4/1/2015
Monica Ozores-Hampton, Ph.D
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
‘it’s a biological
decomposition process
where microorganisms
convert raw organic
materials into
relatively stable
humus-like materials’
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
1
4/1/2015
Aerobic
Vermicomposting
Anaerobic
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
2
4/1/2015
 Air
(oxygen, no less than 5%)
 Moisture (40-60%)
 Particle size (less than 2 inches)
 C:N ratio (35:1 or less)
 Temperature (122-131°F, >140
°F inactive)
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
 Need
free air space above 20%
to maintain 5% oxygen or
higher.
 Correct particle size, bulking
agents, moisture levels, turning,
passive or active aeration are all
important.
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
3
4/1/2015
Air - Oxygen
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
Composting needs a minimum of 40%
during the composting process 4060%
 Less than 40% slows process
 More then 60% produces anaerobic
conditions and lower temperatures
 Final product 20-40%.

Copyright 2015 by Monica Ozores-Hampton. All rights reserved
4
4/1/2015
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
Critical for most efficient composting
 Too large-slows composting, decreases
temperature and loses moisture.
 Too small-anaerobic

Copyright 2015 by Monica Ozores-Hampton. All rights reserved
5
4/1/2015
 Most
life requires about 25:1
 Too high (too much carbon):
process is slow.
 Too low: more N losses and odors
Most problems with compost piles
are solved through mixing green
and brown materials or adjusting
C:N inputs.
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
  Mesophilic
  Thermophilic
  Curing




Copyright 2015 by Monica Ozores-Hampton. All rights reserved
6
4/1/2015
 Temperatures
below 113oF
 Microorganisms multiplying and
breaking down easily available
carbohydrates begin to heat up
pile.
 pH begins to drop as acids are
produced
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
 Usually
130-150oF
 Heat should be controlled
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
7
4/1/2015
 Growth
of actinomycetes and
fungi which digest
hemicelluloses
 Appears to be critical for
developing diseasesuppressiveness of composts
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
Under USEPA regulation 40 CFR Part 503 for
windrow composting of biosolids: temperatures of
55oC for 15 days and turned 5 times will eliminate
pathogen and kill weed seeds
Copyright 2005 by Monica Ozores-Hampton. All rights reserved
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4/1/2015
Characteristics
Range Reasonable
Range Optimal
(C:N) ratio
20:1 – 40:1
25:1 – 30:1
Moisture content
40 – 65%
50 – 60%
Oxygen content
>6%
~16 – 18.5%
pH
5.5 – 9
6.5 – 8.5
Bulk density
800 – 1000 lb per yd3
Temperature
110 – 1400 F
130 – 1400 F
Particle size
1/8 – 2 inches diameter
Varies*
-
Copyright 2015 by Monica Ozores-Hampton. All rights reserved
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