Using Zinc Oxide Nanoparticles to Control Emissions - Pig Performance, Manure Properties and Production Cost
Mixing zinc oxide to reduce hydrogen sulphide amounted to 40 per cent of the average total cost of production, while filtering zinc oxide cost less than four per cent, according to Bernardo Predicala and Alvin Alvarado in the 2011 Annual Report from the Prairie Swine Centre.
21 June 2012
9 minute read
Summary
The impact of pig performance, manure nutrient characteristics and
cost of production was evaluated with several mixing and filtration
methods using zinc oxide (ZnO) nanoparticles to control hydrogen
sulphide (H2S), ammonia (NH3) and odour emissions from
commercial swine facilities. Conditions represented conventional
swine production.
Results indicate the application of mixing and
filtration treatments had no significant effect on pig performance
and manure nutrient characteristics. The cost analysis revealed that
employing air filtration in a 100-head grow-finish room amounted
to around 3.8 per cent of the average total cost of production, while the
mixing method was found to be cost prohibitive at about 40.2 per cent of
the average total production cost.
Introduction
Previous work at the Prairie Swine Centre demonstrated that mixing and filtration methods using zinc oxide (ZnO) nanoparticles were effective in controlling hydrogen sulphide (H2S), ammonia (NH3) and odour emissions from swine facilities. In order to assess the feasibility of its application in commercial swine facilities, the impact of these two treatments approach on pig performance and manure nutrient characteristics as well as on the cost of production was carried out.
Methodology
The effectiveness of mixing and filtration methods using
ZnO nanoparticles was evaluated in room-scale tests
under commercial barn conditions. The experiment was
conducted in two environmental chambers at PSC with
each chamber housing eight pigs at an average weight of 29kg at the start of the trial. One chamber was configured
as a normal swine room (Control) and the other one as a
Treatment room.
Aside from monitoring odour and target
gases (with results presented in PSC Annual Report 2010 pp16-18), the effect of the treatment on pig performance such as
average daily gain and feed intake, manure production rate, water usage and manure characteristics were also assessed.
Cost analysis of the application of nanoparticles in a typical swine
operation was undertaken after the room-scale experiments. The
analysis was carried out with the assumption that the treatment
was applied at the grow-finish stage of production. Thus, all the
expenses incurred for one complete growth cycle in a grow-finish
room including the purchase of material (nanoparticles) and
equipment, and labour and operating costs were estimated. The
total cost associated with these gas and odour control techniques
was then compared to the overall cost of production.
* "Mixing zinc oxide to reduce hydrogen sulphide amounted to 40.2 per cent of the average total cost of production while filtering zinc oxide amounted to only 3.8 per cent of the total" |
Results and Discussion
Impact on pig performance and manure nutrient properties
During the entire 30-day trial period for both mixing and filtration
tests, the average daily water usage and manure production rate of
pigs in the control chamber were not significantly different (P>0.05)
from the treatment chamber as shown in Table 1. Furthermore, the
average daily feed intake (ADFI) and average daily gain (ADG) of
the pigs in the treated chamber were not significantly different
(P>0.05) than those in the control chamber.
Thus, these results
indicated that the application of mixing and air filtration methods with ZnO nanoparticles had no significant
adverse or beneficial effect on pig performance.
| Table 1. Daily water usage, manure production rate, average daily gain, and average daily feed intake of pigs in the control and treated chambers during room-scale tests. | ||||
|---|---|---|---|---|
| Hog performance parameters | Mixing1 | Air filtration1 | ||
| Treated | Control | Treated | Control | |
| Av. daily water use (L day-1-pig-1) |
2.2±0.8 | 2.4±0.1 | 2.4±0.7 | 2.1±0.4 |
| Av. daily manure production (L day-1-pig-1) |
2.28±0.24 | 2.33±0.15 | 2.09±0.05 | 2.07±0.12 |
| Av. daily feed intake, ADFI (kg day-1-pig-1) |
1.70±0.19 | 1.74±0.14 | 1.70±0.13 | 1.68±0.20 |
| Av. daily gain, ADG (kg day-1-pig-1) |
0.79±0.03 | 0.82±0.05 | 0.81±0.06 | 0.80±0.07 |
| 1Mean (±SD) of 3 replicates, representing a total of 48 pigs for each treatment. | ||||
Table 2 shows the results of physical and
chemical analyses conducted on the manure
samples collected from each chamber.
As
expected, the installation of a filter system with
ZnO nanoparticles in the treated chamber had
no measurable impact on the characteristics of
the manure in the tub. On the other hand, the
addition of ZnO nanoparticles into the manure
slurry (mixing) had caused a significant increase
in the amount of zinc by 1,654mg per kg (P<0.05);
all other physico-chemical characteristics were
not significantly different from the control
(P>0.05). In spite of the increase, the zinc
content of the treated slurry was below the
toxicity limit (2,800mg Zn per kg) set by the US
Environmental Protection Agency (USEPA, 1994)
for biosolid applications.
With this preliminary
assessment, the treated manure is not expected
to result to adverse effects when subsequently
applied to crop lands but this would need to be
verified by conducting a full evaluation of the
land application of the treated manure.
| Table 2. Characteristics of manure samples collected from each chamber during room-scale tests. | ||||
|---|---|---|---|---|
| Parameters | Mixing1 | Air filtration1 | ||
| Treated | Control | Treated | Control | |
| Moisture (%) | 86.40±3.58 | 89.00±4.56 | 84.95±5.02 | 87.15±3.46 |
| Total solids (%) | 13.60±3.58 | 10.99±4.57 | 15.05±5.02 | 12.85±3.46 |
| Conductivity, EC (uS cm-1) | 17020±9960 | 24330±1460 | 18350±11240 | 23200±4670 |
| pH | 7.27±0.21 | 7.09±0.04 | 6.86±0.21 | 7.01±0.01 |
| Total Kjeldahl mitrogen (mg per kg) | 9400±2200 | 8400±1700 | 12800±3300 | 12000±2600 |
| Ammonia as N (mg per kg) | 5700±1400 | 5500±1100 | 7400±1300 | 7000±1100 |
| Calcium, Ca (mg per kg) | 2400±1200 | 1700±700 | 3300±400 | 2700±200 |
| Copper, Cu (mg per kg) | 50±28 | 38±15 | 74±13 | 65±14 |
| Iron, Fe (mg per kg) | 294±131 | 223±127 | 346±25 | 284±4 |
| Magnesium, Mg (mg per kg) | 1600±500 | 1200±400 | 1700±400 | 1500±300 |
| Manganese, Mn (mg per kg) | 90±32 | 69±24 | 115±22 | 97±13 |
| Phosphorus, P (mg per kg) | 3000±1200 | 2300±900 | 3600±800 | 3000±300 |
| Potassium, K (mg per kg) | 4800±1100 | 4300±900 | 5100±200 | 4700±300 |
| Sodium, Na (mg per kg) | 1400±300 | 1300±200 | 1300±100 | 1300±200 |
| Sulphur, S (mg per kg) | 1600±400 | 1300±100 | 1500±400 | 1300±300 |
| Zinc, Zn (mg per kg) | 1848±708 | 194±82 | 327±35 | 307±30 |
| 1Mean (±SD) of 3 samples; one sample per trial
2Mean (±SD) of 2 samples collected on days 0 and 15 of the third trial |
||||
Assessment of economic feasibility
A cost analysis was conducted based on the assumption that the treatment was applied to a 100-head grow-finish room (20–110kg) for one complete growth cycle of about 16 weeks. Using the application rate used in the room-scale experiments previously reported, the total amount of ZnO nanoparticles required in the room for a 16-week growth cycle was 68.67kg for mixing method and 4.1kg for air filtration test. As summarized in Table 3, the total cost associated with the application of mixing method with ZnO nanoparticles in a grow-finish stage of operation was around C$67.20 per finished pig while the total cost of operating a filtration system with ZnO nanoparticles was about C$6.30 per finished pig.
| Table 3. Parameters used in the calculation of the total cost of applying ZnO nanoparticles in a grow-finish swine production barn. | ||
|---|---|---|
| Operational information and associated cost | Deployment Technique | |
| Mixing | Filtration | |
| Application rate | 3 g L-1 | 1.8 g in-2 |
| Frequency of application per cycle | 5 | 4 |
| Total amount of ZnO applied per room, kg | 68.8 | 4.1 |
| ZnO unit price per kg1 | 87.7 | 87.7 |
| ZnO cost per pig, $ | 66.2 | 4 |
| Number of hours to apply treatment per cycle, hr | 7.5 | 4 |
| Labour cost per hour, $/hr | 13 | 13 |
| Labour cost per pig, $ | 1 | 0.5 |
| Total costs for required equipment, $ | 370 | 59302 |
| Estimated life span, year | 5 | 5 |
| Total cost of required material per pig, $ | - | 1.66 |
| Capital cost per pig, $ | 0.01 | 1.77 |
| Estimated energy consumption per year, kWh | - | 1871 |
| Energy cost per kWh3, $ | - | 0.1 |
| Operating cost per pig, $ | - | 0.2 |
| Total cost per pig | 67.2 | 6.3 |
| 1based on the current price of NanoActive ZnO (www.nanoscalecorp.com)
2includes estimated cost of installation ($4000) 3SaskPower rate |
||
The result of the cost analysis revealed that the total cost associated
with mixing and filtration methods with ZnO nanoparticles was
about 40.2 and 3.8 per cent, respectively, of the estimated total cost of
C$167.15 for the grow-finish stage of production (MAFRI,
2010).
The total cost was relatively high especially for mixing
because the assumptions used in the cost estimates were based
on the findings from the room-scale experiments which were
conducted with measures to intentionally produce extreme high
levels of the target gases, i.e. if the treatment was found to be
effective under these extreme conditions, then it would work as
well under typical barn conditions with lower levels of the target
gases expected.
Some considerations may be applied in order to lower the cost
without substantially affecting its effectiveness in reducing the
target gases. In mixing method, the total cost could be lowered by
reducing the ZnO cost per pig which constituted about 98 per cent of the
total cost (C$66.2 of C$67.2).
ZnO cost is dependent on the application
rate, and frequency and time of application prior to each pit-pulling
session. Thus, by lowering the application rate, for instance, to 1.5g per litre which also showed considerable reduction on H2S and NH3
levels, and applying the treatment three times per cycle, the total cost
would be reduced from C$67.2 to C$20.40.
The same applies to filtration method; if the frequency of filter installation is reduced
to twice (i.e. on the 1st and 10th week of the cycle) instead of
four times, the total cost can be reduced from C$6.30 to C$4.10.
It should be noted as well that that the ZnO nanoparticles used in
this study were experimental materials purchased at an extremely
high unit price; it has been documented recently that when wider
applications were developed for certain nanoparticles, this allowed
manufacturers to produce them in bulk quantities, thus the unit
price for these nanoparticles were drastically reduced. Hence, it is
anticipated that the total cost for this treatment could still go down
significantly as new uses for nanoparticles are discovered.
Conclusions
Room-scale experiments revealed that the pig performance and
manure nutrient characteristics were not adversely affected by
either mixing or filtration using ZnO nanoparticles.
Cost analysis
for a typical 300-sow operation (7,500 finished pigs per year) using current cost estimates and application parameters indicated that
the implementation of filtration treatment with ZnO nanoparticles
would amount to about 3.8 per cent of the total production cost, which
was economically more feasible than incorporating ZnO into the
manure slurry.
Acknowledgements
Project funding provided by the Saskatchewan Agriculture Development Fund and the National Science and Engineering Research Council are gratefully acknowledged. Strategic funding provided by Sask Pork, Alberta Pork, Manitoba Pork Council, and the Saskatchewan Ministry of Agriculture to the research programs at PSCI are also acknowledged.
June 2012
