Method for harvesting microalgae through alkalescence flocculation-foam separation and separation device

A technology of foam separation and flocculation, applied in enzymology/microbiology devices, biochemical cleaning devices, biochemical equipment and methods, etc., can solve the problems of large amount of foam additives, unsuitable for industrial scale-up, high production capacity, etc. The effect of reducing consumption and additive consumption, strengthening gas-liquid-solid contact mass transfer, and reducing the accumulation of inorganic ions

Active Publication Date: 2015-12-23
TSINGHUA UNIV
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  • Abstract
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  • Application Information

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Problems solved by technology

Chinese patent CN101549231 discloses a method of coupling dissolved air flotation and hydrocyclone separation to quickly separate bubble-carried microalgae. Hydrocyclone separation requires liquid to enter the hydrocyclone at a relatively high flow rate, which consumes a lot of energy and is also unsuitable. industrial amplification
In one embodiment of the patent, the device was used to collect a certain kind of self-produced foam microalgae, and the concentration ratio reached 20 times, but the recovery rate and harvest time were not reported. Due to the lack of necessary technical features, it was impossible to Efficiency to judge
And above-mentioned method all directly carries out froth flotation from dilute algae liquid, and required froth aid consumption is big, and equipment volume is big, and separation time is long, and its economy is still not good;
[0008] In summary, although the existing technology provides a variety of technical methods for microalgae separation, it has high recovery rate and concentration multiple, low cost and high production capacity, and is suitable for industrialized technology of large-scale oil-producing microalgae separation and recovery. Still subject to further development

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  • Method for harvesting microalgae through alkalescence flocculation-foam separation and separation device
  • Method for harvesting microalgae through alkalescence flocculation-foam separation and separation device
  • Method for harvesting microalgae through alkalescence flocculation-foam separation and separation device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] Embodiment 1, weak alkaline flocculation-foam separation continuous harvesting of microalgae:

[0080] 1) Marine Chlorella (MarineChlorella), with a diameter of 3 to 8 μm, is cultivated in the marine chlorella culture medium (adopting f / 2 improved seawater medium, the pH value of the culture medium is 8.4, referred to as the algae culture medium) , the algae cell concentration in the marine Chlorella culture medium was 4.5×10 at the end of the cultivation 7 a / mL;

[0081]2) Using the operation mode of continuous operation, inject the above-mentioned algae culture solution with marine chlorella into the pH adjustment tank I, and add ammonia water (20% by mass fraction) to adjust its pH to 10-10.5; The liquid inlet conduit 1 flows into the settling tank 2 at a flow rate of 60L / h (hydraulic retention time is 1h), and is divided into a flocculated concentrated algae liquid and a supernatant liquid, and the flocculated concentrated algae liquid flows out through the outlet ...

Embodiment 2

[0088] Embodiment 2, weak alkaline flocculation-foam separation continuous harvesting of microalgae:

[0089] The same steps as those in Example 1 were completely adopted, only the flow rate of the culture solution of Chlorella marinae flowing into the settlement tank 2 was changed. When the flow rate of marine chlorella culture solution is different (thereby the hydraulic retention time is different), the separation effect obtained is as shown in table 2, as can be known from table 2: along with the prolongation of hydraulic retention time, higher Recovery and concentration times.

[0090] Table 2. Separation effect of flocculation and sedimentation

[0091] Algae fluid flow (L / h)

Embodiment 3

[0092] Example 3, Weak alkaline flocculation-foam separation intermittent harvesting of microalgae:

[0093] 1) The algae species and culture solution adopted are the same as in Example 1, and the concentration of algae cells in the culture solution of Chlorella marine algae was 4.5×10 when the cultivation ended. 7 a / mL;

[0094] 2) Adopt the operation method of intermittent operation, add 60 L of the above-mentioned marine chlorella culture solution with marine chlorella to the sedimentation tank 2 at a time, and add ammonia water (mass fraction 20%) to adjust its pH to 10 ~10.5; start to settle, so that the settling time of the algae culture solution in the settling tank 2 is 0.5~4h, divided into flocculation concentrated algae liquid and supernatant, the flocculated concentrated algae liquid is extracted through the outlet 4 at the bottom of the settling tank 2, and Store in the intermediate storage tank IV to be separated in the next step; and pass CO into the supernatant...

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Abstract

The invention discloses a method for harvesting microalgae through alkalescence flocculation-foam separation and a separation device. The method comprises the following steps: 1) adjusting the pH value of an algae liquid; 2) performing flocculating settling on the algae liquid in a settling pond after pH adjustment, thereby obtaining a flocculated algae liquid and supernate; and 3) introducing air into a foam separation tower which is filled with the flocculated algae liquid, a surfactant and a separation additive so as to enrich microalgae to foams, and collecting the foams, thereby obtaining the microalgae. The separation device comprises the settling pond and a circulation foam tower, wherein the flocculated algae liquid outlet in the settling pond is connected with an algae liquid inlet of the circulation foam tower through a middle storage tank. The circulation foam tower consists of a foam section and a rising section, and a circulation section is divided into a rising area and a settling area by using a guide cylinder, so that gas-liquid-solid contact mass transfer can be improved, and the separation efficiency can be improved. The method is high in recycling rate and concentration ratio, can operate continuously, is short in separation time and is applicable to large-scale industrial production, high in production capacity and relatively low in cost, and meanwhile circulation of water can be achieved.

Description

technical field [0001] The invention belongs to the technical field of separation and harvesting of microalgae, and in particular relates to a method and a separation device for harvesting microalgae through weak alkaline flocculation-foam separation. Background technique [0002] Microalgae harvesting is considered to be one of the most difficult factors in the process of producing biofuels from microalgae. Usually, the dry weight of algae in the microalgae culture solution is only 0.02-0.5kg / m 3 , generally need to be concentrated to 20-70kg / m 3 above, and then proceed to the next step of the process. At present, the separation and harvesting technologies of microalgae mainly include centrifugal separation, flocculation separation, air flotation / bubble separation and membrane separation. Although centrifugal separation and membrane separation can achieve higher concentration multiples and recovery rates, their cost is high and their production capacity is small, so they...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12N1/12C12M1/00C12M1/04
Inventor 蒋国强于常军王桂伟张建涛
Owner TSINGHUA UNIV
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