Patent Application: US-201213473872-A

Abstract:
a microalgae culture system that provides greater control of a culture due to distribution and the shape of its components . the system allows for the possibility to incorporate gases into the medium , resulting in an increased culture yield and lower energy consumption per unit volume . the system generally includes a pool with a circular mantle , pvc parts and a removable lid .

Description:
the culture system is designed considering escalation , that is , a spatial distribution of ponds that can easily increase the area of production by the incorporation of new cells ( groups of three ponds connected to a central pumping system ) ( see fig7 ). ponds are circular with a cylindrical mantle and conic bottom , preferably of fiberglass or coated cement . the preferred form of construction of the pond is that where the pond diameter is greater than its height . during operation , ponds are covered by a hexagonal removable lid of a transparent material , preferably alveolar polycarbonate ( fig3 and 4 ). for visual inspection of the pond interior , one of the faces of the hexagon can be removed . the system keeps a stable temperature of the culture medium within a suitable range for the growth of microalgae . this is achieved because ponds are partially buried in the ground ( fig4 , dotted line ), which allows to counteract day - night thermal oscillations and not suffer significant variations in the average temperature between winter and summer . the ideal range of ph for the operation of the system is between 6 . 0 and 11 . 0 . the culture system performs propulsion by air . this propulsion system operates connected to a blower outside the installation ( 5 ), this blower allows to feed several modular groups or cells at the same time , producing a mild pumping while performing the gas exchange between the culture medium and the air pumped . the culture medium is distributed into the ponds in the movement of recirculation to maintain a constant stirring , to this end each pond has in its interior a first aerator ( 12 ) which carries the culture medium and the air , the first aerator ( 12 ) comprising , or alternatively consisting of , a straight tube near the liquid surface and above it at an angle between 30 ° and 60 ° respect to the liquid surface , which discharges into the pond tangentially against the cylindrical mantle of such pond , forming a circular flow or vortex which is also part of the propulsion system of the culture medium inside the pond . the second pvc aerator carries the culture medium and the air , and comprises , or alternatively consist of , a semicircular tube ( 16 ) with a plug at one end ( 9 ), located near the bottom of such pond and which is part of the propulsion system of the culture medium inside the pond . said second aerator comprises structure defining perforations through which the mixture of air or gas and culture medium is injected into the pond , such perforations are directed towards the bottom of the pond in order to prevent clogging of the holes by decantation of the cells in the culture ( 8 ). loading of the ponds with the culture medium and algae is made through the hydraulic line ( 6 ). once the pond ( 1 ) is filled with culture medium ( 14 ), recirculation starts . passage of pressurized gasses ( 5 ) is opened through the gas inlet valve ( 10 ), and these may be air , carbon dioxide or a mixture thereof , and the hydraulic line ( 11 ) is closed . the gases push the culture medium upwards and partially mix with water , which returns to the pond ( 1 ) entering tangentially against the circle . this movement generates a circular current . the culture medium is mixed and releases photosynthesis gases that mix with the pressurized gases at the top of the pond . after spinning around the system , the culture medium returns to the center of the pond to the recirculation line ( 4 ). this line allows filling of the ponds with culture medium ( 14 ), incorporation of the inoculums , and harvesting is performed . air line ( 5 ) incorporates gases into the system ( air ) to supply power for the recirculation . the system described in this application has no moving or metallic parts , which gives it a great versatility with respect to the photoreactors described in the state of the art . this feature makes it possible to use the invention for culturing microalgae either from fresh or salt water , among which are arthrospira platensis , monoraphidium graphitti , chlorella vulgaris , anabaena variabilis and nannochloropsis oculata , chlorella neustonica , respectively . growth of the arthrospira platensis microalgae in the photobioreactor described in this application : ambient air is used as a source of co 2 ; density measurements were performed by cell counting using sedgewick - rafter chamber . the results are expressed in cells per milliliter . harvest was weighed completely dry and is expressed in grams . performance calculations are made by adding the period harvesting , divided by the culture area ( 14 m 2 ) and the number of days in the period , the results being expressed in grams per square meter per day ( g / m 2 / day ). rest days and no - harvesting days are included . under standard culture conditions for arthrospira platensis described in example 1 , a continuous harvesting was conducted for 1 week . as a harvesting criterion , harvesting was performed each time the system exceeded an average of 180 , 000 cells per milliliter . under standard culture conditions for arthrospira platensis , a continuous harvesting was conducted for a 1 week . this time the secondary bubbler was incorporated , which aims to increase turbulence , improve incorporation of co 2 into the system and degassing of the medium . as a harvesting criterion , harvesting was performed each time the system exceeded an average of 180 , 000 cells per milliliter . the following table shows the harvesting results . the foregoing descriptions present numerous specific details that provide a thorough understanding of various embodiments of the invention . it will be apparent to one skilled in the art that various embodiments , having been disclosed herein , may be practiced without some or all of these specific details . in other instances , components as are known to those of ordinary skill in the art have not been described in detail herein in order to avoid unnecessarily obscuring the present invention . it is to be understood that even though numerous characteristics and advantages of various embodiments are set forth in the foregoing description , together with details of the structure and function of various embodiments , this disclosure is illustrative only . other embodiments may be constructed that nevertheless employ the principles and spirit of the present invention . accordingly , this application is intended to cover any adaptations or variations of the invention . for purposes of interpreting the claims for the present invention , it is expressly intended that the provisions of section 112 , sixth paragraph of 35 u . s . c . are not to be invoked unless the specific terms “ means for ” or “ step for ” are recited in a claim . murray moo - young and yusuf chisti ( 1994 ). bioreactor applications in waste treatment . resources , conservation and recycling . vol 11 , 13 - 24 asterio sánchez miróna , m . carmen cerón garcía , antonio contreras gómeza , francisco garcía camachoa , emilio molina grimaa and yusuf chisti ( 2003 ). shear stress tolerance and biochemical characterization of phaeodactylum tricornutum in quasi steady - state continuous culture in outdoor photobioreactors . biochemical engineering journal . vol 16 ( 3 ), 287 - 297 han xua , xiaoling miao and qingyu wu ( 2006 ). high quality biodiesel production from a microalga chlorella protothecoides by heterotrophic growth in fermenters . journal of biotechnology . vol 126 ( 4 ), 499 - 507 shakeel a . khan , rashmib , mir z . hussaina , s . prasada and u . c . banerjeeb ( 2009 ). prospects of biodiesel production from microalgae in india . renewable and sustainable energy reviews , vol 13 ( 9 ), 2361 - 2372 . raja , r ., hemaiswarya , s ., kumar , n . a ., sridhar , s ., & amp ; 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