Environmental Engineering Reference
In-Depth Information
⎡
(Organic Nitrogen (mg/kg)
×
if
1
)
⎤
PAN
(lb/dry ton)
=
⎥
×
0.0
02 lb/dry ton
(10.28)
⎢
+
(Ammonia Nitrogen (mg/kg)
×
V
)
⎣
⎦
1
where:
if
1
=
Mineral rate for organic nitrogen (assume 0.20).
v
1
= Volatilization rate ammonia nitrogen.
v
1
= 1.00 if biosolids are injected.
v
1
= 0.85 if biosolids are plowed in within 24 hours.
v
1
= 0.70 if biosolids are plowed in within 7 days.
Example 10.31
Problem:
The biosolids contain 21,000 mg/kg of organic nitrogen and
10,500 mg/kg of ammonia nitrogen. The biosolids are incorporated into
the soil within 24 hr after application. What is the plant available nitro-
gen (PAN) per dry ton of solids?
Solution:
PAN
=
⎡
⎣
(21,000 mg/kg
×
0.20)
+
(10,500
×
0.85)
⎤
⎦
× .002
0
=
26.3 lb/dry ton
10.8.2.3 Application Rate Based on Crop Nitrogen Requirement
In most cases, the application rate of domestic biosolids to crop
lands will be controlled by the amount of nitrogen the crop requires.
To determine the biosolids application rate based on the nitrogen
requirement:
1. Use an agriculture handbook to determine the nitrogen require-
ment of the crop to be grown.
2. Determine the amount of sludge in dry tons required to provide this
much nitrogen:
BiosolidsApplication
Rate (dry tons/ac)
nt Nitrogen Requirement(lb/ac)
PlantAvailable Nitrogen (lb/dryton)
Pla
=
(10.29)
Example 10.32
Problem:
The crop to be planted on the land application site requires
150 lb of nitrogen per acre. What is the required biosolids application
rate if the PAN of the biosolids is 30 lb/dry ton?
Solution:
150 lb/ac
30 lb/d
BiosolidsApplicationRate
=
=
5dry tons/ac
ry ton
