Organic Waste Recycling

Composting 103

Vr = volatile solids content of compost product and recycle fraction

of dry solids

Vm = volatile solids content of mixture, fraction of dry solids

Rw = recycle ratio, based on total wet weight of compost product

recycled to total wet weight of compost feed

Rd = recycle ratio, based on dry weight of compost product recycled

to dry weight of compost feed

Xr

RW = (3.10)

Xc

Substituting Equation 3.10 into Equation 3.9 and rearranging:

Sm – Sc

Rw = (3.11)

Sr – Sm

Similarly
Sr Xr
Rd = (3.12)
Sc Xc

Substituting Equation 3.12 into Equation 3.9 and rearranging:

(Sm/Sc)-1

Rd = (3.13)

1-(Sm/Sr)

Equations 3.11 and 3.13 can be used to calculate the compost recycle ratios
based on wet weight and dry weight, respectively. For the desired moisture
content of 60% in the compost pile (Sm = 0.4), these 2 equations are graphically
interpreted in Figures 3.5 and 3.6, respectively.