The extraction by pulse flow of slurry can be intensified in rotor-stator devices (RSDs). The humic acid (HA) yield after treatment with aqueous alkaline vermicompost slurry (VS) and sapropel slurry (SS) in the RSD is higher than that in the extraction apparatus with a helical ribbon impeller (HRI) at the same specific energy dissipation rate. The increase in the HA yield is caused by the destruction of particles and particle agglomerates of vermicompost and sapropel, deep penetration of the extractant in the pores of particles due to macro- and micropulsations in the fluid flow and cavitation. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.