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Ultrafiltration to Treat Rendering Facility Wastewaters [email protected] 864-656-4502 (work) 864-325-9062 (cell)
Overview of ACREC Research Jessica Meisinger, PhD Director of Education, Science, & Communication National Renderers Association/FPRF Annel Greene, PhD Director, ACREC Clemson University Highlighted Research Project Jinxiang Zhou, PhD Daniel Wandera, PhD Brian Baker (UG) Charlie Grimsley (UG)
Scott Husson, PhD Chemical and Biomolecular Engineering Clemson University Clemson, SC
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We are grateful for the financial support of this work by the Animal Co-Products Research and Education Center with funding from the Fats and Protein Research Foundation. We thank Hydration Technology Innovations (HTI) for providing ultrafiltration membranes and technical insights.
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Animal Co-products Research and Education Center
• To advance the science and technology of animal co-products and the rendering process
• To ensure microbial safety of rendered products for animal feeds and consumer protection
• To promote environmentally sound practices • To develop new market opportunities for the worldwide
rendering industry • To provides educational opportunities in animal co-product
utilization
Dr. Annel K. Greene ACREC Director [email protected] Mission
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ACREC Research Projects
– Chemical engineering – Microbiology – Materials science and
engineering – Bioengineering – Mechanical engineering – Animal science – Food science – Packaging science – Biological science – Experimental statistics
– Chemistry – Architecture – Environmental engineering – Automotive engineering – Agricultural engineering – Soils – Turfgrass – Environmental toxicology – Horticulture – Computer science
• Approximately 50 total since 2004 • More than 40 researchers • Interdisciplinary, innovative projects
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[email protected] 864-656-4502 (work) 864-325-9062 (cell)
Odor Elimination
Daniel Whitehead and Frank Alexis Goal: develop materials that sequester or destroy malodorous volatile organic byproducts of rendering processes • Destroying malodorants with biodegradable nanoparticles • Using nanoparticles to target and eliminate odors • Proved the ability to capture short chain FA pollutants • Proved the nanoparticles are non-toxic, biodegradable • Working on proving selectivity for specific functional groups
– carboxylic acids – Sulfides
• Could lead to effective odor control
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Antioxidant Production
Vladimir Reukov and Alexey Vertegal
Goal: produce a novel antioxidant that is natural, effective, and cost-effective
• Potent antioxidant from animal by-products
• As effective or better than available antioxidants
• Prevent rancidity in feeds
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Salmonella Reduction
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Xiuping Jiang Goal: determine if bacteriophage treatment can be an effective and low-cost approach for controlling Salmonella contamination in the rendering environment. • FDA approved bacteriophages as food additive in 2006 to fight listeria
in ready-to-eat meats • Bacteriophages work in the lab against Salmonella, now testing in
rendering plant and versus biofilms
[email protected] 864-656-4502 (work) 864-325-9062 (cell)
Validation of Rendering as a Kill Step
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Annel Greene Goal: validate that Salmonella and Clostridium perfringens are killed during rendering • Work is investigating thermal death time for several strains of
Salmonella in poultry and beef rendering materials.
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Renderable Gloves and Totes
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Andrew Hurley Goal: reduce glove remains in post-milled protein by designing, developing, testing, and sourcing ‘renderable’ gloves. • Searched a number of candidate materials to find a replacement for
polyethylene collection bags. • Found new biodegradable polymers and developed improved bags
to line rendering collection barrels. • Improving finished fat and protein quality and safety.
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Separating Fat from Protein
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Chris Kitchens Goal: investigate the use of carbon dioxide as a green solvent for enhancing the mechanical expression of fat from rendered materials. • Use liquid CO2 to more effectively extract fats from proteins • Re-engineering the press • Demonstrated in the lab and working on pilot-scale trials • Emerging market in low-fat meats for pet food
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Value Added Fats
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Mark Blenner Goal: engineer yeast to grow on rendered animal fats to produce omega-3 fatty acids. • Polyunsaturated fatty acids are in high demand and sell for a
premium • Convert rendered animal fats into value added molecules like
polyunsaturated fatty acids that are found in fish oils
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Composite materials
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Srikanth Pilla Goal: develop high-strength, hydrophobic, odor-free thermosets and composites from proteinaceous materials from the rendering industry • Engineering rendering protein materials for cars • Develop high strength composites • A high-value non-feed use
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Final Notes on ACREC
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Other Research Projects • Carbon footprint • Lifecycle analysis for GHG
emissions • Feather meal safety • Identifying cost-effective
paths for new high value products from rendered fats
• Non-feed uses of rendered product
• Novel changes in operations
• Active, interdisciplinary research program
• Characterized by Innovation! • Currently focused on nutrition,
plant operation, environmental factors
• Exploring better lab-to-market paths for inventions
Ultrafiltration to treat rendering facility wastewaters [email protected] 864-656-4502 (work) 864-325-9062 (cell)
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Dissolved air flotation (DAF) is used for primary treatment of rendering facility wastewater, but it requires costly chemical additions
- DAF removes suspended solids, grease, and oil from waste water using air bubble flotation method
- chemical additives used to improve flocculation - typical cost is $3.2/1000 gallon waste water
Membrane technologies have advantages for treatment of impaired waters
- provide a positive barrier to reject solids - can be conducted without addition of chemicals (unlike DAF) - offers flexibility in handling feed liquids with fluctuating properties - offers modular design that makes it easy to expand capacity as needed
Hypothesis: membrane filtration can be used to treat rendering facility wastewaters without the polymeric flocculants and chemical additions needed for DAF.
Overall Goal and Research Objectives [email protected] 864-656-4502 (work) 864-325-9062 (cell)
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Goal Develop a membrane alternative to DAF for the low cost treatment of rendering wastewaters
Objectives Evaluate performance of ultrafiltration membranes (primary stage) Evaluate performance of nanofiltration/reverse osmosis membranes (polishing) Understand and model the effects of operating parameters on membrane performance Evaluate membrane cleaning protocols and estimate membrane lifetimes Perform a preliminary cost analysis for operating the membrane process in place of DAF
settling tank
sedimentpump
UF
permeate(treated)
retentate(concentrate)
feedP
P
P
pump
PRO
P
P
recycle
Proof of Concept [email protected] 864-656-4502 (work) 864-325-9062 (cell)
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Compositions vary
Contains high levels of fats, oils and greases, and proteins that must be removed prior to discharge
Table. Pre-DAF waste water from our partner rendering facility
Preliminary Results [email protected] 864-656-4502 (work) 864-325-9062 (cell)
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Performance of treated HTI cellulose acetate UF membrane reduced turbidity by 650-fold, without addition of
polymeric flocculant; reduced COD by 80% and total solids by 90%; yielded a stable, steady state, permeate flux over a 120-
hour period, without the need for intermittent cleaning
Preliminary Operating Cost Analysis for UF [email protected] 864-656-4502 (work) 864-325-9062 (cell)
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Estimates based on data for a DAF unit operating at 160 gal/min flow rate. Included are costs for energy to pump the wastewater chemical additives replacement membrane modules membrane cleaning costs (not shown – pressure effect) Sizing of the membrane modules steady-state permeability of 0.09
L/(m2·h)/kPa pressure of 280 kPa Membrane cost estimate includes a chemical enhanced backwash every 3 day using 600 mg/L hydrochloric acid solution
Module costs provided by HTI, LLC (also provided in-kind support by providing membranes) Manufacturer suggested lifetime for the membrane modules is 2 years
DAF MEM (6 mo) MEM (1 yr) MEM (2 yr)
oper
atin
g co
st ($
/100
0 ga
l)
0
1
2
3
4energy costs for pumpingchemical costsmembrane module costs
flux (J)
-dP/
dt
[or d
(TM
P)/d
t]
J* (t
hres
hold
flux
)
d(TM
P)/d
t But Surely They Foul … Right?
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cake layermembrane
u
Time
Flux
Cake thickness
Below threshold flux
Time
Flux
Above threshold flux
J = permeate flux (volume/area/time) J* = threshold flux TMP = transmembrane pressure
Determination of Threshold Flux (Stable Performance) [email protected] 864-656-4502 (work) 864-325-9062 (cell)
model for threshold flux:
Figure. Threshold flux measurements: a) different UF membranes at 3300 mg/ml TDS and b) different feed concentrations using UF membrane PSF1. TMP was 0.7 bar for CA and 0.2 bar for polysulfone. These are low!!
No difference was observed in threshold fluxes of CA and polysulfone membranes Results were highly reproducible and were not dependent on procedure Lower solid concentrations slowed fouling rate, resulting in higher threshold fluxes.
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0 20 40 60 80 100
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7original feed1/10 conc. of the feed1/45 conc. of the feedb
Flux (L/m2h)
d(TM
P)/d
t (b
ar/m
in)
0 5 10 15 20 25 30 35 40
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7PSF 1CAa
Flux (L/m2h)
d(TM
P)/d
t (b
ar/m
in)
Role of the Membrane [email protected] 864-656-4502 (work) 864-325-9062 (cell)
Feed (Pin)
Permeate (Pperm)
Scheme: Direct flow
Roverall = Rmembrane + Rc𝐚𝐚𝐚𝐚𝐚𝐚𝐚𝐚
Resistance equation:
Transient and major resistance (obtained by measurements)
overall
1 dV PA dt R
∆=µ ⋅
Measured at various ∆P
cakelayer cVRA
= α ⋅ρ
( )s' Pα = α ∆s is a measure of cake compressibility s = 0 (incompressible) s = 1 (highly compressible)
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Role of Applied Pressure (Less is More) [email protected] 864-656-4502 (work) 864-325-9062 (cell)
Figure: resistance versus the filtration volume. Rcakelayer increases with increasing V, as expected. (HTI polysulfone membrane)
Figure: determination of compressibility factor, s = 1.13 (highly compressible cake)
V (ml)
0 10 20 30 40 50 60 70
R c (X
1014
m-1
)
0
1
2
3
40.41 bar0.69 bar1.45 bar2.07 bar2.76 bar3.45 bar
ln (TMP)0 1 2 3 4 5 6
ln(
)
-37.5
-37.0
-36.5
-36.0
-35.5
-35.0
-34.5
-34.0
For the same permeate volume (V) processed, the mass of solids deposited is the same regardless of TMP
Yet, cake layer resistance is higher at higher TMP due to the cake compression Compressibility factor is used to quantify cake layer compressibility.
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Polishing Step Purification [email protected] 864-656-4502 (work) 864-325-9062 (cell)
settling tank
sedimentpump
UF
permeate(treated)
retentate(concentrate)
feedP
P
P
pump
PRO
P
P
recycle
Figure: Comparison of membrane technologies [adapted from Koch Membrane Systems, Membrane technologies: Targeted technology makes the difference www.kochmembrane.com/Learning-Center/Technologies.aspx (accessed Oct. 2013).
Ultrafiltration (UF) removes high molecular weight organics but allows passage of salts and small molecules Polishing step purification therefore is needed to reduce COD and salt levels (TDS)
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Polishing Step Purification [email protected] 864-656-4502 (work) 864-325-9062 (cell)
The best performing membrane achieved 1600 L/m2 capacity prior to cleaning. A cascade of UF/NF or UF/RO membranes can reduce COD and TDS levels by as much as 99% relative to the initial feed, without the addition of chemicals or polymers used in DAF Preliminary operating cost analysis found that a two-stage UF/NF or UF/RO system has 33-55% of the cost for DAF depending on the assumed membrane lifetime.
Nanofiltration Reverse osmosis
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Summary and Closing Remarks [email protected] 864-656-4502 (work) 864-325-9062 (cell)
This project has demonstrated that membrane filtration is effective at treating rendering facility wastewaters without chemical additions.
A membrane cascade using an HTI low-permeability UF membrane followed by polishing with a Toray 70UB RO membrane yielded
- essentially 100% reduction in turbidity - 98.5% reduction in COD - 99.4% reduction in total solids
Knowing (and operating just below) the threshold flux will allow sufficiently high flux while keeping fouling rates at acceptable levels.
Determination of effective clean-in-place protocols will be needed for process implementation.
Preliminary operating cost analysis favors a membrane ultrafiltration separation process over dissolved air flotation process.
Knowledge of membrane lifetimes is important to provide accurate operating cost estimates.
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