1. Carbohydrates: Glucose: A monosaccharide commonly used in industrial fermentation, widely used in fermentation production of antibiotics, amino acids, organic acids, etc. But it is a multi molecular compound that can easily cause the proliferation of bacteria, leading to sludge expansion, increasing the COD value in the effluent, affecting the effluent quality, and industrial glucose contains many impurities, making food glucose expensive.
Starch: including polysaccharides, such as starch paste. Starch cannot be directly utilized by most microorganisms and needs to be saccharified to produce hydrolyzed starch for use.
2. Organic acids, such as lactic acid, citric acid, acetic acid, etc., can not only serve as carbon sources, but also regulate the pH value of fermentation broth. When acetic acid is used as a carbon source, it is similar to sodium acetate, but it is more wasteful to use as an industrial product as a carbon source.
3. Alcohols: such as methanol, ethanol, glycerol, etc. Methanol: It has the advantages of low operating costs and low sludge production, and fast denitrification rate. But it is flammable and classified as a Class A hazardous chemical, with strict requirements for storage and use; Microorganisms have a slow response time and cannot be utilized by all microorganisms; And it has a certain toxic effect, and long-term use has an impact on tailwater discharge.
Glycerol: For example, carbon sources containing glycerol can be utilized, such as the low-cost new carbon source of "Changjiang Jiangyu". After initial purification, the COD is 1.5 million after complete dehydration, the moisture content is controllable, the concentration can be adjusted, the impurities are low, the glycerol content is high, neutral, there is no special odor, and the freezing point is low.
4. Oils: Common oils include soybean oil, corn oil, cottonseed oil, and lard. Fungi and actinomycetes can use oils as a carbon source.
5. Biomass carbon source: Non toxic and harmless biological products produced by fermentation of sugars, agricultural waste, etc. through biotechnology principles. The main components are small molecule organic acids, alcohols, and sugars.
It is more easily utilized by microorganisms than a single chemical, with lower usage costs and higher cost-effectiveness. However, the stability of the product needs to be improved, and the equivalent COD of each batch of products needs to be tested before use.
6. Sludge hydrolysis supernatant: The volatile acid VFA from biotransformation comes from the supernatant of sludge hydrolysis, which has a high denitrification rate and can be directly provided by the sewage treatment plant, reducing the problem of carbon source transportation. However, the VFA components produced by different sludge and hydrolysis conditions vary greatly, and the denitrification rate is also different. Moreover, directly using hydrolyzed sludge as an external carbon source requires consideration of the release of nitrogen and phosphorus during the sludge hydrolysis process.
What is the difference in production between fermenters and shake flasks?
When choosing a carbon source, factors to consider include the cost of adding the carbon source, the equivalent COD price of the comprehensive carbon source, and the amount of addition to determine.
The sludge production rate of carbon sources, adding carbon sources will increase sludge production, and the cost of sludge treatment is relatively high.
To ensure the stability of sewage operation, it is necessary to take into account avoiding problems such as sludge expansion, increased effluent COD, and accumulation of nitrite nitrogen.
In addition, the utilization ability and demand of different microorganisms for carbon sources also vary. It is necessary to comprehensively consider the characteristics of specific microorganisms, fermentation methods, production practices, scientific experiment requirements, as well as economic benefits, and select suitable carbon sources.
At the same time, attention should be paid to the appropriate ratio of nutrients, osmotic pressure, pH value, and other preparation principles of the culture medium.
