Compost Process Overview

Wednesday, 1 February 2012  |  HOTBIN Composting

Try to keep to the green column as best you can.

Composting - the process

Mass balance What Goes In Energy balance

 

Sum of materials in C= ~50%

Nutrients
Carbon/Nitrogen, trace elements
Surface area, particle size 
Energy and water balance
In/out lists (food, grass, garden waste)

Sum of energy in
~2400 kJ/kg

 

 

 

Conditions

 

 

 

Aeration / Oxygen
Temperature
Water / moisture
Ph

 

Sum of conditions

Oxygen level (determines dominant bacteria)

Aerobic
(>6-21%)

Anaerobic (<6%)

 

Composting Equipment

HOTBIN
size
insulation
valve/aeration
other

AD plant
closed vessel
gas system

 

 

 

 

Aerobic microorganisms (bacteria, insects etc)
Oxygen
Pests and vermin

Anaerobic microorganisms (bacteria)

No oxygen
SO3, NO3
Pests and vermin

Decomposition intermediates

Odour (Aerobic)
low VP
fragrant VOCs

Odour (anaerobic)
low VP pungent VOCs, H2S

What comes out

Sum of materials out

 

Compost (C 25%)
Quality
Ease, labour
H&S
Environmental

Carbon dioxide & Water

Methane
Energy recovery
Ease (lack of small scale)
H&S
Environmental

Water

Sum of energy out

 

Mass balance

 

Humus (C<3%)

Digestate (C10%)

Energy balance