Ballasted sequencing batch reactor system and method for treating wastewater

Abstract

A ballasted sequencing batch reactor system for treating wastewater including one or more sequencing batch reactors. A weighting agent impregnation subsystem is configured to mix biological flocs and weighting agent to form weighted biological flocs. A weighting agent recovery subsystem is configured to recover weighting agent from the weighted biological flocs and reintroduce the recovered weighting agent to the weighting agent impregnation subsystem.

1 . A ballasted sequencing batch reactor system for treating wastewater comprising:
 one or more sequencing batch reactors;   a weighting agent impregnation subsystem configured to mix biological flocs and weighting agent to form weighted biological flocs;   a weighting agent recovery subsystem configured to recover weighting agent from the weighted biological flocs and reintroduce the recovered weighting agent to the weighting agent impregnation subsystem.   
     
     
         2 . The system of  claim 1  further including a sludge storage tank configured to receive settled sludge from the one or more sequencing batch reactors, store the settled sludge therein, and regulate the flow of settled sludge to weighting agent recovery subsystem. 
     
     
         3 . The system of  claim 1  in which the weighting agent recovery subsystem includes a separator subsystem for separating the weighting agent from the weighted biological flocs. 
     
     
         4 . The system of  claim 3  in which the separator subsystem includes a shear mill. 
     
     
         5 . The system of  claim 3  in which the separator subsystem includes a centrifugal separator. 
     
     
         6 . The system of  claim 3  in which the separator subsystem includes an ultrasonic separator. 
     
     
         7 . The system of  claim 3  in which the separator subsystem includes a shear mill and a wet drum magnetic separator. 
     
     
         8 . The system of  claim 3  in which the separator subsystem includes a shear mill and a centrifugal separator. 
     
     
         9 . The system of  claim 3  in which the separator subsystem includes an ultrasonic separator and a wet drum magnetic separator. 
     
     
         10 . The system of  claim 3  in which the separator subsystem includes an ultrasonic separator and a centrifugal separator. 
     
     
         11 . The system of  claim 4  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. 
     
     
         12 . The system of  claim 1  in which the weighting agent impregnation subsystem includes an impregnation tank and at least one mixer. 
     
     
         13 . The system of  claim 1  in which the capacity of the system is increased by reducing the duration of a settle phase. 
     
     
         14 . The system of  claim 1  in which the one or more sequencing batch reactors are configured to decant clear effluent from settled sludge to provide a treated effluent. 
     
     
         15 . The system of  claim 14  in which the weighted biological flocs enhance the quality of the treated effluent by reducing the concentration of suspended solids and related contaminants therein. 
     
     
         16 . The system of  claim 1  further including a wasting subsystem for wasting settled sludge from the weighting agent recovery subsystem to control a population of microorganisms in a mixed liquor in the one or more sequencing batch reactors. 
     
     
         17 . The system of  claim 16  in which the capacity of the system is increased by increasing the concentration of the mixed liquor in the one or more sequencing batch reactors by reducing the amount of settled sludge wasted by a wasting subsystem. 
     
     
         18 . The system of  claim 17  in which the capacity of the system is increased by reducing the duration of a react phase. 
     
     
         19 . The system of  claim 17  in which the amount of settled sludge wasted by the wasting subsystem is reduced to increase the concentration of mixed liquor suspended solids for enhancing nitrification and/or de-nitrification of ammonia in the mixed liquid. 
     
     
         20 . The system of  claim 19  in which nitrification is enhanced by increasing the amount of dissolved oxygen introduced into the one or more sequencing batch reactors. 
     
     
         21 . The system of  claim 1  in which a coagulant is added to the one or more sequencing batch reactors for removing phosphorus by precipitation and/or coagulation. 
     
     
         22 . The system of  claim 1  in which a flocculant is added to the one or more sequencing batch reactors for enhancing settling and thickening of the weighted biological flocs and for providing agglomeration of non-impregnated biological flocs and/or partially impregnated biological flocs with weighted biological flocs. 
     
     
         23 . The system of  claim 1  in which the weighting agent impregnation subsystem includes a venturi mixer/eductor. 
     
     
         24 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 100 μm. 
     
     
         25 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 40 μm. 
     
     
         26 . The system of  claim 1  in which a majority of the weighting agent has a particle size less than about 20 μm. 
     
     
         27 . The system of  claim 1  in which the weighting agent includes magnetite. 
     
     
         28 . The system of  claim 1  further including a mixer disposed in each of the one or more sequencing batch reactors for maintaining the suspended solids or the mixed liquor in suspension. 
     
     
         29 . A method for treating wastewater using one or more sequencing batch reactors, the method comprising:
 a) receiving influent wastewater in the one or more sequencing batch reactors;   b) forming biological flocs in the one or more sequencing batch reactors;   c) impregnating weighting agent into the biological flocs to form weighted biological flocs; and   d) recovering weighting agent from the weighted biological flocs to reintroduce the weighting agent to step c).   
     
     
         30 . The method of  claim 29  further including the step of separating the weighting agent from the weighted biological flocs. 
     
     
         31 . The method of  claim 29  further including the step of collecting the weighting agent and recycling the weighting agent to step c). 
     
     
         32 . The method of  claim 29  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. 
     
     
         33 . The method of  claim 29  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. 
     
     
         34 . The method of  claim 29  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. 
     
     
         35 . The method of  claim 29  further including the step of introducing dissolved oxygen to a population of microorganisms to promote growth of biological flocs in a mixed liquor defined by a concentration of mixed liquor suspended solids. 
     
     
         36 . The method of  claim 35  further including the step of introducing a flocculant to the mixed liquor to enhance settling and thickening of the weighted biological flocs and to establish agglomeration of non-impregnated biological flocs and/or partially impregnated biological flocs with the weighted biological flocs. 
     
     
         37 . The method of  claim 35  further including the step of separating and collecting the weighted biological flocs from the mixed liquor in the one or more sequencing batch reactors to provide a secondary effluent and a settled sludge. 
     
     
         38 . The method of  claim 37  further including the step of recycling the majority of the settled sludge to step b). 
     
     
         39 . The method of  claim 37  further including the step of decanting the clean effluent from the settled sludge in the one or more sequencing batch reactors to provide a treated effluent. 
     
     
         40 . The method of  claim 37  further including the step of wasting the remaining settled sludge using a wasting subsystem to control the population of the microorganisms in the mixed liquor. 
     
     
         41 . The method of  claim 29  further including the step of increasing the capacity of the system by reducing the duration of a settle phase. 
     
     
         42 . The method of  claim 39  further including the step of enhancing the quality of the treated effluent by reducing the concentration of suspended solids and related contaminants therein. 
     
     
         43 . The method of  claim 27  further including the step of wasting settled sludge from the weighting agent recovery subsystem to control a population of microorganisms in a mixed liquor in the one or more sequencing batch reactors. 
     
     
         44 . The method of  claim 43  further including the step of increasing the capacity of the system by increasing the concentration of the mixed liquor in the one or more sequencing batch reactors by reducing the amount of settled sludge wasted by a wasting subsystem. 
     
     
         45 . The method of  claim 44  further including the step of increasing the capacity of the system by reducing the duration of a react phase. 
     
     
         46 . The method of  claim 43  further including the step of reducing the amount of settled sludge wasted by the wasting subsystem to increase the concentration of mixed liquor suspended solids which enhances nitrification and/or de-nitrification of ammonia in the mixed liquid. 
     
     
         47 . The method of  claim 35  further including the step of enhancing nitrification by increasing the amount of dissolved oxygen introduced into the one or more sequencing batch reactors. 
     
     
         48 . The method of  claim 29  in which the weighting agent is impregnated into the biological flocs in step b) by mixing the mixed liquor and the biological flocs at a predetermined energy level.