Abstract:
A method for treating grain comprising circulating concentrated ozone through an evenly distributed column of grain to maintain a concentration of between 50 and 100 ppm.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of co-pending U.S. application Ser. No. 10/243,558, filed Sep. 13, 2002, which claims priority to provisional application No. 60/323,900, filed Sep. 21, 2001. 
    
    
     BACKGROUND 
     Field of the Invention 
     Traditional methods for treating grain involve the fumigation of the grain with toxic chemicals such as phosphine and methyl bromide. Both of these fumigation techniques have been effective at killing insects, however, they do pose a danger to those who come in contact with the chemicals and they have not been effective in treating mold, fungus, and some bacteria that also infest the surface of grain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The FIGURE depicts a grain elevator incorporating the teachings of the present invention. 
     
    
    
     SUMMARY AND OBJECTS OF THE INVENTION 
     It is an object of some embodiments of the present invention to provide a method for treating grain for fungus, mold, bacteria, dust, and insects by exposing the grain to a high concentration of ozone for an extended period of time. The present invention utilizes a powerful fan or fans placed at the bottom of the grain storage facility such as, for example, a silo or grain elevator to draw down through the grain a flow of gas containing ozone between 50 and 100 ppm. Ozone generators placed in the head space at the top of the elevator produce ozone in a concentration in excess of 100 ppm. Monitors placed in this head space assure that the ozone concentration remains at these levels. If the ozone generators are not capable of maintaining the concentration at 100 ppm in the head space, then the draw is reduced by slowing the fan speed. A duct takes drawn gases from the bottom of the elevator and re-circulates those gases into the head space to reduce the amount of ozone needed to be generated during a second pass. To assure that the gases come in contact with all of the grain in the elevator, a technique labeled “pulling the core” is utilized wherein a quantity of grain is removed from the bottom of the elevator at its center to remove a column of grain from the core of the column of grain thereby evenly distribute the grain within the elevator. The material which is pulled from the core is then sent back to the top of the column and evenly distributed across the top. It has been found that this pulling of the core technique greatly enhances the efficiency of the ozination process. 
     It has been found that to assure the eradication of all insects, exposure for approximately seventy-two hours is required. Mold, bacteria and some insects will begin to die within the first twenty-four hours. Some fungal pores could require longer exposure. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following discussion is directed towards grain stored within a vertical elevator  10 . It will be understood by those skilled in the art that the same techniques can be used for grains stored in other facilities. In one embodiment, a quantity of ozone is injected into a grain bin, vessel, or truck prior to the grain being loaded into said container in order to treat the grain for mold, bacteria, fungi, and biological load as the grain is loaded. In another embodiment, grain is delivered to the elevator by truck and is dumped into a loading bin  11  which has placed near its bottom an auger  12  which transports the grain from the loading bin to the top of the elevator  13 . In this embodiment, the loading bin is partially enclosed and has injected therein a sufficient quantity of ozone to create a concentration of approximately 100 ppm within the loading bin and the enclosed auger. Because ozone not only kills insects but also tends to drive insects away, the auger and loading bin are not completely sealed, but have sufficient spaces available for insects to flee the grain as it is loaded and transported to the top of the elevator. The purpose of this initial exposure is not necessarily to kill the insects, but to drive the insects out of the grain before it is treated. Once the grain is moved by the auger into elevator  10 , a large fan  14  is activated at the bottom of the elevator is to draw gases from the top of the elevator out through the bottom of the elevator. In one embodiment, ozone is introduced into the top of a container, such as said elevator, in an amount sufficient to maintain a concentration of between 50 and 200 ppm throughout the entire grain containment area of said container, which maybe reduced to 35 ppm if only mold is to be treated. These gases exit the elevator into a large duct  16  which takes the gases back to the top of the elevator before recycling. The ozination process, to achieve maximum efficiency, should occur every thirty days. As a result, this process will often occur when the elevator is full of grain. 
     When the elevator is full it has been discovered that to be effective in uniformly treating the grain, the central core of grain must be pulled from the elevator, removed out through the bottom of the elevator and redistributed to the top of the column of grain to evenly distribute the grain and allow for uniformed permeation of gases. Ozone generators  18  provide sufficient ozone to create a concentration of at least 100 ppm in the head space  17  in the top of elevator  13 . If the ozone generators do not have a sufficient capacity to create this concentration, then the speed of the fan at the bottom of the elevator must be reduced to maintain a 100 ppm concentration of zone in the head space. 
     Because the ozone reacts with the biologic load on the outer surface of each grain, it takes a significant period of time before un-reacted ozone at a 50 ppm concentration passes from the head space out through the bottom of the elevator on its first pass. It has been found that this can take as many as seventy hours for the first pass. Subsequent passes take as few as two hours because of the significantly reduced biological load on the outer surface of the grain. It has been found that if the concentration is maintained for three days, that almost all insect, mold, bacteria, and fungus will be destroyed. Ozone monitors in the head space and bottom of the column verify the concentration of ozone so that the generators will create a sufficient quantity of ozone to maintain the concentration. Smell from mold and fungus disappears after 24 hours. Some insects are killed after 12 hours but complete insect eradication usually requires 72 hours. 
     As mentioned before, if the generators are not capable of maintaining this high concentration, the fan speed must be reduced to maintain the over 100 ppm concentration at the head space and more importantly, the 50 ppm concentration at the bottom of the column. This concentration may be reduced to 35 ppm if only mold is to be treated. 
     It will be appreciated by those skilled in the art that this concentration can be increased; however, the inventors have found that any reduction below 100 ppm greatly reduce the efficiency of the process. 
     It will also be appreciated that after the gases are recycled from the bottom of the elevator, during some of the later passes, a significant concentration of ozone still exists and the ozone generators will not be required to generate as much ozone. After the initial biological load has been destroyed, a greater concentration of ozone will remain after passing through the grain column. 
     After completion of the processing of the grain, the ozone generators are removed and the gases are recycled through the grain column until the ozone levels are reduced to a level where it is safe for operators to work in the vicinity of the elevator. Because ozone is highly oxidative and reacts quickly, this usually does not require a great amount of time.