The effect of moisture content, particle size and consolidation stress on flow properties of vermicompost

 Physical properties of granular solids are essential to design appropriate, efficient, and economic bulk solids handling and storage equipment.  Flow of vermicompost is often restricted by caking and bridging, which occurs during transportation and storage.  This problem could be due to a number of factors including storage moisture, temperature, particle size, and consolidation stress.  There is lack of study on the effect of the mention factors simultaneously on flow index, cohesive strength and angle of internal friction of vermicompost.  The aims of this work were to discuss the primary factors affecting flowability of vermicompost as granular solids and powders, as well as using shear testing methodologies for this biomass material.  The experiments were conducted on samples selected from a wormy culture farm, Karaj, Iran, by Jenike’s shear cell technique.  The data was statistically analyzed using the three factors completely randomized design to study the effects of particle size, moisture content and consolidation stress on vermicompost flow properties.  The results showed that a significant difference between the flow index values at different stress levels.  Greater moisture content and smaller particle size caused poor flowability of vermicompost.  Increasing the moisture content and decreasing the particle size from 1.18 to 0.3 mm, the vermicompost reduced its flowability from free flowing at moisture content of 25% (w.b.) to cohesive at moisture content of 35% (w.b.).   Keywords: biomass flowability, flow index, shear test, vermicompost