Animal Waste-Lagoon Aeration Services
A large industrial dairy or feedlot operation can generate as much waste as a mid-sized city. While cities spend millions of dollars each year to process and dispose of municipal waste, feedlot owners cannot afford such expenditures. Factory farms are thus limited to disposing the manure in uncovered manure lagoons, or else spreading it on surrounding land.
The sheer magnitude of the waste often leads to its over-application onto nearby fields. The predictable result is a threat to the safety of the air as well as ground and surface water sources. The contaminants of concern are disease pathogens such as E.coli and salmonella, and a host of air pollutants such as hydrogen sulfide, ammonia, volatile organic compounds, and particulate matter. In addition there are concerns over antibiotics, metals, and toxic substances in the waste.
Feedlot owner/operators use one of two methods to process animal waste. These methods are anaerobic digestion and aerobic digestion. Byproducts of anaerobic digestion include high odor, formaldehyde, mercaptans, aldehydes, and other compounds that can harm crops or soil. In contrast, aerobic digestion results in a liquid compost that can be highly beneficial to crops and soils.
The main function of an anaerobic lagoon is to remove, destroy, and stabilize organic matter, but not to “purify” the water. The advantage of this system is in its ability to concentrate solid wastes. High levels of gas and odor are evident near these types of lagoons. These systems are characterized by a relatively solids-free liquid zone located above a layer of bottom sediment.
The end products of aerobic digestion are mainly carbon dioxide and water. Virtually any degree of processing can be obtained in an aerobic lagoon since digestion is a function of time, oxygen availability, and carbon content.
Aerobic lagoons can be in the form of oxidation ponds or mechanically aerated ponds. Oxidation ponds depend upon naturally occurring dissolved oxygen from the air or from algae in the water. Because the oxygen demand is so high in a manure lagoon, the surface area of an oxidation pond must be large to enhance the air exchange at the water surface.
Mechanical aeration seems to be the more practical mode of treatment in a waste lagoon. The advantage of aerobic digestion is a reduction in volatile organic compounds, a reduction or elimination of odors, and a reduction of solids which are turned into carbon dioxide gas. Furthermore, oxygen is known to kill harmful pathogens. Aerobic digestion is said to turn the wastewater into a form of compost tea making it not only fit, but highly beneficial for spraying onto crop fields.
The level of aeration needed to turn a lagoon from anaerobic to aerobic will vary greatly from farm to farm. A pond is considered to be aerobic when the level of dissolved oxygen equals at least two milligrams per liter. It takes this level of oxygen to adequately support aerobic bacteria. Because of the size of many lagoons, and the huge burden of waste, it can take a multitude of aerators to reach this level of dissolved oxygen.
There are several types of aerators available to the confined-animal operator. These include bubble diffusers, venturis, paddle wheels, and self-aspirating aerators.
Self-aspirating aerators inject dissolved oxygen into the subsurface regions of the waste lagoon. They do this by creating a low-pressure zone at the end of an air tube. In the process they create a mild current that circulates the water without stirring up the odor.
Self-aspirating aerators normally contain a set of propellers that turn beneath the water surface. However, the latest self-aspirating aerator on the market, called the Toring TT200, uses a circular turbine instead of propellers. According to our tests, the efficiency of the Toring TT200 is one of the highest in the market today. The Toring TT200 uses a pontoon- mounted, highly efficient electric motor from 1½ to 4.0 horsepower.
It is virtually impossible for the Toring TT200 to clog, even in an animal waste lagoon. The motor warranty is passed to the user, and all of the other parts are guaranteed for life. The Toring TT200 is ideal for any animal waste lagoon.