids suspended in the vicinity of the hollow fibers themselves.

One of the main features of the ZeeWeed membrane is the possibility of reversing the filtration flow, creating the conditions for carrying out a real counter-current washing cycle of the membrane. In application terms, the execution of a backwash of the membranes at pressures similar to or higher than those applicable in filtration (up to 0.5 bar) favors the mixing of the mixed liquor, limiting the possibility of the formation of areas with a high concentration of solids suspended near the membranes and therefore the risk of areas of dehydrated sludge forming between the membranes.

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