1. Technical Field
The present invention relates to the elimination of pollution from groundwater. More specifically, the present invention relates to methods and apparatus for a multi-phase separation system typically utilized to remove the chemical additives Methyl Tertiary-Butyl Ether (MTBE) and Volatile Organic Compounds (VOC's) from fluids such as groundwater.
2. Background Art
The prior art is directed to methods and apparatus for removing chemical additives from fluids such as groundwater.
Methyl Tertiary-Butyl Ether (hereinafter “MTBE”) is a synthetic organic chemical primarily utilized as a fuel additive or oxygenate and was initially blended in gasoline to increase octane ratings after the phase-out of lead and aromatics. Thus, MTBE was intended to (a) to enhance the combustion of gasoline by keeping fluids in solution within the gasoline so the fluids do not freeze and foul engine components, and (b) to reduce air polluting nitrogen oxygen compound emissions (typically referred to as NOX emissions such as NO and NO2) by increasing the rate and efficiency of oxidation of fuels during combustion. The use of the MTBE oxygenate increased significantly when oil companies were required to comply with legislative actions and accompanying regulations regarding air pollution, i.e., to meet the requirements and standards of the Environmental Protection Agency (EPA) and the states.
MTBE became one of the most produced chemicals in the United States and the most important market was in the State of California. As a result of the use of MTBE as a gasoline oxygenate, the air quality in California has improved. However, drinking water wells have been contaminated by MTBE as a result of leaking underground gasoline storage tanks that contained the MTBE oxygenate. These and other reported contaminations have resulted in a public debate directed to the benefits and drawbacks of the use of the MTBE oxygenate. Studies conducted by the University of California directed to the health consequences and environmental assessment of MTBE are ongoing.
MTBE is typically added to gasoline during the refining process, transferred to terminals, loaded into transport trucks, and finally distributed to gasoline dispensing stations. At the dispensing stations, the gasoline including the MTBE and VOC additives is stored in underground tanks and usually enters the groundwater by (1) escaping from leaking tanks, piping and valves. Other ways for MTBE to enter the environment include (2) incomplete combustion of internal combustion engines, (3) spillage and evaporation during the manufacture and transportation of MTBE and gasoline containing MTBE (including the transport through underground pipelines), (4) water craft exhaust especially from two-cycle engines and (5) spillage and evaporation when vehicles and water craft are refueled. MTBE is a carcinogen, i.e., cancer causing in humans, and a pollutant when in groundwater and is highly “hydro-scopic”, i.e., it has a high affinity for water.
A Volatile Organic Compound (hereinafter “VOC”) is considered hazardous to humans and can also be a carcinogen in humans. VOC's are also included in gasoline and include benzene, xylene and ethylene to name a few. These chemicals are also typically used in many heavy industrial applications and processes such as, for example, those of the steel industry. In particular, the example chemicals of benzene, xylene, and ethylene can be found in solvents, paints, printing materials, coating materials, thinners and the like. Both MTBE and VOC can leak from storage tanks and associated piping, fittings and valves, and can also be released during fuel spills, water craft exhaust and the like. A specific example of leakage problems has occurred in the recent past in Santa Monica, Calif. where it was discovered that single-walled gasoline storage tanks were leaking gasoline including the MTBE and VOC additives into the soil and eventually entering the underlying water table. Regulators required the replacement of the single-walled storage tanks with double-walled storage tanks. However, the water table had already been polluted.
Once spilled onto the soil, the gasoline including the chemicals MTBE and VOC form a gas plume, i.e., a column of fluid material that is absorbed into the soil. As the column of fluid sinks further into the soil, the gas plume becomes wider and the soil becomes saturated with the chemicals. The groundwater, in effects, attracts the MTBE and VOC's. Because of the “hydro-scopic” nature of MTBE, the MTBE tends to separate from the gas plume and seek the groundwater because the groundwater is denser. Unfortunately, the MTBE eventually reaches the groundwater resulting in pollution thereof. The groundwater, once polluted with these chemicals, becomes unfit for human consumption, bathing, agriculture irrigation and the like. Consequently, the clean-up and removal of these chemicals after spillage becomes very important to preserving the quality of groundwater for both the human and animal species.
Much effort has been directed to perfecting apparatus and methods for removing leaked or spilled MTBE and/or VOC's from the soil and groundwater. Two patents which are directed to this purpose and which are typical of the prior art include U.S. Pat. No. 5,863,510 issued to Pozniak et al. on Jan. 26, 1999 entitled Modular Interchangeable Treatment System, and U.S. Pat. No. 5,104,525 issued to Roderick on Apr. 14, 1992 and entitled Portable Self-Contained Water Remediation Package. Pozniak et al. '510 purport to disclose in FIG. 5 a treatment plant 250 which includes a spray aeration, vacuum extraction unit 251. Beginning in the last paragraph of column 8, Pozniak et al. purport to disclose preheated water from a pre-heater 261 that is introduced through nozzles 264 to a spray aeration tank 263 of the vacuum extraction unit 251. Pozniak et al. states that due to the combined effects of heating the contaminated-water in heat exchanger 267 and the vacuum created by vacuum pump 262, the majority of the VOC's in the contaminated water are volatilized and the vapor from the nozzles 264, 268 is pulled out of the spray aeration tank 263 by vacuum pump 262 and subsequently destroyed in the internal combustion engine 290.
In the art, Pozniak et al. '510 actually teaches an air sparging system which sprays the contaminated water into the base of the spray aeration tank 263 via nozzles 264 and 268 and pump 266. Air is introduced and the contaminated water is heated by the heat produced by the internal combustion engine 290. The re-circulated water is heated and contacts the air in the top of the aeration tank 263. The air releases and strips the contaminants from the contaminated water and the contaminants are burned in the internal combustion engine 290 or release to atmosphere. Pozniak et al. in effect teach a heated water re-circulation (multi-pass) system exhibiting a single change of phase where a high vacuum does not exist in the aeration tank 263.
Roderick '525 discloses a similar air stripper system as shown in FIG. 6 which employs a basin pump 74 to drive contaminated fluid into stripper column sections 14 and 16. An electric driven air pump 66 conveys air under pressure through conduit 68, and into the air stripper column 14 and upward through packing 62 to contact contaminated water passing there through to separate volatile contaminants from the contaminated water. The volatile contaminants are then carried out the upper end of the stripper column while the cleansed water is drawn from the lower portion of the stripper column 14. Roderick '525 fails to disclose the use of a high vacuum environment in the removal of the contaminants.
Thus, there is a need in the art for a multi-phase separation system typically utilized to remove the chemical additives Methyl Tertiary-Butyl Ether (MTBE) and Volatile Organic Compounds (VOC's), i.e., contaminants, from fluids such as groundwater comprising a pre-filtering module to provide a filtered contaminated fluid for delivery to a condenser module which utilizes the cooler contaminated fluid to condense a contaminated gas phase to a contaminated liquid for disposal, a phase reaction chamber which operates under a high vacuum-low vapor pressure environment for separating and carrying away the contaminated gas phase from the contaminated fluid in a first change of phase, the contaminated gas phase being condensed to the contaminated liquid in a second change of phase.
USPTO Backgrounds
USPTO Backgrounds