Membrane technology

Membrane technology is an important component in the separation of suspended substances of dissolved molecular groups from polluted waste water. The aim here is to focus on the concentration of polluted industrial waste water, the desalination of process and sea water as well as the production of industrial water, drinking water and ultra pure water. Organic and inorganic compounds, micro-organisms, pyrogens, colloids and bacteria are held back by more than 98%.

Application-related separation effect

The separation effect is achieved by using a semi-permeable membrane. The separation efficiency depends on the characteristics of the membrane and the molecular size of substances to be separated. Different types and structures of membrane materials are used. They are available in modular design as plate, winding, hollow fibre or tubular modules. Depending on the task definition and application, STULZ-PLANAQUA uses module types from different manufacturers.

Technical details

Reverse osmosis

The raw water to be treated is collected in an outside reservoir. A transfer pump (1) pumps the raw water through a coarse filter (2) to a mixed-media filter (3). Here depth filtration takes place in the filter bed to a particle size of < 5 microns. A safety measure, a cartridge filter (4) is fitted downstream to the mixed-media filter. A high-pressure pump (5) brings the raw water flow to the process-related operating pressure (20-80 bar).

Separation takes place in the modular group (6) through a semi-permeable membrane. The resulting permeate is discharged as pure water via a quality control system (9) for re-use. If the threshold value of the permeate is exceeded, the permeate is returned to the raw water collectors. The concentrate stream is discharged via a pressure control valve (7) for further treatment. A flushing system (8) is fitted for the chemical cleaning of the membrane surface when contaminated. Depending on the type of contamination, the respective rinse solution is used.

Ultrafiltration / Microfiltration

In contrast to reverse osmosis (solution-diffusion membrane), the ultra and microfiltration has membrane pores for selective separation based on the different pore diameters. With microfiltration suspensions, colloidal solutions, micro-organisms and very high molecular weight substances can be removed. Ultrafiltration is used for the separation of tiny particles, dissolved macromolecular substances and germs and viruses. In addition to classical cross-flow technology, vacuum-operating modular systems that are characterized by significantly lower energy consumption are increasingly used. An important application is for example the separation of activated sludge in so-called membrane biologies. Depending on the prevailing conditions, STULZ-PLANAQUA uses the procedural concept that proves to be the best when all economic aspects are considered.