Abstract:
An apparatus and method for treating wastewater with a flocculent. The wastewater is mixed with a flocculent so that the contaminants and pollutants within the water are absorbed by the flocculent. The mixture is then transported to a gravity bed filter having a filter media conveying means. The filter media is conveyed to a second end as the mixture is transported to the first end. Clean water seeps from the mixture and is collected in a basin. Thus, the wastewater treatment may continuously operate without interruption. Such an apparatus offers the advantage of possibly being made smaller in size than typical wastewater treatment plants and thus may be made mobile.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates generally to wastewater treatment equipment. The invention relates more particularly to an apparatus for the continuous treatment of wastewater and method thereof, using a flocculent clay-based powder.  
       BACKGROUND OF THE INVENTION  
       [0002]     A clean and healthy water supply is vital to society. The need therefore exists to remove waste products from contaminated and polluted water, referred herein throughout this specification as wastewater. Various systems have been developed to treat wastewater. Many such systems are designed as large fixed location wastewater treatment plants. However, as governmental mandates are increasingly implemented to regulate the production and disposal of wastewater, and the by-products produced by the treatment thereof, the need for smaller waste treatment facilities with mobile capabilities increases to treat wastewater which is produced or located at locations remote from conventional wastewater treatment plants.  
         [0003]     A significant source of wastewater is cleaning equipment which use water as the primary cleaning fluid. The wastewater created by this cleaning equipment typically contains oils, greases, suspended solids, heavy metals, diesel fuel, emulsions, latex paints, and other similar hydrocarbon and metallic contaminants. Even if the wastewater is filtered to remove these contaminants and pollutants, it is difficult to safely and economically dispose of the filtered waste by-products.  
         [0004]     One known wastewater treatment system that can be produced on a smaller scale uses a clay-based powder (such as Montmorillonite and a cationic polymer) as a flocculent to remove emulsified oils and metals from water. The acids in the powder break the oil emulsion. The oil and other contaminants are fixated within the clay-based powder through a process of flocculation and encapsulation. The floc settles to the bottom, or floats to the top, of the water treatment tank, with mostly clear water therebetween. The floc is separated from the mostly clear water and may then be further filtered to further remove some excess water included with the floc.  
         [0005]     The cleaned water may then be either recycled for further use or safely discharged to the environment, sewer system, storm drains or sewer treatment system. The entrapped contaminants and pollutants form a sludge with clay-based powder which may be suitable for disposal in a Class II non-hazardous industrial landfill.  
         [0006]     U.S. Pat. No. 5,979,012 teaches a mobile clay-based flocculent wastewater apparatus using this technology. That apparatus collects the wastewater, then mixes the wastewater with flocculent to allow complete encapsulation of the contaminants. The mixture is then allowed to settle for a few minutes so that the floc settles to the bottom and/or floats to the top (depending on the contaminants and pollutants), and a volume of mostly clear water forms. Then, the mostly clear water volume is first transferred and filtered through a filter cloth through which only clean water may pass. The remaining sludge is then transferred onto the filter cloth and more clean water is filtered from the sludge. The clean water is retained in a storage tank for further use or disposal. The remaining sludge may then be wrapped in the filter cloth and properly disposed of.  
         [0007]     The above-described process for treating the wastewater with the apparatus of U.S. Pat. No. 5,979,012 is known as a batch process. In other words, only a certain volume of wastewater is treated at a time, and no new wastewater is introduced into the system until treatment of the wastewater being processed is completed. While this process is acceptable for some applications, for use on cleaning equipment it would be advantageous for the treatment process to be continuous so that the cleaning operation did not need to be stopped while the wastewater is being treated, or for large amounts of wastewater to be stored. Thus, a need exists for a wastewater treatment apparatus which has mobile capabilities and affords a continuous and uninterrupted treatment operation.  
       SUMMARY OF THE INVENTION  
       [0008]     Embodiments of the present invention may provide a wastewater treatment apparatus utilizing a clay-based flocculent powder. Incoming wastewater is mixed with the flocculent powder so that contaminants and pollutants within the water are encapsulated with the flocculent. The mixture, otherwise known as floc, is then filtered to separate the clean water from the floc. The clean water may then be reused or disposed of. The remaining floc sludge may then be safely disposed of  
         [0009]     Prescribed amounts of wastewater and flocculent powder may be continuously added to the mixture in a mixing tank, and floc continuously transferred from the mixing tank to be filtered. The floc is transferred to a gravity bed filter where clean water is separated from the floc. The gravity bed filter includes a conveyor belt which is covered with a layer of filter media.  
         [0010]     The filter media is provided in a long continuous length and is moved over the conveyor belt as the floc is deposited thereon. Clean water seeps out of the floc through the filter media and collects in a clean water storage tank. The remaining sludge adheres to the filter media and is deposited in a disposal container for later disposal.  
         [0011]     Embodiments of the present invention are particularly well suited for use with cleaning equipment with which a continuous supply of water is used during the cleaning operation, or other applications where mobility is needed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0012]      FIG. 1  is a partially schematic broken side elevation of a preferred embodiment of the invention.  
         [0013]      FIG. 2  is an enlarged and partially schematic view of the mixing tank and gravity bed filter shown in  FIG.1 .  
         [0014]      FIG. 3  is an enlarged and partially schematic view of an alternative configuration for the gravity bed filter. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]      FIG. 1  shows the wastewater treatment apparatus in conjunction with a surface cleaner mounted on a mobile platform  10 . The mobile platform  10  may be any vehicle, such as the truck which is shown, or trailer, ship, airplane, train, etc. A cleaning head  12  is mounted to the mobile platform  10  for cleaning of a surface. Cleaning fluid is provided to the cleaning head  12  via a supply conduit  14 , and the cleaning fluid is removed from the cleaned surface via a suction conduit  16 .  
         [0016]     Water is supplied from a water supply tank  18  and/or from a municipal water source. Cleaning additives such as detergents, degreasers and coalescents may be added to the supply water from an additive tank  20 . The water passes through a supply pump  22  to increase the pressure at which the cleaning fluid is to be supplied to the cleaning head  12 , or other surface cleaning implement such as a wand sprayer or brush. A boiler  24  may be provided if the cleaning fluid is to be supplied at an elevated temperature or as steam.  
         [0017]     After the cleaning fluid is applied to the surface, the cleaning fluid with entrapped contaminants pollutants and particulates removed from the surface are transported via suction conduit  16  to the wastewater treatment apparatus. Typically, suction of the cleaning fluid is provided by some suction means such as a vacuum source, fluid pump, fan, cyclone, etc. The preferred embodiment shown in  FIG. 1  utilizes a vacuum source  26  by which air flow into the cleaning head  12  and out the suction conduit  16  provides the suction for transporting the cleaning fluid with entrapped contaminants, pollutants and particulates, which will now be defined as wastewater.  
         [0018]     From the suction conduit  16  the wastewater passes through a particulate filter  28  to separate out any gross particulate matter such as cigarette butts, gum, sticks and stones. The filtered wastewater is then collected in a wastewater storage tank  30 . The storage tank  30  may be an oil/water separator in which oil is separated from the wastewater before the flocculent treatment. The storage may also be a solids separator in which some suspended solids in the wastewater may settle and be separated from the wastewater. The storage tank  30  may function as both an oil/water separator and a solids separator, which is commonly known as an oil/water solids separator. The wastewater is then transported to the wastewater treatment apparatus  40  for treatment. The wastewater may be gravity fed to the wastewater treatment apparatus  40  or a wastewater pump  32  may be used if necessary depending on configuration.  
         [0019]     The particulate filter  28  may comprise any device for filtering out gross particulates, and each are intended to be coved by the definition of particulate filter. Examples of particulate filters include bag filters, cyclone filters, etc.  
         [0020]     The wastewater treatment apparatus  40  includes a flocculent supply  42 , a mixing tank  44 , a gravity bed filter  46 , and clean water basin  52 , which are shown in more detail in  FIG. 2 .  
         [0021]     Wastewater and flocculent are supplied into the mixing tank  44  in predetermined amounts. Determination of the amount of flocculent to be used may be made by the operator depending on the application of the apparatus and condition of the wastewater. Determination of the amount of flocculent to be used may also be automatically controlled in response to signals from a contaminant sensor (not shown) in the incoming stream of wastewater entering the mixing tank  44 .  
         [0022]     A mixer  45  is provided in the mixing tank  44  and generates a sufficient amount of shear to allow for flocculation of the mixture, and encapsulation and absorption of the contaminants and pollutants by the clay platelets. The clay flocculent surrounds oils, emulsions, suspended solids, and heavy metals, forming a floc mixture. The floc will tend to rise to the top or settle to the bottom of the mixing tank  44 , depending upon the contaminant/pollutant which has attached to the clay platelets. The floc may then be transported to the gravity bed filter  46 . Various means of transporting the floc are possible. A sump pump  48  may be provided at the bottom of the mixing tank  44 . Also, a raceway  50  may be provided at a top edge of the mixing tank  44  for floc to spill over and flow to the gravity bed filter  46 .  
         [0023]     The mixer  45  shown in  FIG. 2  comprises a motor having a shaft and an impeller. However, any device which creates turbulence in the mixing tank may be used and is intended to be included within the definition of a mixer. Examples of other types of mixers include pumps, paddlewheels, gases pumped through the mixture, magnetically driven rotators, etc.  
         [0024]     The gravity bed filter  46  includes filter media  54 , filter media conveying means  56  that conveys and suspends the filter media  54  over the clean water basin  52 , and a filter media waste container  58 .  
         [0025]     The filter media  54  is supplied from a large capacity filter media supply means  60 , such as a large roll, as a continuous sheet over the filter media conveying means  56 . The filter media conveying means  56  may comprise a conveyor belt assembly or other device to convey the continuous supply of filter media  54  over the clean water basin  52 . The floc is transported at a first end of the filter media conveying means  56  on the filter media  54 . Clean water may then seep out of the floc and through the filter media  54  to be collected in the clean water basin  52 , as the floc and paper media is conveyed over the clean water basin  52 . The filter media  54  may be conveyed at a predetermined rate or in response to the accumulation of floc on the filter media  54 . At a second end of the filter media conveying means  56  the filter media  54  and remaining floc sludge are collected in a filter media waste container  58  for later disposal.  
         [0026]     The clean water collected within basin  52  may then be discharged for reuse or disposal, selection of which may be controlled by a valve (not shown). A clean water pump  62  may be provided if necessary.  
         [0027]      FIG. 3  shows an enlarged view of an alternative embodiment of the gravity bed filter  46 . In this embodiment there is a more noticeable, and intend, sloping of the filter media conveying means  56  near the center thereof. The floc mixture is transported from the mixing tank  44  near the center of the filter media conveying means  56 . The floc tends to bind and clog the filter media  54 , thus preventing adequate seepage of the water therethrough and into the clean water basin  52 . With the sloped or bowed configuration of the filter media conveying means  56 , water will tend to pool, possibly between an upper and lower layer of floc. A float switch (not shown) may then be provided so that if a predetermined amount of water pools or accumulates at the center the filter media conveying means will be activated by the float switch and an amount of filter media  54  will be advanced to expose the accumulated water to a portion of filter media  54  which has not been clogged by the floc. Thus, the accumulated water may then seep through the filter media and into basin  52 . The advantage of this embodiment is that only the necessary amount of filter media to allow for seepage of the water is advanced, preventing waste of the filter media.  
         [0028]     The filter media  54  may be made of any porous material that allows the clean water to seep therethrough while retaining the flocculent sludge. Filter media preferably is constructed of paper or cloth. However, the use of other materials is possible, such as metal, plastic, or ceramics.  
         [0029]     While the above-preferred embodiment is shown and described in conjunction with a surface cleaning device, the wastewater treatment apparatus may be used separately or in conjunction with various other devices. Although the invention has been described relative to the above-specific embodiment, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that the intended scope of protection for the invention is only limited by the scope of the claims appended hereto.