Method for separating algae and other contaminants from a water stream

Abstract

A method and apparatus for treating raw influent water to remove particles, algae and toxic chemicals from the water. Basically, air is dissolved in recirculated water under high pressure in an air contactor unit, the air saturated water is intimately mixed with the raw, particle bearing, water in a particle mixing system, and the water, particle and air mixture is passed through an air bubble separator wherein bubbles formed when the pressure on air saturated water is reduced carry away toxic gases and particulate material. If desired for further cleaning the water can be sent through a second series of air contactor, particle mixer and air bubble separation, but with a gas comprising ozone to further remove suspended particles and non-volatile dissolved organic matter. In order to improve mixing of the particles and the air saturated water passing through tubes, preferably a pattern of dimples is formed on at least part of the interior wall of the tubes. Upon completion of the process the water is ready for use or for further filtration in a conventional filtration plant.

I claim:  
     
         1 . Water decontamination apparatus which comprises: 
 an air contactor means for introducing air into recirculated water at a pressure of at least about  70  psi to substantially saturate water therein;    a particle mixer for receiving and mixing said saturated water from said gas contactor means with influent water containing at least some contaminants to be removed;    means for directing said water from said air contactor means to said particle mixer at a pressure less than said gas contactor pressure so that a plurality of very small bubbles form in said particle mixer;    an air bubble separator having a water inlet adjacent to its bottom for receiving water from said particle mixer;    said air bubble separator comprising means for causing vortex rotation of received water for coalescing said bubbles and entrained particles along an axis and causing decontaminated water to move along an outer wall of said air bubble separator;    first outlet means for removing said coalesced bubbles and any entrained particles;    second outlet means from said air bubble separator for removing said decontaminated water;    means for removing gases from said bubble separator; and    means for directing a portion of said decontaminated water from said second outlet to said air gas contactor means as said recirculated water.    
     
     
         2 . The apparatus according to  claim 1  wherein said gas contactor means includes a plurality of hollow porous tubes and includes means for directing said air into said tubes and said recirculated water into spaces between said tubes so that said air moves through said porous tubes and is adsorbed by said recirculated water.  
     
     
         3 . The apparatus according to  claim 1  further including a pressure regulator for maintaining pressure at a predetermined level in said gas contactor means prior to passage of said saturated water to said particle mixer.  
     
     
         4 . The apparatus according to  claim 3  wherein said pressure is maintained at about 100 psi.  
     
     
         5 . The apparatus according to  claim 1  wherein said particle mixer comprises an elongated helical tube coil, the internal surface of said tube coil having a predetermined pattern of dimples over at least a portion of said surface.  
     
     
         6 . The apparatus according to  claim 1  wherein said air bubble separator comprises a vertically oriented tube having a central axis, an outer wall and upper and central sections above said lower section with a water outlet in said upper section.  
     
     
         7 . The apparatus according to  claim 6  wherein said water inlet is oriented at a predetermined angle so that a rotating water vortex is formed and said lower section comprises a sump below said water inlet for collecting heavy particles and a drain for periodically removing said heavy particles.  
     
     
         8 . The apparatus according to  claim 6  wherein said central section has a diameter less than that of the upper and lower sections and includes gradual transitions therebetween.  
     
     
         9 . The apparatus according to  claim 6  wherein said upper section includes a weir over which water rotating in said vortex along said outer wall flows into a circumferential product trough and a water outlet means for removing water from said product trough.  
     
     
         10 . The apparatus according to  claim 6  wherein said upper section further includes a waste trough for receiving floating waste and a waste outlet means for removing said floating waste.  
     
     
         11 . The apparatus according to  claim 6  wherein said upper section includes a gas relief means for removing gases from said upper section and level controller means for maintaining a predetermined water level in said upper section.  
     
     
         12 . The apparatus according to  claim 6  wherein said particle separator is a unitary rotationally molded structure comprising a tubular column having a central region narrower than end regions, an approximately cylindrical upper section having an outlet for decontaminated water, an approximately cylindrical top section having an outlet for coalesced air bubbles and entrained contaminants.  
     
     
         13 . The apparatus according to  claim 12  further including a gas relief valve in said top section for releasing gases.  
     
     
         14 . The apparatus according to  claim 13  further including level sensor means for sensing the level of water in said top section and for opening said valve when water level reaches a predetermined low level and for closing said valve when water level reaches a predetermined high level.  
     
     
         15 . The apparatus according to  claim 1  further including air compressor means for supplying air at a predetermined pressure to said gas contactor means.  
     
     
         16 . The apparatus according to  claim 1  wherein said means for directing water from said particle mixer to said air bubble separator comprises pipes having an internal surface with dimples over at least a portion thereof.  
     
     
         17 . Water decontamination apparatus which comprises: 
 a first gas contactor means for introducing air into recirculated water at a pressure of at least about 70 psi to substantially saturate water therein;    a first particle mixer for forming a mixture of saturated water from said first gas contactor means with influent water containing at least some particles to be removed;    means for directing said saturated water from said first gas contactor means to said first particle mixer;    means for directing said influent water to said first particle mixer at a pressure less than said first gas contactor pressure so that a plurality of very small bubbles form in said particle mixer;    a first air bubble separator having a water inlet adjacent to its lower section for receiving said mixed water from said first particle mixer;    said first air bubble separator comprising means for causing vortex rotation around an axis of received water for coalescing said bubbles along said axis;    means for removing said coalesced bubbles and any entrained material from said first air bubble separator;    first water outlet means from said first air bubble separator;    means for removing gases from said bubble separator; and    a second gas contactor means for receiving water from said first water outlet means;    means for introducing a gas comprising oxygen and ozone into a second gas contactor means to produce a plurality of very small dissolved bubbles;    a second particle mixer for receiving water from said second gas contactor means;    a second bubble separator comprising means for coalescing said bubbles along an axis;    second means for removing said coalesced bubbles and any entrained material;    second outlet means for removing treated water from said second bubble separator; and    means for directing a predetermined portion of said treated water back to said first particle mixer as said recirculated water.    
     
     
         18 . The apparatus according to  claim 17  wherein said gas contactor means includes a plurality of hollow porous tubes and includes means for directing said air into said tubes and said recirculated water into spaces between said tubes so that said air moves through said porous tubes and is adsorbed by said recirculated water.  
     
     
         19 . The apparatus according to  claim 17  further including a pressure regulator for maintaining pressure at a predetermined level in said means for directing water from each of said first and second gas contactor means to said first and second particle mixers, respectively.  
     
     
         20 . The apparatus according to  claim 19  wherein said pressure is maintained at about 100 psi.  
     
     
         21 . The apparatus according to  claim 17  wherein each of said first and second particle mixers comprises an elongated helical tube coil, the internal surface of said tube coil having a predetermined pattern of dimples over at least a portion of said internal surface.  
     
     
         22 . The apparatus according to  claim 17  wherein said first and second bubble separators each comprises a vertically oriented tube having a central axis, an outer wall and upper and central sections above said lower section with a water outlet in said upper section.  
     
     
         23 . The apparatus according to  claim 17  wherein each said water inlet is oriented at a predetermined angle so that a rotating water vortex is formed and said each said lower section comprises a sump below said water inlet for collecting heavy particles and a drain for periodically removing said heavy particles.  
     
     
         24 . The apparatus according to  claim 17  wherein each said first and second central sections has a diameter less than that of the upper and lower sections and includes gradual transitions therebetween.  
     
     
         25 . The apparatus according to  claim 17  wherein each said first and second upper sections includes a weir over which water rotating in said vortex along said outer wall flows into a circumferential product trough and a water outlet means for removing water from said product trough.  
     
     
         26 . The apparatus according to  claim 17  wherein each said first and second upper section further includes a waste trough for receiving floating waste and a waste outlet means for removing said floating waste.  
     
     
         27 . The apparatus according to  claim 17  wherein each said first and second upper sections includes a gas relief means for removing gases from said respective upper sections and level controller means for maintaining a predetermined water level in said respective upper sections.  
     
     
         28 . The apparatus according to  claim 17  further including air compressor means for providing high pressure air to said first and second gas contactor means and including oxygen concentrating means and ozone generator means between said air compressor and said second gas contactor means.  
     
     
         29 . The apparatus according to  claim 17  wherein said means for directing water from each said first and second particle mixers to each said first and second gas bubble separators comprises pipes having an internal surface with dimples over at least a portion thereof.  
     
     
         30 . The apparatus according to  claim 17  wherein said particle separator is a unitary rotationally molded structure comprising a tubular column having a central region narrower than end regions, an approximately cylindrical upper section having an outlet for decontaminated water, an approximately cylindrical top section having an outlet for coalesced air bubbles and entrained contaminants.  
     
     
         31 . The apparatus according to  claim 30  further including a gas relief valve in said top section for releasing gases.  
     
     
         32 . The apparatus according to  claim 30  further including level sensor means for sensing the level of water in said top section and for opening said valve when water level reaches a predetermined low level and for closing said valve when water level reaches a predetermined high level.  
     
     
         33 . A method of removing contaminants from water which comprises the steps of: 
 directing recirculated first product water into an air contacting means;    directing air at a pressure of at least about 70 psi into said air contacting means to at least partially saturate said recirculated water;    directing said at least partially saturated water to a particle mixer;    directing influent water containing at least some organic particles to said particle mixer;    mixing said at least partially saturated water and said influent water while reducing pressure to allow a plurality of very small air bubbles to form in the resulting mixture and to entrain particles;    directing said mixture to an air bubble separator;    causing said mixture to rotate about an axis in said air bubble separator so that said bubbles coalesce along said axis with first product water spaced from said axis;    removing said coalesced bubbles and entrained solid material; and    removing said first product water and recirculating a portion of said first product water.    
     
     
         34 . The method according to  claim 33  wherein said mixing is increased by causing turbulent flow over dimples in walls of said particle mixer.  
     
     
         35 . The method according to  claim 33  further including regulating pressure of water passing from said air contacting means to said particle mixer to a predetermined level at least about 70 psi.  
     
     
         36 . The method according to  claim 35  wherein said pressure is regulated to approximately 100 psi.  
     
     
         37 . The method according to  claim 33  further including collecting heavy particles at a lower end of said air bubble separator.  
     
     
         38 . The method according to  claim 33  further including removing air bubbles and buoyant particles from a predetermined location at about an upper end of said air bubble separator.  
     
     
         39 . The method according to  claim 38  further including removing air and any gases present from an upper end of said air bubble separator above said predetermined location.  
     
     
         40 . The method according to  claim 39  further including maintaining an interface between said bubbles and buoyant particles and said air and gases at a predetermined level.  
     
     
         41 . A method of removing contaminants from water which comprises the steps of: 
 directing recirculated second product water into a first air contacting means;    directing air at a pressure of at least about 70 psi into said first air contacting means to at least partially saturate said recirculated water;    directing said at least partially saturated water to a first particle mixer;    directing influent water containing at least some organic particles to said first particle mixer;    mixing said at least partially saturated water and said influent water while reducing pressure to allow a plurality of very small air bubbles to form in the resulting first mixture and to entrain particles;    directing said first mixture to a first air bubble separator;    causing said first mixture to rotate about an axis in said air bubble separator so that said bubbles coalesce along said axis with first product water spaced from said axis;    removing said coalesced bubbles and entrained solid material;    directing said first product water to a second air contacting means;    directing air at a pressure of at least about 30 psi into an oxygen concentrator to increase the proportion of oxygen therein;    directing gas from said oxygen concentrator to an ozone generator to increase the proportion of ozone therein to a predetermined extent;    directing gas from said ozone generator into a second air contacting means to at least partially saturate said first product water;    directing said at least partially saturated first product water to a second particle mixer;    mixing said at least partially saturated first product water while reducing pressure to allow a plurality of very small air bubbles to form in the resulting second mixture and to entrain particles;    directing said second mixture to a second air bubble separator;    causing said mixture to rotate about an axis in said second air bubble separator so that said bubbles coalesce along said axis with a second product water spaced from said axis;    removing said coalesced bubbles and entrained solid material; and    removing said second product water.    
     
     
         42 . The method according to  claim 41  wherein said mixing in each of said first and second particle mixers is increased by causing turbulent flow over dimples in walls of said particle mixers.  
     
     
         43 . The method according to  claim 41  further including regulating pressure of water passing from each of said first and second air contacting means to said first and second particle mixers, respectively, to a predetermined level at least about 70 psi.  
     
     
         44 . The method according to  claim 43  wherein said pressure is regulated to approximately 100 psi.  
     
     
         45 . The method according to  claim 41  further including collecting heavy particles at a lower end of each of said first and second air bubble separators.  
     
     
         46 . The method according to  claim 41  further including removing air bubbles and buoyant particles from a predetermined location at about an upper end of each of said first and second air bubble separators.  
     
     
         47 . The method according to  claim 42  further including removing air and any gases present from an upper end of each of said first and second air bubble separator above said predetermined location.  
     
     
         48 . The method according to  claim 47  further including maintaining an interface between said bubbles and buoyant particles and said air and gases at a predetermined level.  
     
     
         49 . A particle mixer for use in a water decontamination system, which comprises; 
 an elongated helical tube;    first inlet means for admitting a first water selected from the group consisting of at least partially decontaminated, at least partially air saturated, water at a pressure of at least about 70 and at least partially decontaminated, partially ozone saturated, into an inlet end of said elongated helical tube;    second inlet means for introducing a second, raw, water at lower pressure than that of said liquid into said tube to mix said first and second water;    whereby a plurality of very small gas bubbles spontaneously form in the resulting mixed water;    an outlet pipe for removing said resulting mixture of mixed water and small gas bubbles;    at least a portion of the interior surface of said tube bears a plurality of spaced dimples turbulence inducing.    
     
     
         50 . The particle mixer according to  claim 49  further including a plurality of said dimples in the interior surface of said outlet pipe.  
     
     
         51 . An air bubble separator for use in a water decontamination system, which comprises: 
 an elongated, tubular, housing having an inner wall and a central axis;    water inlet means adjacent a first end of said housing for directing a mixture of water, bubbles and contaminants into said housing;    means for causing vortex rotation of received water for coalescing said bubbles along said axis and causing decontaminated water to flow along said inner wall;    means for removing said coalesced bubbles and any buoyant entrained material from said housing;    means for removing decontaminated water from said housing;    means for removing gases from said housing.    
     
     
         52 . The air bubble separator according to  claim 51  wherein said housing comprises an inlet section, a central section and an outlet sections with a contaminated water inlet in said inlet section for receiving water from said particle mixer and a decontaminated water outlet in said outlet section.  
     
     
         53 . The air bubble separator according to  claim 52  wherein said water inlet means for directing said water from said particle mixer is oriented at a predetermined angle to said axis so that a rotating water vortex is formed.  
     
     
         54 . The air bubble separator according to  claim 52  further including a sump adjacent to said water inlet, opposite said central section, for collecting heavy particles and a drain for periodically removing said heavy particles.  
     
     
         55 . The air bubble separator according to  claim 52  wherein said central section has a diameter less than that of the outlet and inlet sections and includes gradual transitions therebetween.  
     
     
         56 . The air bubble separator according to  claim 52  wherein said outlet section includes a weir over which water rotating in said vortex along said outer wall flows into a circumferential product trough between said outer wall and weir which communicates with said water outlet for removing water from said product trough.  
     
     
         57 . The air bubble separator according to  claim 52  wherein said outlet section further includes a waste trough for receiving a mixture of bubbles and buoyant waste and a waste outlet means for removing said floating waste.  
     
     
         58 . The air bubble separator according to  claim 52  wherein said outlet section includes a gas relief means for removing gases from said outlet section and level controller means for maintaining a predetermined water level in said outlet section.  
     
     
         59 . The air bubble separator according to  claim 52  wherein said column is a unitary plastic structure formed by rotational molding.  
     
     
         60 . The air bubble separator according to  claim 59  wherein said housing comprises an inlet section, a central section and an outlet sections with a contaminated water inlet in said inlet section for receiving water from said particle mixer, a approximately cylindrical first portion of said outlet section having a decontaminated water outlet and an approximately cylindrical second portion of said outlet section having an outlet for coalesced bubbles and any entrained particles therewith.  
     
     
         61 . The air bubble separator according to  claim 59  wherein said second portion has a diameter from about 10 to 25 percent greater than the diameter of said first portion.