CN101219844A - A kind of process of biological treatment of acid mine wastewater - Google Patents

Abstract

A process for biologically treating sulfate-containing acidic wastewater and recovering elemental sulfur, which belongs to the technical field of environmental protection and wastewater treatment, and is characterized in that it is a carbon source for treating acidic sulfuric acid using the acidic fermentation product of sewage plant sludge as sulfate-reducing bacteria The process of recovering elemental sulfur from saline wastewater: Sulfate-reducing bacteria SRB in anaerobic bioreactors biologically reduce sulfate SO ₄ ^2- to hydrogen sulfide H ₂ S or S ^2- colorless sulfur in aerobic biofilm reactors Bacterial CSB oxidizes H ₂ S or S ² into elemental sulfur-biologically oxidizes H 2 S or S 2 into elemental sulfur-filters and scrapes sand in a slow sand filter; uses extraction equipment to fully dissolve elemental sulfur S in the sand filter material-solid-liquid separation equipment extracts CS ₂ and sand Filter material, biofilm phase separation-distillation equipment distills and extracts the solution-drying equipment to dry and recover elemental sulfur S. It not only treats acidic mine wastewater containing sulfate, but also recovers elemental sulfur, and also makes the sludge of sewage treatment plants be recycled and harmless.

Description

A kind of process of biological treatment of acid mine wastewater

1. Technical field

The invention discloses a process for biologically treating acidic mine wastewater, which belongs to the technical field of environmental protection and wastewater treatment. Specifically, it is a technical scheme for biologically treating sulfate-containing acidic mine wastewater and recovering elemental sulfur.

2. Background technology

The wastewater discharged from the mining industry contains high concentrations of sulfate, and its SO ₄ ^2- content is mostly 2000-3000mgSO ₄ ^2- /L, and some are higher than 3000mg SO ₄ ^2- /L, even reaching 5000-6000mg SO ₄ ^2- /L. The wastewater is mostly acidic, with a pH as low as 2.5 to 3.0, and contains various heavy metals such as Fe, Mn, Ni, Zn, Cu, Al, Mg, Cd, and Pb. If this sulfate-containing acidic mine wastewater is discharged directly into the water body without treatment, it will acidify the receiving water body, lower the pH, harm aquatic organisms, and cause potential corrosion. Sulfate-containing acidic wastewater can also damage soil structure and reduce crop yields. At present, neutralization, chemical precipitation and electrodialysis are mainly used to treat this kind of wastewater, but these methods are very uneconomical and produce secondary pollution. The neutralization method is a relatively mature method for treating acidic wastewater. Limestone or lime is mainly used, and alkaline waste liquid is also used to neutralize acidic wastewater. The disadvantages of this method are high treatment cost, large amount of waste residue after treatment, high moisture content, and easy to cause secondary pollution. The wetland method can also be used to treat acid mine wastewater, but the wetland method occupies a large area, and the treatment degree is greatly affected by the environment, and the residual hydrogen sulfide escapes from the soil and will pollute the atmosphere. Biological treatment of acid mine wastewater is based on the principle of natural sulfur cycle, and under anaerobic conditions, the sulfate-reducing bacteria SRB is used to reduce SO ₄ ^2- in wastewater to H ₂ S or S ^2- , and SO ₄ ^2- to H ₂ During the process of S or S ^2- , alkalinity will be released to increase the pH value, and then the reduction product H ₂ S or S ^2- will be oxidized to elemental sulfur by biological or chemical methods. The H ₂ S or S ^2- produced by the reduction of SO ₄ ^2- and the heavy metal ions in the wastewater form metal sulfide precipitation, which greatly reduces the concentration of heavy metal ions in the wastewater while increasing the pH value of the wastewater. Biological treatment of acid mine wastewater has a good treatment effect, no secondary pollution, and elemental sulfur can be recovered. Biological treatment of acid mine wastewater has obvious effects and advantages compared with the above-mentioned several methods, but there is still the problem of selecting a technically feasible and economically reasonable sulfate-reducing bacteria carbon source, and the disposal of the final product of biological treatment also needs to be determined. To the direction of economic rationalization.

3. Contents of the invention

The present invention is a process for biological treatment of acidic mine wastewater, the purpose of which is to solve the problems existing in the above-mentioned existing treatment technology, thereby disclosing a biological treatment of sulfuric acid containing hydrochloric acid using the acidic fermentation product of sewage plant sludge as the carbon source of sulfate reducing bacteria The technical scheme of the mine wastewater and recovery of elemental sulfur.

The present invention is a process for biologically treating acidic mine wastewater, which is characterized in that it is a process for biologically treating acidic sulfate wastewater and reclaiming elemental sulfur by using the acidic fermentation product of sewage plant sludge as a carbon source of sulfate-reducing bacteria. For: Acidic mine wastewater 1 and sewage plant sludge acid-producing fermentation supernatant 2 first enter the sulfate bioreduction reactor 3, and use sulfate-reducing bacteria SRB to biologically reduce SO ₄ ^2- to H ₂ S or S ^2- , part of the effluent 10 of the reactor 3 is refluxed, and then the treated effluent of the reactor 3 enters the H ₂ S or S ^2- biological oxidation reactor 4, and the H ₂ S or S ^2- biological oxidation is made into elemental substances by using the colorless sulfur bacteria CSB Sulfur S, then the effluent containing elemental sulfur S flows through the slow sand filter 5 for filtration, sand scraping, interception of elemental sulfur S, and discharge of biological treatment effluent 11, and then the extraction equipment 6 is used to fully dissolve the elemental sulfur S in the sand filter material , the solid-liquid separation equipment 7 separates the extractant from the sand filter material and the biofilm, and the distillation equipment 8 distills the extractant to precipitate elemental sulfur S, and finally dries through the drying equipment 9 to recover the elemental sulfur 12. The specific steps and condition as follows:

I Biological reduction of sulfate to H ₂ S or S ^2- by sulfate-reducing bacteria SRB

①The sulfate biological reduction process is completed in the anaerobic bioreactor 3;

②The dominant bacterial group in reactor 3 is sulfate-reducing bacteria SRB, which can biologically reduce sulfate to H ₂ S or S ^2- ;

③Using the acidic fermentation product of sewage plant sludge as carbon source, the dosage of sludge acidic fermentation liquid 2 in wastewater is controlled according to the ratio of COD/SO ₄ ^2- in the mixed liquid, and the control range of COD/SO ₄ ^2- is 0.9 ~1.5;

④ The sulfate load is 1.0-7.0kgSO ₄ ^2- /m ³ ·d, the temperature is 20-35°C, the pH value of the influent is 3.5-6.5, and the rising velocity v _up of the EGSB of the anaerobic expanded granular sludge bed reactor is 3.0 ~6.0m/h, reflux ratio is 80:1~200:1, hydraulic retention time HRT is 0.2~0.85d, upflow anaerobic filter AF reflux ratio is 20:1~60:1, HRT is 0.25~ 1.25d, for anaerobic baffle reactor ABR, HRT is 0.2~1.0d, for anaerobic fluidized bed reactor AFBR, HRT is 0.02~0.3d;

II Biological oxidation of H ₂ S or S ^2- to elemental sulfur S by colorless sulfur bacteria CSB

①The H ₂ S or S ^2- biological oxidation process is carried out in the aerobic biofilm reactor 4;

② The dominant bacterial population in reactor 4 is colorless sulfur bacteria CSB, and CSB biooxidizes H ₂ S or S ^2- into elemental sulfur S;

③ Under the condition of influent pH value of 6.5-8.0 and temperature of 15-25°C, control the sulfide load and dissolved oxygen DO concentration, so that the H ₂ S or S ^2- biological oxidation product is elemental sulfur, and the dissolved oxygen DO concentration increases with the vulcanization Increased by the increase of material load;

④ The sulfide load and dissolved oxygen concentration in CSB aerobic bioreactors with different types of fillers need to be determined by experiments;

III Use slow sand filter 5 to intercept elemental sulfur S

① Filtration: Use the slow sand filter 5 to filter the effluent of CSB biological oxidation of H ₂ S, trap the elemental sulfur in the water and the shed biofilm on the surface of the filter bed to achieve solid-liquid separation, and the filtration rate of the slow sand filter is 0.1-0.3 m/h, sand filter layer particle size 0.5~1.2mm, thickness 25cm, support layer sand particle size from bottom to top 5.0~10.0mm, 2.5~5.0mm, 1.2~2.5mm, each layer height 3cm, elemental sulfur and shedding The biofilm is trapped in the sand layer of 5-6cm on the surface of the slow sand filter;

②Sand scraping: Scrape the sulfur-containing sand layer with a thickness of 5-6cm on the surface of the sand filter material;

V recovery of elemental sulfur S

①Extraction: use carbon disulfide CS ₂ as the extraction agent, use the extraction equipment 6 to fully contact the scraped sand filter material with the extraction agent CS ₂ solution, so that CS ₂ can fully dissolve the elemental sulfur particles;

②Separation: using the solid-liquid separation equipment 7, the extraction agent CS ₂ after dissolving elemental sulfur is separated from the sand filter material and the shed biofilm by gravity sedimentation separation, centrifugal separation or filtration separation operation, and the extraction agent CS ₂ solution is obtained;

③ Distillation: the temperature is 48-55°C, the distillation equipment 8 is used to distill out elemental sulfur, and the extraction agent CS ₂ is used for repeated use;

④ Drying: the temperature is 165-175°C, and the precipitated elemental sulfur is dried for 1-2 hours by using the drying equipment 9 to recover the elemental sulfur.

Advantages and purposes of a kind of technology of biological treatment acid mine wastewater of the present invention:

1) Based on the principle of sulfur cycle in nature, the present invention utilizes sulfate-reducing bacteria SRB to reduce SO ₄ ^2- , and biologically treat sulfate-containing acidic mine wastewater with low organic concentration.

2) Acid mine wastewater has high SO ₄ ^2- concentration and low organic matter content. The key to biological treatment of acid mine wastewater is to select technically feasible and economically reasonable carbon sources. Sludge from sewage treatment plants is the solid waste of sewage treatment plants, and its acidogenic fermentation products can be used as cheap carbon sources for biological treatment of acid mine wastewater.

3) The present invention can recycle elemental sulfur while treating acid mine wastewater, and solve the problem of sewage treatment plant sludge disposal, making the sewage treatment plant sludge resourceful and harmless, and achieving waste treatment and waste transformation For Bao's goal, reduce the cost of wastewater treatment. The method is characterized by good treatment effect, no secondary pollution, and elemental sulfur can be recovered. At the same time, the sulfate reduction product S2- can undergo precipitation reaction with heavy metal ions to convert heavy metal ions into metal sulfide precipitation, so that heavy metals in wastewater can be removed.

4. Description of drawings

Figure 1 Biological treatment of sulfate-containing acidic mine wastewater and flow chart of elemental sulfur recovery

The labels in the figure are: 1. Acidic mine wastewater containing sulfate

2. Sewage plant sludge acid fermentation liquid

3. Sulfate bioreduction reactor

4. Hydrogen sulfide biooxidation reactor

5. Slow sand filter

6. Extraction equipment

7. Solid-liquid separation equipment

8. Distillation equipment

9. Drying equipment

10. Backflow of effluent from the sulfate bioreduction reactor

11. Biological treatment of effluent

12. Recovery of elemental sulfur

5. Specific implementation

Embodiment 1. The sulfate bioreduction reactor, the sulfate load is 7.0kgSO ₄ ² /m ³ ·d, the temperature is 35°C, the COD/SO ₄ ^2- value is 1.2, the influent pH value is 6.5, anaerobic expansion The rising velocity v _up of the granular sludge bed reactor EGSB is 3.0m/h, the reflux ratio is 80:1, and the hydraulic retention time HRT is 0.2d; the anaerobic biological filter AF has a reflux ratio of 20:1 and the HRT is 0.25d; Anaerobic baffle reactor ABR, HRT is 0.2d; anaerobic fluidized bed reactor AFBR, HRT is 0.02d; colorless sulfur bacteria CSB biooxidation S ^2- reactor, pH value is 8.0, temperature is 15℃ , the sulfide load is 12.0kg/m ³ ·d, DO≈5.5mg/L in the reactor; the slow sand filter, the filtration rate is 0.1m/h, the filtration cycle is 25d, and the elemental sulfur S is retained in the surface 6cm of sand layer; sand filter layer particle size 1.2mm, thickness 25cm; supporting layer sand particle size from bottom to top 5.0mm, 2.5mm, 1.2mm, each layer height 3cm; extraction equipment, carbon disulfide CS ₂ as extraction agent, the The scraped sand filter material is in full contact with the extraction agent CS ₂ solution, so that CS ₂ can fully dissolve the elemental sulfur particles; the solid-liquid separation equipment separates the extraction agent CS ₂ solution, the sand filter material, and the shed biofilm by filtration separation Distillation equipment with a temperature of 48°C, distilling the extractant CS ₂ solution to precipitate elemental sulfur, and the extractant is reused; drying equipment with a temperature of 175°C, drying the precipitated elemental sulfur for 1 hour to recover elemental sulfur.

Embodiment 2, sulfate bioreduction reactor, sulfate load is 4.0kgSO ₄ ² /m ³ ·d, anaerobic expanded granular sludge bed reactor EGSB, HRT is 0.5d; anaerobic biofilter AF, HRT is 0.75d; for the anaerobic baffle reactor ABR, the HRT is 0.6d;

Embodiment 3, the sulfate bioreduction reactor, the sulfate load is 1.0kgSO ₄ ² /m ³ ·d, the anaerobic expanded granular sludge bed reactor EGSB, the HRT is 0.85d; the anaerobic biofilter AF, the HRT is 1.25d; anaerobic baffle reactor ABR, HRT is 1.0d; anaerobic fluidized bed reactor AFBR, HRT is 0.3d, other is the same as embodiment 1.

Embodiment 4, the sulfate bioreduction reactor, the temperature is 30° C., and the others are the same as Embodiment 1.

Embodiment 5, the sulfate bioreduction reactor, the temperature is 20° C., and the others are the same as Embodiment 1.

Embodiment 6, the sulfate bioreduction reactor, the COD/SO ₄ ^2- value is 0.9, and the others are the same as Embodiment 1.

Embodiment 7, the sulfate bioreduction reactor, the COD/SO ₄ ^2- value is 1.5, and the others are the same as Embodiment 1.

Embodiment 8, sulfate bioreduction reactor, pH value of influent water is 5.0, anaerobic expanded granular sludge bed reactor EGSB, liquid ascending velocity v _up is 4.5m/h, reflux ratio is 140:1, HRT is 0.5 d; anaerobic biological filter AF, HRT is 0.75d; anaerobic baffle reactor ABR, HRT is 0.6d; anaerobic fluidized bed reactor AFBR, HRT is 0.16d, and others are the same as Embodiment 1.

Embodiment 9. The sulfate bioreduction reactor, the influent pH value is 3.5, the anaerobic expanded granular sludge bed reactor EGSB, the liquid ascending velocity v _up is 6.0m/h, the reflux ratio is 200:1, and the HRT is 0.85 d; anaerobic biological filter AF, HRT is 1.25d; anaerobic baffle reactor ABR, HRT is 1.0d; anaerobic fluidized bed reactor AFBR, HRT is 0.3d, and others are the same as Embodiment 1.

Embodiment 10, colorless sulfur bacteria CSB biooxidation S ² -reactor, pH value is 7.0, the other is the same as embodiment 8.

Embodiment 11, colorless sulfur bacteria CSB biooxidation S ² -reactor, pH value is 6.5, other is the same as embodiment 9.

Embodiment 12. Colorless sulfur bacteria CSB biooxidation S ^2- reactor, the temperature is 20°C, the sulfide load is 8.5kg/m ³ ·d, DO≈3.8mg/L in the reactor, and the others are the same as Embodiment 1.

Embodiment 13. Colorless sulfur bacteria CSB biooxidation S ^2- reactor, the temperature is 25°C, the sulfide load is 5.0kg/m ³ ·d, DO≈2.0mg/L in the reactor, and the others are the same as Embodiment 1.

Embodiment 14, the slow sand filter, the filtration rate is 0.2m/h, the filtration cycle is 17d, and the others are the same as Embodiment 1.

Embodiment 15, the slow sand filter, the filtration rate is 0.3m/h, the filtration cycle is 8d, and the others are the same as Embodiment 1.

Embodiment 16, solid-liquid separation equipment, extractant CS ₂ solution, sand filter material and shed biofilm are separated by centrifugation, and the others are the same as Embodiment 1.

Embodiment 17, solid-liquid separation equipment, the extraction agent CS ₂ solution, the sand filter material and the shed biofilm are separated by gravity sedimentation, and the others are the same as Embodiment 1.

Embodiment 18. Distillation equipment, the temperature is 50° C., and the others are the same as Embodiment 1.

Embodiment 19. Distillation equipment, the temperature is 55° C., and the others are the same as Embodiment 1.

Embodiment 20. Drying equipment, the temperature is 170° C., and the drying is for 1.5 hours. Others are the same as Embodiment 1.

Embodiment 21. Drying equipment, the temperature is 165° C., and the drying is for 2 hours. Others are the same as Embodiment 1.

Claims (1)

1. the technology of a biological treatment of mine acidic wastewater, it is characterized in that it being that a kind of sewage plant sludge acid fermentation product that utilizes is for the carbon source of sulphate reducing bacteria biological treatment hydrosulphate waste water and reclaim the technology of elemental sulfur, its technical process is: acidic mine waste water (1) and sewage plant sludge acidogenic fermentation supernatant liquor (2) at first enter in the biological sulphate reduction reactor (3), utilize sulphate reducing bacteria SRB with SO ₄ ^2-Biological reducing is H ₂S or S ^2-, the part water outlet (10) of reactor (3) refluxes, and then the treat effluent of reactor (3) enters H ₂S or S ^2-Biooxidation reactions device (4) utilizes colorless sulfur bacteria CSB with H ₂S or S ^2-Bio-oxidation is elemental sulfur S, the water outlet that the contains elemental sulfur S then slow and filter (5) of flowing through filters, strike-offs, holds back elemental sulfur S, free thing treat effluent (11) side by side, adopt extraction equipment (6) fully to dissolve elemental sulfur S in the sand filtering material again, by solid-liquid separating equipment (7) extraction agent and sand, filtrate, microbial film are separated, by solution behind distillation plant (8) distillation extraction, separate out elemental sulfur S, last drying equipment (9) oven dry, reclaim elemental sulfur (12), step and condition that it is concrete are as follows:

I utilizes sulphate reducing bacteria SRB that biological sulphate reduction is H ₂S or S ^2-

1. biological sulphate reduction technology is finished in anaerobic biological reactor (3);

2. dominant microflora is sulphate reducing bacteria SRB in the reactor (3), and SRB is H with biological sulphate reduction ₂S or S ^2-

3. be carbon source with sewage plant sludge acid fermentation product, the dosage of mud acid fermentation liquid (2) is according to COD/SO in the mixed solution in the waste water ₄ ^2-Ratio is controlled, COD/SO ₄ ^2-Span of control be 0.9～1.5;

4. the vitriol load is 1.0～7.0kgSO ₄ ^2-/ m ³D, temperature is 20～35 ℃, water inlet pH value is 3.5～6.5, anaerobic expanded granular sludge bed reactor EGSB upflow velocity v _UpBe 3.0～6.0m/h, reflux ratio is 80: 1～200: 1, hydraulic detention time HRT is 0.2～0.85d, flow lifting type anaerobic filter AF reflux ratio is 20: 1～60: 1, HRT is 0.25～1.25d, and anaerobic baffled reactor ABR, HRT are 0.2～1.0d, anaerobic fluidized bed reactor AFBR, HRT are 0.02～0.3d;

II utilizes colorless sulfur bacteria CSB with H ₂S or S ^2-Bio-oxidation is elemental sulfur S

1. H ₂S or S ^2-Bio-oxidation technology is carried out in aerobic biofilm reactor (4);

2. dominant microflora is colorless sulfur bacteria CSB in the reactor (4), and CSB is with H ₂S or S ^2-Bio-oxidation is elemental sulfur S;

3. the pH value 6.5～8.0 of intaking, under the condition that temperature is 15～25 ℃, control sulfide load and dissolved oxygen DO concentration make H ₂S or S ^2-The bio-oxidation product is an elemental sulfur, and dissolved oxygen DO concentration improves along with the rising of sulfide load;

4. the sulfide load needs to be determined by test with dissolved oxygen concentration in the CSB aerobe reactor of dissimilar fillers;

III adopts slow and filter (5) to hold back elemental sulfur S

1. filter: adopt slow and filter (5) CSB bio-oxidation H ₂The water outlet of S is filtered, elemental sulfur in the water and the microbial film that comes off are trapped in the filter bed surface, reach solid-liquid separation, slow and filter filtering velocity 0.1～0.3m/h, sand filter blanket particle diameter 0.5～1.2mm, thickness 25cm, the supporting layer sand grains is particle diameter 5.0～10.0mm, 2.5～5.0mm, 1.2～2.5mm from the bottom to top, every layer height 3cm, elemental sulfur and the microbial film that comes off are retained in the layer of sand of slow sand filtration top layer 5～6cm;

2. strike-off: scrape the sulfur-bearing layer of sand of getting sand filtering material top layer 5～6cm thickness;

V reclaims elemental sulfur S

1. extraction: with dithiocarbonic anhydride CS ₂As extraction agent, adopt extraction equipment (6) with scrape sand filtering material and the extraction agent CS that gets ₂Solution fully contacts, and makes CS ₂Fully dissolve simple substance sulphur granule;

2. separate: adopt solid-liquid separating equipment (7), utilize the extraction agent CS after gravitational settling separation, centrifugation or filtering separation operation will be dissolved elemental sulfur ₂Be separated with sand filtering material and the microbial film that comes off, obtain extraction agent CS ₂Solution;

3. distillation: temperature is 48～55 ℃, adopts distillation plant (8) distillation to separate out elemental sulfur, extraction agent CS ₂Reuse;

4. dry: temperature is 165～175 ℃, adopts drying plant (9) with the elemental sulfur drying separated out 1～2 hour, reclaims elemental sulfur.

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