Improved Nitrogen Fixation by Acidification and Dehydration of Slurry

Posted in: Environment by admin on January 1, 1988 | No Comments

The addition of acid to manure to an optimum level of around pH 5 can fix the nitrogen. Further addition of acid to obtain a lower pH value does not improve the nitrogen fixation, for pH high than 5, ammonia losses are greater however not as great as if no acidification is done. The concentration of potassium is increased by the dehydration process and the addition to the manure of orthophosphoric acid (H3PO4-) results in a higher phosphorus concentration in the treated manure. The slurry resulting from the dehydration is difficult to handle and could be mixed to ground vegetable wastes to be used as organic manure.
The experiments were done on a small scale level. Some economic analysis is done for the acidification treatment however not much information is given on the dehydration process.

Sludge and Slurry Disposal Techniques and Environmental Problems – A Review

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The authors mention that the choice of the equipment will be justified with the local conditions particularly regarding odour complaints. In some case, rather than making the high investments needed to purchase the sophisticated equipment and the more powerful tractor required the farmers could turn to specialist contractors or shared machinery systems.

Cost Effectiveness of Environmental Control for Swine

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South Carolina is in the temperate zone and due to its geographic location experiences wide fluctuations in temperatures. The moderate climate in South Carolina has resulted in the construction of a variety of production facilities. Swine production units range from open feedlots to totally enclosed structures with environmental control. Evaporative cooling, refrigeration, forced ventilation and shade are all used to reduce livestock stress. The newer facilities and the renovated facilities offer better control of temperatures, moisture and toxic gases, but at the expense of increased capital and operating cost. The objective of this study was to determine if the increased cost associated with the renovation and installation of environmental control equipment was justified based on increased pig productivity.

Quality Assurance in Olfactometry

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The results presented are not from agricultural application. However interesting information is given on the quality assurance in olfactometry and on the factors that have to be considered to analyse an odour situation. Emphasis has been put on the odour measurement of the threshold level but the psychophysical dose-effect relationship are not linear (odour unit vs. odour strenght). To have a complete ideal of the odour, odour quality and acceptability has to be of prime importance as those two factors give information that is not only perceptual but also related to social values. These factors have to be known as the perception of odour plays an important role in the generation of odor annoyance.
To improve the validity of odour measuments, a calibrated scale should be used to to able to compare the results.

Interesting elements are given to help make a link between factors (odour level, intensity and acceptability) that have to be measured and odor annoyance.

Calculating Profit Maximizing Swine Housing Temperatures

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Minimization of production costs requires the integration of several factors. These include nutrition, housing configuration, and growing environment. The temperature at which optimum feed utilization occurs may not be the economically optimum temperature. The economically optimum temperature of a confinement building is determined by calculating profit potentials at various temperatures.

Odour and Ammonia Emission Following the Application of Pig or Cattle Slurry to Land

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Following the application of dairy or swine manure on to grassland, samples of odorous air have been taken
The air temperature during those experiments was relatively low and varied to a range of 0,4 to 1,4 C. The emission evaluation was done during 48h and odour emission stayed high during the first 4 to 5 hours after spreading. The odour rate was higher with the high application rate for this period but later, both application rates produced equivalent emissions.
The experiment were done at low temperature which may not be representative of all conditions.

Comparison of Fan-Heater Sequencer to Staged Thermostat Controls

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When a staged system of single-speed fans is used to ventilate a livestock barn, the control system must automatically cycle fans on and off to achieve temperature control within the barn. In the past, conventional electro-mechanical thermostats have been used. When several stages of ventilation are needed, and when heaters also must be controlled, the operator needs to set several thermostats within an individual room. Integrated fan-heater sequencers offer the potential to replace staged thermostat systems with a single controller whose operation is adjusted by a single setpoint. The higher cost of the sequencers must be offset by user convenience. Integrated fan-heater sequencers should only be installed if quick on-farm repair service can be guaranteed.

A preliminary Assessment of Machines for Surface Spreading of Sludges and Slurries with Minimum Odour

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This is good review of 15 spreading equipment is given and the result can help in the equipment selection has shown in the abstract.

Tentative Calculations of Gaseous Emissions from Pig Houses by Way of the Exhaust Air

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The values given are only emissions from the livestock buildings and not from the manure storage or the manure spreading. The ammonia emission is estimated at 1,5 ton/year, 0,34 t/year of methane and 0,73 kg/year of hydrogen sulphide for 1000 pigs. Variation from those values can occur with management practices.

Experiences with the Use of Biofilters to Remove Odours from Piggeries and Hen Houses

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Drawing of biofilters are shown in the paper. For odour removal from pig housing, 50 cm thick of material is used and the biofilter can treat 290 m3/h of air per m2 of filter. Garbage compost and fibrous peat have been tested and the peat seems to be the best filter material as the porosity is high and the pressure demand is lower. Higher pressure demand will increase energy cost as the ventilator have to work harder to push the air through the biofilter. Such biofilter are relatively to maintenance however to assure good operation conditions de-dusting has to be done before the air enters the filter material and this material has to be kept moist (generally only during dry periods as the air coming from the building is relatively humid). No cost appreciation is given.