John Paul, Transform Compost Systems

Composting 1000 tonnes per day
A Continuous Aerated Windrow System
TRANSFORM
Compost Systems
John Paul, Ph.D.
CCC Conference 2010

How Do We Deal with Organic Waste Diversion From
Very Large Cities
- some cities have 5000 tonnes + per day of organic waste!

How much organic waste is 1000 tonnes per day
2540 tonne trailers per day!
Even energy recovery processes still need to handle a
lot of bulk material before and after energy recovery!

How much organic waste is 1000 tonnes per day
325 6 yard buckets per day!

We first have to accept some basic
principles of composting

Principles of Composting
1.Composting is an aerobic process and hence needs
aeration and/or turning
2.Composting has the potential to pollute, therefore
must be protected from precipitation in wet climates
3.Composting is a biological process and requires time
4.Composting generates heat which kills pathogens,
increases microbial activity to stabilize carbon, and
evaporates moisture
5.Odor potential increases with increased moisture
content, decreased oxygen supply, and increasing
amounts of food waste

this violates most of the principles of composting
One can say its a slightly more organized version of……

…this!

this can hardly be called composting: it is difficult
to maintain control of the process in either dry or
wet season
CCC Conference 2010

Outdoor Turned Windrows
Inexpensive to begin, but will be quite difficult to maintain
control of the process in either dry or wet season
With 10 m wide x 3 m high windrows – need 500 m 2 per day
With 5 m wide x 2 m high windrows – 1200 m 2 day

Outdoor Turned Windrows
Inexpensive to begin, but will be quite difficult to maintain
control of the process in either dry or wet season

We now have the option of working under a roof, but
space requirements are significant
With 10 m wide x 3 m high windrows – need 500 m 2 per day
With 5 m wide x 2 m high windrows – 1200 m 2 day

Additional challenges with
turned windrow systems
inside a building - not so
easy for a turner operator
to see

Blower off
Blower
on
We now want to optimize our indoor space – we need to turn
more often, or provide forced aeration to speed up the process

We should now consider other
technology choices as well
-Aerated bunker
-Covered aerated windrow
-Continuous aerated bed
-Agitated bed

We should also consider some rules of thumb for
composting
1.Composting is optimized at moisture contents of 50-65%,
and bulk densities of 600 to 700 kg per cubic meter
2.Composting will result in a 30-50% volume loss depending
on process conditions
3.Static aerated systems require greater porosity to prevent
preferential air pathways
4.The amount of drying depends mostly on the
temperature above the composting material
5.Composting is very corrosive, use appropriate building
material

Rules of thumb for composting
Composting is optimized at moisture
contents of 50-65%
Composting at 65% moisture – 1000 tonnes per day = 325 buckets
If we have to decrease to 55%, we have to add 700 tonnes of a 40%
moisture content bulking agent = total of 566 buckets/ day

Technology choices impact capital and operating cost
65% moisture to 55% moisture – from 325 buckets to 566 buckets/day
We double the size of the facility required
If we have to handle 3 x with loader, we now have ~1500 buckets/day
At a cost of $120/hour, and 1 minute/bucket = $ 3400 per day

Rules of thumb for composting
Composting will result in 30-50%
volume loss depending on conditions

Rules of thumb for composting
Static aerated systems require greater
porosity to prevent preferential air
pathways

Rules of thumb for composting
The amount of moisture removed
increases with increasing air
temperature above the composting
mass.
Summer in New York
35% moisture after 10 days
65% moisture coming into
channels

Rules of thumb for composting
Composting is very corrosive, so we
should use appropriate building material

We also have to think about operations cost, and
the type of material that we are processing, and
for worker health and safety, and…..

Can we start with a cost effective, corrosion
resistant building structure

Can we optimize the use of this space with a large
aerated windrow, say 10 m wide by 3 m high
We can aerate this pile with an aeration system in the floor
How are we going to turn or mix this material

We then need a machine
that is remotely
controlled, and moves
the entire windrow 10-12
m through the building,
and can adjust for
volume reduction during
composting

We have a cost effective composting process that optimizes
the use of space, and optimizes the process using aeration
and turning – process time up to 8 weeks.

Higher moisture content material
Catch the leachate at the beginning, and put it back in after 3-4 weeks.
Still have time for pathogen kill in the 8 week process

Summary
We have to start thinking creatively if we are going to benefit from
our organic waste, whether through “energy recovery” production, or
composting.
We have to remember that even “energy recovery” will leave a lot of
organic material behind that we still need to do something with!