Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2001-10-08
2003-05-06
Upton, Christopher (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S615000, C210S150000, C210S188000, C210S916000, C055S514000, C095S273000, C435S266000, C442S030000, C442S056000, C442S221000, C442S227000, C442S315000, C442S375000
Reexamination Certificate
active
06558548
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to waste material confinement areas. More specifically, the present invention relates to covers for use in conjunction with such waste material confinement areas. The invention further relates to methods by which to use and produce such covers.
BACKGROUND OF THE INVENTION
Waste material confinement areas, such as slurry tanks, ponds, concrete cells and waste lagoons are widely used in the treatment of organic waste, including human, animal, and food processing waste. Waste lagoons are especially economically attractive to livestock producers, such as confinement swine producers. However, odors generated from waste material confinement areas, particularly waste lagoons employed in livestock production, must be significantly reduced in order to meet environmental challenges and to avoid exposing the general public to malodorous fumes. Aerobic and anaerobic microorganisms are commonly used to decompose the materials comprising the organic waste. Unfortunately, gases generated by the microorganisms during the decomposition process can be malodorous.
Treatment processes employing anaerobic microorganisms are the most common. Anaerobic microorganisms naturally develop within the depths of waste material confinement areas, due to the lack of available oxygen. Regrettably, anaerobic microorganisms generate numerous malodorous gases during the decomposition process. These off-gases bubble up through the waste liquid and are problematic if allowed to enter the atmosphere.
The familiar smell of ammonia and the “rotten egg” odor of hydrogen sulfide gas are typical of the odors produced during anaerobic decomposition. The metabolism of animal waste within a lagoon typically produces methane gas, carbon dioxide in solution and as a gas, hydrogen sulfide in solution and as a gas, and various volatile organic compounds. In fact, nearly two hundred odorous gases have been documented as a result of manure, rendered or processed animal waste and carcass decomposition, including volatile organic compounds such as para-cresol, phenol, indole and satol, and reduced sulfur gases. Several of the gases produced by anaerobic decomposition are especially malodorous, particularly volatile fatty acids.
Off-gases from anaerobic lagoons can pose other problems, as well. For example, ammonia emissions from anaerobic waste lagoons may contribute to acid rain. Methane emissions from anaerobic lagoons may contribute to global warming.
To capture noxious off-gases, anaerobic waste treatment processes generally employ an impermeable cover to encapsulate waste lagoon surfaces and capture the off-gases as they are released. The cover is typically formed from a polymeric film, such as a polyethylene membrane, suspended above the slurry. Gases trapped under the impermeable cover are subsequently removed by gas collection pipes, weighted sunken troughs, sump pumps, and the like. Such gas collection systems are described in U.S. Pat. No. 5,562,759. However, such covers and gas collection systems are expensive, require substantial support equipment, require time consuming and costly maintenance, are vulnerable to puncture, weather, vandalism, fatigue, and deterioration.
In contrast, wastewater treatment processes employing aerobic microorganisms do not utilize such impermeable membranes. In fact, rather than producing malodorous off-gases, aerobic microorganisms convert waste into innocuous compounds, such as carbon dioxide or nitrites. Further, aerobic microorganisms can degrade malodorous off-gases, such as the volatile fatty acids produced during anaerobic treatments. The aerobic bacteria transform the animal waste into a chemically stable material, reducing both pathogens and odor. Some types of aerobic microorganisms “digest” or oxidize carbohydrates to carbon dioxide and water. Other strains feed on organic substances and convert nitrogen compounds to ammonium. Still others oxidize ammonium salts to nitrites and nitrites into nitrates in a process referred to as “nitrification.”
The aerobic microorganisms may be cultured on substrates submerged within the waste lagoon. However, aerobic microorganisms require oxygen to survive. Therefore, conventional aerobic processes used to treat liquid sludge must mechanically inject air into the waste water, which consumes energy, is costly, and requires maintenance. Further, such aerobic treatments do not totally eliminate the emission of gases having a foul odor, and present technology does not offer any effective odor control for this type digestive system. Numerous patents are directed to waste water treatment systems employing submerged aerobic microorganisms, including U.S. Pat. Nos. 4,165,281; 5,228,998; 6,022,476; 5,232,586; 5,861,095; 5,496,292; 5,580,770; 5,962,309; and 5,980,738.
In addition to submerged aerobic systems, aerobic microorganisms can also be used to treat noxious gas streams. For example, aerobic microorganisms can be grown on media which is either suspended within a closed vessel or floating on the surface of the waste slurry. The noxious gases are then treated as they diffuse though the suspended or floating media, commonly referred to as a “bio-filter.” Exemplary media employed to date includes floating organic matter, such as compost or peat moss, as well as synthetic materials for use in closed vessels.
However, aerobic gas scrubbing systems require a delicate balance of environmental conditions for the continued support of aerobic microorganisms. As noted above, aerobic microorganisms require air to survive. Therefore, once the host media becomes submerged, the function of the aerobic microorganism is terminated in the absence of mechanically introduced oxygen. However aerobic microorganisms can not survive in the total absence of water. Therefore, the bio-filter must be kept moist. Floating organic matter, lacking both sufficient buoyancy and structural integrity, is unstable and short lived as an aerobic bio-filtration substrate due to submersion. Aerobic filtration media suspended within vessels are problematic also, in that such systems require the mechanical introduction of moisture, such as by the use of spray nozzles and the like. Bio-filters employed to scrub gases within a reaction vessel are described in several patents, including U.S. Pat. Nos. 5,480,538; 6,069,003; and 5,714,379. Further, in vessel-type biofilters, the offensive gases must be collected first and then passed through the media. The existing technology and high cost of implementation limits the effectiveness to relatively small, confined areas and is presently too expensive for a majority of applications.
SUMMARY OF THE INVENTION
The present invention provides cost effective, sound waste treatment systems for a wide variety of waste material confinement areas, such as waste lagoons. The waste treatment systems generally include an anaerobic waste material confinement area and a waste material confinement area cover. The waste material confinement area covers of the present invention treat the off-gases produced by the anaerobic microorganisms within the depths of the waste lagoon, thereby eliminating the noxious odors commonly associated with such anaerobic decomposition. The waste material confinement area covers of the present invention are easily installed, highly buoyant, and structurally sound. The waste material confinement area covers are generally formed from two or more floatation panels joined by a fabric layer.
The floatation panels generally include a plurality of polymeric foam particles arranged in a piled laminate structure. At least a portion of the foam particles exhibit a surface energy differential in comparison to water sufficient to wick an adequate amount of water onto the foam particles to collectively sustain a biofilm supported by the floatation panel. At least a portion of the polymeric foam particles within the piled laminate structure are further bonded to at least one adjoining foam particle positioned either above or below the foam particle.
The piled laminate structure generally defin
Marsh Ron
McGregor Wallace
Shanklin Dennis
Svirklys Fred
Alston & Bird LLP
Odor Control Systems, Inc.
Upton Christopher
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