Wastewater treatment system and method

Abstract

The invention is directed to a wastewater treatment system having an anoxic biological treatment zone, an aerobic biological treatment zone and a separator. The concentration of oxygen in streams within the system is strategically managed for improved removal of nutrient from the wastewater. A source of biodegradable carbon may be introduced to reduce the concentration of oxygen within the system. An effective treatment time under anoxic or aerobic conditions may further be varied.

1 . A wastewater treatment system, comprising:
 an anoxic treatment zone;   an aerobic treatment zone fluidly connected to the anoxic treatment zone;   a separator fluidly connected to the aerobic treatment zone; and   means for varying an effective treatment time under anoxic conditions.   
     
     
         2 . The system of  claim 1 , wherein the separator comprises a membrane module. 
     
     
         3 . The system of  claim 1 , further comprising a recycle system fluidly connecting the separator to the anoxic treatment zone. 
     
     
         4 . The system of  claim 3 , further comprising a source of biodegradable carbon fluidly connected to the recycle system. 
     
     
         5 - 16 . (canceled) 
     
     
         17 . A wastewater treatment system, comprising:
 a first biological treatment zone, having an inlet and an outlet;   a second biological treatment zone, having an inlet and an outlet, fluidly connected to the first biological treatment zone;   a third biological treatment zone, having an inlet and an outlet, fluidly connected to the second biological treatment zone; and   a separator, having an inlet and an outlet, fluidly connected to the third biological treatment zone,   wherein the outlet of the separator is fluidly connected to the inlet of the third biological treatment zone, and wherein the outlet of the third biological treatment zone is fluidly connected to the inlet of the second biological treatment zone.   
     
     
         18 . The system of  claim 17 , wherein the outlet of the third biological treatment zone is fluidly connected to the inlet of the first biological treatment zone. 
     
     
         19 . The system of  claim 17 , further comprising a source of biodegradable carbon fluidly connected to the first and second biological treatment zones. 
     
     
         20 . The system of  claim 19 , wherein the biodegradable carbon comprises methanol. 
     
     
         21 . A method of treating wastewater, comprising:
 anoxically treating the wastewater to produce a first water product;   aerobically treating the first water product to produce a second water product;   passing the second water product through a filter membrane to produce a concentrated mixed liquor and a filtrate; and   reducing a concentration of dissolved oxygen in at least a portion of the concentrated mixed liquor.   
     
     
         22 . The method of  claim 21 , further comprising anaerobically treating the wastewater prior to anoxically treating the wastewater. 
     
     
         23 . The method of  claim 21 , wherein the act of reducing the concentration of dissolved oxygen comprises introducing biodegradable carbon. 
     
     
         24 . The method of  claim 23 , wherein the act of introducing biodegradable carbon is performed based on an ORP signal from an ORP sensor. 
     
     
         25 . A method of treating wastewater, comprising:
 introducing the wastewater to an anoxic treatment zone;   introducing the wastewater exiting the anoxic treatment zone to an aerobic treatment zone;   passing at least a portion of the wastewater exiting the aerobic treatment zone through a separator to produce a concentrated mixed liquor and a filtrate;   recycling at least a portion of the concentrated mixed liquor to the aerobic treatment zone; and   recycling at least a portion of the wastewater from the aerobic treatment zone to the anoxic treatment zone.   
     
     
         26 . The method of  claim 25 , further comprising reducing a concentration of dissolved oxygen in the wastewater recycled from the aerobic treatment zone to the anoxic treatment zone. 
     
     
         27 . The method of  claim 26 , wherein biodegradable carbon is introduced to the wastewater recycled from the aerobic treatment zone to the anoxic treatment zone. 
     
     
         28 . The method of  claim 27 , further comprising controlling an amount of biodegradable carbon introduced to the wastewater recycled from the aerobic treatment zone to the anoxic treatment zone based on an ORP signal from an ORP sensor. 
     
     
         29 . The method of  claim 27 , further comprising controlling an amount of biodegradable carbon introduced to the wastewater recycled from the aerobic treatment zone to the anoxic treatment zone based on a COD level of the wastewater. 
     
     
         30 . A method of treating wastewater, comprising:
 contacting the wastewater with anoxic bacteria in an anoxic zone to produce a first water product;   contacting the first water product with aerobic bacteria in an aerobic zone to produce a second water product;   passing the second water product through a separator to produce a concentrated mixed liquor and a filtrate;   establishing a first liquid circuit from an outlet of the separator to an inlet of the aerobic zone; and   establishing a second liquid circuit from an outlet of the aerobic zone to an inlet of the anoxic zone.   
     
     
         31 . The method of  claim 30 , further comprising introducing a source of biodegradable carbon to a liquid in the second liquid circuit. 
     
     
         32 . The method of  claim 30 , further comprising contacting the wastewater with anaerobic bacteria. 
     
     
         33 . The method of  claim 30 , wherein the act of contacting the wastewater with anoxic bacteria is performed during an anoxic treatment time period. 
     
     
         34 . The method of  claim 31 , wherein the source of biodegradable carbon comprises methanol. 
     
     
         35 . The method of  claim 31 , wherein introducing the source of biodegradable carbon is based on an ORP signal from an ORP sensor. 
     
     
         36 . The method of  claim 33 , further comprising an act of increasing the anoxic treatment time period. 
     
     
         37 . The method of  claim 36 , further comprising an act of decreasing the anoxic treatment time period. 
     
     
         38 . A method of treating wastewater, comprising:
 introducing the wastewater to an anoxic biological treatment zone;   introducing the wastewater exiting the anoxic biological treatment zone to an aerobic biological treatment zone;   passing at least a portion of the wastewater exiting the aerobic biological treatment zone through a separator to produce a concentrated mixed liquor and a filtrate; and   adjusting an effective volume of the anoxic biological treatment zone.   
     
     
         39 . The method of  claim 38 , wherein the act of adjusting the effective volume of the anoxic biological treatment zone comprises increasing the effective volume of the anoxic biological treatment zone. 
     
     
         40 . The method of  claim 38 , wherein the act of adjusting the effective volume of the anoxic biological treatment zone comprises controlling introduction of oxygen. 
     
     
         41 . The method of  claim 38 , further comprising introducing the wastewater to an anaerobic biological treatment zone prior to introducing the wastewater to the anoxic biological treatment zone. 
     
     
         42 . The method of  claim 38 , further comprising recycling at least a portion of the concentrated mixed liquor to the aerobic biological treatment zone. 
     
     
         43 . The method of  claim 39 , further comprising the act of decreasing the effective volume of the anoxic biological treatment zone to a design condition. 
     
     
         44 . The method of  claim 40 , wherein controlling introduction of oxygen is based on a flowrate of the wastewater. 
     
     
         45 . The method of  claim 40 , wherein controlling introduction of oxygen is based on a predetermined time interval. 
     
     
         46 . The method of  claim 40 , wherein controlling introduction of oxygen is based on a concentration of a target constituent in the wastewater. 
     
     
         47 . The method of  claim 42 , further comprising recycling at least a portion of the wastewater exiting the aerobic treatment zone to the anoxic treatment zone. 
     
     
         48 . The method of  claim 46 , wherein the target constituent comprises ammonia. 
     
     
         49 . The method of  claim 47 , further comprising introducing biodegradable carbon to the wastewater recycled from the aerobic treatment zone to the anoxic treatment zone based on a signal from a sensor. 
     
     
         50 . A wastewater treatment system, comprising:
 an anoxic treatment zone;   an aerobic treatment zone fluidly connected to the anoxic treatment zone;   a separator fluidly connected to the aerobic treatment zone; and   a controller in communication with an aeration system and configured to generate a first aeration control signal to allow increase of an effective volume of the anoxic treatment zone during a first biological treatment mode of operation, and further configured to generate a second aeration control signal to allow reduction of the effective volume of the anoxic treatment zone to a design condition during a second biological treatment mode of operation.   
     
     
         51 . The system of  claim 50 , further comprising a flowmeter disposed at an inlet of the anoxic treatment zone. 
     
     
         52 . The system of  claim 50 , further comprising a sensor disposed to monitor a concentration of a target constituent in the wastewater. 
     
     
         53 . The system of  claim 51 , wherein the controller generates the first and second aeration control signals in response to a flowrate signal from the flowmeter. 
     
     
         54 . The system of  claim 52 , wherein the controller generates the first and second aeration control signals in response to a concentration signal from the sensor. 
     
     
         55 . The system of  claim 54 , wherein the target constituent comprises ammonia. 
     
     
         56 . A method of facilitating treating wastewater, comprising:
 providing a wastewater treatment system, comprising a first biological treatment zone, a second biological treatment zone fluidly connected to the first biological treatment zone, a membrane module comprising a filter membrane fluidly connected to the second biological treatment zone, a recycle system fluidly connecting the membrane module to the first biological treatment zone, and a source of biodegradable carbon fluidly connected to the recycle system.