An effective technique for fine particle removal using the combined effect of acoustic field and seed nuclei was presented. The key operation parameters, such as sound pressure level, initial particle number concentration, seed nuclei and particle properties on the agglomeration and capture performance of fine particles were investigated experimentally. The results showed that the separation of fine particle was improved efficiently with the combined external fields. Fine particle removal efficiencies increased by 25% with the combined effect of acoustic field and droplets at a SPL of 153 dB. Removal efficiency increased with the seed nuclei size. The value increased from 20% to 50% as the seed particle size increased from 10 to 30 mu m, but removal efficiency showed few changes when seed particle size was larger than 30 mu m. Particle removal efficiency correlated well with the initial particle number concentration in the combined effect fields. The removal efficiency with the combined effect of acoustic field and droplets was much higher than those with the combined effect of acoustic field and solid seed particles in high particle loading. Fine particle removal was significantly impacted by the particle wettability, when the combined effect of acoustic field and droplets was used. The removal efficiency of MWI particles was improved by 20% with the combined effect of acoustic field and droplets, comparing to the removal efficiency of BC particles. Fine particle removal efficiency can be highly improved with the combined external fields, especially in low acoustic intensity. (C) 2018 Elsevier B.V. All rights reserved.