TT stands for Tertiary Treatement, i.e. a process where ultrafiltration has the aim of removing bacteria and macromolecules downstream of a secondary sedimentation process. The application with pressurized membranes is usually used to obtain a very high quality permeate in anticipation of its reuse in agriculture, or for its return within industrial production cycles. The pressurized ZeeWeed® membranes are made of two different materials depending on the type of applications required, PVDF or PES. With the first material, a hollow fiber membrane is obtained whose surface is made up of billions of pores which act as a physical barrier for impurities, but which allow water molecules to pass through. The ZeeWeed PVDF membrane devices for tertiary applications 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. The PES variant differs in the working configuration which is IN-OUT and in the type of construction of the membrane itself, which includes a multi-channel tubular fiber inside which the pressurized wastewater to be filtered is introduced. PES allows the membrane to remain permanently hydrophilic and reduces the tendency to fouling.
The membranes for tertiary applications are organized in modules contained in turn in pressurized vessels organized in pre-assembled skids according to the required surface area; the particular configuration of the module allows it to be directly attached to the other modules and to the permeate collector, thus constituting a self-supporting element ready to be positioned without the need to build frames and piping (Rackless solutions).