阅读说明：本技术 一种利用水华蓝藻生产挥发性短链脂肪酸的方法 (Method for producing volatile short-chain fatty acid by using bloom-forming cyanobacteria ) 是由 王冬波 都明婷 刘旭冉 于 2019-11-28 设计创作，主要内容包括：本发明提供了一种水华蓝藻生产挥发性短链脂肪酸的方法,属于藻类资源化处理与处置领域。本发明过氧化钙预处理技术为主,辅以快速搅拌,最后进行厌氧发酵生产挥发性短链脂肪酸,不仅促进水华蓝藻胞外聚合物及细胞壁的破裂和胞内有机物的释放,提高了其发酵过程中的碳氮比,从而在较短的时间周期内大幅度提高了蓝藻厌氧发酵过程中挥发性短链脂肪酸的产量,同时,避免藻毒素的产生和积累,实现了水华蓝藻减量化、无害化及资源化处理与处置。(The invention provides a method for producing volatile short-chain fatty acid by bloom-forming cyanobacteria, belonging to the field of algae resource treatment and disposal. The calcium peroxide pretreatment technology is mainly assisted by rapid stirring, and finally carries out anaerobic fermentation to produce volatile short-chain fatty acid, thereby promoting the rupture of extracellular polymers and cell walls of the water-blooming cyanobacteria and the release of intracellular organic matters, improving the carbon-nitrogen ratio in the fermentation process, greatly improving the yield of the volatile short-chain fatty acid in the anaerobic fermentation process of the cyanobacteria in a shorter time period, simultaneously avoiding the generation and accumulation of algal toxins, and realizing the reduction, harmless and resource treatment and disposal of the water-blooming cyanobacteria.)

1. A method for producing volatile short-chain fatty acid by using bloom-forming cyanobacteria is characterized by comprising the following steps:

(1) concentrating and precipitating: concentrating and precipitating the salvaged and collected bloom-forming cyanobacteria, and controlling the total solid content to be 10000-20000 mg/L;

(2) pretreatment: transferring the concentrated bloom-forming cyanobacteria into a pretreatment reaction tank; then adding calcium peroxide, wherein the adding amount is 5-20% (w/w) of the total solid content of the blue algae; stirring immediately after adding, wherein the stirring speed is 150-250 rpm, and the pretreatment time is 0.5-2.0 days;

(3) anaerobic fermentation: transferring the pretreated blue algae mixed solution serving as a fermentation substrate to an anaerobic fermentation tank, and blowing off nitrogen for 3-10 min; then inoculating anaerobic fermentation sludge with the volatile solid content of 10000-30000 mg/L, wherein the inoculation amount is 8% -15% (v/v) of the blue algae mixed solution; then sealing the fermentation tank, and carrying out anaerobic fermentation under the stirring condition to produce volatile short-chain fatty acid.

2. The method for producing short-chain volatile fatty acid by using water-blooming cyanobacteria as claimed in claim 1, wherein the concentration and precipitation of the water-blooming cyanobacteria in the step (1) are carried out in a concentration and precipitation tank, and the precipitation time is 3-10 days.

3. The method for producing short-chain volatile fatty acids by using water-blooming cyanobacteria as claimed in claim 1, wherein the calcium peroxide in step (2) is in a powder state, the pretreatment reaction tank is a concrete tank, and the stirring is performed by an iron flap turbine stirrer.

4. The method for producing short-chain volatile fatty acid by using water-blooming cyanobacteria as claimed in claim 1, wherein the pH of the cyanobacteria mixture in the step (3) is 9.0-11.0, the purity of nitrogen used for nitrogen stripping is above 99.5%, the anaerobic fermentation sludge is residual sludge at the bottom of a sludge storage tank in a sewage treatment plant, the temperature of the sealed fermentation tank is controlled to be 25-55 ℃, the stirring intensity is set to be 100-150 rpm, and the fermentation time is 4-8 days.

Technical Field

The invention relates to the field of algae recycling treatment and disposal, in particular to a method for producing volatile short-chain fatty acid by using bloom-forming cyanobacteria.

Background

With the further acceleration of the urbanization process, a large amount of nutrient salts such as nitrogen, phosphorus and the like enter lakes, so that the eutrophication of lake water is increasingly serious, blue algae in the lakes are massively propagated, and the water bloom phenomenon is developed in a large scale, so that a plurality of famous freshwater lakes such as Dian-lake, Tai-lake, nested lake and the like in China face the problem. To solve this problem, researchers have developed a number of preventive and control measures, such as salvage, flocculation algae removal, and biological algae control, that effectively inhibit the further outbreak of water bloom. However, if the salvaged or killed water-blooming cyanobacteria is not treated and disposed scientifically and effectively, secondary pollution is certainly caused to the lake water body or the surrounding environment, and the water-blooming cyanobacteria needs to be treated in a harmless and quantitative reduction manner. Meanwhile, the bloom-forming cyanobacteria contains a large amount of organic matters such as protein, sugar and the like, so that the bloom-forming cyanobacteria turns harm into benefit, changes waste into valuable and has very important practical significance for solving the problems of environment, energy and the like faced by the current situation so as to achieve the purpose of comprehensive treatment.

At present, the research on the resource utilization of the bloom-forming cyanobacteria at home and abroad mainly comprises the processing of the bloom-forming cyanobacteria into high-efficiency amino acid fertilizer, the incineration, the protein extraction and the like, but the dehydration and the detoxification of the cyanobacteria gradually become the bottleneck of the resource utilization of the cyanobacteria in the process of the industrialized development of the bloom-forming cyanobacteria. The blue algae serving as the biomass raw material is subjected to anaerobic fermentation, so that large-scale industrial treatment can be realized, the blue algae does not need to be dehydrated, and algal toxins can be degraded to a certain degree in the fermentation process, so that reduction, harmlessness and recycling of the water bloom algae are realized. Proteins, sugars, and the like rich in algae can be used as substrates by anaerobic microorganisms to produce short-chain fatty acids, hydrogen, methane, and the like. The volatile short-chain fatty acid can be used as an economical and applicable carbon source in the nitrogen and phosphorus removal process of a sewage treatment plant, and can also be recycled as bioplastic, and the production of the volatile short-chain fatty acid becomes a research hotspot in recent years. However, the blue algae has high nitrogen content and low carbon-nitrogen ratio, and extracellular substances and cell walls of the blue algae limit the release and hydrolysis of intracellular organic matters in the anaerobic fermentation process, so that the untreated blue algae has poor effect of producing volatile short-chain fatty acids through anaerobic fermentation. However, to date, research on this problem has been rare, limiting the development of resource utilization of cyanobacteria.

Therefore, how to economically and effectively improve the carbon-nitrogen ratio of the bloom-forming cyanobacteria, promote the rupture of extracellular polymers and cell walls and the release of intracellular organic matters, thereby improving the production of volatile short-chain fatty acids by anaerobic fermentation, simultaneously overcoming the dehydration problem of the cyanobacteria and avoiding the generation and accumulation of algal toxins is a problem to be solved urgently at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for producing volatile short-chain fatty acid by using water-blooming cyanobacteria. The method is mainly based on a calcium peroxide pretreatment technology, is assisted by rapid stirring, and finally carries out anaerobic fermentation to produce volatile short-chain fatty acid, so as to solve the problem of poor effect of producing the volatile short-chain fatty acid by the anaerobic fermentation of blue-green algae.

In order to achieve the purpose, the technical method adopted by the invention comprises the following steps:

(1) concentrating and precipitating: concentrating and precipitating the salvaged and collected bloom-forming cyanobacteria, and controlling the total solid content to be 10000-20000 mg/L;

(2) pretreatment: transferring the concentrated bloom-forming cyanobacteria into a pretreatment reaction tank; then adding calcium peroxide, wherein the adding amount is 5-20% (w/w) of the total solid content of the blue algae; immediately stirring after adding, wherein the stirring speed is 150-250 rpm, and the pretreatment time is 0.5-2.0 days;

(3) anaerobic fermentation: transferring the pretreated blue algae mixed solution serving as a fermentation substrate to an anaerobic fermentation tank, and blowing off nitrogen for 3-10 min; then inoculating anaerobic fermentation sludge with the volatile solid content of 10000-30000 mg/L, wherein the inoculation amount is 8% -15% (v/v) of the blue algae mixed solution; then sealing the fermentation tank, and carrying out anaerobic fermentation under the stirring condition to produce volatile short-chain fatty acid.

Wherein the concentration and precipitation of the bloom-forming cyanobacteria in the step (1) are carried out in a concentration and precipitation tank, and the precipitation time is 3-10 days; in the step (2), the calcium peroxide is in a powder state, the pretreatment reaction tank is a concrete tank, and the stirring is performed by an iron hinge type turbine stirrer; the pH value of the blue algae mixed liquid in the step (3) is 9.0-11.0, the purity of nitrogen used for nitrogen stripping is more than 99.5%, the anaerobic fermentation sludge is residual sludge at the bottom of a sludge storage tank in a sewage treatment plant, the temperature of the sealed fermentation tank is controlled to be 25-55 ℃, the stirring intensity is set to be 100-150 rpm, and the fermentation time is 4-8 days.

The purpose of concentration and precipitation in the invention is to reduce the water content of the blue algae, and the standing precipitation is adopted, so that the problem of mechanical dehydration energy consumption is avoided, and the blue algae with the total solid content of 10000-20000 mg/L is simply obtained. The calcium peroxide pretreatment aims at promoting the rupture of extracellular polymers and cell walls of the water-blooming cyanobacteria and the release of intracellular organic matters, improving the carbon-nitrogen ratio in the fermentation process and reducing the accumulation of algal toxins; the rapid stirring in the pretreatment process is used for fully contacting the calcium peroxide with the blue algae and further crushing the blue algae to reduce the size of the blue algae. The purpose of inoculating anaerobic fermentation sludge is to provide fermentation microorganisms for the pretreated blue algae mixed liquor, improve the yield of volatile short-chain fatty acid and reduce fermentation time.

The invention has the beneficial effects that:

(1) the invention realizes the treatment of producing volatile short-chain fatty acid by the efficient anaerobic fermentation of the bloom-forming cyanobacteria. The adoption of standing precipitation avoids the problem of energy consumption of mechanical dehydration. The calcium peroxide pretreatment aims at promoting the rupture of extracellular polymers and cell walls of the water-blooming cyanobacteria and the release of intracellular organic matters, and improving the carbon-nitrogen ratio in the fermentation process; the anaerobic fermentation sludge is inoculated to improve the yield of the blue algae volatile short-chain fatty acid and reduce the fermentation time.

(2) The invention realizes the harmless treatment of the bloom-forming cyanobacteria. The pretreatment of the calcium peroxide greatly improves the degradation of the algal toxin in the blue algae, and simultaneously provides sufficient nutrient substances for hydrolytic acidification microorganisms for degrading the algal toxin in the subsequent anaerobic fermentation process, thereby avoiding the generation and accumulation of the algal toxin.

Detailed Description

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention. Any insubstantial modifications or adaptations of the invention from the foregoing disclosure by those skilled in the art are intended to be covered by the present invention.