The invention is directed to a process for the simultaneous removal of BOD and phosphate from a liquid containing ammonium, BOD, phosphate and magnesium, the method comprising: feeding the liquid to a reactor containing BOD-oxidising biomass; ensuring that the liquid in the reactor contains an excess to stoichiometry of ammonium and magnesium relative to phosphate, wherein the stoichiometry is related to the stoichiometry of struvite; oxidising at least part of the BOD; adjusting the pH of the liquid in the reactor at a desired value; forming solid material in the reactor, the solid material comprising struvite; separating at least part of the solid material from the reactor effluent; returning a part of the solid material to the reactor The invention is also directed to a reactor for this process The advantage of the process and the apparatus is that in one reactor both BOD and phosphate are removed from the liquid

Process for the Simultaneous Removal of Bod and Phosphate from Waste Water

The invention relates to a method for dephosphorizing manure, in particular pig manure, comprising of causing phosphate to dissolve, which phosphate is present at least partially in the form of phytate in the manure, separating the manure into a solid and a liquid fraction and removing the phosphate from the liquid fraction of the manure. Causing phosphate to dissolve can be achieved in different ways, for instance by storing the manure for a predetermined period of time under conditioned circumstances, or by sustaining a continuous movement of the manure at a temperature of at least 15° C., preferably between 20 and 40° C., to allow free escape therefrom of formed gases, or by the presence of means for complexing divalent ions, or by the enzymatic decomposition of phytate present in the manure. The phosphate is preferably removed from the liquid fraction by causing struvite to be precipitated therefrom.

Method for dephosphorizing pig manure

The method for the phosphorus precipitation from a waste water under formation of magnesium ammonium phosphate (MAP), in a waste water treatment plant, comprises displacing the waste water with magnesium chloride and ammonia in a continuous crystallization stage, and displacing to a stripping stage, in which the waste water is treated with air. The waste water (75-100%) is subjected to a treatment in the crystallization stage. The MAP pellets are removed from the base of a crystallization reactor (1) under utilization of the force of gravity and/or without use of energy from mechanical means. The method for the phosphorus precipitation from a waste water under formation of magnesium ammonium phosphate (MAP), in a waste water treatment plant, comprises displacing the waste water with magnesium chloride and ammonia in a continuous crystallization stage, and displacing to a stripping stage, in which the waste water is treated with air. The waste water (75-100%) is subjected to a treatment in the crystallization stage. The MAP pellets are removed from the base of a crystallization reactor (1) under utilization of the force of gravity and/or without use of energy from mechanical means. In the crystallization stage: the pH is adjusted to 8.0-9.2; the adjustment of the pH takes place via the addition of caustic soda solution; the magnesium chloride in form of an aqueous solution with a concentration of 20 to 40% (w/v) is added; ammonia in form of an aqueous solution is added; the waste water displaced with magnesium chloride is moved by mechanical means; and/or the retention time in the reactor is up to 3 hours. The agitator is included in the stripping process, develops small seed crystals, deposits new precipitation products at the seed crystals, and disposes the formed MAP pellets in the reactor. The process is suitable for: phosphorus precipitation from the waste water quantity of more than 5 m 3>/h or phosphorus precipitation from a total waste water quantity of more than 2000 m 3>/d; phosphorus precipitation from waste water containing phosphorus/phosphate of more than 290 kg/d; and/or phosphorus precipitation from waste water containing phosphorus/phosphate of more than 120 mg/l. In stripping stage: the ventilation is carried out in a stripping reactor (2); carbon dioxide is removed from the waste water by the ventilation and the pH of the waste water is increased; the retention time in the reactor is 2-3 hours; and/or the ventilation takes place with a blower or a surface blower. The waste water is subjected to an anaerobic condition before the crystallization and stripping stages. The anaerobic treatment is carried out in a reactor system, which is an anaerobic simulator, a fixed bed, a fluidized bed, an upflow anaerobic sludge blank (UASB) with a space load of 7.5-8.5 [kgCSB/m 3>.D] or an expanded granular sludge bed (EGSB). The waste water from the reactor runs through a mixing- and an equalizing tank. In the anaerobic stage: the developing biogas from the reactor is removed; the developing biogas is used for power production; the temperature of the waste water is adjusted to 35-38[deg] C; and/or the temperature of the waste water is adjusted using heat exchanger systems. The waste water is subjected to an aerobic treatment for removing the residual concentration of carbon and nutrients. The aerobic treatment stage is carried out in an aerobic treatment tank and/or 3-4 sequence batch reactors (SBR). In the aerobic treatment stage, an aerobic activated sludge process takes place in full-continuous operation and/or a biological phosphorus precipitation is carried out using microorganisms and/or optionally using iron ions. Independent claims are included for: (1) a device for the phosphorus precipitation from waste water; and (2) magnesium ammonium phosphate pellet.

Precipitation of phosphorus from waste water to form magnesium ammonium phosphate, in waste water treatment plant, comprises displacing the waste water with magnesium chloride in crystallization stage, and displacing to stripping stage

A process for the recovery of ammonia from process and waste waters with precipitation of magnesium ammonium phosphate, in which, to accelerate precipitation and separation of magnesium ammonium phosphate from the process or waste water to be treated in one precipitation step, a magnesium phosphate compound and sodium hydroxide solution are added simultaneously, while the pH is held constant in the range of about 8.0 to 10.0, and the precipitated magnesium ammonium phosphate is decomposed in a regeneration step and is returned to the precipitation step as precipitant.

Process for recovery of ammonia from process and waste waters

A method for removing ammonia, or ammonia and phosphates from industrial agricultural or household effluents by causing precipitation as magnesium ammonium phosphate by means of a liquid reagent containing magnesium and phosphate ions and an acid. The effluents have more than 1 gle of ammoniacal nitrogen and the pH is adjusted to between 9 and 11 after addition of the liquid reagent.

Process for removing ammonia from waste waters

In a process for eliminating ammonia and phosphate from waste water (effluent), magnesium salt and/or magnesium oxide and, if required phosphate and/or phosphoric acid are added. The salt MgNH4PO4 . 6 H2O is crystallised out and then separated off. The degree of elimination of the ammonium and of the phosphate in this case can be adjusted by the amounts of the abovementioned substances added. The pH is adjusted to between 7 and 10. The precipitation product contains nutrients valuable for agriculture. It can be provided for fertilising purposes.

Touradj Dipl Ing Yawari

Papers

Process for eliminating ammonia and phosphate from waste water and process water

Verfahren zur eliminierung von ammonium und phosphat aus abwasser und prozesswasser