The invention relates to a method for recycling
high concentration ammonia nitrogen and making
ammonia nitrogen into large granule high purity
struvite. At first, a granulating main body is changed to a three-section tapered
fluidized bed reactor. The reactor is composed of a
feeding tube, a granulating tube, and a
sediment tube; the connection part between the
sediment tube and the granulating tube is in a truncated cone shape, the inclined angel theta of the
generatrix of the connection part is 25 degree to 45 degree; the ratio of the external
diameter of the big end of the granulating tube to the external
diameter of the small end of the granulating tube is equal to 3:1; the ratio of the length of the granulating tube to the external
diameter of the small end of the granulating tube is equal to 50:1; a
pH probe is arranged in the granulating tube, the bottom of the granulating tube and the top of the
feeding tube are both provided with a granulating tube valve; the bottom of the feeding
pipe which is provided with five material inlets is provided with a discharging valve; and the length ratio of the
sediment tube to the granulating tube to the
feeding tube is equal to 2:5:1.
High concentration nitrogen-
phosphor wastewater with a NH4<+>-N concentration of 1000 to 1600 mg / L and a
magnesium chloride solution are simultaneously pumped into the granulating main body, at the same time the
mole ratio of NH4<+>-N: PO4<3>-P:Mg<2+> is controlled at 1.5:1:1.1-1.5:1:1.3, the pH value is controlled at 6 to 7, the
reflux ratio is controlled at 12 to 30, the diameter of the formed
struvite particle is in a range of 3 to 8 mm, the purity of the
struvite particle can reach 97.5% or more, and the
hardness of the struvite particle is (20.3 + / - 1) kg / mm2. The method can used to prepare struvite from
high concentration ammonia nitrogen industrial and poultry culture
wastewater, garbage
leachate, or
sludge fermentation broth.