Sauer/alkalische Brüdenwäsche. Ein Verfahren zur Gewinnung von Ammoniumsalzen und Kohlenstoffquellen für die Denitrifikation aus Prozeßwasser und flüssigen Abfällen
Acid/alkaline vaporwashing. A Method to win ammonium salts and carbon sources for denitrification from process waters and liguid wastes
The legal regulations of closing material cycles in order to preserve valuable resources are obeyed increasingly also in sewage management. At the treatment of process water in sewage plants these demands are observed just by recycling ammonium, which is separated as salt or an aqueous ammonia solution from distillates or separation waters from sludge dewatering. Due to the new developed acid and alkaline vapor-washing it is possible to produce ammonium sulfate and carbon sources for biological denitrification in a compact column simultaneously. From vapors, loaded with ammonia and organic acids, i.e. caused by drying sewage sludge, the acid and alkaline compounds are separated in two independent washing cycles using this method. Ammonium is enriched in the acid washing liquid whereas the salts of the organic acids are concentrated in the alkaline solution. The velocity of mass transfer in a washing system with chemical reaction is limited by the vapor-phase. In spite of this limitatio n and the higher pressure drop, there should be used a bubble tray column for practicable design of an acid and alkaline vapor-washing. The advantages of tray columns are their compact construction and the easy control of pH, concentration and quantity of the liquids. For pure chemical absorption, the efficiency of one tray is only a function of bubble size distribution and the height of the two-phase layer. A reduction of the vapor contamination of more than 90 per cent is achieved in the employed system for a 13 cm high two-phase layer. A limitation of the mass transfer coefficient by the vapor concentration of the transferring compound could not detected in the examined field of concentration.