ShapeShapeauthorShapechevroncrossShapeShapeShapeGrouphamburgerhomeGroupmagnifyShapeShapeShaperssShape

Using Zinc Oxide Nanoparticles to Control Emissions - Pig Performance, Manure Properties and Production Cost

by 5m Editor
21 June 2012, at 12:00am

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.


Bernardo Predicala


Alvin Alvarado

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



Manure samples collected from the manure tub of each chamber during room-scale tests. These samples were sent to a commercial laboratory for analysis.

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