Ballasted anaerobic system and method for treating wastewater

Abstract

A ballasted anaerobic system for treating wastewater including at least one anaerobic treatment reactor. A weighting agent impregnation subsystem is configured to mix weighting agent with the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket in the at least one anaerobic treatment reactor. A weighting agent recovery subsystem is configured to recover the weighting agent from excess sludge and reintroduce the weighting agent to the weighting agent impregnation subsystem.

1 . A ballasted anaerobic system for treating wastewater comprising:
 at least one anaerobic treatment reactor;   a weighting agent impregnation subsystem configured to mix weighting agent with the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket in the at least one anaerobic treatment reactor; and   a weighting agent recovery subsystem configured to recover the weighting agent from excess sludge and reintroduce the weighting agent to the weighting agent impregnation subsystem.   
     
     
         2 . The system of  claim 1  in which the weighted anaerobic sludge blanket is configured to treat the wastewater and provide a treated effluent. 
     
     
         3 . The system of  claim 1  in which the weighting agent impregnation subsystem includes an impregnation tank and at least one mixer. 
     
     
         4 . The system of  claim 3  in which the weighting agent impregnation subsystem includes a storage subsystem for storing virgin weighting agent and dispensing the virgin weighting agent into the impregnation tank. 
     
     
         5 . The system of  claim 1  in which the weighting agent impregnation subsystem includes a venturi mixer/eductor. 
     
     
         6 . The system of  claim 1  in which the weighting agent recovery subsystem includes a separator subsystem for separating the weighting agent from the biological flocs. 
     
     
         7 . The system of  claim 6  in which the separator subsystem includes a shear mill. 
     
     
         8 . The system of  claim 6  in which the separator subsystem includes a centrifugal separator. 
     
     
         9 . The system of  claim 6  in which the separator subsystem includes an ultrasonic separator. 
     
     
         10 . The system of  claim 6  in which the separator subsystem includes a shear mill and a wet drum magnetic separator. 
     
     
         11 . The system of  claim 6  in which the separator subsystem includes a shear mill and a centrifugal separator. 
     
     
         12 . The system of  claim 6  in which the separator subsystem includes an ultrasonic separator and a wet drum magnetic separator. 
     
     
         13 . The system of  claim 6  in which the separator subsystem includes an ultrasonic separator and a centrifugal separator. 
     
     
         14 . The system of  claim 7  in which the shear mill includes a rotor and a stator, wherein the rotor and/or the stator include slots sized as to optimize separation of weighting agent from the weighted biological flocs. 
     
     
         15 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 100 μm. 
     
     
         16 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 40 μm. 
     
     
         17 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 20 μm. 
     
     
         18 . The system of  claim 1  in which said weighting agent includes magnetite. 
     
     
         19 . The system of  claim 2  in which the weighted biological flocs enhance the quality of the treated effluent by reducing suspended solids and associated contaminants therein. 
     
     
         20 . The system of  claim 1  further including a wasting subsystem for wasting excess sludge to control the population of microorganisms. 
     
     
         21 . The system of  claim 18  in which the capacity of the system is increased by increasing the concentration of microorganisms solids in the anaerobic treatment reactor by reducing the amount of the sludge wasted by the wasting subsystem. 
     
     
         22 . A ballasted anaerobic method for treating wastewater, the method comprising:
 a) receiving influent wastewater in at least one anaerobic treatment reactor;   b) forming biological flocs in the at least one anaerobic treatment reactor;   c) impregnating weighting agent into the biological flocs to form weighted biological flocs to create a weighted anaerobic sludge blanket; and   d) recovering weighting agent from the weighted biological flocs to reintroduce the weighting agent to step c).   
     
     
         23 . The system of  claim 22  further including the step of directing the wastewater through the weighted anaerobic sludge blanket to provide a treated effluent. 
     
     
         24 . The method of  claim 22  further including the step of separating the weighting agent from the weighted biological flocs. 
     
     
         25 . The method of  claim 22  further including the step of collecting the weighting agent and recycling the weighting agent to step c). 
     
     
         26 . The method of  claim 22  further including the step of providing weighting agent in which the majority of the weighting agent has a particle size less than about 100 μm. 
     
     
         27 . The method of  claim 22  further including the step of providing weighting agent in which the majority of the weighting agent has a particle size less than about 40 μm. 
     
     
         28 . The method of  claim 22  further including the step of providing weighting agent in which the majority of the weighting agent has a particle size less than about 20 μm. 
     
     
         29 . The method of  claim 22  further including the step of enhancing the quality of the treated effluent by reducing suspended solids and associated contaminants therein.