Liquid purification or separation – Structural installation – Geographic
Reexamination Certificate
2002-05-01
2003-04-29
Upton, Christopher (Department: 1724)
Liquid purification or separation
Structural installation
Geographic
C210S202000, C210S209000, C210S747300
Reexamination Certificate
active
06554998
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to an apparatus for the treatment of anaerobic bodies of water and, more particularly, to an apparatus for treatment of agricultural waste such as may be found in an anaerobic waste lagoon.
Over the past decades there has been a shift from smaller localized family farms toward larger integrated confinement agricultural operations. Specifically, large agricultural operations referred to as concentrated animal feeding operations (CAFO's) may utilize confinement barns to house a large number of livestock such as swine, poultry or dairy cows. Using the swine industry as an example, often numerous hog-confinement operations are grouped in close proximity forming “mega-farms” which may house tends of thousands of hogs. Similarly, the dairy industry operates using large factory farms that house thousands of animals in a relatively small land area. While these larger agricultural operations have numerous advantages, attendant with these larger facilities are pollution problems relating to the handling and treatment of manure and wastewater (hereinafter collectively “wastewater”). By way of example, pollution problems associated with liquid animal waste, such as produced by the swine industry, include nitrogen, phosphorus, solids, bacteria and foul odors that result from anaerobic digestion. Environmental concerns more specifically center on odor and ground and surface water quality issue and impacts.
Traditionally, animal wastes and wastewater is collected and stored in waste treatment lagoons or waste storage ponds where it undergoes minimal treatment. Most agricultural facilities use anaerobic digestion for treatment of animal wastes and wastewater. The primary reasons for using anaerobic digestion is simplicity and cost. Wastewater is simply discharged from the animal storage facility into an open lagoon or plurality of lagoons (ponds used to store and treat thousands to millions of gallons of animal waste) where the waste undergoes natural anaerobic digestion. After retention in the lagoon system, wastewater is usually land applied via spray irrigation. However, over forty (40) noxious gases may be emitted from anaerobic lagoons at hog and/or dairy farms including ammonia, methane and hydrogen sulfide. Additionally, the time required for digestion of the organic wastes is relatively long, from weeks to months. Some current regulations require a minimum residence of 180 days for animal waste facilities using anaerobic lagoons for digestion. Neighbors find odors emanating from lagoons, confinement houses, and fields onto which wastes are sprayed to be a nuisance. In fact, as a result of odor problems associated with anaerobic lagoons, certain states have legally mandated buffer zones or designated land areas between lagoon sites and populated areas.
Oftentimes, the reduction of organics and nutrients within an anaerobic lagoon is minimal and therefore high quantities of nitrogen, phosphorus, etc., are applied to the land during spray irrigation. These nutrients readily build up high residual concentrations in the soil, leach directly into the groundwater, or run-off into surface waters causing algal booms, oxygen deficiencies and fish kills.
New studies have also shown that lagoons are leaking and there have been pollution problems with the groundwater, rivers, lakes, and coastal waters primarily in states where the high concentrations of hog or other farms are located. Another problem attendant with traditional anaerobic settling lagoons is that occasionally the water overflows the lagoons or the earthen containment berms collapse, primarily during periods of heavy rainfall, and the wasterwater runs off into streams, rivers, and lakes, causing severe pollution problems. When wastewater escapes from these lagoons, either resulting from overflows or other failures, the high concentration of pollutants has adverse effects on the receiving waters and commonly results in groundwater contamination and massive fish and other aquatic life kills.
The most critical problem in the recent past has been with the microorganism
Pfiesteria piscicida. Pflesteria piscicida
is a dinoflagellates that cause “red tides”. This bacterium has the ability to take on up to twenty-four (24) different forms during its life cycle and can attack and kill fish within hours. Recent outbreaks of
Pfiesteria piscicida
could be attributed to the increase in nutrients in the water or to the weakening of the fish due to stress caused by lack of oxygen and/or elevated ammonium levels, among other factors.
By way of example, hog anaerobic lagoon liquid has nutrient characteristics including high levels of biochemical oxygen demand (BOD
5
), Total Nitrogen (TN) and Phosphorus that cannot be decreased to acceptable levels by anaerobic treatment alone.
Even with bacterial digestion within an anaerobic lagoon, significant amounts of sludge accumulate in an anaerobic lagoon. Anaerobic lagoons commonly fill to capacity fairly quickly which displaces the designed retention capacity of the lagoon in a short period of time. Anaerobically digested sludge is not suitable for commercial use or land application at typical loading rates in the anaerobically digested state.
Hogs produce two to four times as much waste, per hog, as the average human and in North Carolina alone, hogs produce about 9.5 million tons of manure a year. Additionally, dairy cows produce up to twenty times as much waste, per cow, as the average human. Therefore, a great deal of land is required for spreading the highly concentrated waste since often no discharge is permitted from animal waste facilities. Farmers who specialize in raising large quantities of animals are forced by regulations to use larger and larger areas of land in which to spread the large quantities of wastes generated from higher numbers of animals. This has, and will continue, a trend toward having to sacrifice more land to simply dispose of the waste. The land utilized for land spreading of waste cannot be just any land, but must be carefully selected or altered so as to prevent any rainfall runoff discharging into any surface waters. The land must be planted with species capable of tolerating high nitrogen and high phosphorus containing wastes. The farming industry is running out of places to spread or spray the waste from lagoons.
While efforts are being made to regulate new farm facility construction, abandoned waste lagoons are still prevalent. By way of example, North Carolina has an estimated seven hundred abandoned lagoons.
Continuing efforts are being made to improve agricultural and animal waste treatment apparatus. By way of example, note U.S. Pat. No. 5,472,472 to Northrop and U.S. Pat. No. 5,078,882 to Northrop. U.S. Pat. No. 5,472,472, discloses a process for the transformation of animal waste wherein solids are precipitated in a solids reactor, the treated slurry is passed to a bioreactor zone where soluble phosphorus is precipitated with metallic salts, the slurry is aerobically and anaerobically treated to form an active biomass. The aqueous slurry containing bioconverted phosphorus is passed into a polishing ecoreactor zone wherein at least a portion of the slurry is converted to a beneficial humus material. In operation, the system requires numerous chemical feeds and a series of wetland cells comprising microorganisms, animals and plants. See also U.S. Pat. Nos. 4,348,285 and 4,432,869 to Groeneweg et al.; U.S. Pat. No. 5,627,069 to Powlen; U.S. Pat. No. 5,135,659 to Wartanessian; and U.S. Pat. No. 5,200,082 to Olsen et al. (relating to pesticide residues); U.S. Pat. No. 5,470,476 to Taboga; and U.S. Pat. No. 5,545,560 to Chang.
Another grouping of background patents are those which disclose methods of treating wastewater rich in nutrients. Note U.S. Pat. No. 5,626,644 to Northrop; U.S. Pat. No. 4,183,807 to Yoshizawa et al.
Another grouping of background patents are those which disclose methods of producing humus material or spreadable fertilizer from animal waste. By way of example see U.S. Pat. No. 5,538,529 to N
Derrick, Jr. John R.
Samad Nidal A.
Teran Alfredo J.
Willoughby Wesley Todd
Wood Richard G.
Agrimond, LLC
Hopen Anton J.
Smith & Hopen , P.A.
Upton Christopher
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