A Better Understanding of Odour
Posted in: Environment by admin on January 1, 1999 | No Comments
Odours generated from intensive livestock operations are growing in public concern and in many cases can limit location of newly built facilities. Recent work by Kenneth Adams of Reid Crowther studied the distribution of odour plumes generated from hog buildings. Odour plumes were determined to be very narrow, and dependant on wind and weather conditions. Information gathered from this study will assist engineers in using prevailing wind patterns to assess most suitable location for new swine buildings.
FarmFacts: Holding Pond Site Selection and Design
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Livestock operators may need to contain contaminated runoff from feedlot facilities, silage pits or manure piles to prevent surface water pollution. Control works consisting of diversion ditches/dikes and holding ponds may be needed to contain the runoff. Include holding ponds as part of the feedlot design, which incorporates proper pen slopes to provide good drainage and pen drying. Construct holding ponds in impervious soils, or use man-made materials or imported clay as a liner to provide ground water protection.
The site selection process for the facility and the holding pond is a step by step process. The cost to the developer (time and financial) will increase with each step along the path. The geotechnical nature of the site and regulatory requirements will influence the required commitment from the developer. All sites require pre-screening and initial soils evaluation. For some sites this work will identify the need for a detailed site investigation.
The contruction technique used for holding ponds will determine the effectiveness of the soil seal formed. Detailed engineering may recommend installation of sampling wells to monitor seepage from holding ponds and to determine the effect on ground water quality. A regular monitoring program will allow corrective action to be taken when necessary
Continous Measurement of Hydrogen Sulfide Emission from Two Lrage Swine Finishing Buildings
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Hydrogen Sulfide emissions were continously measured from two mechanically ventilated 1,000 head swine finsihing barns for a period of six months, encompassing two partial growth cycles. Hydrogen sulfide measurements were taken at three different location: pit head-space, pit fans and wall fans. Daily mean hydrogen sulfide emissions ranged from 32 – 1,867 g/d averaging 487 +/- 50 g/d for Barn 3B. Emissions ranged from 131 – 1,770 g/d, averaging 727 +/- from Barn 4B, representing a 47% higher rate than 3B. The mean emsission rates per pig were 580 +/- 63 and 850 +/- 121 for 3B and 4B respectively, with 4B 47% higher.
Siognificant differences in emission rates occurred between the first and second growth cycles. The daily mean H2S emission rate in 3B was 322 g/d and 585 g/d for cycle 1 (before June 16) and 2 (after June 20) respectively, with the second cycle being reported 1.8 times greater than the first cycle. Even greater differences were found with 4B. The mean building H2S emission rates were 351 g/d and 1,296 g/d between the first and second cycle. The emission reported from the second was 6.1 greater than the first cycle. Outdoor temperatures were 9.1 and 5.5 degrees Celcius higher in the second cycle, as a result the airflow rates were 72.7 and 25% greater in the second cycle as well.
Higher temperatures enhance the production of H2S in the manure pit and release of gas from the liquid manure. Air velocity over the manure surface has a significant influence on convective mass transfer of pollutant gas from liquid manure to the air stream in the building. Air speed is influencd by the airflow rate, which automatically adjusts to the indoor temperature.
Swine Waste Application to Hardwood Tree Plantation Systems in North Carolina
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Hardwood tree plantations provide another area of application for manure produced through intensive livestock operations. Nutrient uptake and ultilization occur aboveground in trees, below ground in the soil complex through microbial transformations, soil chemical and physical reactions. Other studies (Milosh, 1993) have indicated that tree plantation systems are effective in removing significant percentages of nitrogen, phosphorus, potassium and other nutrients from wastewater. Certain species, sycamore and sweet gum removed up to 90% of the N and P in the municipal wastewater within 130cm.
Loading effects of wastewater (from a secondary lagoon) of two application rates of 200lbs/ac and 400 lbs/ac were examined on 5 tree species during March 1994. All tree species within the study, with the exception of one experienced increased survival rates, however their survival rate did diminsh with increased wastewater application. Soil nitrate and phosphorus concentrations were comapred at 0-6 inches and 36+ inches of depth. Soil nitrate concentrations at the shallow depth increased during three sampling periods (1995-1996-1997) although soil concentrations within most plots were not substantially greater than 10 mg/L drinking water standard. Nitrate within soil samples increased with swine wastewater application rate. The data suggests that certain species accumulate greater amounts of nitrogen and phosphorus in their tissue and therefore removed in subsequent tree harvest.
Eating Odours with Biofiltration
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Recent work at the University of Minnesota suggests that biofiltration may effectively reduce odour concentration generated from intesnive livestock operations. Exhaust gas generated from mechincally ventilated swine buildings is passed through a biofilter, such as a loam, peat or compost allowing the air to filter or percolate through the material.
FarmFacts: Nutrient Values of Manure
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Determination of the Areal Extent of Odour Plume from Large Hog Facilities in Manitoba
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The location of large hog barns in relation to neighbours, communities and highways is a major factor in establishing public attitudes towards these operations. Little data exists to assist planners determine proper siting by establishing how local topography and weather condition affect the odour plumes created by these operations. This project studied six southern Manitoba hog operations located in locations ranging from sparsely- wooded flat terrain to heavily-treed rolling land. Two-person “odour panels” evaluated the relative strengths of the odour plumes produced under various wind directions and velocities, temperatures and humidity levels. Panelists rated odour concentrations on a scale of 1 to10 at various distances from the odour source under varying weather conditions. The study concluded odours essentially travel in the direction of the wind (longitudinal) and that there is little lateral dispersement in other directions provided the wind is in a constant direction. Neither trees nor rolling terrain have significant effects on odour movement although they tend to deflect wind direction and may dilute odour concentrations. Widest odour plumes occurred during manure spreading operations rather than from barns or earthen manure storages and there appeared to be some correlation between the number of Animal Units on a site and the maximum distance odour plumes traveled.








