Separation of municipal waste water into its solid and liquid components is a technology that has been utilized by municipal sanitation departments for decades. Removal of the biosolids fraction cleans the liquid portion sufficiently that the waste water can be added to the surface waters of Illinois and the U.S. Many city waste water treatment departments use polymer-assisted separation systems that combine the use of chemical flocculents, gravity belt thickeners and belt presses to remove the solids fraction from waste water. The Livestock and Urban Waste Research (LUW) Team has adapted this technology to economically separate liquid swine manure into its biosolid and liquid fractions. This systems approach allows the biosolids fraction to be composted for ultimate use as either an on-farm or off-farm soil amendment while producing a liquid fraction with low odor, low solids and low phosphorus concentrations that can be irrigated as a nitrogen fertilizer for row crops.

Separation System

All slurry pits in all the swine buildings at the ISU Farm farrow to finish swine operation are drained once or twice each week and recharged with 2-3 inches of separated effluent. The raw slurry is drained by an underground sewer line to the slurry processing building. The raw slurry is passed across a gravity screen-roll process separator to remove separable solids. The separated slurry is mixed with polymer and passed across a gravity belt thickener to remove suspended solids. The resulting biosolids are transported to the compost site, mixed with landscape waste and composted. The resulting separated effluent is stored in a slurry store® until land applied during the corn/soybean growing season via a center pivot irrigator.

Slurry separation provides an efficient and cost effective system for managing the odor and nutrient overload associated with swine manure while improving animal welfare, reducing non-point source pollution concerns, and providing a source of beneficial soil amendments for crop production.

Land Application of Separated Effluent

The separated effluent, which makes up 90% of the raw slurry volume, is transferred to a slurry store® tank or other appropriate storage tank where it is aerated before being land applied using center pivot or subsurface irrigation. Because the total solids have been reduced by more than 98 percent in the effluent, clogging in irrigation equipment and piping is not a concern. Additionally, no odor problems have been associated with the use of separated effluent even with above ground irrigation systems.

Land Application of Separated Biosolids

The biosolids, which make up 2-10 percent of the raw slurry volume, are collected, composted and then land applied.

Abbreviations

• IF = Inorganic Fertilizer (Anhydrous Ammonia, Potash, Diammonium Phosphate (DAP)
• SE-MS = Separated Effluent from microscreen
• RS = Raw Slurry
• RS1 = Raw Slurry Before Processing Started
• BS = Biosolids/Separated Solids
• BS-B = Biosolids/Separated Solids from belt press
• BS-MS = Biosolids/Separated Solids from microscreen
• SE = Separated Effluent
• N:P = Ratio of Nitrogen to Phosphorus
• SE-B = Separated Effluent from belt press
• DM (%) = Percent Dry Matter
• N (%) = Percent Nitrogen
• P (%) =  Percent Phosphorus
• K (%) = Percent Potassium
• Ca (%) = Percent Calcium

Component Characteristics

Both the composted biosolids and the separated effluent provide a comparable alternative to using inorganic fertilizers for crop production.

Characteristics of Slurry, Effluent and Solids (Year 2)

Separation Costs

Total separation costs, including equipment, labor, polymer and fuel, come in at less than 1.0 cent per gallon of raw slurry.

BMPs for Effective Slurry Separation

• Frequent separation of slurry
• Fresh slurry (no older than 7 days) is easier and lower cost (requires less polymer) to separate than anaerobic slurry
• Not all liquid manure is the same, slurry composition can vary
• Select a polymer specific to the slurry produced
• Have adequate storage for separated effluent
• Separation equipment should be housed in a heated building to allow year around processing
• Match equipment size (gallons:minute processed) to slurry production
• Have appropriate storage for separated biosolids or an adequate sized compost facility

Composting is an age old practice of waste management whereby the organic components of the waste streams are biologically decomposed under controlled conditions to a stabilized state that can be safely handled, stored or applied to land as a soil amendment.

Composting can occur in the presence of oxygen referred to as aerobic composting, or in the absence of oxygen referred to as anaerobic composting. Most modern compost systems are aerobic for important reasons.

Aerobic composting is

• Free from objectionable odor.
• Makes pathogens and weed seeds inactive.
• Relatively inexpensive.
• Little technological input.

There are three methods of aerobic composting with the windrow method being the most cost effective.

Methods of Aerobic Composting

• Vessel
• Static Pile
• Windrow

Raw Materials

The raw materials for composting can be split into two categories: Carbon sources and Nitrogen sources.

Characteristics of Nitrogen Sources

• Wet
• Decompose quickly
• High in nitrogen
• High bulk density
• Not very rigid

Examples of Nitrogen Sources: Livestock manure, food waste, grass

Characteristics of Carbon Sources

• Dryer
• Decompose slowly
• Lowe in nitrogen
• Low bulk density
• Somewhat rigid

Examples of Carbon Sources: Corn Stalks, leaves, sawdust, wood chips

Fresh Compost: Has undergone partial decomposition, but it is not stabilized and continues to breakdown.

Mature Compost: Generally suitable as an organic soil conditioner, but is only partially stabilized and may temporarily arrest plant growth if it comes in direct contact with the roots.

Cured Compost: Highly stabilized product, excellent organic soil conditioner

Class A: Includes cured compost, suitable for lawn and garden application, referred to as designer compost

Class B: Includes fresh and mature compost, used as an agronomic soil amendment

Analysis of Raw Materials

Analysis of Mature Compost

Solid Livestock Waste
1.59 lbs. manure: 1 lb. landscape waste
652.0 lbs manure: 1 cu. yd. landscape waste
1.96 tons of raw material to make 1 ton compost

Swine Liquor-Grass
.20 lbs. liquid manure: 1 lb grass
135.59 lbs. liquid manure: 1 cu. yd. grass
1.82 tons raw material to make 1 ton of compost

Compost Process
No. of turns - 11
Days between turns - 5.2
Days from first to last turn - 53
Days to compost - 75

Swine Liquor - Wood Chips
3.19 lbs. liquid manure: 1 lb. wood chips
1592.59 lbs. liquid manure: 1 cu. yd. wood chips
5.78 tons of raw material to make 1 ton of compost

Compost Process
No. of turns - 16
Days between turns - 2.2
Days from first to last turn - 33
Days to compost - 151

Key Factors to Composting

• Moisture Content
• Temperature
• Carbon to Nitrogen Ratio
• Nutrient Balance
• Aeration
• pH
• Substrate

Moisture content

• Not less than 45%
• Not more than 70%

Carbon to Nitrogen Ratio

• Between 25:1 and 30:1

Aeration

• To speed up composting it is important to maintain aerobic conditions and proper temperatures within each windrow.

Windrows should be turned to accomplish this.

Windrow Turning Frequency:
First 3 - 5 Days: Turn Daily
Next 3 - 4 Weeks: Turn 2 - 3 Times/Week
Week 5 to End: Turn Once/Week

The Illinois EPA, Bureau of Land and Bureau of Water regulates composting and in some instances permits are required.

Compost Siting Regulations

Permits are not required if:

• The site is located on the farm on which the compost is applied.
• Appropriate setbacks are followed.
  • one-fourth mile from the nearest nonfarm residence
  • one-half mile from the nearest populated area
• The site is protected from flooding.
• The site does not discharge runoff.
• The site is 200 feet from the nearest potable water.
• The site is operated by the farmer who is not a partner or employee of a waste hauler or generator.

Permits are required:

• For livestock operations larger than 1000 head, a National Pollution Discharge Elimination System Permit is needed.
• If compost is sold, a siting permit is needed.
• If livestock waste is combined with landscape waste and exceeds greater than 10 percent of the total volume, an EPA organic waste-composting permit is required.

The Livestock and Urban Waste Research (LUW) Team has developed a successful manure treatment system that couples polymer-assisted separation of liquid manure with composting. This solid-liquid separation of raw swine manure makes it possible to reuse the solid fraction with a high nitrogen and phosphorus content separately from the liquid fraction with a low solids and low phosphorus content. Separation consistently removes more than 90 percent of the solids and approximately 90% of phosphorus from liquid manure. The solids fraction is composted, producing a value-added coproduct that can be sold off-farm or transported longer distances for cropland application. The separated effluent is stored in holding tanks for subsequent land application. This direct utilization of the liquid fraction is advantageous because it is simple, has a low application cost, and allows for direct use of nitrogen. Most importantly, this adaptive management technology changes the nitrogen: phosphorous (N:P) ratio thereby minimizing environmental concerns regarding phosphorous contamination.

Land Application of Separated Effluent

The separated effluent, which makes up 90 percent of the raw slurry volume, is transferred to a slurry store® tank where it is aerated before being land applied using center pivot or subsurface irrigation. Because the total solids have been reduced by over 98 percent in the effluent, clogging in irrigation equipment and piping is not a concern. Additionally, no odor problems have been associated with the use of separated effluent even with above ground irrigation systems.

BMPs for Irrigating Separated Effluent

• Frequent separation of slurry
• Obtain nutrient analysis (NPK) of separated effluent
• Separated effluent must have 90 percent or more of the total solids removed to prevent odor
• Apply based on percent N if greater than 90 percent of the P has been removed
• Apply one-fourth inch of separated effluent at a time to avoid burn
• Do not irrigate on frozen ground to avoid runoff
• Do not irrigate just prior to or during a rain to avoid runoff or leaching
• Surface broadcast when vegetation is growing is preferable to broadcast when no plants are actively growing to reduce odor and loss of N
• Do not apply just prior to or during a rain to avoid runoff or leaching

Both the composted biosolids and the separated effluent provide a comparable alternative to using inorganic fertilizers for crop production.

Abbreviations

• RS = Raw Slurry
• SE = Separated Effluent
• SE-B = Separated Effluent from belt press
• SE-MS = Separated Effluent from microscreen
• BS = Biosolids
• BS-B = Biosolids from belt press
• BS-MS = Biosolids from microscreen
• % Solids = Percent solids
• % N = Percent Nitrogen
• % P = Percent Phosphorus
• % K = Percent Potassium
• % Ca = Percent Calcium
• N:P = Ratio of Nitrogen to Phosphorus

Land Application of Separated Biosolids

The biosolids, which make up two - 10 percent of the raw slurry volume, are collected, composted and then land applied.

BMPs for Land Application of Biosolids

• Obtain nutrient analysis (NPK) of biosolids
• Apply based on % P concentration
• Applying based on % N concentration will result in over applying P
• Do not apply to frozen ground to avoid runoff
• Do not apply just prior to or during a rain to avoid runoff or leaching
• Soil injection is preferable to surface broadcast to reduce odor and loss of N
• Apply based on % dry matter of biosolids

BMPs for Land Application of Composted Biosolids

1. Obtain nutrient analysis (NPK) of compost
2. Apply based on % P concentration
3. Applying based on % N concentration will result in over applying P
4. Apply based on % dry matter of compost
5. Do not apply just prior to or during a rain to avoid runoff or leaching
6. Soil incorporation immediately after surface broadcast is recommended to reduce odor and loss of N
7. Apply based on % dry matter of biosolids

Separation Costs

Total separation costs, including equipment, labor, polymer and fuel, come in at less than 1.0¢ per gallon of raw slurry.

Slurry separation provides an efficient and cost effective system for managing the odor and nutrient overload associated with swine manure while improving animal welfare, reducing non-point source pollution concerns, and providing a source of beneficial soil amendments for crop production.