CN105624042A

CN105624042A - Microalgae harvesting method in process of absorbing industrial flue gas CO2 with microalgae

Info

Publication number: CN105624042A
Application number: CN201410604417.9A
Authority: CN
Inventors: 汪靓; 孙予罕; 魏伟; 赵权宇; 林钟铨; 唐涛; 刘金丽
Original assignee: Shanghai Advanced Research Institute of CAS
Current assignee: Shanghai Advanced Research Institute of CAS
Priority date: 2014-10-30
Filing date: 2014-10-30
Publication date: 2016-06-01

Abstract

The invention discloses a microalgae harvesting method in process of absorbing industrial flue gas CO2 with microalgae. The microalgae harvesting method comprises following steps: 1) microalgae is cultured, and when the concentration of microalgae reaches 0.3 to 10g/L, harvesting is to be performed; 2) in harvesting, under microalgae dark conditions, the concentration of CO2 in inlet gas is increased, continuous aeration is carried out until algae liquid pH value is reduced to be lower than 7; 3) chitosan is added, and aeration is carried out until flocculation of microalgae is caused; and 4) aeration is stopped, concentration of microalgae is carried out via natural sedimentation or air floatation, and microalgae is harvested. According to the microalgae harvesting method, pre-acidification of the microalgae liquid to be harvested is carried out with high concentration CO2 in industrial flue gas, chitosan is added for flocculation of microalgae, and at last microalgae is harvested via sedimentation or air floatation; operation is simple; energy consumption is low; no secondary pollution is caused; and adding of organic or inorganic acids is not needed to achieve ideal microalgae harvesting effect.

Description

Microalgae is utilized to absorb industrial flue gas CO2The harvesting method of microalgae in process

Technical field

The present invention relates to technical field of microalga biology, utilize microalgae to absorb industrial flue gas CO particularly to one₂The harvesting method of microalgae in process.

Background technology

Since 20th century, due to industrial development rapidly, the swift and violent increase of population and using in a large number of non-renewable Fossil fuel (oil and coal) so that CO in air₂The ability that the concentration of isothermal chamber gas can bear far beyond natural ecosystems, creates greenhouse effect. At present, carbon emission reduction has become whole world common recognition, especially for the China originated for main energy sources with coal, reduces CO₂Discharge be the inevitable choice of national development low-carbon economy. Except the low-carbon (LC) high added value comprehensive development and utilization of coal, greatly develop microalgae industry, for CO₂Green reduction of discharging, be consistent with the effective measures of ecological Carbon cycle.

Microalgae biotechnology is used for CO₂During reduction of discharging, generally by the addressing of microalgae mass culture apparatus and industry CO₂The location of emission source combines, and generally all contains the CO of 15��35% (v/v) in the flue gas of the industry such as power plant, cement plant, coking plant, steel plant₂, microdisk electrode then selects the CO of 0.5��5% mostly₂Concentration, such concentration is more conducive to the growth of microalgae and brings more preferably CO₂Absorption efficiency, therefore the way with air mixed diluting can be adopted to reduce CO the flue gas of original position₂Concentration. Notification number is that the Chinese invention patent of CN101632898B proposes one and utilizes microalgae absorption from flue gas CO₂Method and apparatus and online test method, this invention describes utilize duct type Photoreactor cultivate microalgae elimination flue gas in CO₂Equipment and flow process, but how flow process carries out microalgae harvesting after not mentioned microdisk electrode.

The harvesting method of microalgae is broadly divided into two classes: a class is physical method, such as centrifugal, filtrations, air supporting, natural subsidence etc., it is generally required to the harvest equipment that extra interpolation is special, adds the complexity of cost and operation; Equations of The Second Kind is chemical method, mainly adds chemical floc, such as aluminium polychlorid or iron chloride, polyacrylamide, makes homodisperse microalgae cell flocculate into big granule, in conjunction with physical method, such as air supporting or precipitation so that it is to complete algae water and separate. The addition of chemical floc, generally all at more than 100mg/L, all introduces pollution to the microalgae of results and culture fluid, affects the later use of microalgae and water. Chitosan, also known as chitosan, it is the very abundant natural alkaline polysaccharides of a kind of reserves, application is had at numerous areas such as medicine, food, chemical industry, cosmetics, water process, biomedical engineerings, nontoxic, being generally considered safely and effectively microalgae flocculant at present, enrichment microalgae effect is better. The construction unit of chitosan is 2-amino-2 deoxyglucose, is connected by ��-Isosorbide-5-Nitrae glycosidic bond and forms straight-chain polysaccharide macromole.-NH on chitosan chain₂Can in conjunction with H from aqueous solution⁺Rear formation-NH₃ ⁺So that it is self becomes cationic high-molecular. The surface of microalgae cell, generally with a large amount of negative charges, makes its individuality be uniformly dispersed in culture fluid because the opposite sex is repelled each other, it is difficult to spontaneous enrichment settles. Cationic high-molecular can destroy this stable state, and after adding chitosan, microalgae will flocculate, and is then enriched with precipitation. Chitosan generally will be previously dissolved in dilute acid soln, then could be used for microalgae flocculation. Publication number is the method for concentration of application for a patent for invention a kind of marine microalgae of proposition of CN101095459A, the method adopts organic acid (including formic acid, acetic acid, propanoic acid, benzoic acid, lactic acid or the monoxone) aqueous solution adding chitosan to microalgae-culture fluid, microalgae is made to flocculate, then passing through air supporting or precipitation harvesting microalgae, microalgae recovery rate is up to more than 95%.

Summary of the invention

The technical problem to be solved in the present invention is to provide one and utilizes microalgae to absorb industrial flue gas CO₂The harvesting method of microalgae in process, the method is simple to operate, cost is low, nonhazardous.

For solving above-mentioned technical problem, the microalgae that utilizes of the present invention absorbs industrial flue gas CO₂The harvesting method of microalgae in process, comprises the following steps:

1) cultivate microalgae, when microalgae concentration reaches 0.3��10g/L, wait to gather in the crops;

2) when starting to gather in the crops, when microalgae lucifuge, CO in air inlet is raised₂Concentration, continuous aeration drops to acid interval to algae solution pH;

3) chitosan is added, aeration, until microalgae flocculation;

4) stop aeration, gather in the crops after concentrating microalgae with natural sedimentation or air-float method.

Described microalgae is screen the microalgae with good development performance obtained from common environment microalgae, including scenedesmus, chlorella, salt alga, chlamydomonas, Chlorococcum, micro-plan ball algae, nostoc, spirulina, flat algae, chrysophyceae. The cultivation of microalgae can carry out in open raceway pond or closed Photoreactor. During cultivation, the method for mixing air is utilized to make CO₂Concentration be maintained at the scope that micro algae growth is favourable, it is advantageous to CO₂Concentration range is 0.5��5% (v/v).

Step 2) in, lucifuge condition refers to when not providing artificial light source, night not to have a sunlight or covers algae solution with light screening material daytime. CO in air inlet₂Concentration be 5��25% (v/v), or the maximum CO that on-the-spot source of the gas can be provided by₂Concentration. Acid interval is pH=4.8��6.5.

Step 3) in, the concentration of the chitosan of addition is 1��25mg/L, and the gas of aeration is air or flue gas.

The present invention utilizes industrial flue gas to contain high concentration CO₂Feature regulate and control the pH value of algae solution, acidifying in advance needs the algae solution of results, adds chitosan and makes microalgae flocculate, with precipitation or air-float method collection algae after flocculation. Compared with receiving algae method with tradition, the method for the present invention is simple to operate, energy consumption is low, will not produce secondary pollution; Compared with the receipts algae method that the application for a patent for invention of publication number CN101095459A discloses, the method of the present invention other organic or inorganic acid additional need not adjust pH value, to reach desirable microalgae harvesting effect, it is thus able to realize effective utilization of resource on the spot, both reduce cost, in turn simplify operation.

Accompanying drawing explanation

Fig. 1 is the microalgae harvesting process chart of the present invention.

Detailed description of the invention

Embodiment 1

Outdoor gas-lifting type stacked rectangular capsules cultivates a strain scenedesmus (Scenedesmussp.), in order to absorb certain steam power plant flue gas CO₂. CO in the flue gas that this steam power plant discharges₂Concentration, 15��20%, utilizes air compressor machine supply air by CO during cultivation₂Concentration dilution cultivates microalgae to 2%. Microalgae concentration prepares results when reaching 5g/L, and results carry out when night does not have sunlight, closes air compressor machine so that CO in air inlet₂Concentration rise to about 20% (v/v), continuous aeration drops to 5.3 to algae solution pH, add 10mg/L chitosan, keep aeration after 1 minute, stop aeration, allow the microalgae natural sedimentation fully of flocculation, the microalgae of results precipitation, recovery ratio reaches 95%.

Embodiment 2

Outdoor column airlift reactor cultivates a chlorella (Chlorellasp.), in order to absorb certain cement plant flue gas CO₂. CO in the flue gas that this cement plant is discharged₂Concentration, 15��35%, utilizes air compressor machine supply air by CO during cultivation₂It is diluted to 5% to cultivate microalgae. Microalgae concentration prepares results when reaching 3g/L, and results carry out when night does not have sunlight, are turned down by air compressor air intake pressure so that CO in air inlet₂Concentration rise to about 25% (v/v), continuous aeration drops to 5.0 to algae solution pH, add 8mg/L chitosan, keep aeration after 1.5 minutes, stop aeration, allow the microalgae natural sedimentation fully of flocculation, the microalgae of results precipitation, recovery ratio reaches 97%.

Embodiment 3

Outdoor Pig airlift reactor cultivates a chlorella (Chlorellasp.), in order to absorb certain steel plant flue gas CO₂. CO in the flue gas that these steel plant discharge₂Concentration, 18��25%, utilizes air compressor machine supply air by CO during cultivation₂It is diluted to 2% to cultivate microalgae. Microalgae concentration prepares results when reaching 5g/L, covers sunlight with gobo, close air compressor machine so that CO in air inlet when daytime gathers in the crops₂Concentration rise to about 25% (v/v), continuous aeration drops to 5.5 to algae solution pH, add 12mg/L chitosan, keep aeration after 2 minutes, stop aeration, allow the microalgae natural sedimentation fully of flocculation, the microalgae of results precipitation, recovery ratio reaches 98%.

Claims

1. utilize microalgae to absorb industrial flue gas CO₂The harvesting method of microalgae in process, it is characterised in that comprise the following steps:

3) chitosan is added, aeration, until microalgae flocculation;

2. method according to claim 1, it is characterized in that, described microalgae is screen the microalgae with good development performance obtained from common environment microalgae, including scenedesmus, chlorella, salt alga, chlamydomonas, Chlorococcum, micro-plan ball algae, nostoc, spirulina, flat algae, chrysophyceae.

3. method according to claim 1, it is characterised in that step 1), open raceway pond or closed Photoreactor are cultivated microalgae.

4. method according to claim 1, it is characterised in that step 1), utilize the method for mixing air to make CO₂Concentration be maintained at the scope that micro algae growth is favourable.

5. method according to claim 4, it is characterised in that step 1), CO₂Volumetric concentration be 0.5��5%.

6. method according to claim 1, it is characterised in that step 2), CO in air inlet₂Volumetric concentration be 5��25%, or the maximum CO that on-the-spot source of the gas can be provided by₂Concentration.

7. method according to claim 1, it is characterised in that step 2), described acid interval is pH=4.8��6.5.

8. method according to claim 1, it is characterised in that step 3), the gas of aeration is air or flue gas.

9. method according to claim 1, it is characterised in that step 3), the concentration of chitosan is 1��25mg/L.