Wastewater treatment

Abstract

A wastewater treatment system includes wastewater having nitrogen-containing compounds, an anoxic zone having denitrifying bacteria, and an aerobic zone having nitrifying bacteria. The anoxic zone is coupled to the aerobic zone, and wastewater flows from the anoxic to the aerobic zone or vice versa. A fluidized bed heat exchanger configured to accept heat from a heat engine and to transfer the heat from the heat engine to the wastewater is positioned in the aerobic zone or the anoxic zone. The fluidized bed heat exchanger includes particulate media, and fluidization of the particulate media scrubs bacterial growth from portions of the fluidized bed heat exchanger. Treating wastewater can include flowing wastewater having nitrogen-containing compounds into a biological reactor having an anoxic zone and an aerobic zone, and heating the wastewater with heat from a heat engine to facilitate denitrification reactions in the anoxic zone and nitrification reactions in the aerobic zone.

1 - 20 . (canceled) 
     
     
         21 . A method of treating wastewater, the method comprising:
 generating steam from water;   transferring heat from the steam directly or indirectly to wastewater in a wastewater treatment system; and   adjusting the temperature of the wastewater to enhance performance of biological organisms in the wastewater.   
     
     
         22 . The method of  claim 21 , wherein the water has a partial pressure of water vapor that is at or below atmospheric pressure. 
     
     
         23 . The method of  claim 21 , wherein adjusting the temperature of the wastewater to enhance performance of biological organisms in the wastewater comprises adjusting the temperature of the wastewater to a temperature in a range between 20° C. and 35° C. 
     
     
         24 . The method of  claim 21 , wherein generating the steam comprises reducing the pressure above the water with a compressor or a blower. 
     
     
         25 . The method of  claim 21 , wherein the water from which the steam is generated is effluent from the wastewater system. 
     
     
         26 . The method of  claim 25 , wherein the effluent is heated. 
     
     
         27 . The method of  claim 21 , further comprising biological nitrification of nitrogen-containing compounds in the wastewater in at least a portion of the wastewater treatment system, wherein adjusting the temperature of the wastewater facilitates the nitrification. 
     
     
         28 . The method of  claim 21 , further comprising biological denitrification of nitrogen-containing compounds in the wastewater in at least a portion of the wastewater treatment system, wherein adjusting the temperature of the wastewater facilitates the denitrification. 
     
     
         29 . The method of  claim 21 , further comprising deaerating the steam before contacting the steam with the wastewater. 
     
     
         30 . The method of  claim 21 , wherein the steam is at or above atmospheric pressure and flows by natural pressure gradient to a condenser to yield condensed steam, and wherein the condensed steam is contacted with the wastewater in the wastewater treatment system. 
     
     
         31 . The method of  claim 21 , further comprising condensing the steam in a heat exchanger, and contacting the wastewater with the heat exchanger to transfer heat from the steam to the wastewater. 
     
     
         32 . The method of  claim 21 , further comprising contacting the steam with the wastewater to transfer heat from the steam to the wastewater. 
     
     
         33 . A method of treating wastewater, the method comprising:
 providing a first portion of wastewater in a wastewater treatment system to a venturi eductor, wherein the first portion of the wastewater operates as a motive force to create a suction inside the venturi eductor;   pulling a fluid into the venturi eductor via the suction created by the first portion of the wastewater;   combining the first portion of the wastewater and the fluid in the venturi eductor to yield a combined stream; and   mixing the combined stream with a second portion of wastewater in the wastewater treatment system.   
     
     
         34 . The method of  claim 33 , wherein providing the first portion of the wastewater to the venturi eductor comprises pumping the first portion of the wastewater through the venturi eductor. 
     
     
         35 . The method of  claim 33 , wherein the fluid is a third portion of wastewater in the wastewater treatment system. 
     
     
         36 . The method of  claim 33 , wherein the fluid comprises a gas, and providing the first portion of the wastewater to the venturi eductor comprises lowering the pressure in a portion of the wastewater treatment system. 
     
     
         37 . The method of  claim 36 , wherein lowering the pressure in the portion of the wastewater treatment system generates steam, and the steam is combined with the first portion of the wastewater in the venturi eductor to yield the combined stream, wherein combining the steam with the first portion of the wastewater raises a temperature of the first portion of the wastewater, and mixing the combined stream with the second portion of the wastewater raises the temperature of second portion of the wastewater. 
     
     
         38 . The method of  claim 33 , wherein the second portion of the wastewater is in a biological reactor of the wastewater treatment system, and mixing the combined stream with the second portion of the wastewater mixes the contents of the biological reactor. 
     
     
         39 . A wastewater treatment system comprising:
 wastewater;   water with a vapor pressure near or below atmospheric pressure,   a vacuum device; and   a biological reactor,   wherein the wastewater treatment system is configured to provide wastewater to the biological reactor, the vacuum device is configured to generate steam from the water, and the steam is provided to the wastewater to heat the contents of the biological reactor.   
     
     
         40 . The wastewater treatment system of  claim 39 , wherein the vacuum device is selected from the group consisting of a compressor, a blower, and a venturi eductor.