Reverse osmosis is one of the so-called membrane processes, which is based on reversing the natural process of osmosis. Water is forced through a semipermeable membrane at high pressure.
The process of nanofiltration is a membrane process similar to reverse osmosis. The retention of the water constituents during nanofiltration is based on a screening effect and on the repulsion effects of the charged membrane.
Ultrafiltration is a membrane filtration. Depending on the separation limit / pore width of the membrane, particulate water constituents can thus be removed from the water with high efficiency (screening effect).
Like ultrafiltration, microfiltration is a membrane filtration process that allows suspended particles and bacteria to be retained.
The principle of ion exchangers / ion exchangers is based on replacing ions dissolved in water (= electrically charged particles) with other ions from the ion exchanger material.
Filtration (gravel/ sand filters)
In water treatment, filter systems with sand / gravel filters are often used. They are used for particle separation or iron removal and manganese removal.
Filtration (fabric,plastic filters)
The industrially prefabricated filter inserts made of plastic fibers are manufactured as filter cartridges, bag filters, filter fleece or filter cloth. They are used in pressure-resistant filter housings (filter cartridges, bag filters) or in belt filters and are used for particle separation.
Precipitation and Flocculation
Precipitation and flocculation are concerned with converting dissolved or non-separable water constituents into a separable form. Precipitation / flocculation is usually followed by a further processing stage for separating the substances from the water.
Adsorption is understood as the accumulation of substances from gases or liquids on the surface of a solid. In water treatment, trace substances are often removed from the water by attaching to a granular filter material.
UV systems are used in water treatment for disinfection. Many other oxidizing agents, such as chlorine dioxide or hydrogen peroxide, are also used for disinfection, i.e. killing or inactivating germs.
Chemical neutralization is the adjustment of the pH value by the addition of acidic or alkaline chemicals. This method is often used in wastewater treatment.
Electrodeionization (EDI) is an electrochemical process that combines the two methods of electrodialysis and ion exchange. With this method, the most extensive removal of ions and ionizable substances from water is possible.
Degassing / Gas exchange
Gas exchange is about the removal of unwanted gases from the water or the entry of gases into the water.
Sedimentation is based on the fact that water constituents have a greater density than the water and sink. The sedimentation takes place in basins or containers so that the residence time of the water is sufficiently long and the particles can sink. In order to improve the settling behavior and shorten the residence times, flocculation(auxiliary) agents are often used.
During flotation, gas bubbles attach to the water ingredients and transport them to the water surface. Here they are separated with a scraper system.
Biological purification is based on the natural metabolism of microorganisms and uses it to convert unwanted water ingredients into other products.