Patent Publication Number: US-2011076757-A1

Title: Automated algae culture apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial No. 98217748, filed on Sep. 25, 2009. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is related to an algae culture apparatus, use thereof, and an algae culture method, and particularly to an automated algae culture apparatus, use thereof, and an automated algae culture method. 
     2. Description of Related Art 
     The use of culture equipment to culture algae and absorb carbon dioxide through photosynthesis to reduce carbon emissions has been known to persons in the art. Efficiencies of carbon fixation by microalgae may reach tens of times of that by land plants, thereby making algae the best example in using living organisms for reducing carbon emissions. 
     Currently, algae culture equipment, such as that used in large-scale farms, utilize open horizontal pools, so that large areas are required and heavy influences by the weather are present. Yields are therefore unstable, and there is also the danger of external bio-contamination. In order to overcome these problems, so-called sealed photosynthetic bioreactors are produced. In the so-called photosynthetic bioreactors, a culture medium is filled therein, and after inoculating the algae, carbon dioxide is provided by an aerating method, and the algae is cycled in the photosynthetic bioreactor. 
     When the algae grows to a certain concentration, by using a continuous centrifuge, press filter, and spray dryer, the algae is dried into dried algae for further processing. 
     This type of photosynthetic bioreactors is mostly used on algae farms or in professional laboratories, and multiple auxiliary equipments, such as aerators, nutrient supplement tanks, water supply pumps, algae recycle equipment, and professional operators, are required for operation and maintenance. Hence these photosynthetic bioreactors may only be used in professional commercial operations and are hard to popularize. 
     In addition, in current days when global warming is serious, if algae culture equipment is popularized so that algae is easily cultured in public space or households, just as in fishtanks common in most households, it would be beneficial to further enlarging the scale of saving power and reducing carbon emissions. In addition, in public spaces crowed with people, culturing microalgae rapidly and effectively purifies the indoor air. The above are all advantages that cannot be achieved by current professional culture equipment. 
     There are two main technical obstacles that are required to be overcome. One is how to easily and effectively harvest microalgae, so that the biomass of algae in the culture equipment is maintained at log phase and reaches the greatest density. The other is how to maintain, in the sealed culture system, stability of the environment, for example maintaining parameters such water quality, pH value, nutrient contents, lighting conditions, and aeration at levels suitable for algae growth for long periods of time. 
     SUMMARY OF THE INVENTION 
     In light of the above, an objective of the invention is to provide an automated algae culture apparatus, so as to miniaturize and popularize algae culture equipment. 
     The invention provides an automated algae culture apparatus which includes at least one photosynthetic reactor module and an auxiliary equipment module. The photosynthetic reactor module includes a transparent container used to contain an algae solution which includes algae. The auxiliary equipment module includes a hydraulic filter, a buffer tank and an aerator. The hydraulic filter is used to filter the algae in the algae solution and is communicated with a water outlet of the transparent container to filter the algae by gravity force. The buffer tank is communicated with a water inlet of the transparent container. The aerator is communicated with an air inlet of the transparent container. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the photosynthetic reactor module further includes an auxiliary light source which is disposed on the transparent container. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the hydraulic filter includes a filter bag or filter screen. 
     According to an embodiment of the invention, in the automated algae culture apparatus, when the automated algae culture apparatus includes a plurality of photosynthetic reactor modules, an arrangement of the photosynthetic reactor modules includes a parallel arrangement, a serial arrangement, or a matrix arrangement. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the hydraulic filter is communicated with the buffer tank. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the hydraulic filter is communicated with the aerator. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the auxiliary equipment module further includes a fluid level restoring pump which is communicated with the transparent container and the buffer tank. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the auxiliary equipment module further includes a central controller which is used to monitor an environmental parameter of the algae solution. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the environmental parameter includes a temperature of the algae solution, a pH value of the algae solution, a fluid level of the algae solution, a first carbon dioxide concentration at a gas inlet of the transparent container, the second carbon dioxide concentration at a gas outlet of the transparent container, a lighting time, a harvest time, or any combination of the above parameters. 
     According to an embodiment of the invention, the automated algae culture apparatus further includes an anti-fogging filter module which covers the gas outlet of the transparent container, and the anti-fogging filter module includes a filter screen and an anti-fogging partition. The filter screen is disposed above the gas outlet. The anti-fogging partition is disposed between the gas outlet and the filter screen. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the transparent container includes a thin-plate container or a columnar container. 
     According to an embodiment of the invention, in the automated algae culture apparatus, depending on whether the photosynthetic reactor module and the auxiliary equipment module are disposed in separation or in combination, the automated algae culture apparatus includes a separate apparatus or a combined apparatus. 
     According to an embodiment of the invention, in the automated algae culture apparatus, the auxiliary equipment module corresponds to one or more photosynthetic reactor modules. 
     Due to the above, since the automated algae culture apparatus in the invention integrates a plurality of components into the auxiliary equipment module, the algae culture equipment is miniaturized and popularized. 
     In addition, by using the automated algae culture apparatus, the algae is automatically recycled by the central controller and the hydraulic filter. Moreover, the algae harvested is capable of further being used in applications such foods, cosmetics, or biofuels. 
     Furthermore, the use of the automated algae culture apparatus in the invention includes applications in reducing energy consumption and carbon emissions, purifying air, landscaping and lighting. 
     In order to make the above and other objects, features and advantages of the present invention more comprehensible, several embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic view showing an automated algae culture apparatus according to an embodiment of the invention. 
         FIGS. 2 to 7  are schematic views each showing an automated algae culture apparatus according to other embodiments of the invention. 
         FIG. 8  is a flowchart showing an automated algae culture method according to an embodiment of the invention. 
         FIG. 9  is a graph showing growth curves of  Spirulina  according to the first experimental embodiment of the invention. 
         FIG. 10  is a graph showing growth curves of  Spirulina  according to the second experimental embodiment of the invention. 
         FIG. 11  is a graph showing a calibration curve for concentrations of algae according to the first and second experimental embodiments of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic view showing an automated algae culture apparatus according to an embodiment of the invention.  FIGS. 2 to 7  are schematic views each showing an automated algae culture apparatus according to other embodiments of the invention. In  FIGS. 2 to 7 , same modules as those in  FIG. 1  may include same elements, wherein the same elements have same reference numerals and are not repeatedly described. 
     Referring to  FIG. 1 , an automated algae culture apparatus  100  includes at least one photosynthetic reactor module  102  and an auxiliary equipment module  104 . In the automated algae culture apparatus  100 , the auxiliary equipment module  104  may correspond to one or more photosynthetic reactor modules  102 . According to the present embodiment, a situation in which one auxiliary equipment module  104  corresponds to one photosynthetic reactor module  102  is described. 
     The photosynthetic reactor module  102  includes a transparent container  106  used to contain an algae solution  108  which includes algae. The algae cultured in the present embodiment may be classified into freshwater algae or saltwater algae according to their aquatic environments for growth, or into microalgae or macroalgae according to their size. The algae cultured according to the present embodiment is, for example, green algae, blue green algae, or red algae. In addition to the algae planted therein, the algae solution  108  also includes a culture medium used for culturing the algae. A material of the transparent container  106  is, for example, glass, acrylic, or plastic. A manufacturing method thereof utilizes, for example, injection molding, vacuum molding, extrusion molding, or blow molding. 
     Referring to both  FIGS. 1 and 2 , the transparent container in the invention is not limited to the transparent container  106  shown as a thin-plate container in  FIG. 1 . Any container which is transparent and contains the algae solution  108  would suffice. For example, the transparent container may be a columnar container  106   a  of an automated algae culture apparatus  100 - 1  in  FIG. 2 . 
     In addition, still referring to  FIG. 1 , the photosynthetic reactor module  102  may further include an auxiliary light source  110  disposed on the transparent container  106 , so as to illuminate the algae in the algae solution  108  for a sufficient time at night. The auxiliary light source  110  includes, for example, light-emitting diode (LED) crystalline grains or fluorescent lamps. According to the present embodiment, LED crystalline grains are used as an example for description. A power of the auxiliary light source  110  is, for example, from 30 W to 300 W. 
     The auxiliary equipment module  104  includes a hydraulic filter  112 , a buffer tank  114  and an aerator  116 . Referring to both  FIGS. 1 and 3 , depending on whether the photosynthetic reactor module  102  and the auxiliary equipment module  104  are disposed in separation or in combination, the automated algae culture apparatus  100  is a separate apparatus or a combined apparatus. According to the embodiment in  FIG. 1 , the automated algae culture apparatus  100  is a combined apparatus in which the photosynthetic reactor module  102  and the auxiliary equipment module  104  are combined as one, but the invention is not limited thereto. According to the embodiment in  FIG. 3 , an automated algae culture apparatus  100 - 2  is a separate apparatus in which the photosynthetic reactor module  102  and the auxiliary equipment module  104  are separated from each other. 
     Referring to all  FIGS. 1 ,  3  and  4 , although in  FIGS. 1 and 3 , one auxiliary equipment module  104  corresponds to one photosynthetic reactor module  102 , the invention is not limited thereto. For example, in an automated algae culture apparatus  100 - 3  in  FIG. 4 , one auxiliary equipment module  104  may correspond to a plurality of (two) photosynthetic reactor modules  102 . 
     In addition, referring to all  FIGS. 5 to 7 , when the automated algae culture apparatus includes a plurality of photosynthetic reactor modules  102 , persons having ordinary skills in the art may arrange the photosynthetic reactor modules  102  in a specific manner according to requirements. In an automated algae culture apparatus  100 - 4  in  FIG. 5 , an arrangement of the photosynthetic reactor modules  102  is, for example, a parallel arrangement. In an automated algae culture apparatus  100 - 5  in  FIG. 6 , an arrangement of the photosynthetic reactor modules  102  is, for example, a serial arrangement. In an automated algae culture apparatus  100 - 6  in  FIG. 7 , an arrangement of the photosynthetic reactor modules  102  is, for example, a matrix arrangement. 
     Equally, although the automated algae culture apparatuses  100 - 4 ,  100 - 5 , and  100 - 6  in  FIGS. 5 to 7  are combined apparatuses having components combined as a whole, the following describes a form in which one auxiliary equipment module  104  corresponds to one photosynthetic reactor module  102 . However, persons having ordinary skills in the art may refer to the disclosure in  FIGS. 3 and 4 , so as to design the automated algae culture apparatuses  100 - 4 ,  100 - 5 , and  100 - 6  in  FIGS. 5 to 7  into separate devices and/or into fauns in which one auxiliary equipment module  104  corresponds to a plurality of photosynthetic reactor module  102 . 
     Still referring to  FIG. 1 , the hydraulic filter  112  utilizes hydraulic pressure of the algae solution  108  in the transparent container  106  to filter the algae in the algae solution  108 . In addition, the hydraulic filter  112  is communicated with a water outlet  118  of the transparent container  106  to filter the algae by gravity force, and does not require connection to a power source. The hydraulic filter  112  includes a filter bag or a filter screen  120 . A material of the filter bag or filter screen  120  is, for example, non-woven cloth, polytetrafluoroethylene (TEFLON®), plastic, or synthetic fiber. A pore size of the filter bag or filter screen  120  is, for example, 0.5 μm to 200 μm, and may be selected depending on the type of algae cultured. 
     The buffer tank  114  is communicated with a water inlet  122  of the transparent container  106 , so as to maintain a required fluid level of the algae solution  108  in the transparent container  106 . By further being communicated with the hydraulic filter  112 , the buffer tank  114  contains the filtrate filtered by the hydraulic filter  112 . A ratio of the total capacities of the transparent container  106  to that of the buffer tank  114  is 10% to 80%. When the algae is harvested, generally 30% to 80% of the total algae solution is filtered, so that the remaining algae solution provides a sufficient initial concentration for culturing in a next stage. The filtrate may be reused for one week to half a year until changing and replenishing the water, depending on conditions of the different species of algae. If the volume of the buffer tank  114  is less than the volume of the filtered algae solution because of spatial limitations, the fluid level restoring pump  126  continuously replenishes the transparent container  106  with the filtrate. Since the algae solution in the transparent container  106  is continuously diluted by the filtrate, the filtering time is prolonged to increase the total filtered quantity, thereby obtaining a predetermined harvest quantity of dry algae. 
     The aerator  116  is communicated with an air inlet  124  of the transparent container  106  and pumps the air surrounding the aerator  116 . An aerator head  116   a  of the aerator  116  pumps the air into the algae solution  108  in the transparent container  106 , causing mixing and dissolution of carbon dioxide. Since carbon dioxide is heaver than oxygen and nitrogen, which are the main constituents of air, the aerator  116  may pump air from lower positions, so as to obtain higher concentrations of carbon dioxide. Alternative, the air inlet of the aerator  116  may be communicated with a vent of a factory, a kitchen, or an incinerator, or to foul air in a public space or household, so as to obtain higher concentrations of carbon dioxide. 
     In addition, the aerator  116  may be communicated with the hydraulic filter  112 , so that the air pressure in the aerator  116  is utilized to pump the remaining algae solution  108  or filtrate into the buffer tank  114  and to blow dry the filtered algae, thereby forming dried algae. 
     In addition, the auxiliary equipment module  104  may further include a fluid level restoring pump  126  and a central controller  128 . The fluid level restoring pump  126  is communicated with the transparent container  106  and the buffer tank  114  and is capable of injecting the filtrate in the buffer tank  114  and the nutrients added in the filtrate into the transparent container  106 . The nutrients may be directly added into the buffer tank  114  as a liquid or solid powder. Alternatively nutrient powder may be added into a new filter bag or filter screen  120 , so that every time the algae solution  108  is filtered, the nutrients are dissolved into the filtrate. The nutrients are then transferred into the transparent container  106  by the fluid level restoring pump  126 . 
     The central controller  128  is used to monitor an environmental parameter of the algae solution  108 . The environmental parameter is, for example, a temperature of the algae solution, a pH value of the algae solution, the fluid level of the algae solution, a first carbon dioxide concentration at the gas inlet  124  of the transparent container  106 , a second carbon dioxide concentration at the gas outlet  130  of the transparent container  106 , a lighting time, a harvest time, or any combination of the above parameters. The central controller  128  uses, for example, a temperature sensor  132 , a pH value sensor  134 , a fluid level sensor  136 , and a carbon dioxide concentration sensor  138  of the auxiliary equipment module  104  to respectively measure the temperature of the algae solution, the pH value of the algae solution, the fluid level of the algae solution, the first carbon dioxide concentration at the gas inlet  124  of the transparent container  106 , and the second carbon dioxide concentration at the gas outlet  130  of the transparent container  106 . By measuring the first carbon dioxide concentration at the gas inlet  124  of the transparent container  106  and the second carbon dioxide concentration at the gas outlet  130  of the transparent container  106 , the efficiency of carbon dioxide absorption is timely known. In addition, an optical density (OD) sensor (not shown) may be added in the transparent container to monitor the concentration of the algae solution in real time. 
     On the other hand, the automated algae culture apparatus  100  further includes an anti-fogging filter module  140  which covers the gas outlet  130  of the transparent container  106 , so as to eliminate the water vapor and odor in the gas emitted from the photosynthetic reactor module  102 . If the present system is disposed outdoors or is used for processing factory exhaust gas, the anti-fogging filter module  140  is optional. 
     The anti-fogging filtering module  140  includes a filter screen  142  and an anti-fogging partition  144 . The filter screen  142  is disposed above the gas outlet  130 . The filter screen  142  is, for example, an activated carbon filter screen. The anti-fogging partition  144  is disposed between the gas outlet  130  and the filter screen  142 . When the automated algae culture apparatus  100  is equipped with the anti-fogging filter module  140 , the carbon dioxide concentration sensor  138  used to sense the second carbon dioxide concentration at the gas outlet  130  of the transparent container  106  is disposed in the anti-fogging filter module  140  and above the filter screen  142 . 
     In light of the above, since each of the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  integrates several components into the auxiliary equipment module  104 , a complete automated algae culture system is established by utilizing each of the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6 , thereby miniaturizing, simplifying, and popularizing the algae culture system. 
     Therefore, the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  are capable of being used at windowsides in an indoor space, so that when the sun is bright during daytime, sunlight is absorbed and heat insulated, thereby lowering the burden on the air conditioning system and purifying the air at the same time. Carbon dioxide is also absorbed, and oxygen generated during photosynthesis is emitted into the indoor space. At night, the auxiliary light sources in the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  may be switched on, thereby maintaining photosynthesis and being used as a source for mild indoor lighting. Moreover, by culturing algae of different colors (such as green algae, blue green algae, and red algae), the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  are capable of displaying different colors, thereby being great applications on indoor walls. Therefore, the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  simultaneously have functions of purifying air, reducing energy consumption and carbon emissions, lighting, landscaping, and being decorative art. 
       FIG. 8  is a flowchart showing an automated algae culture method according to an embodiment of the invention. In the automated algae culture method, the automated algae culture apparatus which is used is, for example, one of the automated algae culture apparatuses  100 ,  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 , and  100 - 6  in  FIGS. 1 to 7 . 
     Referring to  FIG. 8 , a step  5100  is performed first, in which the algae solution including algae is added in the transparent container. The algae solution also includes the culture medium. 
     Next, a step S 102  is performed. By monitoring the environmental parameter using the central controller, abnormalities in the automated algae culture apparatus are prevented. The environmental parameter is, for example, the temperature of the algae solution, the pH value of the algae solution, the fluid level of the algae solution, the first carbon dioxide concentration at the gas inlet of the transparent container, the second carbon dioxide concentration at the gas outlet of the transparent container, the lighting time, the harvest time, or any combination of the above parameters. 
     A step S 104  is then performed. When the harvest time is reached, a plurality of water pumping cycles is performed. Each water pumping cycle includes following steps. First, the algae solution is automatically drained to the hydraulic filter, so that the algae and the filtrate are filtered, wherein the filtrate flows into the buffer tank. Next, the filtrate flows back from the buffer tank to the transparent container, until the predetermined fluid level of the algae solution is reached. Before the filtrate flows back from the buffer tank to the transparent container, nutrients may be further added into the filtrate. In step S 104 , for example, the central controller controls the time during which the valves are open, so that the algae solution is automatically drained to the hydraulic filter, and the filtrate flows back from the buffer tank to the transparent container by, for example, the fluid level restoring pump. 
     Next, a step S 106  is selectively performed. By blow drying the algae filtered out by the hydraulic filter using the aerator, the dried algae is formed. Meanwhile, the remaining algae solution or filtrate is pumped into the buffer tank by the aerator. 
     Thereafter, in a step S 108 , the algae which is filtered is recycled. A method for recycling the algae is, for example, taking out the filter bag or filter screen from the hydraulic filter, so that the algae attached to the filter bag or filter screen is recycled. 
     As known from the above embodiments, the above automated algae culture apparatus is capable of automatically recycling the algae through the central controller and the hydraulic filter. In addition, the algae recycled using the above method is capable of being used in applications such as foods, cosmetics, or biofuels. 
       FIG. 9  is a graph showing growth curves of  Spirulina  according to the first experimental embodiment of the invention.  FIG. 10  is a graph showing growth curves of  Spirulina  according to the second experimental embodiment of the invention.  FIG. 11  is a graph showing a calibration curve for concentrations of algae according to the first and second experimental embodiments of the invention. 
     For operational conditions in the first experimental embodiment and the second experimental embodiment, the automated algae culture apparatus and method according to the above embodiments are used to culture the algae  S. maxima , and the algae is aerated with air, whereas no additional carbon dioxide is supplemented. 
     Referring to all  FIGS. 9 to 11 , the concentrations of the algae in  FIGS. 9 and 10  are represented by absorption values (at a wavelength of 680 nm). In  FIG. 9 , the absorption value for the initial concentration of the algae solution is 0.1, and in  FIG. 10 , the absorption value for the initial concentration of the algae solution is 0.2. During the 5 to 8 day period for culturing, each absorption value for the final concentrations may reach 5 to 8 times the absorption values for the initial concentrations. By applying the absorption values for the final concentrations in  FIGS. 9 and 10  to the calibration curve representing absorption values and concentrations in  FIG. 11 , it is calculated that the final concentration of the algae solution in  FIG. 9  is about 0.36 g/L, and the final concentration of the algae solution in  FIG. 10  is about 0.5 g/L. 
     As known from the first and second experimental embodiments, by using the automated algae culture apparatuses in the above embodiments, the culture concentration is increased 5 to 8 times in one week. If high concentrations of carbon dioxide are added into the automated algae culture apparatus, the culture efficiency is further enhanced one to two times. 
     In summary, the above embodiments have at least the following advantages: 
     1. The automated algae culture apparatuses according to the above embodiments miniaturize and popularize the algae culture equipment. 
     2. The automated algae culture method is capable of automatically recycling algae, and the algae which is recycled is capable of being used in applications such foods, cosmetics, or biofuels. 
     3. The automated algae culture apparatuses in the above embodiments are capable of being used for reducing energy consumption and carbon emissions, purifying air, landscaping and lighting. 
     Although the present invention has been disclosed above by the embodiments, they are not intended to limit the present invention. Anybody skilled in the art can make some modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protecting range of the present invention falls in the appended claims.