Manure management


Manure management refers to capture, storage, treatment, and utilization of animal manures in an environmentally sustainable manner. It can be retained in various holding facilities. Animal manure can occur in a liquid, slurry, or solid form. It is utilized by distribution on fields in amounts that enrich soils without causing water pollution or unacceptably high levels of nutrient enrichment. Manure management is a component of nutrient management.
In confined spaces the gasses from manure can lethally asphyxiate humans. There is also a drowning danger.

Risks posed by gases in livestock manure

Livestock manure produces several gases including four main toxic gases, hydrogen sulfide, methane, ammonia and carbon dioxide. In animal housing it is very common in swine and beef breeding to have manure storage under the building's floor. In this setup low concentrations of these toxic gases are commonly noted throughout the year. The highest concentrations of these gases are noted during manure agitation, stirring the manure to homogenize the manure for pumping out of the storage. During these times the concentrations easily approach levels that can pose health issues to the workers and animals in the facilities.
Four-gas monitors are ideal for situations involving manure, where simultaneous exposure to any or all of hydrogen sulfide, methane, ammonia, and carbon dioxide is possible. Four-gas monitors typically do not directly detect carbon dioxide, but this gas is minimally toxic on its own. It is important to note that four-gas monitors alone do not guarantee an individual’s safety when working with manure. Thus, four-gas monitors should always be used in conjunction with other prevention measures, including: proper ventilation ; use of a breathing apparatus and harness when entering a manure pit; removal of persons and animals from building where manure is being agitated; consideration of proper storage conditions; clear signage to denote hazardous areas and exclusion zones as well as fencing around manure lagoons; and an operation-level written protocol for entering permit-required confined spaces.

Hydrogen sulfide

Hydrogen Sulfide, is a naturally occurring gas that is flammable, colorless and poisonous. H2S has a characteristic rotten egg smell, though pungent at first it quickly deadens the sense of smell. People are typically only able to smell at low concentrations. is heavier than air causing the gas to travel close to the ground and collect in low-lying areas. Common names for hydrogen sulfide include hydrosulfuric acid, stink damp and sewer gas.

Effects

Acute

Hydrogen sulfide is most commonly inhaled, though through prolonged exposure skin and eye irritations resulting in painful dermatitis and burning eyes can occur. Symptoms of acute exposure include nausea, headaches, disturbed equilibrium, tremors, convulsions and skin and eye irritations. At high levels, inhalation of hydrogen sulfide will result in unconsciousness and death due to its effect on the body resulting in the lack of oxygen use in the cells. the typical odor threshold for H2S is 0.01 to 1.5 ppm with the loss of smell occurring at levels around levels of 100 to 150 ppm. Concentrations of 500 to 700 ppm can result in death within 30 to 60 minutes, 700 to 1000 ppm result in death within minutes, while death is nearly instantaneous at levels of 1000 to 2000 ppm.

Chronic

Chronic exposure to hydrogen sulfide can cause several long term health issues, though does not accumulate in the body. Repeated or prolonged exposures have been reported to cause low blood pressure, headache, loss of appetite, chronic cough, inflammation of the eye membrane, weight loss and ataxia.

Regulations for exposures

The Occupational Safety and Health Administration and National Institute for Occupational Safety and Health have set recommended exposure limits and permissible exposure limits for exposure in the workplace. NIOSH's REL for a 10-minute maximum exposure is 10 ppm, OSHA's PEL for general industry, i.e. agriculture, construction, etc., is 20 ppm and OSHA's PEL levels are enforceable. NIOSH also reports an IDLH or immediately dangerous to life and health, at 100 ppm, this is the level at which the effects of exposure would interfere with a person's ability to escape.