Abstract:
The method of treating hydrocarbon contamination, in soil, that includes providing and operating a rotary tiller having tilling elements that rotate into and out of the soil to till and loosen the soil, and to elevate soil upwardly so that loosened elevated soil then drops downwardly, and is aerated, and dispersing into the soil aqueous streams that contain microbes or chemicals characterized as reacting with hydrocarbon in the loosened soil to produce CO 2  and water, thereby to decontaminate the soil.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to clean up of hydrocarbon polluted soil and more particularly to dispersing of microbes into hydrocarbon pollutant-containing soil to reduce pollutant levels. 
     Hydrocarbon pollution occurs in many ways, and areas, among which are the following: 
     1) spillage into the ground as at gasoline service stations (i.e. from rusted tanks, etc.); and 
     2) leakage into the ground, i.e. formation, at or near oil wells. 
     Cleanup of such hydrocarbon pollutants is difficult, time consuming and expensive. While microbes have been employed to consume hydrocarbons, it is difficult to deploy the microbes, accurately and in sufficiently quantity into polluted in situ soil. 
     There is need for improved methods and apparatus to rapidly and effectively treat soil so as to overcome hydrocarbon pollution in soil. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide improved methods and apparatus to meet the above need. Basically, the improved method of treating hydrocarbon contamination in soil includes the steps: 
     a) providing and operating a rotary tiller having tilling spaces or elements that rotate into and out of the soil to till and loosen the soil, and to elevate or impel soil upwardly so that loosened elevated soil than drops downwardly, and becomes aerated, 
     b) and dispersing into the soil aqueous streams that contain microbes characterized as reacting with hydrocarbons in the loosened soil to produce CO 2  and water, thereby to decontaminate the soil. 
     Typically, soil to be treated extends generally horizontally, and the rotating tiller is traveled generally horizontally or parallel to the exposed soil surface to progressively till the soil, and also throwing it upwardly for aeration, while the aqueous streams of microbes are dispersed into the loosened and rising or falling soil. The contaminated soil may have originated underground, as for example at a gasoline or hydrocarbon fuel filling station, and such soil is removed and spread out for treatment. 
     Dispersing of the aqueous streams of microbes may be effected in the path of tiller travel, or at the successive locations of the tiller; and ducting may be provided at tiller rotary arms to be ejected up and down, forwardly and rearwardly, into soil being tilled and rising and falling; and other ducting may be provided in closely spaced relation to the traveling tiller, and from which such aqueous streams of microbes are ejected onto soil to soak the soil being tilled or to be tilled as referred to. 
     Ducting at the rotating arms typically communicates with the rotary backsides of the arms from which said streams are ejected into the soil being tilled and aerated. 
     The tiller arms preferably have terminals which extend sidewise or laterally to act as knives or spades and elevators to cut into and elevate soil, aqueous streams being ejected at locations on the arms at spaced locations from such terminals. 
     A further object includes allowing said microbes to consume the hydrocarbon in the aerated soil, thereby to de-contaminate the soil. 
     An additional object includes returning the de-contaminated soil to underground locations from which contaminated soil has been removed. 
     Another object includes rotating the tiller at speeds above 300 to 1000 revolutions per minute, to obtain rapid lifting of the soil, for aeration; and ejecting the microbe streams at pressures above about 100 psi, to obtain sufficient penetration into the soil being tilled and elevated, and added displacement of such soil. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
    
    
     DRAWING DESCRIPTION 
     FIG. 1 is a side elevation showing apparatus of the invention treating soil; 
     FIG. 2 is an elevation showing soil removed from an underground location, and being transported to a site, for treatment; 
     FIG. 3 is a perspective view of tilling apparatus, and showing aqueous streams containing microbes, being dispersed as the tiller rotates; 
     FIG. 4 is a front elevation showing dispersing of such streams from a rotating axle; 
     FIG. 5 shows aqueous stream or fluid delivery into an end portion of the axle; 
     FIG. 6 is a section showing bearing and seal elements at the axle end; 
     FIG. 6 a  is an enlarged view of the same; and 
     FIG. 6 b  shows connection of the bearing and seal elements to a rotary axle having a tiller arm; 
     FIG. 7 is a frontal view showing a non-rotary duct or pipe to disperse microbe bearing fluid into the soil, proximate the tiller; 
     FIG. 8 shows porting in the axle and the tiller arms, to pass fluid; 
     FIG. 9 is an elevation showing operation of tilling apparatus in relation to a remote source of fluid such as mixed water and soil decontaminant microbes; 
     FIG. 10 is like FIG. 9, but shows remote sources of fluid or fluids such as mixed water and chemicals, and also catalysts; 
     FIGS. 11 and 12 are plan and side elevation views of a modified tiller arm and spade. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a rotary tiller  10  having an axle  11 , arms  12  carried by the axle to rotate therewith, and spades or knives  13  carried by the arms to project sidewise or laterally. The angled spades  13  rotate into and out of the soil layer  14  at a speed and depth such that the soil is tilled, loosened, and lifted or elevated as at  15 . The loosened and/or elevated soil tumbles or falls downwardly, and the soil is thorough aerated in such manner as to promote oxygen access to aqueous fluid streams or drops being dispersed into the soil. Such aeration assists in reaction of microbes in the fluid with contaminant hydrocarbons in the soil, to form CO 2  and water. Efficient decontamination of soil is thereby achieved, as over a period of a few days following such treatment. 
     FIG. 2 shows hydrocarbon contaminated soil  20  removed from an underground source at  20   a,  and delivery to a conveyor, or conveyors,  22  and  22   a  for spreading of the layer  14  referred to in FIG.  1 . Source  20   a  may for example comprise a soil zone adjacent an underground leaking fuel tank at a gasoline filling station, for vehicles. Arrow  80  indicates return of decontaminated soil to  20   a.    
     The tiller  10  in FIG. 1 is traveled in a direction  23 , as by a tractor  24  having drive wheels  25 . A support  126  is carried by tractor wheel support axle  51 , at a controlled elevation relative to the soil layer  14 , such that desired depth of travel of the spades  13  in the soil layer is achieved, in relation to tiller travel speed, and tiller rotation angular velocity, for most effective distribution of microbes in the aqueous streams and into the soil, i.e. thorough dispersal into the displaced soil. A power drive in the tiller, to rotate axle  11 , is indicated at  26 , and may have a speed control at  26   a.  The weight of support  126  urges the tiller arms and spades into the soil. 
     FIG. 8 shows delivery at  30  of aqueous streams containing microbes, from the bore  31  of the rotating axle  11  to ducting at  32  and port  33  in an arm carrier or manifold  34 , and in a tiller arm  35 . Nozzles [ 36 ] at ports  33  disperse liquid in spray streams indicated at  37 . The axle axis of rotation is seen at  11   a.  Nozzles are at the sides of the arms that face generally rearwardly, so as not to become clogged with soil. 
     FIG. 3 shows liquid delivery from the axle  11  to pipes  40  extending at the rear sides of arms  35   g,  and dispersing of liquid from nozzles  50  at spaced locations along the pipes. Soil cutting and lifting spades  42  are integral with arms  35   g , and extend sideward relative to the arm planes of rotation. The FIG. 3 tiller is preferred. FIG. 4 shows liquid delivery from an alternate axle  11   a  ′ to spray nozzles  50   a  on the axle. 
     The solution sprayed into the soil consists of a concentrate of naturally occurring microbes (aerobic and/or anaerobic) in water. The solution is prepared by soaking bacteria-containing particles (for example the product known as “WASTE 60” produced by Janco, Inc., St. Louis, Mo.) in water for 1-10 hours to form the concentrate. For example about 120 grams of such particles is soaked in 15 gallons of water. That concentrate is then diluted (100 to 3,500 parts of concentrate to 1,000,000 parts of water) to form the solution that is sprayed. Preferably about 3000 ppm is used. 
     The microbes employed consist of one or more of the following: 
     achromobacter 
     arthrobacter 
     aspergillus 
     bacillus 
     candida 
     cladosporium 
     corynebacterium 
     myrothecium 
     punicillium 
     phialophora 
     pseudomonas 
     rhodothorula 
     streptomyces 
     trichoderma 
     a blend of aerobic and facultative organisms. 
     The present method and apparatus avoids need for complex steps and apparatus disclosed in U.S. Pat. No. 5,039,415, and differs materially therefrom. 
     FIGS. 5 and 6 show rotating bearing and seal members  60  and  61  in a housing  62  that may be used at the junction of a fixed non-rotating liquid delivering pipe  52 , (not shown in FIG. 1) and at the end of the rotating axle  11 , as described herein. See also FIG. 6 a.  FIGS. 1 and 7 show an auxiliary duct or pipe  70 , which is non-rotating, and which extends near but forwardly of the tiller. Aqueous liquid carrying microbes is also delivered at  72  to pipe  70 , and sprayed downwardly from ports or nozzles  74  into or onto the soil, just prior to its penetration and lifting by the rotating spades. Pipe  70  also extends transversely of the path of travel of the tiller, and may extend above the soil, and parallel to the tiller axis of rotation. Supports  73  are connected to  26 . Enhanced dispersal of the microbes is thereby achieved. A source (tank and pump)  66  for liquid containing microbes to be delivered at  67  to pipe  70  and to the tiller axle bore  31  is shown in FIG.  1 . Valves  69  and  68  control the rates of delivery to the pipe  70  and tiller axle bore  31  respectively. 
     In a specific example, the following parameters apply: 
     rate of tiller rotation—about 300 rpm to 1000 rpm 
     forward travel rate—½ mph to 3 mph 
     depth of soil being tilled—1½ feet to 4½ feet 
     liquid pressure at nozzles—100-150 psi 
     size of nozzle openings—½ inch 
     numbers of nozzles per tiller arm or space—10 
     axle diameter—5 to 7 inches 
     Apparatus embodying the invention comprises: 
     a) a rotary tiller having an axis of rotation, knives that extend generally parallel to said axis to cut into and lift soil being tilled, arms carrying the knives, and nozzles carried by the arms to spray soil decontaminant fluid into the soil being tilled and elevated by the rotated knives, 
     b) means to travel the tiller above the soil and to rotate the tiller to cause the knives to cut into the lift soil, for aeration and mixing with said fluid, 
     c) means and supply said fluid under pressure for flow to said nozzles, for forcible spraying into soil particles dropping after elevation. 
     In FIG. 9, tiller apparatus  10   a , for example as described above, is pulled by a tractor  151 . A supply means or source  152  is remotely located, to supply mixed water and decontaminant microbes, under pressure, for flow to nozzles at or proximate the tiller apparatus  10   a  like that at  10  as described above. Such flow is via a flexible hose or conduit  153  extending from  152  to a spray bar  154  and/or a hollow rotary shaft  155  at the tiller, for flow to spray nozzle on  154  or on tiller arms  12 , as described above. The tractor and tiller typically travel toward or advance back and forth, and relative to the source  152 . A reel  157  at the source apparatus  158  operates to reel and unreel the hose as the tiller travels relatively toward or away form the source, whereby the hose remains taut and the tiller does not entangle with the hose. The unreeled hose length lies on the ground  159  and typically extends to about 1,200 feet maximum. A known machine  152  is identified as a Bauer machine. 
     FIG. 10 is like FIG. 9, except that sources  140  and  141  are provided, for soil chemicals and water (mixed), and for water and catalyst (mixed), one usable catalyst consisting of peroxide, for reaction with the chemicals as for example ferrous sulfate at the tiller location. Hose  146  extends from source  140  to the tiller spray bar  154  and spade carrying hollow shaft  155  and hose  147  extends from the source  141  to the rear spray bar  149  at the tiller. See also junction  146   a.  Catalyst sprayed with water from bar  149  contacts the sprayed chemicals, on the tilled earth, to activate them. 
     If desired, hose  147  can be eliminated, and water and catalyst spayed upwardly and sidewardly from apparatus  141 , to fall on the ground tilled or to be tilled by the tiller, to which chemicals (ferrous sulfate) have been supplied, as described. Multiple traveling tillers can be supplied with fluid from a control supply (microbes or chemicals). 
     FIGS. 11 and 12 show further details of a modified tiller arm  161 , with spray nozzles  162  located on the back side of arm  161 . A spade  163  is bolted to the arm  161  at  164 , In the above, the reaction of ferrous sulfate and hydrogen peroxide produces, inter alia CO 2  and heat, at 20 to 40 degrees Centigrade.