Membrane Technology

Membrane technology is an important component in the separation of molecular groups in suspended substances from polluted wastewaters. In this case, the focus is on the build-up concentration of contaminated industrial wastewater, desalination of process and seawater as well as production of service, drinking and ultra-pure water. Organic and inorganic compounds, microorganisms, pyrogens, bacteria as well as colloids are retained by over 98%.

Separation Effects related to Applications

The separation effect is achieved by using a semi-permeable membrane. The degree of the separation effect depends on the characteristics of the applied membrane and the molecular size of the substances to be separated. Membrane material of different types and structures are used for the application. They are available in modular construction designs as disc, bunch, hollow-fiber or tubular modules. STULZ-PLANAQUA employs modular construction types from different manufacturers depending on the task to be completed and application.

Technical Details

Reverse Osmosis

The raw water to be prepared is collected in an externally arranged storage system. A transfer pump (1) transports the raw water via a coarse filter (2) to a mixed-media filter (3). Here, a depth filtration is carried out in the filter bed up to a particle size of < 5 µm. A cartridge filter (4) is operated later as the safety component for the mixed-media filter. A high-pressure pump (5) brings the raw water current to the operating pressure (20 – 80 bar).

The substances are separated in the modular group (6) by means of a semi-permeable membrane. The existing permeate is discharged as purified water via a quality control system (9). When the limit is exceeded, the permeate flows back to the raw water collector. The concentrate current is discharged via a pressurized valve (7). A rinsing system (8) is installed for the chemical treatment of the membrane surface. A corresponding rinsing solution is applied.

Ultrafiltration / Microfiltration

In contrast to reverse osmosis (solution-diffusion membrane), ultra-filtration and microfiltration are porous membranes, which carry out selective separations based on different pore diameters. Suspensions, colloidal solutions, microorganisms and very high-molecular substances are separated using microfiltration. Ultra-filtration is used for the separation of smallest particles, dissolved macro-molecular materials as well as germs and viruses. Besides the classical cross-flow technology, immersed modular systems, which operate under pressure, are increasingly used, which show outstanding performance due to a significantly lower energy requirement. An important application, for example, is the separation of activated sludge in the so-called membrane biology techniques. STULZ-PLANAQUA applies the best processing concept depending on the available conditions.