CN106115936B

CN106115936B - Method for removing chromium-containing sewage pollutants

Info

Publication number: CN106115936B
Application number: CN201610581674.4A
Authority: CN
Inventors: 李娜
Original assignee: Rongsheng Chemical Co ltd
Current assignee: Rongsheng Chemical Co.,Ltd.
Priority date: 2015-07-26
Filing date: 2015-07-26
Publication date: 2021-10-15
Anticipated expiration: 2035-07-26
Also published as: CN106007242A; CN105967462A; CN106007238A; CN106007240A; CN105967464A; CN106007244A; CN106007238B; CN105967462B; CN105948279B; CN106115936A; CN106007244B; CN104973738A; CN105948279A; CN105967461A; CN106007243B; CN106007242B; CN106007237B; CN106007237A; CN106007240B; CN106007243A

Abstract

The invention relates to a method for removing chromium-containing sewage pollutants, which comprises the following steps of firstly carrying out solid-liquid separation on sewage through a solid-liquid separator to remove large solid particle substances, then enabling the liquid to enter a sedimentation tank for sedimentation for 12 hours, removing solid flocculates from the liquid through a circular hole filter screen, enabling the liquid filtered through the circular hole filter screen to enter a biological reaction tank, adjusting the pH to be 7, adding 10 g of a compound microbial inoculum per cubic meter of the liquid every time, adding the compound microbial inoculum for 1 time every day, continuously adding the compound microbial inoculum for one week, finally standing for 3 days, and discharging the liquid. The method can effectively remove pollutants containing ammonia nitrogen sulfur phosphorus and chromium, has low input cost and has better application prospect.

Description

Method for removing chromium-containing sewage pollutants

Technical Field

The invention belongs to the technical field of environmental protection, and particularly relates to a method for removing pollutants in sewage.

Background

With the development of industrial production and the improvement of living standards of people, the amount of industrial sewage and the amount of urban sewage, which pollute rivers and lakes where people live or pollute the rivers, lakes, etc., have been or are becoming one of the reasons for harming the living environment of people, are rapidly increasing at an alarming speed.

In order to meet the continuously improved requirements of the public on the environmental quality, the nation sets up more and more strict emission standards for nitrogen, and research and development of economic and efficient nitrogen removal treatment technology becomes a key point and a hotspot of research in the field of water pollution control engineering. Although there are many methods for removing ammonia effectively, such as physical methods like reverse osmosis, distillation, soil irrigation; the chemical method comprises an ion exchange method, ammonia stripping, a chemical precipitation method, breakpoint chlorination, electrodialysis, electrochemical treatment and catalytic cracking; biological methods include nitrification and algae cultivation, but physical methods have poor treatment effect, compared with chemical methods, biological methods have the following advantages that 1) each chemical product is a product with strong pertinence, and can lose efficacy when meeting other chemical substances, and biological agents have spectral removal on pollutants; 2) the chemical product can temporarily eliminate certain harmful substances and cover odor, but cannot prevent the generation of the harmful substances; 3) after the chemical product is used, residues are left in the water body, which may cause secondary pollution. The biological preparation contains natural microorganisms without pathogenic bacteria and pathogens, the microorganisms take organic nutrients in the sewage as food under the catalysis of enzyme, and after the sewage is purified, the microorganisms are gradually reduced along with the reduction of the pollutants until the microorganisms are eliminated; 4) the paint is non-toxic, non-corrosive, convenient to use, basically does not need to add equipment or engineering, and saves the capital investment.

The sewage mainly comprises domestic sewage and industrial wastewater. The components of industrial sewage are relatively complex, particularly a large amount of artificially synthesized compounds enter the environment, the substances mainly comprise ammonia nitrogen, sulfide and phosphorus-containing compounds, and the substances cannot be decomposed and utilized by microorganisms in a short time due to the complexity of the structures of the substances, so that the microorganisms cultured and domesticated by the activated sludge in the traditional wastewater treatment method cannot effectively remove the pollutants, the substances are accumulated in the environment for a long time, great pollution is caused to the ecological environment which depends on the survival of people, and great harm is brought to the physical and mental health of human beings. A certain part of industrial pollution enterprises in China are penalized and are not willing to invest and treat wastewater, and even if a sewage treatment device runs abnormally. Therefore, the development of a sewage treatment technology with less construction investment, low operation cost and good treatment efficiency is urgent.

Disclosure of Invention

In order to overcome the defects of the prior art and effectively and simply remove pollutants such as ammonia nitrogen, sulfur, phosphorus, heavy metals and the like in the sewage, the invention provides a method for removing the pollutants in the sewage, which is realized by the following method:

a method for removing chromium-containing sewage pollutants comprises the following steps:

the preparation of the compound microbial inoculum comprises the steps of mixing the mixed bacterial liquid and the carrier according to the weight ratio of 1:1, uniformly stirring, standing for 6 hours, and finally drying at low temperature of 4 ℃, wherein the water content is controlled at 6% after drying, so as to obtain the compound microbial inoculum; the carrier is prepared by mixing bamboo charcoal, chitosan and diatomite according to the mass ratio of 2:2:1, and the particle size of the bamboo charcoal is preferably 10 meshes;

the sewage pretreatment comprises the steps of firstly carrying out solid-liquid separation on sewage through a solid-liquid separator to remove large solid particle substances, then enabling the liquid to enter a sedimentation tank for sedimentation for 12 hours, then removing solid flocculate from the liquid through a circular hole filter screen, enabling the diameter of a circular hole of the circular hole filter screen to be 0.1mm, carrying out biological oxidation, enabling the liquid passing through the circular hole filter screen to enter a biological reaction tank, adjusting the pH to be 7, adding 10 g of composite microbial inoculum per cubic meter of the liquid every time, adding for 1 time every day, continuously adding for one week, finally standing for 3 days, and discharging the liquid.

Preferably, the compound microbial inoculum is prepared by mixing the following raw material bacteria in parts by weight:

10 parts of rhodococcus, 9 parts of thiobacillus denitrificans, 7 parts of pseudomonas stutzeri, 6 parts of sphingomonas, 5 parts of bacillus pumilus and 2 parts of phanerochaete chrysosporium; the concentration of each raw material bacteria is controlled at (1-2) × 10⁸One per ml. The above mentioned species may be conventional strains of the prior art,

preferably, the first and second electrodes are formed of a metal,

the Rhodococcus is Rhodococcus rhodochrous (Rhodococcus rhodochrous) ATCC 15906;

the Thiobacillus denitrificans is Thiobacillus denitrificans (Thiobacillus Denitriclaims) ATCC 25259;

the Pseudomonas stutzeri is Pseudomonas stutzeri (Pseudomonas stutzeri) CCTCC NO: M209107;

the Sphingomonas is CGMCC N0.4589;

the Bacillus pumilus is Bacillus pumilus (Bacillus pumilus) ATCC 27142;

the Phanerochaete chrysosporium is Phanerochaete chrysosporium (Phanerochaete chrysosporium) ATCC 24725.

The bacteria of the invention can be purchased from commercial approaches such as CGMCC, CCTCC, American type culture collection and storage (ATCC) and the like.

Preferably, the Thiobacillus denitrificans is ATCC25259 strain into which a coding gene encoding any one of the following protein variants, 30G/E, 59L/S, 63L/T, 92F/L, 121E/G, 189R/V, 240E/P, 253Q/S, 300C/P, 309G/S, 321A/P, 339S/I, 359L/H, 363V/G, respectively, with respect to the original amino acid sequence of the protein, see GenBank: NP _ 745112.1.

The invention also provides a transgenic strain capable of efficiently absorbing chromium, and the strain is prepared by mixing amino acid sequences such as Genbank: the sequence NP-745112.1 was introduced into Thiobacillus denitrificans to achieve its object.

And the amino acid sequence may have mutations at positions 30G/E, 59L/S, 63L/T, 92F/L, 121E/G, 189R/V, 240E/P, 253Q/S, 300C/P, 309G/S, 321A/P, 339S/I, 359L/H, 363V/G which are not used. (30G/E indicates the substitution of the G amino acid to the E amino acid at position 30 of the original sequence). These mutated amino acid sequences are truncated to give similar effects to strains into which the mutated amino acid sequences have been introduced. However, the applicant has confirmed through a large number of experiments that not all the substitutions have similar effects, and the thiobacillus denitrificans after a large number of substitutions together with other strains do not have a good effect of sewage treatment.

Designing primers by using DNAMAN software, respectively adding enzyme cutting sites, synthesizing the nucleotide sequence PDA gene according to the whole gene of an amino acid sequence NP-745112.1, amplifying to obtain a target fragment, carrying out PCR amplification to obtain a target gene PDA (simultaneously introducing corresponding mutation sites into a gene sequence through multiple PCR to obtain different mutant genes), carrying out double enzyme cutting on a PCR product by using restriction enzyme, connecting the product with a cloning expression vector PWB980 which is also subjected to double enzyme cutting, and transforming a successfully verified recombinant plasmid into the thiobacillus denitrificans to obtain the chromium-degrading genetic engineering bacteria.

The scale-up culture of each strain of the present invention is a conventional culture method in the art, and can be obtained by a culture method described in the literature.

The method has the main beneficial effects that the sewage is treated by the pure microbial inoculum, the sewage is effectively purified, and the phosphorus and nitrogen are removed simultaneously, so that the heavy metal chromium in the sewage can be removed simultaneously, the contradiction that the phosphorus and nitrogen removal effects are difficult to simultaneously consider the heavy metal removal in the traditional process is solved, and the method has a better application prospect.

Detailed Description

Example 1

A method for removing contaminants from wastewater, comprising the steps of:

the preparation of the compound microbial inoculum comprises the steps of mixing the mixed bacterial liquid and the carrier according to the weight ratio of 1:1, uniformly stirring, standing for 6 hours, and finally drying at low temperature of 4 ℃, wherein the water content is controlled at 6% after drying, so as to obtain the compound microbial inoculum; the carrier is prepared by mixing bamboo charcoal, chitosan and diatomite according to the mass ratio of 2:2: 1; the mixed bacterial liquid is prepared by mixing 10 parts of rhodococcus, 9 parts of thiobacillus denitrificans, 7 parts of pseudomonas stutzeri, 6 parts of sphingomonas, 5 parts of bacillus pumilus and 2 parts of phanerochaete chrysosporium by weight; the concentration of each raw material bacterium is controlled to be I X I08/ml.

Firstly, carrying out solid-liquid separation on sewage NH3-N of 300mg/L, sulfide of 80mg/L, phosphorus-containing pollutant of 70mg/L and cadmium of 35mg/ml through a solid-liquid separator to remove large solid particle substances, then, allowing the liquid to enter a sedimentation tank for sedimentation for 12 hours, and removing solid flocculates from the liquid through a round hole filter screen, wherein the diameter of a round hole of the round hole filter screen is 0.1 mm;

and (3) biological oxidation, namely, allowing the liquid passing through the circular hole filter screen to enter a biological reaction tank, adjusting the pH to 7.0, adding 10 g of the compound microbial inoculum per cubic meter of the liquid every time, adding the compound microbial inoculum I times every day, continuously adding the compound microbial inoculum for one week, finally standing for 3 days, and discharging the liquid. Through detection, the ammonia nitrogen content in the sewage is respectively 12.5mg/L, the sulfide content is 4.5mg/L, the phosphorus-containing pollutant content is 2.5mg/L, and the removal rate is more than 95%; the chromium content is 33mg/mL, and the removal effect is not obvious.

Example 2

Designing primers by using DNAMAN software, respectively adding enzyme cutting sites, synthesizing the nucleotide sequence GP gene according to the whole gene of an amino acid sequence NP-745112.1, amplifying to obtain a target fragment, carrying out PCR amplification to obtain the target gene GP (simultaneously introducing corresponding mutation sites 30G/E, 59L/S, 63L/T, 92F/L, 121E/G, 189R/V, 240E/P, 253Q/S, 300C/P, 309G/S, 321A/P, 339S/I, 359L/H and 363V/G into the gene sequence through multiple PCR so as to obtain different mutant genes), connecting double-enzyme-cutting PCR products with a cloning expression vector PWB980 which is also subjected to double enzyme cutting, transforming a successfully verified recombinant plasmid into the thiobacillus denitrificans ATCC25259, obtaining the genetic engineering bacteria for degrading chromium.

Example 3 verification of Sewage treatment Effect of Thiobacillus denitrificans genetically engineered bacterium and the rest of the microbial Agents

According to the method of example 1, a corresponding sewage treatment experiment was performed, in which the sewage was the same batch as that of example 1 and had the same concentration of the contaminant. The compositions of the components of the microbial inoculum are completely the same as those of the example 1.

Experiments show that the genetically engineered bacteria of different mutation sites prepared in example 2 have obviously enhanced effect on removing chromium compared with the original bacteria, and the genetically engineered bacteria of 30G/E, 59L/S, 63L/T, 92F/L, 121E/G, 189R/V, 240E/P, 253Q/S, 300C/P, 309G/S, 321A/P, 339S/I, 359L/H and 363V/G. The total treatment time was not more than 4 days, with the following results: the sewage is the same batch of sewage, thereby ensuring the consistent conditions.

The concentration of each pollutant in the sewage is as follows: 300mg/L of NH3-N, 80mg/L of sulfide, 70mg/L of phosphorus-containing pollutant and 35mg/ml of chromium.

From the results, the microbial inoculum formed by the thiobacillus denitrificans and other strains constructed by the genetic engineering has better chromium removal effect besides better original ammonia nitrogen, sulfide and phosphorus removal effect, and has enhanced synergistic effect between the thiobacillus denitrificans and other strains in the genetic engineering in the aspect of removing ammonia nitrogen, sulfide and phosphorus.

Claims

1. A method for removing chromium-containing sewage pollutants is characterized by comprising the following steps: firstly, carrying out solid-liquid separation on sewage through a solid-liquid separator to remove large solid particle substances, then enabling the liquid to enter a sedimentation tank for sedimentation for 12 hours, removing solid flocculate from the liquid through a circular hole filter screen, enabling the liquid filtered through the circular hole filter screen to enter a biological reaction tank, adjusting the pH to 7, adding 10 g of composite microbial inoculum for each cubic meter of liquid every time, adding for 1 time every day, continuously adding for one week, finally standing for 3 days, and discharging the liquid; the compound microbial inoculum is prepared by mixing the following raw material bacteria in parts by weight: 10 parts of rhodococcus, 9 parts of thiobacillus denitrificans, 7 parts of pseudomonas stutzeri, 6 parts of sphingomonas, 5 parts of bacillus pumilus and yellow2 parts of Phanerochaete sporotrichum; the concentration of each raw material bacteria is controlled at (1-2) × 10⁸Per ml; the thiobacillus denitrificans is a strain ATCC25259 which is transformed with a coding gene encoding a protein variant in which the following mutation 121E/G is made with respect to the original amino acid sequence of the protein, which is referred to GenBank: NP _ 745112.1.

2. A protein variant characterized in that: the protein variant is subjected to the following mutation 121E/G relative to the original amino acid sequence of the protein, which is shown in GenBank: NP _ 745112.1.