Large scale mixotrophic production systems

Abstract

Systems for culturing mixotrophic microorganisms on a large scale in thermally stable open systems are disclosed. Embodiments of the system include features such as lit portions, dark portions, organic carbon delivery systems, gas delivery systems, submersible thrusters for mixing, and turning vanes for guiding fluid flow. Multi-functional embodiments of the turning vane provide guidance for fluid flow and other functions such as heat exchange, nutrient delivery, gas delivery, organic carbon delivery, delivery of light, and parameter measurement by sensors.

What is claimed is: 
     
         1 . A mixotrophic bioreactor system, comprising:
 a. An open raceway pond comprising:
 i. An inner volume; 
 ii. Two straight away portions separated by a center wall and bounded by straight outer walls and a floor; and 
 iii. Two U-bend portions connecting the two straight away portions to form a continuous looped flow path, and bounded by a curved outer wall and a floor; 
   b. At least one submersible thruster disposed within the inner volume a distance from the floor, wherein the at least one thruster is positioned at a U-bend exit and configured to maximize thrust in a straight line flow of an aqueous liquid culture through the straight away portions and add momentum to the aqueous liquid culture along the looped flow path as it exits the U-bend portions of the looped flow path where some velocity of the aqueous liquid culture may be lost due to change in flow direction;   c. At least one support structure coupled to at least one of the center wall and an outer wall, the support structure suspending the at least one submersible thruster from above at a position within the inner volume of the open raceway pond; and   d. At least one organic carbon delivery device comprising an outlet positioned to deliver an organic carbon source to the inner volume of the open raceway pond.   
     
     
         2 . The mixotrophic bioreactor system of  claim 1 , further comprising at least one dissolved oxygen delivery device selected from group consisting of aeration tubing, a sparger tube, a membrane lining at least part of the floor of the raceway pond, a microbubble generator, an oxygen concentrator, a liquid oxygen injector, an oxygen saturation cone, and venturi injection by a foam fractionation device. 
     
     
         3 . The mixotrophic bioreactor system of  claim 2 , wherein the dissolved oxygen delivery device is aeration tubing or a sparger tube. 
     
     
         4 . The mixotrophic bioreactor system of  claim 3 , wherein oxygen is supplied to the culture by venturi injection. 
     
     
         5 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one organic carbon delivery device comprises a pH auxostat system. 
     
     
         6 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one thruster comprises multiple submersible thrusters and the thrusters are disposed within 20% of the U-bend end of the straight away portions. 
     
     
         7 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one submersible thruster comprises multiple submersible thrusters positioned parallel to each other and/or at spaced intervals within the inner volume of the open raceway pond. 
     
     
         8 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one submersible thruster comprises multiple submersible thrusters positioned in a staggered arrangement with relation to each other within the inner volume of the open raceway pond. 
     
     
         9 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one submersible thruster is disposed between the center wall and the outer wall of at least one of the straight away portions. 
     
     
         10 . The mixotrophic bioreactor system of  claim 1 , wherein the at least one submersible thruster is oriented to circulate a fluid medium through the continuous loop of the open raceway pond. 
     
     
         11 . The mixotrophic bioreactor system of  claim 1 , further comprising at least one heat exchanger. 
     
     
         12 . The mixotrophic bioreactor system of  claim 11 , wherein the at least one heat exchanger is disposed within at least one from the group consisting of the outer walls, the center wall, the floor, and under the floor of the open raceway pond. 
     
     
         13 . The mixotrophic bioreactor system of  claim 1 , further comprising a cover over at least part of the open raceway pond. 
     
     
         14 . A mixotrophic bioreactor system, comprising:
 a. An open raceway pond comprising:
 i. A floor; 
 ii. Two straight away portions separated by a center wall and bounded by straight outer walls and the floor; and 
 iii. Two U-bend portions connecting the two straight away portions to form a continuous looped flow path, and bounded by a curved outer wall and the floor; 
 iv. Wherein the floor is flat to create an inner volume that has a consistent depth along the entire looped flow path; 
   b. At least one submersible thruster disposed within the inner volume a distance from the floor, wherein the at least one thruster is positioned at a U-bend exit and configured to maximize thrust in a straight line flow of an aqueous liquid culture through the straight away portions and add momentum to the aqueous liquid culture along the looped flow path as it exits the U-bend portions of the looped flow path where some velocity of the aqueous liquid culture may be lost due to change in flow direction;   c. At least one support structure coupled to at least one of the center wall and an outer wall, the support structure suspending the at least one submersible thruster from above at a position within the inner volume of the open raceway pond; and   d. At least one organic carbon delivery device comprising an outlet positioned to deliver an organic carbon source to the inner volume of the open raceway pond.   
     
     
         15 . The mixotrophic bioreactor system of  claim 14 , further comprising at least one dissolved oxygen delivery device selected from group consisting of aeration tubing, a sparger tube, a membrane lining at least part of the floor of the raceway pond, a microbubble generator, an oxygen concentrator, a liquid oxygen injector, an oxygen saturation cone, and venturi injection by a foam fractionation device. 
     
     
         16 . The mixotrophic bioreactor system of  claim 15 , wherein the dissolved oxygen delivery device is aeration tubing or a sparger tube. 
     
     
         17 . The mixotrophic bioreactor system of  claim 16 , wherein oxygen is supplied to the culture by venturi injection. 
     
     
         18 . The mixotrophic bioreactor system of  claim 14 , wherein the at least one organic carbon delivery device comprises a pH auxostat system. 
     
     
         19 . The mixotrophic bioreactor system of  claim 14 , wherein the at least one thruster comprises multiple submersible thrusters and the thrusters are disposed within 20% of the U-bend end of the straight away portions. 
     
     
         20 . The mixotrophic bioreactor system of  claim 14 , wherein the at least one submersible thruster is oriented to circulate a fluid medium through the continuous loop of the open raceway pond.