handling sand-laden manure - ut extension...sand separation lane •recommended targets: –at least...

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?