Integrating an intermittent aerator in a swine wastewater treatment system for land-limited conditions

Posted in: Environment by admin on January 1, 1999 | No Comments

Savaging in Gilts and Sows

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Humidity control strategies for winter conditions

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Most control systems are temperature controlled, relying on constant minimum ventilation rate (MVR). A survey on the different conventional control systems used was conducted. Less than half of those surveyed used the recommended MVR settings. Under or overestimating MVR settings can negatively affect relative humidity (RH) and contaminant concentrations in the barn. A system that could automatically adjust ventilation according to room humidity and improve the overall conditions in the building and optimize energy requirements would be very useful. A computer model was developed to evaluate the benefits of temperature and humidity control (THC) systems that take into account the room RH over a more conventional temperature control (TC) system. Simulations comparing heating and ventilation systems were based on average temperature, energy demand and respective fluctuations of humidity and CO2 concentrations. Overall, the strategy selected as being optimum was THC with proportional control, a 75% RH set point and a proportional band of 5%.

Clinical, biochemical, and hygiene assessment of stabled horses provided continuous or intermittent access to drinking water.

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The effects of weaning at 7, 14 and 28 days on piglet behaviour.

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Quantification of the pain and distress responses to castration in young lambs.

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Adrenocorticotropic hormone and cortisol in calves after corticotropin-releasing hormone

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One technique used to assess chronic stress in animals is to determine how responsive they are to a corticotropin-releasing hormone (CRH) or an adrenocorticotropic hormone (ACTH) challenge. This is a physiological means of mimicking a severe stress. Animals that have been chronically stressed should have the capacity to respond to such challenges with a larger release of the stress hormone cortisol. This study examined the dose of CRH needed for such a test and the time frame over which a response should be measured. The study was done with 12-wk old calves. Calves were injected with varying doses of CRH and their responses in terms of ACTH and cortisol were assessed over the next 5 hours. The cortisol concentrations between 20 and 90 min post-injection was predictive of the total release of cortisol following treatment. It is suggested that a challenge test should include several samples during that period of time.

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.