During Reversed Osmosis (RO) in water purification not only pure water but also a high salt fraction (brine) is generated. In order to prepare this brine for discharge to a sewer system or WWTP Colsen develops a pellet reactor in close collaboration with PEKA Kroef (Odiliapeel, NL). Via co-crystallization of salts on an inorganic “germ” pellets are generated with a diameter of 2 to 8 mm. At this point in time the system is capable of removing > 80% of the phosphates. The pellets thus formed are separated and dried. They constitute a perfect nutrient mix directly applicable as fertilizer in agricultural applications. The simple design the so-called MemPhos reactor coincides with relative low investment costs. Operational costs are also minimal, because the use of chemicals is reduced to a bare minimum.