Composition and method for removing suspended solids from wastewater

Abstract

Bacterially generated polymers used as coagulants and flocculents for the removal of suspended solids from wastewater. Polymer producing bacteria such as Bacillus polymyxa NRRL 21881 are added to wastewater treatment systems. The bacteria reproduce in the system, substantially increasing the number of coagulants. Throughout their lives, the bacteria treat BOD 5 in the system. When BOD 5 levels are sufficiently low, the bacteria will produce polymers to increase their ability to capture organic matter. The polymers will capture the suspended particles in the water, creating strands of polymer connected particles. As different strands come into contact, they will become entwined, creating flocs. These flocs will combine and absorb the suspended particles which they encounter. If the flow of the system becomes laminar, the flocs will agglomerate to densities sufficient to allow them to fall out of suspension. The result is a reduction in effluent TSS without an offsetting increase in BOD 5 .

I claim:  
     
         1 . A method of removing suspended solids from an aqueous solution comprising: 
 establishing turbulent conditions in said aqueous solution;    adding to said solution cultures of exo-polymer producing bacteria capable of producing at least about 0.4 grams of exo-polymer for each gram of exo-polymer producing bacteria wherein said exo-polymers are capable of capturing said suspended solids in said turbulent conditions;    establishing sufficient levels of dissolved oxygen in said solution to support the production of said exo-polymers by said bacteria;    establishing sufficiently low BOD 5  levels in said solution to stimulate the production of said exo-polymers by said bacteria; and    establishing non-turbulent conditions in said aqueous solution whereby said exo-polymer producing bacteria and their captured suspended solids may flocculate and settle.    
     
     
         2 . A method of removing suspended solids from an aqueous solution comprising: 
 establishing turbulent conditions in said aqueous solution;    adding cultures of bacteria capable of producing exo-polymers having a molecular weight of at least about 100,000 to said solution wherein said exo-polymers are capable of capturing said suspended solids in said turbulent conditions;    establishing sufficient levels of dissolved oxygen in said solution to support the production of said exo-polymers by said bacteria;    establishing sufficiently low BOD 5  levels in said solution to stimulate the production of said exo-polymers by said bacteria; and    establishing non-turbulent conditions in said aqueous solution whereby said exo-polymer producing bacteria and their captured suspended solids may flocculate and settle.