Method and system for harvesting micro organisms

Abstract

In an embodiment of the invention, aqueous growth medium in a pond can be used to grow algae which can be pumped to a primary dewatering device where the algae can be separated from the harvested growth media based on the flow of the harvested growth media and gravity. The flow through the primary de-watering device can be optimized to maintain log phase growth in the pond, while minimizing the pumping cost and maximizing the concentration of total solids in the primary de-watered algae.

What is claimed is: 
     
         1 . A device for cultivating and harvesting algae comprising:
 an open pond including a paddle seeded with an aqueous growth medium (AGM) at a AGM level;   an intrachannel clarifier located in the open pond including an entrance, a solid back wall, one or more baffles, a sloped solid floor with at least one outlet, where the entrance is below the AGM level and adjacent the low point of the sloped solid floor, where the at least one outlet is positioned at the low point of the sloped solid floor, where the solid back wall is at least partially above the AGM level, where a portion of the AGM enters the intrachannel clarifier through the entrance at a first flow rate and the intrachannel clarifier fractionates the AGM into at least a top fraction having a first concentration of algae and a bottom fraction having a second concentration of algae, where at least one exit for the top fraction is direct flow to the open pond for algaculture, where the bottom fraction exits through the at least one outlet;   a secondary de-watering device (SDWD) including one or more inlets and a plurality of outlets;   one or more tubes connecting the at least one outlet of the intrachannel clarifier through the one or more inlets to the SDWD; and   a flow control device to regulate a second flow rate of the bottom fraction from the intrachannel clarifier through the one or more tubes into the SDWD.   
     
     
         2 . The device of  claim 1 , where the intrachannel clarifier fractionates based on one or more of the first flow rate, a settling time and the second flow rate. 
     
     
         3 . The device of  claim 1 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 5 percent; and   an upper limit of approximately 60 percent of the concentration of algae in the AGM.   
     
     
         4 . The device of  claim 1 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 0.5 Optical Density; and   an upper limit of approximately 2 Optical Density.   
     
     
         5 . The device of  claim 1 , further comprising a pump to remove the bottom fraction to the SDWD at a transport rate. 
     
     
         6 . A device for cultivating and harvesting algae comprising:
 an open pond including a paddle seeded with an aqueous growth medium (AGM) at a AGM level;   an intrachannel clarifier located in the open pond including an entrance, a solid back wall, one or more baffles, a sloped solid floor with at least one outlet, where the entrance is below the AGM level and adjacent the low point of the sloped solid floor, where the at least one outlet is positioned at the low point of the sloped solid floor, where the solid back wall is at least partially above the AGM level, where a portion of the AGM enters the intrachannel clarifier through the entrance at a first flow rate and the intrachannel clarifier fractionates the AGM into at least a top fraction having a first concentration of algae and a bottom fraction having a second concentration of algae, where the second concentration is greater than the first concentration with increased settling time, where at least one exit for the top fraction is direct flow to the open pond for algaculture, where the bottom fraction exits through the at least one outlet;   a secondary de-watering device (SDWD) including one or more inlets and a plurality of outlets;   one or more tubes connecting the at least one outlet of the intrachannel clarifier through the one or more inlets to the SDWD; and   a flow control device to regulate a second flow rate of the bottom fraction from the intrachannel clarifier through the one or more tubes into the SDWD, where the intrachannel clarifier fractionates based on one or more of the first flow rate, the settling time and the second flow rate.   
     
     
         7 . The device of  claim 6 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 5 percent; and   an upper limit of approximately 60 percent of the concentration of algae in the AGM.   
     
     
         8 . The device of  claim 6 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 0.5 Optical Density; and   an upper limit of approximately 2 Optical Density.   
     
     
         9 . The device of  claim 6 , further comprising a pump to remove the bottom fraction to the SDWD at a transport rate. 
     
     
         10 . A device for cultivating and harvesting algae comprising:
 an open pond including a paddle seeded with an aqueous growth medium (AGM) at a AGM level;   an intrachannel clarifier located in the open pond including an entrance, a solid back wall, one or more baffles, a sloped solid floor with at least one outlet, where the entrance is below the AGM level and adjacent the low point of the sloped solid floor, where the at least one outlet is positioned at the low point of the sloped solid floor, where the solid back wall is at least partially above the AGM level, where a portion of the AGM enters the intrachannel clarifier through the entrance at a first flow rate and the intrachannel clarifier fractionates the AGM into at least a top fraction having a first concentration of algae and a bottom fraction having a second concentration of algae, where the second concentration is greater than the first concentration with increased settling time, where at least one exit for the top fraction is direct flow to the open pond for algaculture, where the bottom fraction exits through the at least one outlet;   a secondary de-watering device (SDWD) including one or more inlets and a plurality of outlets;   one or more tubes connecting the at least one outlet of the intrachannel clarifier through the one or more inlets to the SDWD;   a pump to remove the bottom fraction to the SDWD at a transport rate; and   a flow control device to regulate a second flow rate of the bottom fraction from the intrachannel clarifier through the one or more tubes into the SDWD, where the intrachannel clarifier fractionates based on one or more of the first flow rate, the settling time, the transport rate and the second flow rate.   
     
     
         11 . The device of  claim 10 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 5 percent; and   an upper limit of approximately 60 percent of the concentration of algae in the AGM.   
     
     
         12 . The device of  claim 10 , where the entrance, the flow control device and the one or more baffles adjust the second concentration of algae between:
 a lower limit of approximately 0.5 Optical Density; and   an upper limit of approximately 2 Optical Density.