JPH0341240B2 - - Google Patents

Description

[Detailed description of the invention]

"Field of Industrial Application" This invention relates to a method for suppressing sulfate reduction reaction in anaerobic treatment performed when organic wastewater is treated by anaerobic fermentation such as methane fermentation, and an antibiotic that inhibits sulfate-reducing bacteria. It is. "Conventional technology" Treatment of organic wastewater by anaerobic fermentation such as methane fermentation is more effective than aerobic treatment such as activated sludge method.
This water treatment method has the following advantages: the aeration power is unknown, the amount of sludge produced is small, methane gas is produced that can be used as an energy source, and high-load primary treatment is possible. suitable for the treatment of wastewater containing ``Problems to be Solved by the Invention'' However, among the above-mentioned highly concentrated organic wastewaters, some, such as alcohol distillation wastewater and pulp wastewater, often contain large amounts of sulfate ions. When such wastewater is subjected to methane fermentation, sulfate-reducing bacteria proliferate under the same growth conditions as methane bacteria, and sulfate ions are reduced to sulfide ions that inhibit the growth of methane bacteria and methane fermentation, resulting in methane fermentation. As a result, methane production and wastewater treatment capacity decrease, and in severe cases, methane fermentation stops. Additionally, since the hydrogen normally used to generate methane is used to reduce sulfate ions, the methane concentration in the produced gas decreases, and most of the produced gas becomes carbon dioxide, reducing its value as an energy source. Additionally, the concentration of corrosive hydrogen sulfide gas in the product gas increases. Therefore, when performing anaerobic treatment, it is considered necessary to suppress the reduction of sulfate ions by inhibiting the growth of sulfate-reducing bacteria in the wastewater. Adding substances has also been considered, but it was previously known that certain antibiotics have an inhibitory effect on sulfate-reducing bacteria; Since this was not known, no attempt had been made to add antibiotics to wastewater in anaerobic treatment. This invention was made in view of the above circumstances, and provides an antibiotic fruit that inhibits the growth of sulfate-reducing bacteria and does not inhibit the growth of methane bacteria, and
The purpose of this antibiotic is to suppress the sulfuric acid reduction reaction in wastewater and perform anaerobic treatment in good conditions. "Means for Solving the Problems" The method for suppressing sulfuric acid reduction reaction in anaerobic treatment of the present invention is a method for suppressing sulfuric acid reduction reaction in anaerobic treatment, when organic wastewater containing sulfate ions is treated by anaerobic fermentation, methane bacteria are added to the organic wastewater. An antibiotic is added that selectively inhibits the growth of coexisting sulfate-reducing bacteria. In addition, the sulfate-reducing bacteria-inhibiting antibiotics of this invention include bacitracin, carbenicillin sodium,
Cycloheximide, dihydrostreptomycin, fradiomycin sulfate, gentamicin sulfate crystals, lincomycin hydrochloride, methicillin sodium, neomycin sulfate, novobiocin sodium, benzylpenicillin sodium (sodium salt of penicillin G), rifampicin, geneticin, vancomycin hydrochloride, diyosamycin , kitasamycin, and oleandomycin, or a mixture of two or more thereof. "Function" In the method for suppressing sulfuric acid reduction reaction in anaerobic treatment of the present invention, when organic wastewater containing sulfate ions is treated by anaerobic fermentation, sulfuric acid reducing bacteria coexisting with methane bacteria are added to the organic wastewater. By adding an antibiotic that selectively inhibits the growth of sulfate ions, the reduction of sulfate ions by the sulfate-reducing bacteria is prevented, and the generation of sulfide ions that inhibit methane fermentation is prevented, and the sulfate-reducing bacteria are also prevented from producing methane. It also prevents the consumption of hydrogen necessary for generation. Therefore, when organic wastewater is treated anaerobically using this method, methane fermentation is carried out in good conditions, and wastewater treatment is effectively carried out. In addition, when the sulfate-reducing bacteria-inhibiting antibiotic of the present invention is used, it is possible to efficiently perform anaerobic treatment of organic wastewater, and due to its sulfate-reducing bacteria-inhibiting property, iron tanks, It can also prevent pipes from being corroded by hydrogen sulfide gas produced by sulfate-reducing bacteria, and can be widely applied to damage caused by sulfate-reducing bacteria. “Example” An example of the present invention will be described below. In this example, a sulfate-reducing bacteria-inhibiting antibiotic that inhibits the growth of sulfate-reducing bacteria and does not inhibit the growth of methane bacteria is added to organic wastewater containing sulfate ions, such as alcohol distillation waste liquid or pulp waste liquid. The organic wastewater is then subjected to methane fermentation for anaerobic treatment. Examples of such sulfate-reducing bacteria-inhibiting antibiotics include gentamicin. and,
When this gentamicin is added to a fermenter (or reactor, digester, etc.) at an appropriate concentration of about 10 ppm, the activity of sulfate-reducing bacteria is suppressed by the action of gentamicin.
No reduction of sulfate ions to sulfide ions occurs,
Methane fermentation can be carried out in good conditions. In addition, sulfate-reducing bacteria-inhibiting antibiotics such as gentamicin can also inhibit the generation of corrosive hydrogen sulfate gas by sulfate-reducing bacteria, so they can be used not only in fermenters, reactors, or digesters during reaction treatment, but also in soils. It is also possible to prevent iron oil pipes, gas pipes, water pipes, etc. from being corroded by hydrogen sulfide gas under moderate anaerobic conditions. In addition to the above-mentioned gentamicin, the sulfate-reducing bacteria-inhibiting antibiotics include dihydrostreptomycin, fradiomycin sulfate, neomycin and other aminoglycosides, benzylpenicillin sodium, methicillin sodium and other β-lactams, bacitracin, novobiocin, Antibiotics that primarily inhibit the growth of Gram-positive bacteria, such as oleandomycin;
There are antibiotics that primarily inhibit the growth of acid-fast bacteria, such as rifampicin, and antibiotics that inhibit the growth of filamentous fungi, such as cycloheximide. Also, when these antibiotics are used, the same effects as when gentamicin is used can be achieved. "Experimental Example" (Experiment 1) Screening Test In order to search for a substance that inhibits the growth of sulfate-reducing bacteria and does not inhibit the growth of methane bacteria, a screening test was conducted based on the flow shown in Table 1. In this screening test, methane bacteria were able to utilize methanol as a carbon source, and the optimal growth temperature for their methane fermentation range was 55°C.
Methanosarcina sp.
Desulfotomaculum nigrificans (DSM 574), which has an optimal growth temperature almost equal to the above optimal growth temperature, was used as a sulfate-reducing bacterium.
was used. And for each strain of these bacteria,
The culture media shown in Tables 2 and 3 were prepared.

【table】

[Table] However, the above medium should be kept at 120℃ by autoclaving.
It is sterilized for 15 minutes and its pH is adjusted to 7.2. This screening test was conducted in an atmosphere of 80% nitrogen, 10% carbon dioxide, and 10% hydrogen.

[Table] However, the above medium should be kept at 120℃ by autoclaving.
It is sterilized for 15 minutes and its pH is adjusted to 7.2. This screening test was conducted in an atmosphere of 80% nitrogen, 10% carbon dioxide, and 10% hydrogen. The formulations of the vitamin solution and trace element solution in Table 3 are shown in Table 4 and Table 5, respectively.

【table】

[Table] In such a screening test, if sulfate-reducing bacteria survive and grow in the culture medium, sulfate is reduced using sodium lactate as a reducing agent and interacts with iron in Mohr's salt to produce iron sulfide. , the medium turns black. Therefore, in this screening test, the growth of sulfate-reducing bacteria was confirmed by the blackening of the medium. Furthermore, when methane bacteria grow, they precipitate in the form of nodules at the bottom of the test tube containing the culture solution, so the culture solution does not become cloudy. Furthermore, as methane bacteria grow, methane gas is generated, and this is used to confirm growth. As a result of conducting screening tests on a large number of antibiotics in this manner, 17 antibiotics shown in Table 6 were found to be effective. The effective concentration listed on the right side of each antibiotic name is the concentration that allows methane fermentation to occur in the best condition, but it is also possible to suppress the growth of sulfate-reducing bacteria at concentrations other than this concentration. and
In that case as well, methane fermentation can be carried out efficiently. Furthermore, as the penicillin in the antibiotic name column in Table 6, benzylpenicillin sodium was used.

[Table] (Experiment 2) Symbiotic test Gentamicin was selected from the antibiotics shown in Table 6 that were found to be effective in Experiment 1, and a symbiotic test was conducted using the medium shown in Table 7. This symbiosis test was conducted using the same experimental methods as Experiment 1, including a single culture of methane bacteria, a mixed culture of methane bacteria and sulfate-reducing bacteria, and a mixed culture of methane bacteria and sulfate-reducing bacteria to which 10 ppm of gentamicin was added. I did this. Growth of methane bacteria was detected by monitoring the amount of methane gas generated, and growth of sulfate-reducing bacteria was detected by monitoring changes in sulfate ion concentration.

[Table] As a result of this symbiosis test, as shown in Figures 1 and 2, when gentamicin was added to a system in which methane bacteria and sulfate-reducing bacteria were mixed, the results were as good as in the system with methane bacteria alone. methane fermentation was carried out, and the growth of sulfate-reducing bacteria was also suppressed. In addition, as in the symbiosis test above, using the medium shown in Table 7, a mixed culture of methane bacteria and sulfate-reducing bacteria added with each antibiotic listed in Table 6 above, except for the above-mentioned gentamicin, was carried out. Even when each antibiotic was added, methane fermentation was carried out as well as when gentamicin was added, and the growth of sulfate-reducing bacteria was also suppressed. "Effects of the Invention" According to the method for suppressing sulfuric acid reduction reaction in anaerobic treatment of the present invention, when organic wastewater containing sulfate ions is treated by anaerobic fermentation, methane bacteria coexist in the organic wastewater. Since an antibiotic that selectively inhibits the growth of sulfate-reducing bacteria is added, it is possible to suppress the reduction of sulfate ions by the sulfate-reducing bacteria and prevent the generation of sulfide ions that inhibit methane fermentation, and also to prevent methane production. It is possible to prevent the hydrogen necessary for this from being consumed by the sulfate-reducing bacteria. Therefore, when organic wastewater is anaerobically treated using this method, methane fermentation can be carried out in good conditions, and wastewater treatment can be carried out effectively. Furthermore, according to the sulfate-reducing bacteria-inhibiting antibiotic of the present invention, anaerobic treatment can be efficiently carried out because it inhibits the growth of sulfate-reducing bacteria and does not inhibit the growth of metal bacteria. Due to its bacteria-inhibiting properties, it can also prevent iron tanks, piping, etc. used in the anaerobic treatment from being corroded by hydrogen sulfide gas produced by sulfate-reducing bacteria. In addition, this sulfate-reducing bacteria-inhibiting antibiotic can also prevent iron oil pipes, gas pipes, water pipes, etc. from being corroded by hydrogen sulfide ions produced by sulfate-reducing bacteria in anaerobic environments such as soil. It can be widely applied to damage caused by other sulfate-reducing bacteria and can be used in a wide range of industrial fields.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the results of the symbiosis test, with Figure 1 being a graph showing the relationship between culture time and sulfate ion concentration, and Figure 2 being a graph showing the relationship between culture time and methane gas generation amount. This is a graph representing

Claims (1)

[Claims] 1. When organic wastewater containing sulfate ions is treated by anaerobic fermentation, an antibiotic that selectively inhibits the growth of sulfate-reducing bacteria that coexists with methane bacteria is added to the organic wastewater. A method for suppressing sulfuric acid reduction reaction in anaerobic treatment, characterized by adding the sulfuric acid reduction reaction. 2. Among the antibiotics added in the method for inhibiting sulfuric acid reduction reaction in anaerobic treatment described in paragraph 1, bacitracin, carbenicillin sodium, cycloheximide, dihydrostreptomycin, fradiomycin sulfate, gentamicin sulfate crystals, lincomycin hydrochloride, methicillin sodium, Neomycin sulfate, novobiocin sodium, benzylpenicillin sodium, rifampicin,
1. A sulfate-reducing bacteria-inhibiting antibiotic comprising one or a mixture of two or more selected from geneticin, vancomycin hydrochloride, diyosamycin, kitasamycin, and oleandomycin.