Post on 29-Jul-2020
Handling Sand-laden
Manure
Wesley C. Wright, P.E. October 22, 2015
Free Stall Bedding
– Cows rest 10 or more hours per day
– Proper bedding should:
• Provide comfort
• Conform to cow’s body
• Resist compaction and provide traction
• Maintain a low moisture content
• Inhibit bacterial growth
– Inhibiting bacterial growth is crucial to cow cleanliness, udder health, and ultimately milk quality
– Major pathogens causing mastitis:
• Strep. Uberis
• Strep. Dysgalactiae
• Coag. Neg. Staphs.
• Coliforms
• Staph. aureus
• Strep. ag
• Mycoplasma
Bacteria in Bedding
Environmental
Contagious
Bedding Bacteria Levels
• Minimal Risk
– Less than 300,000 cfu/g
• Moderate Risk
– 300,000 to 1,000,000 cfu/g
• High Risk
– Greater than 1,000,000 cfu/g
Organic Bedding
– Dried Manure solids
– Paper
– Straw
– Peanut Hulls
– Sawdust
– Shavings
– Crop Residue
Inorganic Bedding
– Gypsum
– Limestone Screenings
– Sand
Pros/Cons of Organic Bedding
– Pros:
• Readily available
• Low cost
• Absorbs moisture
– Cons:
• Supports growth of environmental mastitis pathogens – Research has found <24 hours >1,000,000 cfu/g (high risk)
Pros/Cons of Inorganic Bedding
– Pros:
• Increases traction
• Inert
• Drains moisture
– Cons:
• Gypsum- could elevate H2S levels in manure slurry
• Limestone- prone to packing
• Sand- abrasive to equipment
Sand makes Good Bedding
– It’s comfortable
– Provides excellent traction
– Limits bacterial growth
– Does not cause hock abrasions
– Can be recycled
– Easy to maintain in the Free Stall Barn
Free Stall Barn Flush System
Free Stall Barn Flush System
– Targets
• Flush Velocity - >5 feet/second
• Flush Depth - 3-4 inches
• Contact time - 10-12 seconds
– Controlled by
• Flush rate - gallons/minute
• Flush Time – seconds
• Slope of alleys
• Length and width of the alleys
Alley Slope %
Alley Length (ft)
Alley Slope %
Alley Length (ft)
Alley Slope %
Alley Length (ft)
Alley Slope %
Alley Length (ft)
Alley Slope %
Alley Length (ft)
Alley Slope %
Alley Length (ft)
Why recycle sand from
sand-laden manure?
Why recycle sand? – Scenario
• 300 Cows / Free stalls
• 30 lbs./day sand per free stall
• 3,300,000 lbs./year sand – 1650 tons
• 70 tandem truck loads – $600 per load for certified mason’s sand
• $42,000 per year
– Over 10 years • $420,000
• 1 inch of sand over 7 acres
• Fill a >2,000,000 gallon lagoon
Recycling Sand Separation Lane
Sand Separation Lane
• Separation based on Density – Water and manure - ~60 lbs. / cubic foot
– Sand - ~120 lbs. / cubic foot
• Dilution and Suspension – High Velocity Flush
• Reduce the Velocity
–IF done correctly, sand settles and manure moves on in the flush.
Sand Separation Lane
• Recommended Targets:
– At least 150 feet in length
– Slope 0.20-0.25%
– Recommended Width 10-12 feet
– Flush velocity at the end of the lane 1-2 feet/second
– Uniform grade sand - ~0.5 mm
Case Study
Little River Dairy
Problems
• Free Stall Barn flush not getting the alleys clean
• Deposition in the Gravity Trench causing overflow
• No separation in the Sand Lane
Solution
Free Stall Barn Flush
Solution
Gravity Trench
Solution
Sand Separation Lane
Sand Separation Lane
• Target
– Slope 0.20-0.25%
Sand Separation Lane
• Target
Sand Separation Lane
• Target
– Recommended Width 10-12 feet
Sand Separation Lane
• Target
Sand Separation Lane
• Target
– Velocity at the end of the lane 1-2 feet/second
Sand Separation Lane
• Target
Sand Separation Lane
• Target
– Uniform grade of sand ~0.5 mm
Sand Separation Lane
• Target
Adjusting the Sand Lane
Iteration 1 – April 2014
Adjusting the Sand Lane
Iteration 2 – June 2014
• Long sweep 90⁰
• 30 inch wide
• Flare throat
with 3 energy disrupter blocks
Sand Grain Size (mm)
0.01 0.1 1 10
% P
assin
g
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0ASTM Range for Coarse Sand
New Recycled Sand
Old Sand
New Sand
4/9/20
14
4/11
/201
4
4/14
/201
4
4/16
/201
4
6/13
/201
4
6/23
/201
4
6/25
/201
4
7/2/20
14
7/9/20
14
7/16
/201
4
7/28
/201
4
% O
rga
nic
Ma
tte
r
0
2
4
6
8
10
12
14
Recycled Sand Quality
• October 7, 2015 Sample
– 0.51% organic matter
• Milk - Somatic Cell Counts
– Indicator of cows immune response to pathogenic bacteria
– Monthly average over the last year 133,000
• Normal - 100,000
• US limit - 750,000
Remember
• Free Stall Barn Flush – Slope - 3%
– Velocity - >5 feet/second
– Depth - 3-4 inches
– Contact time - 10-12 seconds
• Sand Separation Lane – Velocity at end of lane - 1-2 feet/second
– Uniform grade sand - ~0.5 mm
• (Certified Mason’s Sand)
Questions?