Microbial method for domesticating co-metabolizable degradation of 2,4, 6-trichlorophenol by taking domestic sewage as carbon source
Technical Field
The invention belongs to the field of biological sewage treatment, and particularly relates to a microbial method for domesticating domestic sewage as a carbon source and co-metabolizing and degrading 2,4, 6-trichlorophenol, which can be used for treating 2,4, 6-trichlorophenol-containing wastewater in the environment.
Background
Trichlorophenol is widely applied to industrial production, and factory effluent often contains high-concentration trichlorophenol due to substandard discharge. 2,4, 6-trichlorophenol is taken as a typical industrial raw material, and the application range is wider. Trichlorophenols have been listed as a priority for controlling contaminants because of the "trio" effect that trichlorophenols can cause.
At present, co-metabolism is widely used in wastewater treatment as a biological treatment technology capable of effectively removing toxic pollutants. The co-metabolism refers to that under the condition that the microorganism can not rapidly degrade or degrade toxic organic matters, one or more harmless organic matters which can be rapidly degraded or utilized by the microorganism are added into a degradation system, and the organic matters and the toxic organic matters can be degraded and mineralized by the microorganism together, so that the method for rapidly removing the toxic organic matters is finally achieved. The harmless organic matters are called as co-metabolism carbon sources, which not only can solve the problem that organic carbon sources are insufficient when the toxic organic matters are degraded by microorganisms, but also can improve the tolerance of the microorganisms to the toxic organic matters, improve the stability of a treatment system and finally achieve the effect of efficiently removing target pollutants. However, the traditional acclimatization method based on the co-metabolism technology mainly selects glucose, starch, sodium acetate and the like to artificially synthesize carbon sources, so that the investment is huge, and huge burden is brought to the treatment of the phenol-containing wastewater. The domestic sewage contains abundant types of carbon sources, the source is wide, the domestic sewage is used as the carbon source, on one hand, the domestic sewage is consumed, the burden of a water plant is reduced, on the other hand, the carbon source in the domestic sewage can promote the removal rate of the microorganism parachlorophenol, and the co-metabolism degradation efficiency is improved. In addition, in the research of co-metabolism treatment of phenol-containing wastewater, no report of using domestic sewage as a carbon source is seen, so that the method has novelty and originality.
The method takes domestic sewage as a co-metabolism organic carbon source, takes an SBR reactor as a main domestication device, and domesticates the aerobic microorganisms capable of degrading 2,4, 6-trichlorophenol.
Disclosure of Invention
The invention provides a method for domesticating microorganisms capable of co-metabolizing and degrading 2,4, 6-trichlorophenol by taking domestic sewage as a carbon source, aiming at the problem of excessive investment in domesticating microorganisms and operating a degradation device in the traditional co-metabolizing technology.
The invention adopts domestic sewage and artificially prepared 2,4, 6-trichlorophenol as reaction inlet water of an SBR reactor. The process of water distribution in the domestication device is as follows: water distribution and domestic sewage containing 2,4, 6-trichlorophenol are pumped into an SBR reactor through a peristaltic pump, and after microbial aerobic degradation, effluent is pumped into a water collecting tank through the peristaltic pump.
The method comprises the following steps:
(1) starting the SBR reactor: taking secondary sedimentation tank sludge from a municipal sewage treatment plant as inoculated sludge, sieving the inoculated sludge, leaching for more than three times, removing impurities, and maintaining the sludge concentration of the SBR reactor between 3000-4000 mg/L;
(2) the runtime adjustment operation is as follows:
the first stage is as follows: in the period of 9-12 days, only introducing domestic sewage into the domestication system to recover the microbial activity; and a second stage: when the domestic sewage is kept to enter water when the domestication in the first stage is finished, 2,4, 6-trichlorophenol is added in a mode that the concentration gradient is sequentially increased, and the domestic sewage is added in a mode that the concentration gradient is gradually increased from low concentration to high concentration, namely, the trichlorophenol concentration in the system is in a range of 10 mg/L-100 mg/L, after each concentration is added, when the effluent water cannot detect the 2,4, 6-trichlorophenol, the inlet water concentration of the 2,4, 6-trichlorophenol is increased until the degradation amount of the chlorophenol by microorganisms reaches the maximum, the domestication in the second stage is finished, and the system enters a stable operation stage;
the drainage ratio of the SBR reactor in the operation process is 70 percent; in the first domestication stage, active sludge is not discharged from the system, sludge discharge is started in the second operation stage, the sludge age (SRT) of the system is maintained for 35-40 days, and the sludge concentration is maintained at 3000-4000 mg/L.
And during the whole domestication period, starting the stirrer to ensure that the interior of the SBR reactor is in a complete mixing state, adjusting the gas flow meter to carry out aeration, and maintaining 5-6 mg/L of dissolved oxygen in the SBR reactor.
The SBR reactor runs for two periods a day, and the Hydraulic Retention Time (HRT) is 20-24 hours.
The invention relates to a method for domesticating microorganisms capable of co-metabolizing and degrading 2,4, 6-trichlorophenol by taking domestic sewage as a carbon source, which has the following characteristics:
(1) domestic sewage is used as a carbon source, and an artificial carbon source is not required to be added, so that the economic burden in the process of co-metabolism and degradation of 2,4, 6-trichlorophenol is reduced.
(2) The carbon sources in the domestic sewage are rich in types, and can more quickly domesticate the microorganisms capable of degrading the 2,4, 6-trichlorophenol than artificially adding a single carbon source.
(3) The microorganism domesticated by the domestic sewage and co-metabolically degrading the 2,4, 6-trichlorophenol can tolerate and degrade the 2,4, 6-trichlorophenol more than 90 mg/L.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for acclimating a microbial method for co-metabolizing and degrading 2,4, 6-trichlorophenol by using domestic sewage as a carbon source.
In fig. 1: 1- -water tank containing 2,4, 6-trichlorophenol, 2- -domestic sewage tank, 3- -SBR bioreactor, 4- -effluent collecting tank, 1.1, 2.1 and 3.7 are all peristaltic pumps, 3.1 and 3.4 are respectively water inlet and outlet of SBR bioreactor, 3.5- -gas flowmeter, 3.2- -aeration head, 3.6- -air pump, 3.3- -stirrer.
The specific implementation mode is as follows:
the acclimatization scheme will be specifically described below with reference to the acclimatization apparatus and examples of the present invention, but the present invention is not limited to the following examples.
The acclimatization system is shown in figure 1, all reaction devices are made of organic glass, and the effective volume of SBR is 3L. The domestic sewage is domestic sewage of family district of Beijing industry university, and the specific indexes are as follows: SCOD 200-300 mg/L, NH4 +-N=50~60mg/L,NO2 --N≤0.5mg/L,NO3 -N is less than or equal to 0.5 mg/L; the concentration of the 2,4, 6-trichlorophenol in the water preparation tank is 40-50 mg/L. The flow sequence of the inlet water in the system is as follows: the first stage is as follows: domestic sewage enters the SBR reactor (3) through the water inlet pump (2.1), the water inlet pump (1.1) does not operate, and effluent water is discharged into the water collecting tank (4) through the pump (3.7); and in the second stage, while the inflow of domestic sewage is maintained, the water distribution containing 2,4, 6-trichlorophenol enters the SBR reactor (3) through a water pump (1.1), and the effluent enters a water collecting tank (4) after co-metabolism degradation.
Example 1:
(1) starting the SBR reactor: taking return sludge of a secondary sedimentation tank taken from a town sewage treatment plant as inoculated sludge, sieving the inoculated sludge to remove impurities, cleaning for more than three times, and keeping the sludge concentration in the SBR reactor between 3000-4000 mg/L;
(2) the runtime adjustment operation is as follows:
2.1) first stage: in the period of 9-12 days, the acclimation system only introduces biological sewage to recover the activity of microorganisms and domestic sewage; and a second stage: and (3) adding 2,4, 6-trichlorophenol in a concentration gradient increasing mode while maintaining the domestic sewage after the first-stage domestication is finished, adding the trichlorophenol from low concentration to high concentration, so that the trichlorophenol concentration in the system is in a range of 10 mg/L-100 mg/L, after each concentration is added, when the effluent water cannot detect the 2,4, 6-trichlorophenol, increasing the water inlet concentration of the 2,4, 6-trichlorophenol until the degradation amount of the microorganism on the trichlorophenol reaches the maximum, indicating that the second-stage domestication is finished, and enabling the system to enter a stable operation stage. The procedure is as in table 1:
table 1: acclimatization process
2.2) the drainage ratio of SBR is 70 percent in the running process; in the first domestication stage, activated sludge is not discharged from the system, sludge discharge is started in the second operation stage, 70-80 mL of mixed sludge is discharged every day, the sludge age (SRT) of the system is maintained for 35-40 days, and the sludge concentration is maintained at about 3000-4000 mg/L. The SBR reactor runs for two periods a day, and the Hydraulic Retention Time (HRT) is 20-24 hours. SBR was run per cycle as follows:
table 2: operating phase of SBR per cycle
2.3) during the acclimatization period, starting a stirrer to ensure that the interior of the SBR reactor is in a complete mixing state, adjusting a gas flowmeter, and maintaining 5-6 mg/L of dissolved oxygen in the SBR reactor;
the experimental results show that: after the system runs stably, under the condition that domestic sewage is used as a carbon source, more than 80mg/L of 2,4, 6-trichlorophenol can be removed stably, the presence of the trichlorophenol cannot be detected in effluent, no additional carbon source needs to be added into the system, and COD (chemical oxygen demand) of the effluent is 30-50 mg/L.