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Reviews ? Mid- and Large-scale Continuous Flow Systems (cont.) |
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Written by Administrator
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Sunday, 11 September 2005 |
Oregon Soil Corporation Reactor (OSCR)
Specifications:
Length: 4' (photo: built 8' long)
Width & Height: 3'
Surface area: ~12 ft2
OSCR Plans Features:
- 56-page construction & operating guide
- All wood construction
- Easy-access harvest chamber
- Optional insulated/heated compost chamber
OSCR Review,
by Pat Reed
I just finished building the OSCR worm bin last week and I love it. It
took the better part of three weekends to complete it. Maybe if I were
better at woodworking it might have gone faster.
Through the course of cutting and assembly I could tell that much
thought went into the design. I followed the directions carefully and
applied the primer coat of paint before assembling all the pieces.
There were a few things that didn't measure out perfectly, and because
of this, I would recommend 'ripping' at least one extra 2 x 4 (but not
cutting it into pieces until needed) Also, my skill saw expertise left
something to be desired as the bin was slightly out of square when
finished, so it might be wise to get the plywood cut at the lumber yard.
If I could offer the authors of this plan one suggestion, it would be
to have a couple of photos of a finished bin as well as one partially
finished. The line drawings are great, but I never knew what it would
look like until I had it built. I didn't know the heater (btw, very
cleverly designed) would slide out of the box when unneeded, or how the
bottom of the bin could be harvested...so I shot some photos during
construction to share with anyone who wants to see them. (If that's
permissable with the authors)
I used stainless steel cable for the bottom which I obtained from a person who builds salt water fishing gear.
The soil heating cable I was lucky enough to find at a local nursery
which had had it on the shelf for three years...the only one left.
I beefed up the bottom of the bin with 2x4's screwed and glued to the
bottoms of the plywood so I could get a hand truck under it to move it.
It's heavy.
Instead of cement or 6 mil plastic on the harvesting floor, I cut a
piece of 1/8 inch masonite to fit, so when the castings come down, I
can pull the masonite out like a drawer, and scoop them up with a dust
pan.
I had considered building the OSCR many months before I actually bought
the plans. I wondered if it was worth the cost and if I could
accomplish the job with my limited knowledge of carpentry. I also
wondered if I really needed a bin that large (12 square feet sounded
huge)
During the summer months my little herd grew bigger and I realized that
my plastic bins were not rodent proof. I might have problems during the
winter. There was also the fact that the sideways migration plan I was
experimenting with was probably not as efficient as the upwards
migration that OSCR uses. After the three coats of paint were applied,
and all the fittings, I was finally able to dump the worms into their
new lodgings. This took some time as I was trying to harvest the
castings at the same time. My slogan was "No worm shall be left behind."
In conclusion, the plans contain much more information about how to
start the system, what to do if there are any problems, and how to
incorporate vermiculture into a school situation. They are worth the
cost, because I now have a bin that is rodent proof, heatable, and
continuous flow.
OSCR Review,
by Philip Jones
I bought the plans and site license for an OSCR bin last summer and
finally got around to building it about six weeks ago. I found it
pretty straightforward to cut out the pieces and get the OSCR built
following the instructions, but I have a shop full of woodworking
equipment. All told, I spent about six hours getting it built and about
four days getting it caulked and painted.
The OSCR is built from two and a half 4' x 8' sheets of 5/8" thick
exterior plywood and five 8' long 2x4s. The plywood has to be cut into
seven pieces (two for the front and one each for the top, bottom, back,
and two sides). Unless you have a panel saw designed for cutting sheet
goods, I recommend that you have the plywood cut into pieces for you at
the lumberyard. Most lumberyards will do this for a small fee, and you
will save yourself a lot of time, trouble, and potential danger by
having the lumberyard do this. The 2x4s need to be "ripped" (cut
lengthwise) in half before cutting the resulting pieces into a variety
of shorter pieces for interior framing and structural support. I do not
recommend using 2x2s to avoid the ripping operation: the 2x2s will
measure 1.5" x 1.5" while the ripped 2x4s will measure 1 1/2" by 1
11/16". Sacrificing that extra 3/16 inch by using 2x2s will cut back on
the unit's strength. Again, if you don't have a table saw, get the
lumberyard to rip the 2x4s for you.
I found the measurements given in the plans to be accurate (this is
more unusual than you might think), and I strongly recommend following
the assembly sequence given to you in the plans. The authors have
carefully thought through the assembly sequence, and I guarantee that
deviating from their instructions will turn an easily do-able process
into a more difficult one. During assembly, the structural support
pieces cut from the 2x4s are glued and screwed to the plywood pieces. I
recommend using a water resistant glue (like Titebond II) and
galvanized screws. Since you'll be driving a lot of screws, a cordless
drill with a clutch will save you a lot of time. Additionally, a couple
of clamps will help you hold the pieces in their proper alignment while
you are drilling, countersinking, and driving the screws.
The authors provide an estimate of $153.70 for the total cost of the
basic OSCR. I found this to be about on target. Although I paid more
for some items than the authors estimate, I also paid less for others,
so things balanced out. Two items that I had a little trouble finding
were: 1) a 70 foot length of weed-eater cord, and 2) a 5# box of
Rocktite brand pourable cement. The weed-eater cord is used to form the
"bottom" of the composting chamber by weaving it back and fourth from
the front to the back of the OSCR through holes you drill. The pourable
cement is poured around the drain in the harvest chamber floor to form
a surface that directs water run-off to the drain. My source for the
weed-eater cord was Country Home Products (800-446-8746). They sell
very thick (130 mil and 155 mil) cords in 150 foot rolls. The Rocktite
cement is like no other product I have ever seen, and I strongly
recommend you not try to substitute. Rocktite is made by Hartline
Products Co., Inc. (216-291-2303).
The most difficult part of the whole project is getting it painted. You
have to paint it inside and out with 3 coats of paint (1 coat of primer
and 2 coats of exterior latex). Since there's no way to paint all
surfaces at once, you are constantly doing a partial paint job, letting
it dry, turning the bin, painting some more, etc.
I've got the OSCR set up in the basement now with 12 pounds of worms
and they seem to be doing fine. One word of caution. The OSCR is 3'
wide, 4' long, and 3' tall. My 3' door to the outside was actually only
35" wide. That's why the OSCR is in the basement.
Earthworms Make Great Waste Managers,
A Large-scale Continuous Flow System
An Australian company, feeds this type of
reactor to convert of over 20,000 metric tons of mixed organic wastes
per year into vermicompost.
Vermitech Systems
Specifications:
Width: 7'
Lengths: Modular 8' worm bed sections, 2' for equipment, thus, 10', 18', 26', etc.
System Features Include:
Vermitech 200 review,
by S. Zorba Frankel
The Medical University of South Carolina also uses a Vermitech system
to process roughly 200 pounds of cafeteria food waste each day. Since
July 13, 1999, the recycling team has been picking up a 32-gallon
plastic tub from the University's main cafeteria and taking it to the
worms' lair.
The University uses a larger Vermitech system, 18' long by 7' wide, to
handle their organic waste. Unlike the Grand Traverse system, this bin
has no lid. Instead, several bars curve upward and span the width of
the bin. When temperatures are cool, these bars support a thick tarp
that covers the bin. The composting chamber consists of two eight-foot
sections and an air conditioner and hydraulic equipment occupy the last
two-foot section. They also use a Vermitech shredder with an attached
conveyor belt that delivers the feedstock to the bin.
Christine von Kolnitz, MUSC recycling coordinator, led the process to
bring worms to the University. She likes the Vermitech system very
much. “They eat it up as fast as we shred it. We can't feed them
enough. Also, it's not too labor intensive.” They shred up the food and
the conveyor sends a large pile of food and cardboard onto the surface
of the bedding. They use a rake to spread out the food and then they
clean up. Once a month or every two weeks they turn on the hydraulic
system to cut off the bottom layer of castings. Once the castings are
scooped up and put in a cart they clean the floor and they're done. The
grounds department says they can use all the castings the worms can
provide. The system for MUSC has a payback of three years. Christine
has only one dislike for the system, that the shredder leaves some
material in the drum, which they have to sweep out.
For their new system, MUSC constructed a small structure, beginning
with an 18' x 24' sloped concrete pad with a drain. The pad is coated
with acrylic so that castings can be cleaned up easily. The structure
also provides electricity, water and airflow. A large fan that forces
air out high on one side of the building, and draws air in next to the
bin, creating a flow underneath and through the bin. Funds for their
project came from several sources, and their startup costs, including
the building and supplies, were $54,000.
They learned a lot through their hands-on experience. Initially they
used newspaper as a carbon-rich portion of their feedstock, alternating
between shredding newspaper and food waste, then raking out the pile
deposited in the bin. This worked, but sometimes left some larger, dry
chunks of newspaper. They then tried feeding just shredded food waste.
That was better, but the excess moisture created caused worms to go "on
tour," crawling down and onto the floor. They've found that cardboard
works better for them and mixes better than food. At this point, they
find they only need to add minimal water to the system. Altogether,
they spend an hour and a half working with the bin each afternoon.
Because this is Charleston, SC, the air conditioner unit, which is
built into the unit, stays on all the time in summer. During the
winter, the outside vent is covered and the tarp remains on the bin
except during feeding.
Vermitech 100 Review
by Randy Smith
Here in Grand Traverse County, worms are processing 5-35 pounds of food
scraps each day in their home, a Vermitech 100 system. Since setting it
up on Earth Day, 1998 in our County Building, it has accepted all the
preconsumer and some of the postconsumer food waste from our building's
cafeteria and some of the food waste from our Sherriff's 159-bed jail.
The system has a 4' x 8' enclosed bed with insulated panels and stands
3' tall, with two panels on top that hinge open. A large shredder, also
designed by Vermitech, blends paper and food waste into a homogeneous
blend and shoots it into the top of the bin through a spout. The worms
- all 100,000 of them, we estimate, are in an 18" bed laying on a
grate. This is a continuous flow system, with a bar that is pulled
across the top of the grate, "slicing" off an inch or so of
vermicompost with each pass. We add material until it's within a couple
of inches of the top of the bin (thus giving it the maximum amount of
time in the unit) and shave off 3"-4" of vermicompost at a time, about
once a month. Doors open below the grate to allow access to the
finished materials.
It's a good system. However, it's not just like operating fifty small
worm bins. Like any living system, it works best the more regular you
are with feeding and maintenance. Since our food source depends on what
people don't eat, it's highly variable. The waste paper we feed comes
from our restroom hand towels and napkins from our cafeteria. The paper
carbon source is fairly consistent, but the nitrogen food waste varies
a lot in moisture and volume and is seasonal. In the summer we have a
lot more fruits and vegetables than in the winter, not as much. So
we've had to adjust our operation to work with that fluctuation in
feedstock, as well as complement our labor.
The County custodians manage the system, located in the basement right
next to the cafeteria. Our health department required that it be vented
to the outside, which we accomplished through the building's existing
exhaust system. Six custodians are involved with our soil factory. Two
custodians take charge of grinding and feeding the system. The others
collect the materials for the system. They do a very good job, and the
system would not work without their participation.
When we began to consider the location for the system, we decided that
an area used to store extra furniture and office equipment looked best.
We had to redesign and upgrade the room. We tiled the floor, added a
wall, a door, ventilation, insulation and electrical 3-phase power.
Essentially, we created a smaller room within a larger room. We wanted
to be sure that the blending operation, which makes a certain amount of
noise, wouldn't distract or interfere with other workers. As it turned
out, the night crew would do the blending at 11pm, eliminating the
concern altogether!
Ours was the second Vermitech system manufactured. We budgeted $15,000
for the project. We also received a $1,650 grant from our local
community foundation, and we came in under budget. I believe it is a
great value. If we maximized the use of the system, we could save
$5,000 a year in disposal costs, get a valuable soil resource and help
the environment. We aren't receiving as much food as expected from the
jail, so we currently figure that the payback period will be five
years.
We've learned that watching conditions in the bin carefully pays off.
For example, in summer, when we get a lot of melon, we often see
temperature increases and so we'll throw a little ice in the bin, fork
the bed and open dampers to allow more air movement. Another difficulty
we've learned to work with is keeping adequate moisture in the bin over
the weekend or extended holiday. When we initially considered the
system that exhausts air from the bin, we thought, "that's great;
oxygen will be drawn into the bin from below." What we didn't realize
is that it would dry the system out as quickly as it does. So, to
prevent drying, we add 1-2 gallons of water per day.
On the other hand, Vermitech told us to aerate the 4' x 8' bed material
with a garden fork -- to stick the fork in and wiggle it around a bit.
But, with our exhaust system and the custodians' attention to detail,
we don't need to do that, saving up to 30 minutes of work daily. We
check for clumps of dried material, and we find these every so often,
when we forget to water it regularly, like after a three-day holiday
weekend. Arrangements need to be made to get more water in the bin.
Otherwise, we'll be six gallons shy by Monday. We have tried using wet
burlap over the top, putting plastic over the top and damping off the
ventilation for the weekend. But what actually worked best is something
one of the operators tried -- layering ice cubes on top of the
decomposing food. It melted slowly and did the trick. I can't give
enough credit to our custodians that operate the system: they do an
excellent job. Oh, one more tip: when we give a lot of tours, the open
lids drys the bedding, so we add more water.
During the planning stages in 1997, we had a lot of interest in the
worms! Practically everyone fishes here. There is a lot of interest in
selling the worms and using the castings, particularly by the grounds
department. But, we see about a 90% volume reduction by weight in the
material we put in. So this "Soil Factory," as everybody calls it
(nobody knows what a "Vermitech" is!) puts out a minuscule amount of
vermicompost compared to what went in! And so there's some disappointed
folks around here!
The bin equipment has been real sturdy. The shredder has had a couple
of upgrades. A safety breaker in the blender would trip repeatedly, and
they replaced it with a heavier-duty model. The blades also have been
upgraded, and Vermitech modified them for us under their warranty. So
their service has been very good.
Holcombe's Earthworm Reactor
Editor's Review
by Kelly Slocum
In 1991 Dan Holcombe, president of Oregon Soil Corporation, built a
vermiprocessing table based on the continuous flow design developed by
Dr. Clive Edwards in the 1980’s. Referring to it as a “worm reactor,”
the system was designed so that it could process large volumes of
organic material and produce large volumes of vermicompost under the
management of a single operator.
Holcombe’s worm reactor is a modular unit approximately 40 inches high
over all and eight feet wide, with a working bed depth of approximately
24 inches. Because of it’s modular design it can be built to almost any
length, with the unit Holcombe currently operates being 125 feet long.
This gives the unit 1000 square feet of surface area.
The floor of the working bed is made from hog wire to enable the
finished vermicompost to fall through when harvested. Finished
vermicompost tends to hold together, even when resting on the wide hog
wire floor, and does not readily fall through the mesh openings. The
material needs to be disturbed to enable harvesting. A floor made from
a small mesh size would effectively hold the vermicompost in the unit,
making harvesting far more difficult, if not impossible. Holcombe
initially sets up the reactor by laying several sheets of newspaper
over the hog wire and bedding on top of it to prevent the fresh
material from falling through.
To enable one person to efficiently feed the system the reactor uses an
automated overhead gantry to deliver a consistently even layer of feed
stock to the bedding surface. Feed stock is shoveled into the gantry
which runs along rails set on top of the bin side walls, spreading a
thin, even layer of feed stock. At peak operation Holcombe’s worm
reactor can process roughly 6000 pounds of organic material per day,
feeding approximately 6000-7000 pounds of worms. Feed stock consists of
produce waste picked up from several Fred Meyer grocery stores in the
Portland Oregon area. Dan spent several weeks working with store
employees, teaching them to remove plastic wrap and rubber bands so the
feed stock would not be contaminated with materials that would not
break down. The produce waste is picked up from the grocery stores,
mixed with compost to aid in absorbing excess moisture and ensure good
porosity, and fed to the system the same day.
Holcombe’s worm reactor is housed in an unheated greenhouse to protect
it from the nearly constant winter rains in the Pacific Northwest.
System temperature is maintained by the microbial activity in the
decomposing feed stock. Keeping large scale systems cool enough for
worm activity is more of a challenge than keeping them warm, requiring
that Holcombe monitor the system’s feeding rate carefully to ensure
overheating does not occur. Moisture is monitored closely and Dan uses
a hose to add water if necessary. Because produce waste is high in
moisture varying volumes of compost are added to each load of feed
stock to balance the moisture level for optimum worm activity.
The worm reactor uses an automated harvesting system to remove finished
vermicompost from beneath the table. A breaker bar dragged across the
hog wire floor shakes loose a thin layer of vermicompost which falls
through the wide mesh. A series of automated paddles are then engaged
to scrape the vermicompost from under the table so the operator can
shovel it into a pile for drying. At peak operation Holcombe’s system
produces approximately two to three tons ( five to seven yards) of
vermicompost per day.
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Last Updated ( Sunday, 02 October 2005 )
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