TWI615467B - Microalgae harvest module and method of harvesting microalgae - Google Patents

Abstract

A method of harvesting microalgae. A flocculant and magnetic particles are added to the culture solution containing the microalgae cells to form microalgae magnetic flocs suspended in the culture solution. The culture solution containing the microalgae magnetic floes is placed in a harvesting container. A magnetic field is applied to the outer wall of the harvesting container so that the microalgae magnetic flocs are adsorbed on the inner wall of the harvesting container to be separated from the culture liquid. In the case where the microalgae magnetic flocs are adsorbed on the inner wall of the harvesting container, the culture liquid in the harvesting container is removed. The magnetic field is removed to obtain microalgal magnetic floes. In addition, a microalgae harvesting module is also provided.

Description

Microalgae harvesting module and microalgae harvesting method

The invention relates to a harvesting module and a harvesting method, and in particular to a method for harvesting a microalgae harvesting module and microalgae.

In recent decades, global demand for microalgal biomass for food, feed, biodiesel, and chemicals has increased, and microalgal biomass has great potential to replace many of today's agricultural biomass sources. However, according to the analysis of the American ASP (Aquatic Species Program) program, the cost of the concentrated separation and drying dehydration process accounts for 38% of the total cost of microalgae biodiesel production. The International Microalgae Biomass Organization (ABO) also pointed out The collection of microalgae cells accounts for at least 20~30% of the total production cost. It is also said that microalgae production has so far been limited by high cost economic value products.

In general, after the cultivation of microalgae, the utilization of microalgae usually includes procedures such as harvesting, drying, wall breaking and product extraction, wherein the harvesting process has a significant impact on the yield of the product. At present, a variety of microalgae harvesting technologies have been developed, including technologies such as centrifugal harvesting, filtration and harvesting, floatation and harvesting, and coagulation and harvesting. Among them, centrifugal harvesting is one of the most common methods for microalgae harvesting, which has the advantage of harvesting microalgae cells. The rate is as high as 95% or more, but the disadvantage is that the hardware cost of the centrifuge is high and the energy consumption for operation is also high. Therefore, centrifugal harvesting is commonly used for microalgae products that require relatively pure and high margins. Conversely, filtration has the advantage of low energy consumption, but it is only suitable for collecting microalgae cells with a specific size or more, so its recovery efficiency is not high, and it is mainly used for harvesting agglomerated microalgae.

The floating harvesting uses a high pressure to produce micro-bubbles, and most of the microalgae cells are brought to the liquid surface by the rise of the microbubbles, and the upper liquid level is collected by the water flow. The harvesting efficiency of the harvesting harvest can reach about 70%, and the culture liquid after harvesting can be recycled and continuously used for microalgae cultivation. However, since the microbubbles are continuously released at a high pressure when the algae is harvested, there is a disadvantage of high energy consumption. According to the method of changing the surface charge of the microalgae cells, the coagulation recovery is usually a slow agitation by adding a flocculant or a direct current to cause aggregation of the microalgae cells. Since the accumulated microalgae cells can settle quickly, the harvesting efficiency of the microalgae can be increased by about 70 to 95% by filtering or directly removing the moisture of the upper layer, and the energy consumption is low. In addition, if the microalgae settled by flocculation are not taken again, the water content of the recovered algae is still high. Although it can be treated by filtration, this will result in additional cost effects for coagulation recovery.

That is to say, since the microalgae cells have only a small volume of about 3 to 30 μm, and it is difficult to maintain the density of the algae in a high state in the cultivation of microalgae which continuously maintains a high degree of growth, the current microalgae cells are collected. The method of receiving is difficult to solve both cost and harvesting efficiency. However, improving harvesting efficiency is one of the key technologies to be developed by the microalgae breeding industry. Therefore, it is necessary to develop a microalgae harvesting system with low energy consumption, easy mass production and high collection rate to meet the requirements of industrial feasibility.

The invention provides a microalgae harvesting module, which can achieve the purpose of low energy consumption and high harvesting efficiency.

The microalgae harvesting module of the invention comprises a breeding unit and a harvesting unit. The culture unit comprises a culture tank for accommodating the culture liquid containing the microalgae cells, and when the microalgae cells are to be collected, the flocculant and the magnetic particles are added to the culture tank, wherein the microalgae cells, the flocculant and the magnetic body The particles form microalgae magnetic floes suspended in the culture solution in the culture tank. The harvesting unit includes a harvesting container and a magnetic field generating device. The harvesting container is coupled to the culture tank for accommodating the culture liquid containing the microalgae magnetic floc. The magnetic field generating device provides a removable magnetic field to the outer wall of the harvesting container, and in the presence of the magnetic field, the microalgal magnetic flocs are collected on the inner wall of the harvesting container to be separated from the culture liquid.

In an embodiment of the invention, the harvesting unit is a detachable harvesting unit detachably coupled to the breeding unit.

In an embodiment of the invention, the harvesting unit further includes a collector for collecting microalgae magnetic floes retained in the harvesting container after the magnetic field is removed.

In an embodiment of the invention, the harvesting container is a hollow tube, and the collector is a piston having a push rod, and the piston and the inner wall of the hollow tube are in a sliding fit.

In an embodiment of the invention, the magnetic field generating device is a permanent magnet or an electromagnet.

In an embodiment of the invention, the first infusion tube is further included, wherein the culture The trough has an output port, and the harvesting container has an input port, and the output port of the culture trough is connected to the input port of the harvesting container via the first infusion tube.

In an embodiment of the invention, the recycling unit is further connected to the harvesting unit, and the recovery unit comprises a culture liquid storage tank connected to the harvesting container for storing the culture liquid from the harvesting container.

In an embodiment of the invention, a pump is further included for pumping the culture solution in the culture solution storage tank into the culture tank.

In an embodiment of the invention, the culture tank is a photobioreactor.

In an embodiment of the invention, the material of the culture tank comprises polyvinyl chloride (PVC), polyethylene (PE), polymethylmethacrylate (PMMA) or glass.

In an embodiment of the invention, the aquaculture unit further includes an aeration control device coupled to the bottom of the culture tank.

The method of harvesting the microalgae of the present invention comprises the following steps. A flocculant and magnetic particles are added to the culture solution containing the microalgae cells to form microalgae magnetic flocs suspended in the culture solution. The culture solution containing the microalgae magnetic floes is placed in a harvesting container. A magnetic field is applied to the outer wall of the harvesting container so that the microalgae magnetic flocs are adsorbed on the inner wall of the harvesting container to be separated from the culture liquid. In the case where the microalgae magnetic flocs are adsorbed on the inner wall of the harvesting container, the culture liquid in the harvesting container is removed. The magnetic field is removed to obtain microalgal magnetic floes.

In an embodiment of the invention, a method for obtaining microalgae magnetic flocs A microalgae magnetic floc retained in the harvesting container is collected using a collector.

In an embodiment of the invention, the harvesting container is a hollow tube, and the collector is a piston having a push rod, and the piston and the inner wall of the hollow tube are in a sliding fit.

In an embodiment of the invention, the culture fluid removed from the harvesting container is further included.

In an embodiment of the invention, the flocculating agent is a metal-containing inorganic coagulant or a polymer coagulant.

In an embodiment of the invention, the metal-containing inorganic coagulant comprises ferric chloride (FeCl ₃ ) or aluminum trichloride (AlCl ₃ ).

In an embodiment of the invention, the magnetic particles include ferroferric oxide (Fe ₃ O ₄ ), ferric oxide (Fe ₂ O ₃ ), or a combination thereof.

Based on the above, the microalgae harvesting module and the microalgae of the present invention are harvested by using a flocculating agent and magnetic particles and applying a magnetic field to recover microalgal magnetic floes having a compact structure and a low volumetric water content. In this way, the microalgae harvesting with low energy consumption, high recovery efficiency and water reuse can be realized, which meets the needs of industrial development.

The above described features and advantages of the invention will be apparent from the following description.

10‧‧‧Microalgae harvesting module

100‧‧‧ farming unit

110‧‧‧ culture tank

112, 114, 212, 214, 412, 414 ‧ ‧ infusion port

120‧‧‧Aeration control device

200‧‧‧ harvesting unit

210‧‧‧ harvesting containers

210a‧‧‧ outer wall

210b‧‧‧ inner wall

220‧‧‧Magnetic field generating device

230‧‧‧ Collector

232‧‧‧Put

234‧‧‧Piston

300‧‧‧ pump

400‧‧‧Recycling unit

410‧‧‧ culture solution storage tank

510, 520, 530‧‧‧ Infusion tube

F‧‧‧Microalgae magnetic flocs

MD, MD’‧‧‧ culture solution

MF‧‧‧ magnetic field

S10~S50‧‧‧Steps

1 is a schematic view of a microalgae harvesting module in accordance with an embodiment of the present invention.

2A to 2C are partial enlarged views of the harvesting unit of Fig. 1.

3A and 3B are partial schematic views of a harvesting unit of a microalgae harvesting module according to an embodiment of the invention.

4 is a schematic flow chart of a method for harvesting microalgae according to an embodiment of the present invention.

Fig. 5A is a photomicrograph of a control group in Experimental Example 1, in which the culture solution contains only microalgae cells.

Fig. 5B is a photomicrograph of the experimental group in Experimental Example 1, in which the culture solution contains microalgae cells, a flocculating agent, and magnetic particles.

Fig. 6 is a line graph showing the recovery efficiency of microalgae cells to which different concentrations of Fe ₃ O ₄ magnetic particles were added in Experimental Example 2.

Fig. 7 is a growth line graph of the microalgae culture solution repeatedly used in microalgae cell culture after the continuous culture for 14 days and the recovery of the microalgae in Experimental Example 3.

1 is a schematic view of a microalgae harvesting module in accordance with an embodiment of the present invention. Referring to FIG. 1 , the microalgae recovery module 10 includes a culture unit 100 and a recovery unit 200 . In the present embodiment, the microalgae recovery module 10 includes, for example, a pump 300 and a recovery unit 400.

The culture unit 100 includes a culture tank 110 for accommodating the culture liquid MD containing microalgae cells, a flocculating agent (not shown), and magnetic particles (not shown), wherein the microalgae cells, the flocculating agent and the magnetic particles The microalgae magnetic floc F suspended in the culture solution MD is formed in the culture tank 110. In detail, first in the culture tank 110 The culture medium MD cultures the microalgae cells, and after the microalgae cell culture is completed (ie, at the end of the culture), the flocculant and the magnetic particles are added to the culture tank 110, so that the microalgae cells, the flocculating agent and the magnetic particles form microalgae magnetic flocculation. Matter F. In the present embodiment, the culture unit 100 includes, for example, an array in which a plurality of culture tanks 110 are connected in parallel, but is not intended to limit the present invention. In other embodiments, the culture tanks 110 may also be arranged in other ways, such as in series or in a combination of series and parallel. Further, the number of the culture tanks 110 is, for example, one to 100, and is not particularly limited, and may be adjusted as needed. However, it is not intended to limit the invention. The culture tank 110 is, for example, a closed photobioreactor or an open culture tank, and the culture tank 110 is, for example, a tubular container. The culture unit 100 further includes, for example, an aeration control device 120 coupled to the bottom of the culture tank 110. The illumination source of the culture tank 110 is, for example, sunlight or an artificial light source such as a fluorescent lamp, a light-emitting diode, or the like. The material of the culture tank includes polyvinyl chloride, polyethylene, polymethyl methacrylate, glass or other permeable material. In this embodiment

The above-described microalgae strains, for example strains of the genus Chlorella (Chlorella), green algae, blue-green algae Nannochloropsis sp (Nannochloropsis), Spirulina (fromSpirulina) Isochrysis sp (Isochrysis), Synechococcus ( Synechococcus ) or Haematococcus . Preferred microalgae strains are, for example, green algae, blue-green algae, Chlorella vulgaris, or Haematococcus.

The flocculating agent is, for example, a metal-containing inorganic coagulant or a polymer coagulant. In the present embodiment, the flocculating agent is, for example, an inorganic metal solution such as ferric chloride which is soluble in a liquid to form Fe ³⁺ or Fe ²⁺ or aluminum trichloride. The magnetic particles are, for example, particles comprising a magnetic field attracting, including triiron tetroxide, ferric oxide or a combination thereof. In the present embodiment, the concentration of the magnetic particles is, for example, 12.5 mg/L to 50 mg/L.

In the present embodiment, the culture tank 110 has an infusion port 112 and an infusion port 114. The infusion port 112 is, for example, a liquid inlet port of the culture tank 110, and the infusion port 114 is, for example, a liquid outlet port of the culture tank 110. The infusion port 112 and the infusion port 114 are, for example, further provided with a regulating valve (not shown) for controlling the flow rate of the culture medium containing the microalgae cells flowing into the culture tank 110, and the microflow flowing out of the culture tank 110. The flow rate of the culture solution of the algal magnetic floc F.

The harvesting unit 200 includes a recovery container 210 and a magnetic field generating device 220. The harvesting container 210 is coupled to the culture tank 110 for accommodating the culture liquid MD containing the microalgae magnetic floc F. In the present embodiment, the harvesting unit 200 is, for example, a detachable harvesting unit that is detachably coupled to the culture unit 100. That is, the harvesting unit 200 can be separated from the farming unit 100 to facilitate subsequent processing. In the present embodiment, the harvesting container 210 is, for example, a tubular container having an infusion port 212 and an infusion port 214. The infusion port 212 is, for example, a liquid inlet port of the collection container 210, and the infusion port 214 is, for example, a liquid outlet port of the collection container 210. In the present embodiment, the microalgae recovery module 10 further includes a first infusion tube 510 that connects the infusion port 114 of the culture tank 110 with the infusion port 212 of the recovery container 210. That is, the culture liquid MD containing the microalgae magnetic floc F enters the recovery container 210 through the culture tank 110 via the first infusion tube 510.

2A to 2C are partial enlarged views of the harvesting unit 200 of Fig. 1. The magnetic field generating device 220 provides a removable magnetic field MF to the outer wall 210a of the recovery container 210. In detail, as shown in FIG. 2A, the microalgae are contained before the magnetic field MF is supplied. The culture solution MD of the magnetic floc F remains in the recovery container 210. In the state where the magnetic field MF is supplied, as shown in Fig. 2B, the microalgae magnetic floc F is collected on the inner wall 210b of the harvesting container to be separated from the culture liquid MD'. When the magnetic field MF is supplied to the outer wall 210a of the harvesting container, the microalgae magnetic floc F is adsorbed on the inner wall 210b of the collecting container to be separated from the culture liquid MD, so that the culture liquid MD' is, for example, a clarified culture liquid. After the culture solution MD' is removed and the magnetic field MF is removed, as shown in FIG. 2C, the microalgae magnetic floc F remains in the harvesting container 210. In particular, in the present embodiment, since the microalgae magnetic floc F is in the form of algal mud, as shown in FIG. 2C, after the magnetic field MF is removed, the microalgae magnetic floc F remains substantially adhered to the mining. The inner wall 210b of the container is closed.

The magnetic field generating device 220 is, for example, a permanent magnet or an electromagnet in which an electromagnet generates a magnetic field by a current. The magnetic field generating device 220 is disposed, for example, on opposite sides of the outer wall 210a of the harvesting container 210 to form a magnetic field MF such as that shown in FIG. 2B. In Fig. 1, a set of magnetic field generating devices 220 arranged in parallel is taken as an example, but in other embodiments, a plurality of sets of parallel magnetic field generating devices may be provided.

As shown in FIG. 3A and FIG. 3B, in the embodiment, the harvesting unit 200 further includes a collector 230. When the harvesting unit 200 is removed from the microalgae recovery module 10, the collector can be used. 230 collects the microalgae magnetic floc F remaining in the harvesting container 210. In the present embodiment, the harvesting container 210 is, for example, a hollow tube, and the collector 230 is, for example, a piston 234 having a push rod 232 that is in sliding engagement with the inner wall of the hollow tube. Of course, the present invention is not limited thereto. In other embodiments, the recovery container 210 and the collector 230 may have other structures.

In the present embodiment, as shown in FIG. 1, the recovery unit 400 is connected to the recovery unit 200. The recovery unit 400 includes, for example, a culture solution storage tank 410 connected to the recovery container 210 for storing the culture solution MD' from the recovery container 210. The culture solution storage tank 410 has an infusion port 412 and an infusion port 414. The infusion port 412 is, for example, a liquid inlet port of the culture solution storage tank 410, and the infusion port 414 is, for example, a liquid outlet port of the culture solution storage tank 410. In the present embodiment, the microalgae recovery module 10 further includes a second infusion tube 520 that connects the infusion port 214 of the recovery container 210 with the infusion port 412 of the culture solution storage tank 410. That is, the culture liquid MD' separated from the microalgae magnetic floc F via the second infusion tube 520 enters the culture solution storage tank 410 from the recovery container 210. In addition, in the embodiment, the microalgae recovery module 10 further includes a third infusion tube 530 connected to the infusion port 414 of the culture solution storage tank 410 and the infusion port 112 of the culture tank 110. That is, the recovered culture solution MD' is introduced into the culture tank 110 from the culture solution storage tank 410 via the third infusion tube 530. In the present embodiment, the pump 300 is connected, for example, to the recovery unit 400 for sucking the culture solution MD' in the culture solution storage tank 410 into the culture tank 110. In this way, the purpose of reusing the culture solution MD' can be achieved.

In the present embodiment, the recovery unit 400 further includes, for example, a turbidity meter (not shown) for measuring the turbidity of the recovered culture solution MD' to detect the biomass concentration in the culture solution MD'. Moreover, since the harvesting unit 200 can operate in a closed or open environment, the microalgae harvesting module 10 can be a closed or open system.

Next, the above-described microalgae recovery module 10 will be described as an example to describe the method of harvesting microalgae according to an embodiment of the present invention, but the present invention is not limited thereto. That is, The method of harvesting the microalgae of the present invention can be carried out by other equipment.

4 is a schematic flow chart of a method for harvesting microalgae according to an embodiment of the present invention. Referring to FIG. 1 to FIG. 4 simultaneously, first, step S10 is performed to add a flocculating agent and magnetic particles to the culture liquid MD containing microalgae cells to form microalgae magnetic floc F suspended in the culture liquid MD. In this embodiment, the step S10 includes placing the culture medium MD containing the microalgae cells in the culture tank 110, culturing the microalgae cells, and after the microalgae cell culture is completed (and at the end of the culture), the flocculant and the flocculant are The magnetic particles are added to the culture tank 110 such that the microalgae cells, the flocculating agent, and the magnetic particles form the microalgae magnetic floc F. Among them, the flocculant changes the surface charge of the microalgae cells in the culture medium MD, and in the process, the microalgae cells form a magnetic microalgae magnetic floc F with the magnetic particles.

Next, in step S20, the culture solution MD containing the microalgae magnetic floc F is placed in the harvesting container 210. In the present embodiment, for example, the regulating valve for controlling the infusion port 112 is opened and the flow rate is controlled by the regulating valve, so that the culture liquid MD containing the microalgae magnetic floc F flows to the harvesting container 210 via the first infusion tube 510, as shown in the figure. 2A is shown.

Then, as shown in FIG. 2B, step S30 is performed to apply a magnetic field MF to the outer wall 210a of the harvesting container 210 so that the microalgae magnetic floc F is adsorbed on the inner wall 210b of the harvesting container 210 to be separated from the culture liquid MD'. . In the present embodiment, this step S30 includes turning on the means for generating the magnetic field MF or placing the magnetic field generating means on the outer wall 210a of the harvesting container 210. As a result, the microalgae magnetic floc F with magnetic particles is collected by the magnetic material outside the container 210 when passing through the recovery container 210. The field is attracted and attached to the inner wall 210b of the harvesting container 210. At this time, the culture liquid MD' in the recovery container 210 is, for example, a culture liquid MD' which substantially removes the microalgae magnetic floc F.

Then, as shown in Fig. 2C, step S40 is performed to remove the culture liquid MD' in the recovery container 210 in the case where the microalgae magnetic floc F is adsorbed on the inner wall 210b of the recovery container 210. In the present embodiment, this step S40 further includes recovering the culture liquid MD' removed from the recovery container 210. 'Step S50 is performed to remove the magnetic field MF to obtain the microalgae magnetic floc F. In this embodiment, as shown in FIG. 3A and FIG. 3B, the step S50 includes disassembling the recovery container 210 from the microalgae recovery module 10, and then removing the magnetic field MF, wherein the microalgae magnetic floc F is substantially retained. On the inner wall 210b of the recovery container 210. Then, by pushing the push rod 232 to move the piston 234 in the recovery container 210, the microalgae magnetic floc F is pushed out from the recovery container 210, and the microalgae magnetic floc F is collected. In this way, the harvesting of the microalgal magnetic floc F is completed.

In the present embodiment, the microalgae harvesting is further performed by using the culture solution MD' in the culture solution storage tank 410. In detail, first, the residual biomass concentration in the culture solution MD' in the culture solution storage tank 410 is detected using a turbidimeter. Next, the nutrient solution required for culturing the microalgae is added to the culture solution MD' based on the detected biomass concentration. Then, the culture solution MD' is returned to the culture tank 110 via the third infusion tube 530 to perform another culture for microalgae harvesting. In particular, the method of harvesting the microalgae of the present embodiment does not affect the subsequent oil extraction efficiency.

In the above-mentioned microalgae harvesting module and microalgae harvesting method, by flocculation The agent causes the microalgae cells to form magnetic microalgae magnetic flocs with the magnetic particles, so that the microalgae magnetic flocs can be harvested by applying a magnetic field. In particular, since the microalgae magnetic flocs are adsorbed on the inner wall of the harvesting container, they can be easily separated from the culture liquid in the harvesting container, thereby obtaining microalgae magnetic properties having a compact structure and a low volumetric water content. Flocs. In addition, since the microalgae magnetic flocs have a good separation effect from the culture solution, the culture solution can be recovered for reuse. In this way, microalgae harvesting with low energy consumption, low cost, high harvesting efficiency and water reuse can be realized, which meets the needs of industrial development.

Next, the recovery efficiency of the harvesting method of the microalgae of the present invention will be described by way of an experimental example.

Experimental Example 1: Formation of microalgae magnetic flocs

In this experimental example, a culture solution containing microalgae is provided, the microalgae is Chlorella sp., the culture solution is artificial seawater, and the cultured algae strain has a concentration of about 2 g of microalgae per liter of culture liquid. The above microalgae-containing culture solution was divided into an experimental group and a control group, and further added with a concentration of 10 mL/L of the culture solution of ferric chloride as an inorganic metal flocculant and a concentration of 25 mg/L of tetraoxide three in the experimental group. Iron acts as a magnetic particle. The control group and the experimental group were observed using an optical microscope, and the results are shown in Fig. 5A and Fig. 5B, respectively.

5A and 5B, the microalgae of the comparative example was dispersed in the culture solution, and the microalgae of the experimental example was aggregated with the magnetic particles to integrate the microalgae magnetic flocs. That is, the microalgae and magnetic particles form microalgal magnetic floes in the presence of a flocculant.

Experimental Example 2: Harvesting efficiency of microalgae

The microalgae harvesting module of the above embodiment was used to carry out the harvesting of the microalgae. In this experimental example, the cultured microalgae cells have a concentration of about 0.6 g of microalgae/liter of culture medium, and the concentrations of the microalgae-containing medium are respectively added to the culture medium containing 12.5 mg/L, 25 mg/L, and 37.5 mg/L. And ferroferric oxide magnetic particles of 50 mg/L of the culture solution. During the experiment, after the culture liquid containing the microalgae magnetic flocs is introduced into the harvesting container, the magnetic field of the harvesting container is applied for different time periods, and then the concentration of the microalgae cells in the culture liquid recovered by the culture liquid storage tank is measured. The surface magnetic flux density of the magnetic field is 4700~4900 Gauss (attractiveness is 77.8 Newtons). According to the microalgae cell concentration before the introduction of the harvesting container and the concentration of the microalgae cells recovered in the culture solution storage tank, the harvesting efficiency of the microalgae cells was calculated, and the recovery efficiency line diagram is shown in FIG. 6 .

From the recovery efficiency line graph in Fig. 6, it can be seen that when the ferroferric oxide magnetic particles are added at a concentration of 12.5 mg/L, 25 mg/L, 37.5 mg/L, and 50 mg/L, the microalgae cells are harvested. The efficiency has a significant effect after the magnetic field lasts for 30 seconds, and the recovery efficiency of the microalgae cells can reach more than 90% of the harvesting efficiency after 60 seconds. In addition, the microalgae magnetic floc formed has a low water content per unit volume and a harvesting concentration of up to 150 g/L. Based on the values obtained in this experimental example, one metric ton of microalgae solution can be harvested by adding only about 20 grams of magnetic particles.

Experimental Example 3: Recycling of culture solution

The microalgae harvesting module of the above embodiment was used to carry out the harvesting of the microalgae. In this experimental example, three cultures were sequentially performed. During the experiment, the same ambient temperature, culture temperature, pH value of the culture solution and illumination were maintained, and the growth of the microalgae was detected according to the absorbance (OD) at 682 nm. First, in The culture medium containing the microalgae cells (referred to as the first culture solution) is added to the culture unit for the first culture, and after 4 days of culture, the microalgae cell concentration is increased from 0.2 g/L to 1.25 g/L, which includes The microalgae culture solution is recovered by the recovery unit, and the culture solution in the culture solution storage tank is recovered. Next, the second culture is carried out using the recovered culture solution (referred to as the second culture solution), and the nutrient solution required for the microalgae is added to the recovered culture solution and grown for 5 days, and the concentration of the recovered culture solution is approximately The above harvesting and recovery operations were repeated from 0.25 g/L to 1.12 g/L. Then, using the recovered culture solution (referred to as the third culture solution) for the third culture, the nutrient solution required for the microalgae is added to the recovered culture solution and grown for 5 days, and the concentration of the recovered culture solution is approximately Growth from 0.25 g/L to 1 g/L. After 14 days of continuous culture and two microalgae recovery, the growth line diagram is shown in Fig. 7.

From the growth line graph in Fig. 7, it is understood that the recovered culture solution can be adapted for recycling for the next cultivation, harvesting, and recovery. Therefore, the microalgae harvesting module of the above embodiment has practicality.

In summary, in the microalgae harvesting module and the microalgae harvesting method of the present invention, the microalgae cells and the magnetic particles are aggregated into the magnetic microalgae magnetic flocs by the flocculating agent, and then the magnetic field is applied. Ways to harvest microalgae magnetic floes. In particular, since the microalgae magnetic floc is strongly adsorbed by the magnetic force on the inner wall of the harvesting container, it can be easily and quickly separated from the culture liquid in the harvesting container, thereby obtaining a compact structure and a low volumetric water content. Microalgae magnetic flocs. Compared with the conventional method of using a flocculating agent, after the algae body is agglomerated, it is still necessary to remove the remaining medium or water by centrifugation or filtration, and the harvesting method of the microalgae of the present invention can be greatly shortened. The harvesting time and cost of algae enable the harvested microalgae cells to be widely used in health foods, biological baits or raw materials for biomass energy after further processing or extraction.

Since the harvesting unit can use various magnetic field devices to provide a magnetic field, it is easy to adjust the magnetic field strength and turn the magnetic field on or off in such a manner as to directly set or remove the magnet or power the electromagnet, thereby increasing the convenience of use. In addition, the harvesting unit can be operated in a closed or open environment. Therefore, the harvesting unit can be easily combined with the existing breeding unit or incorporated into the breeding system to form the microalgae harvesting module, and since the size of the harvesting unit can be determined according to parameters such as the number and size of the culture tank to be subjected to. Appropriate adjustments are not particularly limited and are therefore beneficial for large-scale harvesting. More importantly, the use of magnetic particles does not affect the oil extraction efficiency of the microalgae cells after harvest, and the magnetic particles can be recycled, and the remaining culture solution separated from the microalgae magnetic floes can continue to the next batch. The second microalgae cultivation. Therefore, the present invention provides a microalgae harvesting module and a microalgae harvesting method with low energy consumption, high recovery rate and water resource reuse, which can greatly reduce the operating cost of microalgae harvesting and breeding, and is in line with industrial development. demand.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

S10~S50‧‧‧Steps

Claims (12)

A microalgae harvesting module comprises: a culture unit comprising a culture tank for accommodating a culture solution containing a microalgae cell, a flocculating agent and a magnetic particle, wherein the microalgae cell, The flocculating agent and the magnetic particles form a microalgae magnetic floc suspended in the culture solution in the culture tank, wherein the culture tank is a photobioreactor for performing illumination, and the flocculant comprises trichlorination Iron (FeCl ₃ ) or aluminum trichloride (AlCl ₃ ); and a recovery unit comprising: a recovery container coupled to the culture tank for containing the culture liquid containing the microalgae magnetic floc a magnetic field generating device for providing a removable magnetic field to the outer wall of the harvesting container, wherein the microalgae magnetic floc is collected on the inner wall of the harvesting container in the presence of the magnetic field a first infusion tube, wherein the culture tank has an output port, the recovery container has an input port, and the output port of the culture tank is connected to the input port of the recovery container via the first infusion tube a recycling unit, and the recovery receipt Connecting, the recovery unit comprises a culture solution storage tank connected to the recovery container for storing the culture solution from the collection container; and a pump for storing the culture solution storage tank The medium in the solution is pumped into the culture tank. The microalgae recovery module according to claim 1, wherein the recovery unit is a detachable recovery unit detachably connected to the culture unit. The microalgae recovery module according to claim 1, wherein the recovery unit further comprises a collector for collecting magnetic flocculation of the microalgae retained in the recovery container after removing the magnetic field. Things. The microalgae recovery module according to claim 3, wherein the recovery container is a hollow tube, and the collector is a piston having a push rod, the piston and The inner wall of the hollow tube is a sliding fit. The microalgae recovery module according to claim 1, wherein the magnetic field generating device is a permanent magnet or an electromagnet. The microalgae recovery module according to claim 1, wherein the material of the culture tank comprises polyvinyl chloride, polyethylene, polymethyl methacrylate or glass. The microalgae recovery module according to claim 1, wherein the culture unit further comprises an aeration control device coupled to the bottom of the culture tank. A method for collecting microalgae, comprising: providing a culture tank for accommodating a culture solution containing microalgae cells, adding a flocculating agent and a magnetic particle to the culture solution to form a suspension in the culture solution; a microalgae magnetic floc, wherein the culture tank is a photobioreactor for illuminating, the flocculating agent is a metal-containing inorganic coagulant, and the metal-containing inorganic coagulant comprises ferric chloride (FeCl _{3 )} Or aluminum trichloride (AlCl ₃ ); placing the culture solution containing the microalgae magnetic floc in a recovery container; applying a magnetic field to the outer wall of the recovery container, so that the microalgae magnetic floc is Adsorbing on the inner wall of the harvesting container to separate from the culture liquid; in the case where the microalgae magnetic floc is adsorbed on the inner wall of the harvesting container, removing the culture liquid in the harvesting container And removing the magnetic field to obtain the microalgal magnetic floc. The method for obtaining the microalgae magnetic floc as described in claim 8, wherein the method of obtaining the microalgae magnetic floc comprises collecting the microalgae magnetic floc retained in the harvesting container using a collector. The method for harvesting microalgae according to claim 9, wherein the harvesting container is a hollow tube, and the collector is a piston having a push rod, and the inner wall of the piston and the hollow tube For sliding fit. The method for harvesting microalgae as described in claim 8 of the patent application includes The culture solution removed from the harvesting container is recovered. The method for recovering microalgae according to claim 8, wherein the magnetic particles comprise ferroferric oxide (Fe ₃ O ₄ ), ferric oxide (Fe ₂ O ₃ ), or a combination thereof.