Anaerobic lagoon
The manure then undergoes the process of anaerobic respiration, whereby the volatile organic compounds are converted into carbon dioxide and methane.
[1] Anaerobic lagoons have been shown to harbor and emit substances which can cause adverse environmental and health effects.
These overflows release harmful substances into the surrounding land and water such as: antibiotics, estrogens, bacteria, pesticides, heavy metals, and protozoa.
Because of repeated overflows and resultant health concerns, North Carolina banned the construction of new anaerobic lagoons in 1999.
There has also been a significant push for the research, development and implementation of environmentally sound technologies which would allow for safer containment and recycling of CAFO waste.
[7] In this system, the animals are kept in pens with grated floors so the waste and spray water can be drained from underfloor gutters and piped to storage tanks or anaerobic lagoons.
[7] Aerobic lagoons provide a higher degree of treatment with less odor production, though they require a significant amount of space and maintenance.
[8] The liquid level CAFO wastewater enters at the bottom of the lagoon so that it can mix with the active microbial mass in the sludge layer.
[13] A study by the Minnesota Pollution Control Agency has found that concentrations of hydrogen sulfide near lagoons have exceeded the state standard, even as far away as 4.9 miles.
[2] These leaks and overflows can contaminate surrounding surface and ground water with some hazardous materials which are contained in the lagoon.
However, those who have a weakened immune system, such as cancer patients and young children, have an increased risk for a more severe illness or even death.
However, the amount of E. coli found in the lumen of grain fed cattle can be significantly reduced by switching an animal to grass only a few days prior to slaughter.
It is particularly problematic because it is resistant to most lagoon treatment regimens[4] In a study performed in Canada, 37 percent of swine liquid-manure samples contained Cryptosporidium.
[22] Other common pathogens (and their symptoms) include:[4] Antibiotics are fed to livestock to prevent disease and to increase weight and development, so that there is a shortened time from birth to slaughter.
[4] Due to concerns over antibiotic-resistant bacteria, the American Medical Association passed a resolution stating its opposition to the use of sub-therapeutic levels of antimicrobials in livestock.
[13] Growth hormones such as rBST, estrogen, and testosterone are administered to increase development rate and muscle mass for the livestock.
Studies have shown that these hormones, if they escape the lagoon and are emitted into the surrounding surface water, can alter fertility and reproductive habits of aquatic animals.
For the farrowing sow operation, digester and primary lagoon effluent concentrations ranged from 9,600 to 24,900 ng/L for estrone, 5,000 to 10,400 ng/L for estriol, and 2,200 to 3,000 ng/L for estradiol.
Natural estrogen concentrations in ground water samples were generally less than 0.4 ng/L, although, a few wells at the nursery operation showed quantifiable but low levels.
"[24] Manure contains trace elements of many heavy metals such as arsenic, cadmium, copper, iron, lead, manganese, molybdenum, nickel, and zinc.
[13] Trace elements of these metals and salts from animal manure present risks to human health and ecosystems.
[13] In 1999, Hurricane Floyd hit North Carolina, flooding hog waste lagoons, releasing 25 million gallons of manure into the New River and contaminating the water supply.
[25] Ronnie Kennedy, county director for environmental health, said that of 310 private wells he had tested for contamination since the storm, 9 percent, or three times the average across eastern North Carolina, had fecal coliform bacteria.
Normally, tests showing any hint of feces in drinking water, an indication that it can be carrying disease-causing pathogens, are cause for immediate action.
[30] The U.S. Department of Agriculture (USDA) has also evaluated the prospect of creating a cap and trade program for CAFO's carbon dioxide and nitrous oxide emissions.
