The Sidestreams of Biodiesel Production

The Sidestreams of Biodiesel Production
A Curriculum for Agricultural Producers
Prepared by
For the
National Center for Appropriate Technology
With funding and cooperation from the
USDA Risk Management Agency
What Side streams?
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Glycerin
Wash water
Excess Methanol
Absorbents
Glop and/or bad batches
WVO Sludge
Glycerin
Important to have a plan
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Product of the process
Can shut production down
Environmental consciousness
EPA’s definition of hazardous
waste your glycerol must have a
flash point under 140 ºF and pH
less than 12.5.
Glycerin
How much glycerin do we get?
About 18% of the finished product is crude
glycerin before methanol recovery.
Must remove methanol before doing
anything with glycerin.
Glycerin
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Soap making
Animal feed
Vermiculture composting
Aerobic Composting
Anaerobic biodigesters
Burning glycerin for process heat
Glycerin Soap
• NOT a real solution - Glycerin soap with a lot
of glycerin tends to sweat and get slimy
• We used about 1/4 gallon of glycerin in our
soap batch along with virgin oils.
• We followed a recipe from The Transparent
Soap book.
• UtahBiodieselSupply.com
• A liquid pumice for washing your hands in the
lab can be made from 100% glycerin.
Glycerin Soap
Vanilla Oatmeal, Almond, Spiced Fig, Lavender
and Unscented!
Glycerol and Animal Feed
• GRAS: General
Recognized as Safe
• Maximum:150 ppm of
methanol content
• University of Arkansas
research: Poultry Feed
• University of Missouri:
Cattle Feed
• Iowa State University:
Pig feed
Vermiculture Composting
Plant Vermiculture
Composting
Ideal Conditions: Moist, 72-74oF, 6-8pH, no
aerobic activity (turn if smells).
• Food - Waste vegetable
produce (no meat, dairy, citrus
or oil).
• Bedding - Shredded paper
• Glycerin diluted in H2O, applied
to bedding, then added to pile.
Co-op Vermiculture
Composting
• 4 bins, all approximately 4 cu ft.
• Weekly they receive
1/2 qt. - 2 qts glycerin each.
• Bedding is leaves.
• Food and garden produce
waste added weekly.
• We track amount of glycerin
added and worm castings
produced
• Nothing to report yet
Vermiculture Composting
• Relatively slow (5-6 months) compared
to aerobic decomposition (6-8 weeks)
• Need bedding material and nitrogen
input (coffee grinds, leaves, shredded
paper, farm produce waste)
• Worm castings = high value product
• Future worm tractor experiment
Aerobic Decomposition
(Composting)
• NOT just throwing all your organic
waste into one place
• Using bacteria and microorganisms to
break down wastes to reach a C:N ratio
of 15:1 (finished compost)
• Need to add both carbon and nitrogen
inputs to start feeding the compost.
Aerobic Decomposition
Small Scale Composting
Aerobic Decomposition
Small Scale Composting
• We add about 20 gallons of glycerin to each
pile (3 cu yds).
• Too carbon rich to add much more as it lowers
our compost temperature.
• We need to maintain the compost temperature
over 130oF for 90 days(?) to obtain organic
certification.
• Not a sustainable solution: 1 pile roughly
equals 1 batch biodiesel. We only need about
4-5 piles per season for our 0.85 acre farm.
Medium Scale Composting
Burlington Biodiesel Co-op
Medium Scale Composting
• Pile composed of 40 tons of wood chips,
started with a load of chicken manure.
• Tree service drops truck loads of wood chips
for free.
• 160ºF and still burning after 5 ½ months.
• Co-op disposes of all glycerin (after
methanol removal) and magnesol in compost.
• Magnesol does not break down.
Large scale/Industrial
Composting
• Piedmont disposes its unusable oil and
glop batches at an industrial compost
site.
• “The Pit”
• Industrial compost operations may allow
free dump of waste grease and/or
glycerin for small scale producers.
Biodigesters - Anaerobic
Decomposition
• Biodigesters can be used to turn animal and
food waste into methane gas
• Biodigesters might be able to break down
glycerin
• Methane gas can be reused as process heat
• Normally you add 25% animal waste, 25%
vegetable waste, 50% water.
• Very difficult to store the gas in cylinders
• Extreme caution to not breath Hydrogen
Sulfide (H2S), which is HIGHLY toxic and also
produced in anaerobic digestion
Biodigester
Burning Glycerin
Guatebiodiesel is packing a PVC tube with:
1 part shredded newspaper, 1 part sawdust, 1
part glycerin
Fire is started in a wood burning stove with
wood, and glycerin logs are added when hot.
Burns very hot with a clear blue flame.
If you start to see a smoldering black flame
you are producing acrolein (carcinogen
found in cigarette smoke). Add oxygen
and heat. (<300oF)
AUGI Research on Glycerin
Combustion
1. High levels or particulate matter (via the ash analysis), chlorine, and water contents in combination with the low energy
value indicated that crude glycerin is not sufficient for consideration as a sole source fuel in an industrial triple pass
fire tube boiler application.
2. Even with specialized modifications made to the boiler, the energy value in crude glycerin is inadequate for successful
start-up and continuous boiler operation.
3. The high level of residual chlorine contained in the crude glycerin sample is too high for long term boiler operation and
can adversely affect internal mechanisms of the boiler.
4. The high level of particulate matter (ash content) contained in the crude glycerin samples is too high for safe boiler
operation.
5. In order to maintain a flame in the industrial fire tube boiler, a small amount of crude glycerin (10% V/V) was co-fired with
yellow grease (90% V/V).
6. Pump mixing was not adequate to maintain a consistently blended fuel. Differences in the densities of crude glycerin and
yellow grease require an advanced mixing mechanism in order to maintain a homogeneous fuel mixture.
7. Higher boiler maintenance costs and excessive clean-up schedules reduce the favorable economical consideration that
crude glycerin low market values proffer
8. Changes in the boiler fuel from that which the boiler was originally designed to burn can reduce boiler efficiency and
negatively impact the load.
9. The current estimated cost per million Btu for the fuel blend (10% crude glycerin / 90% yellow grease) was calculated at
$13.32. The higher market prices for yellow grease does not make this a competitive fuel in comparison with
natural gas costs at the industrial level.
AG Solutions Boiler
• Has “the ability… to be fueled
with new or used vegetable
oils off all types and with some
of the glycerin byproduct from
the biodiesel production. We
have several customers who
currently utilize their glycerin
as part of their fuel.”
• http://www.agsolutionsllc.com
Wash water
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A biodiesel wash will typically be 3050% water by volume.
Very high biological oxygen demand
(BOD)
Water from a first wash can contain
around 6% BOD and less than 1% oil,
biodiesel, free fatty acids, glycerol,
soap, and catalyst.
3-4 washes ->
water used is 2-4x the amount of
biodiesel batch
Reverse osmosis, ultra filtration, and
ozone generators can effectively
reduce BOD
High pH (must soften water)
Wash Water
• BOD is an indicator of organic water pollution
• BOD in wash water is around 12,000 mg/L OFF THE CHARTS HIGH
• For reference, a pristine river has a BOD of
about 1 mg/L, treated sewage is about 20,
influent coming into most waste water
treatment facilities is about 200, untreated
sewage is about 600
• To lower BOD: Dilute and Oxygenate
• High BOD leads to slime
Wash water constructed
wetlands
Excess Methanol
• Methanol recovery systems through
distillation (boils at 148.5º F at 1 atm)
• For methanol recovery see “Biodiesel Safety
and Best Management Practices for SmallScale Noncommercial Use and Production”:
pubs.cas.psu.edu/FreePubs/pdfs/agrs103.pdf
• Watch out for VERY DANGEROUS methanol
vapor that is toxic and can flash (requires 4x
the density of gasoline vapors).
Methanol Recovery
Absorbents (e.g. Amberlite
and Magnesol)
Magnesol
Does not break down
Bad Batches / Glop /
WVO Sludge
• Waste Oil BurnerBad Batches can either be re-reacted, or used
in a waste oil burner for process heat, along
with some amount of WVO.
• Pilot light issue with oil burners and biodiesel
• We ship out serious glop/sludge to industrial
compost site
Resources
Agricultural Utilization Research Institute
http://www.auri.org/research/glycerin%20report%20fin
al.pdf
International Journal of Poultry Science 5 (11): 10011007, 2006 ISSN 1682-8356 © Asian Network for
Scientific Information, 2006
Evaluation of Glycerine from Biodiesel Production as
a Feed Ingredient for Broilers
S. Cerrate, F. Yan, Z. Wang, C. Coto, P. Sacakli and
P.W. Waldroup2 Department of Poultry Science,
University of Arkansas, Fayetteville AR 72701, USA