activity and aeration, friction, collision, an investigation to compost
particle was carried out as follows.
3.2.1. Particle size distribution
Gradation test is used to assess the particle size distribution of a
granular material (Gabhane et al., 2012). Fig. 5 shows the particle
size distribution of matured compost in DHAF and TSC. Fig. 5(a)
shows that the majority of organic fertilizer produced in DHAF is
the particles with a size of less than 3.0 mm, what’s more, the particle
with a size of less than 1.0 mm accounted for 64.28% of total
weight. Normally, best compost should have 90% cumulative passing through 12.6 mm sieve (Gabhane et al., 2012). After treated
with DHAF, the compost has 100% cumulative passing through
12.6 mm sieve and 64.28% cumulative passing through 1.0 mm
sieve, which is far more than standard value given above. Fig. 5
(b) shows a different result that particle with a size of
2.0–3.0 mm occupies the majority of 39.07% in TSC. However, particle
with a size of less than 1 mm accounted for only 4.96% of total
weight, the difference indicates that DHAF could convert food
waste into tiny particle in contrast with TSC. The reason can be
attributed into shear force and frictional force during continuous
movement and collision of food waste in DHAF. Tiny particle has
a larger specific surface area which gives the rapid production
process a reasonable answer.