Biosolids and nutrients: know your product
Dan M. Sullivan, Oregon State University, Corvallis, OR USA [email protected]
ACWA Workshop. Best Practices for Biosolids Management
Lane Community College. April 16, 2013.
Farmers want to know…
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What is it (source, analysis)?
Regulations?
What are nutrients worth?
Transportation, storage, application?
Does it fit my needs?
What is it? Positive spin.
• Biosolids, n. Biosolids are the nutrient‐rich organic product of wastewater treatment. A beneficial resource, biosolids contain essential plant nutrients and organic matter and are recycled as a fertilizer and soil amendment. National Biosolids Partnership. http://biosolids.org/docs
What is it? Negative spin.
• Sewage sludge, n. Sewage sludge is the product of municipal wastewater treatment. Often thought to consist of only “human waste,” sewage sludge in fact contains organic, inorganic, and biological pollutants from commercial, industrial, and household wastes, and compounds added to and formed during treatment processes.
New Solutions: A Journal of Environmental and Occupational Health Policy.
http://www.riles.org/musings42.htm
The Biosolids Triangle
Regulators
Land managers
or “customers”
Success
Biosolids managers
Reduce nutrient loss
to environment
Produce a
profitable crop
Success
Routine procedures
for land application
What is it? PNW 511‐E
Biosolids nutrients (dry wt basis)
What about those metals?
Kinds of biosolids
• Class B for pathogens:
– Liquid (2‐5% solids)
– Cake or dewatered (16 to 25% solids)
– Air‐dried (80+% solids)
– Lime‐stabilized (liquid or cake)
• Class A for pathogens:
– Heat‐dried (98% solids)
– Composted
– Hot‐digested (ATAD): 20% solids
Liquid (slurry) biosolids
Dewatering biosolids
Dewatered biosolids application
Dewatered biosolids application
Class B biosolids: crop rotation issues
• Best crop: perennial grass, pasture/hay
• Next best crop: cereals, grass seed
• Grain or seed crops: DEQ requires 30 days between biosolids application and harvest
Class B biosolids: restrictions
• Vegetable fruit processors: most do not allow biosolids
• Organic certification: no biosolids
• Site permit (DEQ) or agreement with generator may restrict N fertilizer application
Salts? Long‐term dryland application site
Hermiston (6 in. annual precip.) Soil analysis
None
Biosolids
Organic Matter
(%)
1.2
2.2
pH
7.5
6.7
EC (mmho/cm)
0.2
0.3
Nutrient Balance
Example: nutrient balance
Tall fescue grown for grass hay or silage (intensive mgmt; 4 cuttings/yr)
Nutrient
Nitrogen
Phosphorus
Potassium
Sulfur
Zinc
Copper
Biosolids
Nutrient
Input
Grass
Nutrient
Removal
Net nutrient
input to soil
lb/acre
400
160
24
80
6.8
4.7
lb/acre
220
32
240
40
0.4
0.1
lb/acre
130
128
-216
40
6.4
4.6
Biosolids vs. Manure?
• Biosolids nutrient management is similar to that for manures, except:
– biosolids are higher in S, lower in K than
manure
• Biosolids are often a more consistent source of nutrients than manure
• Biosolids processing affects N forms: – Balance between organic N and
ammonium-N
Typical available N from biosolids
Available N per unit of organic amendment =
a (Organic N in amendment) plus
b (ammonium-N in amendment) plus
1 (nitrate-N in amendment)
where:
a = fraction of organic N mineralized to
available N during a growing season
b = fraction of NH4-N retained after
application
What happens to N that doesn’t mineralize
(convert to available N)
during first year after application?
Cumulative available N from
an organic source
Year 1
= available N
2
+
3
+
+
4
+
+
+
5
+
+
+
+
Long-term trial, Puyallup WA
500
Residual
Application
a
Apparent nitrogen recovery, kg ha
-1
a
Biosolids High
400
a
a
a
300
b
a
b
Inorganic N
b
b
b
b
c
b
b
b
b
a
b
c
200
c
a
c
b
d
100
Biosolids Low
b
c
a
a
Biosolids Medium
a
d
d
d
d
a
d
b
d
c
d
c
a
b
b
c
c
0
1994
1996
1998
2000
2002
2004
c
c
c
d
2006
a
b
a
a
bc
bb
b
ab
bc
c
c
2008
a
ab
bc
c
2010
Year
Cogger et al., 2013 (WSU)
Fate of biosolids N and inorganic
(fertilizer N)
Soil sampled in 2011, 10 yr. after last biosolids application
Cogger et al., Puyallup, WA (WSU)
Article in “Cool Forages” book (available soon at Farmwest.com)
Phosphorus
Plant nutrient
Potential water pollutant
Biosolids are rich in P
When applied to supply N for a crop, P accumulates
• P accumulation monitored by agronomic soil testing
• Agronomic testing extracts a small fraction of total soil P that is correlated with P that roots can “extract” from soil.
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Soil test P:
Agronomic & Environmental Interpretations
In: Sharpley et al., 1999;
ARS-149
Phosphorus: Landscape view
In: Sharpley et al., 1999;
ARS-149
0-30 cm SAMPLING DEPTH
100
non-application buffer areas
biosolids application areas
90
High Risk
BRAY 1 P (mg kg-1)
80
70
60
Medium Risk
50
Low Risk
40
Agronomic
Sufficiency
Level
30
20
10
0
1
2
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
SITE
Nitrogen fertilizer equivalency of heat‐dried municipal biosolids for soft white winter wheat Dan M. Sullivan, Oregon State University, Corvallis, OR USA [email protected]
Why heat dry biosolids?
• Wastewater treatment plants are adding additional processing capabilities
– to provide higher levels of treatment (Class A)
– to produce products for new markets
• Heat‐dried biosolids meet USEPA Class A requirements for pathogen elimination – so they can be marketed like any other organic
amendment
Heat dried biosolids
• Produced in rotating drum Andritz dryer
– Inlet = 455 to 480 oC
– Outlet = 100 oC
• Pelleted
• Oil added to reduce dust
• Bulk or bagged
• Similar to MillorganiteTM?
Objectives
• Evaluate the nitrogen fertilizer equivalence (NFE) or of heat‐dried biosolids in western Oregon
• Compare fall (preplant) vs. spring biosolids application under western Oregon conditions (winter leaching of nitrate‐N)
Experimental Design
 Oregon State University Hyslop Agronomy Farm, Corvallis, OR
 Soil test values for other nutrients not limiting for winter wheat  Broadcast S all plots:  30 kg SO4‐S/ha Early spring (tillering; Feb)
• Fall preplant biosolids application increased vegetative growth
OSU Hyslop Agronomy Farm, Feb 18, 2010.
Biosolids pellets remain “intact” for weeks on soil surface
April 2011 (20‐d after biosolids application)
Jointing (stem elongation)
Grain harvest
2011 Grain Harvest
Grain Yield (Mg/ha)
11
Grain N uptake (kg/ha)
160
2011
2011
10
140
Urea
9
SGro
Spring
37% FNE
8
7
Urea
SGro
Spring
41% FNE
120
100
6
80
SGro
Fall
26% FNE
5
SGro
Fall
29% FNE
60
4
3
40
0
100
200
300
400
Total N application rate (kg/ha)
0
100
200
300
400
Total N application rate (kg/ha)
Variety: Geotze (fungicide 2X)
Three‐year summary
NFE% based on relative grain N uptake vs. urea
Fall SGro heat-dried biosolids
Spring SGro heat-dried biosolids
60
45
50
35
40
N Fert
Equivalent 30
(% of total N)
20
10
0
2009
2010
2011
Avg
Future for heat‐dried biosolids
products?
• Wastewater treatment facilities large and small are installing biosolids dryers to produce Class A product
• Current research is evaluating heat‐dried biosolids
produced by different facilities
– Andritz dryer (Soundgro; this study)
– Fenton dryer (LaCenter and Sumner, WA)
– Thermaflite dryer (WA)
• Pelleting technology differs among treatment facilities; some products have fine particles and are dusty. Thanks!
Dan M. Sullivan, Oregon State University, Corvallis, OR
[email protected]