NOVELTY - The method comprises adding aggregating signaling compounds or their precursors and/or crushed aerobic granular biomass to an activated sludge, where: an amount of the aggregating signaling compounds is equivalent to an amount extracted from an aerobic granular biomass that is 1-10 wt.% of the total estimated dry biomass in the activated sludge; and an amount of the crushed aerobic granular biomass is present in an amount of 1-10 wt.%. The method further comprises extracting the aggregating signaling compounds from the aerobic granular biomass.    USE - The method is useful for accelerating growth of aerobic granules (claimed) that is useful in wastewater treatment.    ADVANTAGE - The method is capable of greatly accelerating the growth of the aerobic granules with excellent settleability, thus reducing the working hours and cost of the wastewater treatment.    DETAILED DESCRIPTION - The method comprises adding aggregating signaling compounds or their precursors and/or crushed aerobic granular biomass to an activated sludge, where: an amount of the aggregating signaling compounds is equivalent to an amount extracted from an aerobic granular biomass that is 1-10 wt.% of the total estimated dry biomass in the activated sludge; and an amount of the crushed aerobic granular biomass is present in an amount of 1-10 wt.%. The method further comprises extracting the aggregating signaling compounds from the aerobic granular biomass. The aggregating signaling compounds are extracted from the aerobic granular biomass by: (a) suspending the aerobic granular biomass in a liquid to generate a mixture; (b) homogenizing the mixture by sonication; (c) concentrating the biomass in the mixture by centrifugation; and (d) separating the mixture into a liquid comprising the aggregating signaling compounds and biomass. The liquid comprising the aggregating signaling compounds is added directly to the activated sludge or is stored at less than or equal to -20 degrees C for 3 months before being added to the activated sludge. The step (a) is preceded by harvesting the aerobic granular biomass from a breeder reactor containing a mother liquor, comprising the liquid and the aerobic granular biomass, by concentrating the aerobic granular biomass in the mother liquor and separating the aerobic granular biomass from the liquid, where the concentration step comprises centrifugation of the mother liquor. The breeder reactor is a sequencing batch reactor, and has 1-10 vol.% of the activated sludge. The breeder reactor initially comprises a precursor activated sludge, and is operated under high selection pressure conditions to generate the mother liquor. The high selection pressure conditions comprise a settling time of 2-30 minutes and/or a high shear force. The precursor activated sludge comprises self-aggregating microbial species with high hydrophobicity. The crushed aerobic granular biomass is prepared by obtaining the aerobic granular biomass and then mechanically crushing, where the mechanical crushing is achieved by a mechanical beater or a blender. The crushed aerobic granular biomass is suspended in the liquid and then homogenized by sonication, before the crushed aerobic granular biomass is added to the activated sludge, where the crushed aerobic granular biomass is concentrated by removal of the liquid. The activated sludge is contained within a wastewater reactor. The wastewater reactor is a sequencing batch reactor or a membrane bioreactor. The activated sludge is a flocculated activated sludge.    DESCRIPTION OF DRAWING(S) - The diagram shows a flow diagram of a method for accelerating growth of aerobic granules in a wastewater treatment reactor.