Method for recovering nitrogen and phosphorus in anaerobic digestion solution of municipal sludge and special device for method

The invention discloses a method for recovering nitrogen and phosphorus in an anaerobic digestion solution of municipal sludge and a special device for the method. The method comprises steps as follows: the anaerobic digestion solution of the municipal sludge is pre-treated; MAP (MgNH4PO4.6H2O) is subjected to pyrolysis in a pyrolysis adsorption column; ammonia nitrogen in the anaerobic digestion solution is adsorbed in the pyrolysis adsorption column; phosphorus in an effluent after adsorption is recovered; recovered precipitates are transferred to the pyrolysis adsorption column for pyrolysis and regeneration after being dried, and ammonia nitrogen is recovered; nitrogen and phosphorus in the anaerobic digestion solution is recovered circularly. A dry type pyrolysis method is adopted under the low-temperature condition, ammonia nitrogen in the anaerobic digestion solution are separated and concentrated, and energy consumption of a reaction is reduced; an integrated pyrolysis and adsorption device is adopted, adjustment and control are convenient, and operation and maintenance are facilitated; the recovery efficiency of nitrogen and phosphorus is high in the recovery process; a phosphorus source is not required to be supplemented in the recovery process, and the cost of reagents for recovery of nutrient elements is greatly reduced; the content of organic matters and heavy metal in nutrient element recovery products is extremely low, and the method and the special device have higher economic value.