Mass: main stem, woody branches, green branches, foliage. ⢠Tree components analyzed for Total N and Total P (others). ⢠Total N and Total P was estimated for ...
Removal of Nitrogen and Phosphorus by Eucalyptus and Populus at a Tertiary Treated Municipal Wastewater Spray Field Patrick J. Minogue1, Masato Miwa1, Donald L. Rockwood2 and Cheryl L. Mackowiak1 1North
Florida Research and Education Center 2School of Forest Resources and Conservation
Background
• Tallahassee population 170,000+ • Waste treatment 32 million gal/day • Wastewater Effluent 28.43 million gal/day • CONCERN: Spray fields on unconfined aquifer may contribute to groundwater pollution
Changes in Spray Field Operation • Spray field crop removals • Grazing - Gone • Forages • Corn • $227 Million upgrade • $160 M Advanced Wastewater Treatment Level • $4.6 M Wastewater Re-use for irrigation • What crop will grow on 3 ppm N?
Pivots at SE Spray Field, Tallahassee, FL
Objective • Evaluate fast-growing tree species and genotypes for phytoremediation of N and P from tertiary treated municipal wastewater and biomass production for energy • To determine: – Species suitability, genotype differences – Nutrient removals, partitioning in tree parts – Dry biomass production and partitioning in trees – Soil nutrient changes and nutrient budgets
Phytoremediation
Treatments and Experimental Design • • • •
Populus deltoides – 14 clones Eucalyptus grandis – 5 half-sib families Eucalyptus amplifolia – 4 half-sib families 2 hr daily irrigation 93.8 m3 ha-1 d-1 (9.4 mm d-1) – 2.73 mg L-1 NOx-N – 6.52 mg L-1 total N – 0.30 mg L-1 total P
• Randomized Complete Block with 3 Reps
Measurements • • • •
Weekly effluent monitoring for nutrients Soil nutrient monitoring to 2 m Periodic tree height and diameter measures 27 month Populus harvest: – Stem volume: total height, diameter every 1.2 m – 5 clones selected to represent a range of tree volume • Mass: main stem, woody branches, green branches, foliage • Tree components analyzed for Total N and Total P (others) • Total N and Total P was estimated for a fully-stocked stand (0.91 x 0.91 spacing) for each of the five selected clones.
October 2008, 7 months from planting • All species grew approximately 3 m • Survival was greater than 96% • E. grandis> P. deltoides> E. ampifolia
Weather Air Temperature ( F)
Monthly Mean Temperature and Number of Freezing Days 90 Mean Temp.
80
60
Min. Daily Temp.
50
# Freezing Days
40
1950-1980 # Freezing Days Norm
30 20
20
10
15
0
10 5 0
Month-Year
Freezing Days
70
1971-2000 Mean Temp. Norm
Survival of E. grandis (EG), E. amplifolia (EA), and P. deltoides (PD) 100
a† a
90
Survival (%)
80
a
EG EA
70
a
b
PD
60
50
b
40
b c
30 20 10
c 0
Month-Year Means not followed by the same letter with in a month are significantly different using Duncan’s New Multiple Range comparisons at α=0.05. †
Populus Stem Volume and Total Dry Weight at 27 Months Clone ID 110412 133-3 112740 151A-1 S7C1 S13C20 72C-7 111733 79-4 94-4 50B-3 91B-4 134-1 90-3 †
Stem Vol.
Total Dry Wt.
(m3 tree-1) 0.0169 a† 0.0159 ab 0.0124 abc 0.0116 abc 0.0100 abc 0.0109 abc 0.0096 abc 0.0072 bc 0.0069 bc 0.0068 bc 0.0065 bc 0.0058 bc 0.0041 c 0.0038 c
(kg tree-1) 9.37 8.68 6.44 5.64 6.16 5.64 5.08 3.97 3.41 3.65 3.82 2.89 2.05 1.86
Means within a column not followed by the same letter are significantly different using Duncan’s New Multiple Range Comparisons at α=0.05 .
Populus Dry Biomass Portioning Above-ground, Average for 5 Clones • 69% Main Stem • 14 % Woody Branches • 13% Foliage • 4% Green Branches From other work, biomass partitioning changes with age. • 11 Month old – 40% stem • 6 Year old – 80% stem
N and P Concentration 5 Selected P. deltoides clones, 27-months-old Clone
Woody Branch
Stem
Green Branch
Foliage
----------------------------------- (g kg-1) ----------------------------------TOTAL NITROGEN
110412
3.756
b
6.333
b
12.733
112740
4.400
b
5.644
b
10.256
S7C1
4.489
b
6.056
b
12.300
S13C20
4.244
b
6.044
b
10.744
111733
6.211 a
8.233 a
b c
b c
18.833 a
24.167
b
21.844
c
23.489
b
24.322
b
28.356 a
TOTAL PHOSPHORUS 110412
0.600
b
1.144
2.822 ab
1.878
c
112740
0.533
b
0.733
2.522
b
1.900
c
0.767 a
1.078
2.556
b
2.067
b
S13C20
0.567
b
0.756
2.078
1.978
bc
111733
0.656 ab
1.044
3.067 a
S7C1
†
c
2.500 a
Means within a column not followed by the same letter are significantly different using Duncan's New Multiple Range comparisons at α=0.05.
Estimated N and P Accumulation P. deltoides clones, 3 x 3 ft spacing 27 months Clone
Dry Weight ---------------------- tons
N
P
per acre ----------------------
110412
50.0
0.35
0.05
112740
34.4
0.24
0.03
S7C1
32.8
0.24
0.03
S13C20
30.1
0.22
0.02
111733
21.2
0.21
0.02
Projected Net Phytoremediation Clone 110412, 0.91X0.91 m spacing, 27 month whole tree harvest Source
Spray Field Input Atmospheric Input Whole Tree Harvest Net Phytoremediation Percentage Removed
Total Nitrogen
Total Phosphorus
lb/acre 320 6 -704 -378
lb/acre 15 ---92 -77
215%
615%
Conclusions • Populus deltoides has potential for high biomass production and phytoremediation of N and P discharge from tertiary treated wastewater. • Although many previous studies have demonstrated the potential for fast-growing exotic Eucalyptus in phytoremediation, exceptionally cold winters over two consecutive years caused severe winter injury.
Conclusions • Populus deltoides clones varied in biomass and N and P accumulation responses. • Low biomass producing clones had the greatest nutrient concentrations, but high biomass producing clones effectively removed more N and P.
Conclusions • A significant amount of N and P was accumulated in the main stems and foliage, suggesting whole tree harvest following full leaf development in the spring may optimize N and P removal. • More research is needed to address how successive harvests, background soil nutrient concentrations, and other nutrient amendments may address the sustainability of this practice.
Reference • Minogue, P.J., M. Miwa, D.L. Rockwood, and C.L. Mackowiak. (In Press). Removal of nitrogen and phosphorus by Eucalyptus and Populus at a tertiary treated municipal wastewater sprayfield. International Journal of Phytoremediation. (Accepted November 23, 2011, 11 pages)
