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Mechanical Manure Solids/Liquid Separation With Recycling of Solids for Bedding

Photos taken at Kelsay Dairy, Whiteland, Indiana

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Automatic scrapers on grooved concrete cycle about once per hour.
Continuous cycling of scraper helps to eliminate odors.
A rubber-bladed scraper is used in barns without automatic scrapers.
Barns without scrapers are also scraped frequently, at least twice per day.
Waste is scraped into deep gutters at the end of each alley.
Waste in deep gutters is flushed to a collection pit using recycled waste water.
From the collection pit beneath a barn, the manure can be directed to the mechanical separator or to the lagoon
In the manure separator building.... the pipes across the top of the page are for separated effluent, overflow from the mechanical separator, and slurry to the separator unit, respectively from left to right.
Another view of the pipes extending upward to the overhead location of the separator.
Upstairs in the manure separator building...the hose from above feeds slurry into the separator unit, while the lower hose removes the overflow from the separator.
The mechanical separator or "squeezer" forces solids out the end, while separated effluent is removed through the hose extending from the bottom of the unit.
Another view of the mechanical manure liquid/solids separator.
Separated solids fall to the storage area below.
Separated solids. On a fertilizer basis, the manure solids on this particular farm have had the following analysis:

Moisture 72.2%, Ash 25.7%, Nitrogen .63%, Phosphorus .19%, Potassium .14%, Calcium .66%, Magnesium .22%, Sulfur 0%, Copper 15 parts per million, and Zinc 63 prts per million. As sampled, the N-P-K rating was 13-4-3. Available nitrogen was about 40-45%. (Soil testing laboratory, Auburn University)

Composting separated solids is critical if they are to be used as a bedding material for cattle. The solids are drier and the heat generated during composting can reduce bacteria populations. Also, composting stabilizes nutrients in the solids and helps to reduce odor.
Solids spreader for bedding freestalls.
Freestalls bedded with manure solids.
Stage one lagoon --- Effluent from solids/liquid separator and some slurry.
Stage two lagoon --- Effluent from stage one. Used as flush water in freestall barn. Applied as fertilizer the manure samples tested as:

pH 6.3, Dry Matter 4.67%, Total Nitrogen 17.55 lbs per 1000 gallons, Ammonium Nitrogen 7.5 lbs per 1000 gallons, P205 15.64 lbs per 1000 gallons, K20 6.10 lbs per 1000 gallons, and available Nitrogen 11 lbs per 1000 gallons (Dr. Alan Sutton, Purdue University Animal Sciences Department).

Stage two lagoon. Notice Interstate Highway traffic in immediate background.