Improved A / O device and process for treating sulfur-containing petroleum wastewater

Abstract

The invention discloses an improved A / O device and process for treating sulfur-containing petroleum wastewater. The improved A / O device comprises a grating tank, an anaerobic biological reaction tank, an aerobic biological reaction tank, a spraying device, a reflux water tank and a reflux system. The sulfate reducing bacteria reduce SO4 < 2-> into sulfides under anaerobic conditions, and the sulfides and the heavy metals generate metal sulfide precipitates; the denitrifying sulfur-oxidizing flora utilizes reductive and intermediate-state sulfur compounds as electron donors and NOx <-> as electron acceptors to carry out denitrification under an aerobic condition, and elemental sulfur precipitates and nitrogen are synchronously generated. H2S gas generated by the anaerobic biological reaction tank is sprayed and absorbed by alkali liquor and then is subjected to aerobic biological reaction, and effluent of the aerobic biological reaction tank is deoxidized and then flows back to the anaerobic biological reaction tank again for treatment. Compared with the prior art, the improved A / O system and the improved A / O process have the advantages that the desulfurization effect is greatly improved, the waste gas treatment efficiency is improved, the pollution caused by waste gas emission is reduced, and the problem of comprehensive treatment of sulfur-containing petroleum wastewater is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an improved A / O device and process for treating sulfur-containing petroleum wastewater. Background Art

[0002] The petroleum and petrochemical industry is a high-consumption, high-emission, and high-pollution industry. Among them, the wastewater generated in the petrochemical production process is an important source of pollution. Oil production wastewater is usually produced along with the separation and treatment of crude oil, and is re-injected into the ground as raw water in the middle and late stages of crude oil extraction. The concentration gradually becomes so high that it cannot be injected again, and then it has to be directly discharged to the outside world in a way that pollutes the environment. Sulfur-containing wastewater discharged directly into the water body without treatment will acidify the receiving water body, reduce the pH value of the water body, harm aquatic life, and produce potential corrosion, and destroy the soil structure. Desulfurization engineering is an important link in wastewater treatment that cannot be ignored. How to effectively treat sulfur-containing wastewater in the production process of the petrochemical industry and reduce the impact of wastewater on the environment is one of the crucial links for the petrochemical industry to achieve green production.

[0003] The A / O process, also known as the anoxic / aerobic process, utilizes denitrifying bacteria in the anoxic phase to remove carbon sources from the wastewater, significantly reducing the load on the aerobic tank while simultaneously adjusting the pH within the tank to meet the requirements of the aerobic reaction. The subsequent aerobic phase deeply removes residual organic matter from the denitrification phase. The two process units operate simultaneously, with the anoxic and aerobic units alternating between them, achieving optimal treatment results: short-term nitrification and denitrification, a vibrant biomass, and a low activated sludge treatment load. Chen Liang et al. used the A / O process to treat Class IV factory wastewater, achieving consistent effluent quality standards. Luo Hongjie et al. used the A / O process to treat industrial park wastewater, achieving Class A standards in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants (GB18919-2002)." However, existing A / O processes have design flaws. The circulating fluid in the anoxic tank originates from the aeration tank and contains a certain amount of dissolved oxygen, making it difficult to maintain the ideal anoxic state, affecting denitrification efficiency and making it difficult to achieve a 90% denitrification rate.

[0004] Sulfate-reducing bacteria (SRB) are a group of anaerobic microorganisms that use organic matter such as lactic acid or pyruvic acid as electron donors and sulfate as the terminal electron acceptor to reduce sulfate to sulfide ions under anaerobic conditions. Sulfate is involved in the metabolism of SRB, so SRB can reduce the concentration of sulfate in the solution, thereby achieving the purpose of treating sulfate wastewater. SRB also plays a key role in the removal of heavy metals in sewage. On the one hand, SRB oxidizes organic matter in organic wastewater to form bicarbonate. In addition, the reduction of sulfate requires the consumption of hydronium ions, which increases the pH value of the water body. The metal ions will be precipitated in the form of alkaline hydroxides and removed. On the other hand, SRB can remove SO4 2- Restore to S 2- , S 2- It can combine with heavy metal (M) ions in sewage through chemical reactions to form metal sulfide precipitation, thereby settling heavy metal ions in the liquid environment and improving water quality. The main reactions involved are: ① Organic matter + SO4 2- +SRB+e - →S 2- +HCO 3- ;②S 2- +M 2+ →MS. Sulfate-reducing bacteria (SRBs) not only remove sulfur-containing compounds by precipitating heavy metal ions from the environment into alkaline compounds, but also possess a layer of extracellular polymers (EPS) outside their cells that adsorb and remove heavy metal ions. This method is simple and easy to implement, with low treatment costs and high throughput. Operation requires only the regular addition of an appropriate amount of culture medium to the anaerobic tank, without concern for the toxic effects of heavy metal ion concentrations in wastewater on the bacteria. The direct treatment of mixed heavy metal wastewater by SRBs is designed for the rapid removal of heavy metals in wastewater and can be applied to industrial wastewater treatment.

[0005] The denitrifying sulfur-oxidizing bacterial community is composed of aerobic denitrifying bacteria and sulfur-oxidizing bacteria. It can couple denitrification and sulfur oxidation under aerobic conditions, and can also efficiently remove pollutants under anaerobic conditions. This bacterial community uses ammonium salts as a nitrogen source, and through the decomposition of heterotrophic bacteria, it converts residual organic matter in the water into organic acids, hydrogen sulfide, ammonia and other matrices, and uses this as raw material for bacterial synthesis and proliferation, and synergistically participates in the water purification process. This microbial consortium can effectively remove organic matter, sulfur-containing compounds and ammonia nitrogen, and achieve simultaneous bioremediation of multiple pollutants. In an aerobic environment, the bacterial community achieves the coupled removal of sulfur-nitrogen pollutants through the synergistic effect of sulfur oxidation and aerobic denitrification. Sulfur-oxidizing bacteria use sulfide as an electron donor and dissolved oxygen as an electron acceptor to oxidize sulfur compounds to obtain energy. The core reaction is: O2+2S 2- -e -→S↓+S2O3 2- +SO3 2- +SO4 2- This process can not only effectively remove sulfur-containing pollutants from water bodies, but also recover high-purity elemental sulfur through the sulfur oxidation pathway. At the same time, aerobic denitrifying bacteria can use oxygen or nitrate as electron acceptors to carry out oxygen / nitrate dual pathway metabolism, thereby enhancing the denitrification capacity of the device. Its core nitrogen metabolism reaction is: NO3 - + organic carbon → N2↑+CO2+H2O. Through this coupled metabolic mode, the bacterial community can achieve simultaneous sulfur oxidation and denitrification under aerobic conditions, thereby improving the efficiency of pollutant removal. In an anaerobic environment, the bacterial community exhibits similar niche characteristics to sulfate-reducing bacteria and can form a microecological symbiotic system with them. At this time, sulfur-oxidizing bacteria use sulfide as an electron donor and nitrate or nitrite (NO x - ) is an electron acceptor, and energy is obtained through denitrification coupled with sulfur oxidation. Its core nitrogen metabolism reaction is as follows: 2NO x - +2xe - +4xH + =2xH2O+N2↑. This reaction, through a coupled sulfur-nitrogen cycle mechanism, converts toxic sulfide, ammonia nitrogen, and nitrate nitrogen into harmless sulfate and gaseous nitrogen, achieving the dual goals of synergistic pollutant removal and sulfur resource recovery. The metabolic advantage of this bacterial community lies in the fact that sulfur-oxidizing bacteria can gradually oxidize sulfide into elemental sulfur and high-valent sulfur compounds, while aerobic denitrifying bacteria can sequentially reduce nitrate to nitrogen gas, thus forming a system for the simultaneous and deep removal of sulfur and nitrogen pollutants. Compared to a single bacterial species, this bacterial community exhibits greater environmental adaptability through complementary metabolic functions.

[0006] Combining sulfate-reducing bacteria, aerobic denitrifying bacteria, and sulfur-oxidizing bacteria with the existing A / O process is an effective treatment method for sulfur-containing petroleum wastewater. However, this method suffers from similar drawbacks to denitrification using the A / O process: the circulating fluid within the anaerobic bioreactor comes from the aerobic bioreactor and contains a certain amount of dissolved oxygen, making it difficult for the anaerobic bioreactor to maintain an ideal anoxic state, thus affecting the desulfurization effect and desulfurization rate of the wastewater. Summary of the Invention

[0007] The purpose of the present invention is to address the problem that the internal circulating liquid flowing back from the post-aerobic section to the anaerobic section in the existing A / O process contains a certain amount of dissolved oxygen, making it difficult for the pre-anaerobic section to maintain an ideal anoxic state, affecting the desulfurization and denitrification effects, and resulting in low desulfurization and denitrification rates. The present invention provides an improved A / O device and process for treating sulfur-containing petroleum wastewater. The spray device coupled to the aerobic biological reactor sprays hydrogen sulfide waste gas, thereby improving the efficiency of sulfur-containing waste gas treatment, reducing waste gas pollution, fully achieving harmless waste gas treatment, increasing the depth of the A / O desulfurization reaction, and improving the desulfurization rate. A recirculation tank is coupled after the aerobic biological reactor, utilizing the nitrogen generated in the aerobic reactor to remove oxygen, allowing the wastewater after the aerobic reaction to be deoxygenated and then circulated back to the anaerobic tank for reaction, thereby improving the desulfurization effect of the anaerobic reactor.

[0008] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0009] An improved A / O device for treating sulfur-containing petroleum wastewater, comprising a grid tank, an anaerobic biological reaction tank, an aerobic biological reaction tank, a spray device, a return water tank and a return system;

[0010] The grid pool, the anaerobic biological reaction pool, the aerobic biological reaction pool and the reflow water pool are connected in sequence through pipelines;

[0011] The upper part of one side wall of the spray device is provided with a spray liquid inlet and a hydrogen sulfide gas inlet, and the bottom is provided with an absorption liquid outlet; the anaerobic biological reaction tank is provided with a hydrogen sulfide gas outlet, and the hydrogen sulfide gas outlet is connected to the hydrogen sulfide gas inlet through a pipeline; the aerobic biological reaction tank is provided with an absorption liquid inlet, and the absorption liquid inlet is connected to the absorption liquid outlet through a pipeline;

[0012] The aerobic biological reaction tank is provided with a nitrogen outlet, the reflux water tank is provided with a nitrogen inlet, and the nitrogen outlet and the nitrogen inlet are connected through a pipeline;

[0013] The reflux system consists of a reflux pipe and a reflux pump arranged on the reflux pipe; the reflux water pool is provided with a reflux liquid outlet, and the reflux liquid outlet is connected to the anaerobic biological reaction tank through the reflux pipe.

[0014] Wherein, a one-way valve is provided at the hydrogen sulfide gas outlet of the anaerobic biological reaction tank, so that the hydrogen sulfide gas generated in the anaerobic biological reaction tank automatically flows into the spraying device.

[0015] The spray device is provided with an S-shaped channel formed by a partition, and an S-shaped pipe with a liquid nozzle is provided in the S-shaped channel; the spray liquid inlet is connected to the S-shaped pipe; the hydrogen sulfide gas inlet is connected to the S-shaped channel; the bottom of the spray device is set as an inclined surface, which is used to collect the alkaline solution that absorbs hydrogen sulfide and return it to the aerobic reaction tank.

[0016] After the hydrogen sulfide waste gas enters the S-shaped channel, it is purged from front to back. The partition set inside the spray device forces the waste gas to follow the S-shaped channel, moving from left to right while being sprayed with alkali solution and absorbed. It then leaves from the absorption liquid outlet at the bottom of the spray device and enters the aerobic reaction tank for further treatment.

[0017] The bottoms of the anaerobic bioreactor and aerobic bioreactor are provided with stirring devices to fully mix the wastewater and accelerate sedimentation, thereby effectively purifying the wastewater. The bottoms of the tanks are both funnel-shaped for precipitating and recovering metal sulfides and elemental sulfur.

[0018] The present invention also discloses an improved A / O process for treating sulfur-containing petroleum wastewater. The improved A / O device for treating sulfur-containing petroleum wastewater is used to treat the sulfur-containing petroleum wastewater, comprising the following steps:

[0019] Step 1: After the sulfur-containing petroleum wastewater is filtered through the grid pool, it is mixed with the wastewater returned from the return water pool, and the mixture is passed together into an anaerobic biological reaction pool inoculated with sulfate-reducing bacteria for anaerobic treatment, thereby producing anaerobic treated wastewater, H2S gas, and metal sulfide precipitate, which is deposited at the bottom of the anaerobic biological reaction pool and then discharged;

[0020] Step 2: The H2S gas generated in step 1 is passed into the spray device, absorbed by the alkali solution sprayed by the spray device to form an absorption liquid, which is discharged through the absorption liquid outlet of the spray device and passed together with the anaerobic treated wastewater generated in step 1 into an aerobic bioreactor inoculated with a denitrifying sulfur-oxidizing bacteria group for aerobic treatment, thereby generating aerobic treated wastewater, elemental sulfur and nitrogen. The wastewater that meets the standards after aerobic treatment is discharged to the outside, and the wastewater that does not meet the standards is passed into the reflux pool, and the elemental sulfur is precipitated and deposited at the bottom of the aerobic bioreactor before being discharged;

[0021] Step 3: The nitrogen generated in step 2 is passed into the recirculation pool to deoxygenate the substandard wastewater in the recirculation pool. After deoxygenation, the wastewater is returned to the anaerobic biological reaction pool for further treatment.

[0022] In step 1, the inoculation amount of the sulfate-reducing bacteria is 1-3% of the effective volume of the anaerobic bioreactor. The inoculated sulfate-reducing bacteria are in the logarithmic growth phase and their OD 600The pH value in the anaerobic biological reaction tank is 6.0-8.0, the temperature is 25-40° C., and the hydraulic retention time is 120-150 h.

[0023] In step 2, the inoculation amount of the denitrifying sulfur oxidizing bacteria group is 1-3% of the effective volume of the aerobic bioreactor. The inoculated denitrifying sulfur oxidizing bacteria group is in the logarithmic growth phase and its OD 600 is 0.2-0.3; the dissolved oxygen in the aerobic biological reaction tank is 0.8-1.2 mg / L, the bottom stirring rate is 60-100 rpm, the pH value is 6.0-8.0, the temperature is 25-35° C., and the hydraulic retention time is 120-150 h; the alkali solution is preferably an aqueous sodium hydroxide solution; hydrogen sulfide gas is absorbed by the alkali solution, and the sulfur element is converted into sulfur ions and transferred from the gas phase to the liquid phase, and is discharged from the absorption liquid outlet along with the absorption liquid and flows into the aerobic biological reaction tank for aerobic treatment.

[0024] In step 1, the sulfate-reducing bacteria is Desulfovibrio desulfuricans (ATCC29577), which can be purchased from the market.

[0025] In step 2, the denitrifying sulfur-oxidizing bacteria are a mixed flora consisting of Thiobacillus thiosulfurans and Ochrobacterium hominis. The deposit number of Thiobacillus thiosulfurans is CGMCC No. 12756, and for detailed information, refer to Chinese patent CN106478786A; the deposit number of Ochrobacterium hominis is CGMCC No. 26344, and for detailed information, refer to Chinese patent CN118530880A.

[0026] Wherein, the grid spacing of the grid pool is 10-40 mm, preferably 20 mm.

[0027] The culture medium for culturing the sulfate-reducing bacteria comprises the following components: 4-6 g / L sodium lactate, 1.5-3.0 g / L Na2SO4, 0.8-1.5 g / L NH4Cl, 0.5-2 g / L yeast extract, 0.3-0.8 g / L K2HPO4, 0.1-0.3 g / L MgSO4, 0.05-0.2 g / L CaCl2, 0.05-0.2 g / L FeSO4 and 0.05-0.2 g / L ascorbic acid.

[0028] The culture medium components for culturing the denitrifying sulfur oxidizing bacteria group are: Na2S2O35-8g / L, sodium succinate 5-10g / L, KNO32-3g / L, KH2PO41-3g / L, NaHCO30.8-1.2g / L, MgCl20.5-1.0g / L, NH4Cl 0.3-0.7g / L and FeSO40.01-0.03g / L.

[0029] The present invention addresses the shortcomings of the prior art by proposing a coupled process for treating sulfur-containing petroleum wastewater using a modified A / O process. This process primarily relies on microbial treatment of industrial sulfur-containing petroleum wastewater, effectively addressing the challenges of existing sulfur-containing petroleum wastewater treatment processes, including low treatment load, high cost, low degradation rate, and low desulfurization rate. Sulfate-reducing bacteria in an anaerobic reactor first convert sulfate ions in the sulfur-containing petroleum wastewater into sulfur metal precipitates and hydrogen sulfide gas, thereby removing sulfur and heavy metals from the wastewater. In a spray system, the hydrogen sulfide generated in the anaerobic reactor is absorbed by alkaline solution, converted into sulfide, and then transported to an aerobic reactor for further treatment. In the aerobic bioreactor, denitrifying sulfur-oxidizing bacteria achieve simultaneous sulfur oxidation and denitrification under aerobic conditions through coupled metabolism. Using nitrate or nitrite in the sulfur-containing petroleum wastewater as electron acceptors and sulfide as electron donors, the denitrifying sulfur-oxidizing bacteria oxidize the sulfide in the wastewater into elemental sulfur and convert the nitrate or nitrite into nitrogen, achieving simultaneous sulfur removal. Wastewater that does not meet the standards after treatment in the aerobic bioreactor flows into the return water tank, where nitrogen generated in the aerobic reactor is then introduced into the return water tank for deoxygenation. The wastewater from the return water tank flows into the anaerobic bioreactor for further treatment, achieving a closed-loop cycle.

[0030] Beneficial effects:

[0031] (1) The present invention connects a return water tank after the aerobic biological reactor, and utilizes the nitrogen generated by the denitrification in the aerobic biological reactor to remove the dissolved oxygen in the wastewater containing a certain amount of dissolved oxygen from the aerobic biological reactor in the return water tank, so that the wastewater after deoxygenation can still maintain its ideal anaerobic state after flowing back to the preceding anaerobic biological reactor, thereby ensuring the desulfurization effect of the anaerobic biological reactor. Compared with the existing technology, the desulfurization effect is greatly improved. The process of the present invention is used to treat high-concentration sulfur-containing petroleum wastewater, and the desulfurization rate is as high as 97.8%, which is 15% higher than that of the traditional A / O process.

[0032] (2) The process of the present invention sprays and absorbs the hydrogen sulfide waste gas generated in the anaerobic biological reactor during the treatment process and then further treats it, thereby improving the efficiency of waste gas treatment and reducing the pollution of waste gas emissions. The generated nitrogen is used as deoxygenating gas in the recirculation pool and the anaerobic biological reactor, fully realizing the harmless treatment of the waste gas.

[0033] (3) The aerobic bioreactor of the present invention does not need to add an organic carbon source, and the denitrifying sulfur oxidizing bacteria can convert NO X - The hydrolyzate is converted into N2, S 2- Converted into elemental sulfur, sulfur-oxidizing bacteria are autotrophic bacteria that can obtain energy by oxidizing and reducing sulfur and use inorganic carbon as a carbon source to synthesize organic matter; and the reaction sediment is very small. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0035] Figure 1 The present invention utilizes microorganisms to carry out desulfurization and denitrification of sulfur-containing petroleum wastewater.

[0036] In the figure: 1. Grid pool, 2. Anaerobic bioreactor, 3. Aerobic bioreactor, 4. Spraying device, 5. Return water pool. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the following examples. It should be understood that the following embodiments are only used to illustrate the present invention, rather than to limit the present invention.

[0038] Specific techniques or conditions not specified in the examples were carried out according to those described in the literature in the field or according to the product instructions. Reagents or instruments used without manufacturer specified were all conventional products available through regular channels.

[0039] The culture medium components for culturing the sulfate-reducing bacteria in the following examples are: sodium lactate 6 g / L, Na2SO4 2.5 g / L, NH4Cl 1.5 g / L, yeast extract 1.5 g / L, K2HPO4 0.6 g / L, MgSO4 0.2 g / L, CaCl2 0.1 g / L, FeSO4 0.05 g / L, and ascorbic acid 0.1 g / L.

[0040] The culture medium components for culturing the denitrifying sulfur oxidizing bacteria in the following examples are: Na2S2O3 5g / L, sodium succinate 6g / L, KNO3 1.5g / L, KH2PO4 1.5g / L, NaHCO3 1g / L, MgCl2 0.5g / L, NH4Cl 0.5g / L, FeSO4 0.01g / L.

[0041] In order to demonstrate the desulfurization effect of the device and process of the present invention on petroleum wastewater with different sulfur contents and from refineries in different regions, the following examples select wastewater with different sulfur contents generated by refineries in three different regions for treatment.

[0042] The Desulfovibrio spp. used in the following examples was purchased from Wuhan Huizao Biotechnology Co., Ltd. with the product number HZB417988.

[0043] Example 1 Improved A / O Device for Treating Sulfur-Containing Petroleum Wastewater

[0044] like Figure 1As shown, the improved A / O device for treating sulfur-containing petroleum wastewater of the present invention includes a grid tank 1, an anaerobic biological reaction tank 2, an aerobic biological reaction tank 3, a spray device 4, a return water tank 5 and a return system; the grid tank 1, the anaerobic biological reaction tank 2, the aerobic biological reaction tank 3 and the return water tank 5 are connected in sequence through pipelines;

[0045] The upper part of one side wall of the spray device 4 is provided with a spray liquid inlet and a hydrogen sulfide gas inlet, and the bottom is provided with an absorption liquid outlet. The spray device 4 is provided with an S-shaped channel formed by a partition, and an S-shaped pipe with a liquid nozzle is provided in the S-shaped channel; the spray liquid inlet is connected to the S-shaped pipe; the hydrogen sulfide gas inlet is connected to the S-shaped channel; the bottom of the spray device is provided with an inclined surface for collecting the alkaline solution that has absorbed hydrogen sulfide and returning it to the aerobic reaction tank. The anaerobic biological reaction tank 2 is provided with a hydrogen sulfide gas outlet, which is connected to the hydrogen sulfide gas inlet of the spray device 4 through a pipe; a one-way valve is provided at the hydrogen sulfide gas outlet of the anaerobic biological reaction tank 2, so that the hydrogen sulfide gas generated by the anaerobic biological reaction tank automatically flows into the spray device. The aerobic biological reaction tank 3 is provided with an absorption liquid inlet, which is connected to the absorption liquid outlet at the bottom of the spray device 4 through a pipe.

[0046] After the hydrogen sulfide waste gas enters the S-shaped channel, it is purged from front to back. The partition set inside the spray device forces the waste gas to follow the S-shaped channel, moving from left to right while being sprayed with alkali solution and absorbed. It then leaves from the absorption liquid outlet at the bottom of the spray device and enters the aerobic reaction tank for further treatment.

[0047] The aerobic biological reaction tank 3 is provided with a nitrogen outlet, and the recirculation water tank 5 is provided with a nitrogen inlet. The nitrogen outlet of the aerobic biological reaction tank 3 and the nitrogen inlet of the recirculation water tank 5 are connected through a pipeline.

[0048] The bottom of the anaerobic biological reaction tank and the aerobic biological reaction tank is equipped with a stirring device to fully mix the wastewater and accelerate sedimentation, thereby effectively purifying the wastewater; the bottom of the tank is set in a funnel shape for precipitation and recovery of metal sulfides and elemental sulfur.

[0049] The reflux system consists of a reflux pipe and a reflux pump arranged on the reflux pipe; the reflux pool 5 is provided with a reflux liquid outlet, which is connected to the anaerobic biological reaction tank 2 through the reflux pipe.

[0050] Example 2 Improved A / O process for treating sulfur-containing petroleum wastewater from a refinery in Qilu

[0051] This example uses the improved A / O process of the present invention to treat petroleum wastewater from a refinery in Qilu, which has a relatively high sulfur content. The sulfide (oxidized sulfur) content is 2538 mg / L, and the nitrate nitrogen content is 1800-2000 mg / L. The specific steps are as follows:

[0052] The petroleum wastewater after simple filtration in the grid pool (grid spacing 20mm) is passed into the anaerobic biological reactor 2, and the wastewater pH is adjusted to 6 and the temperature is 25℃. The anaerobic biological reactor 2 has been inoculated and cultured in advance to OD 600 =0.3 of sulfate-reducing bacteria, Desulfovibrio sulfuricans, with an inoculum concentration of 1% of the effective volume of anaerobic bioreactor 2. The hydraulic retention time for anaerobic bioreactor 2 is 150 hours. The bottom of anaerobic bioreactor 2 is designed in a funnel shape to facilitate solid-liquid separation and to precipitate and remove metal sulfides generated during the anaerobic bioreactor process.

[0053] The wastewater after anaerobic biological treatment flows into the aerobic biological reactor 3, and the pH of the wastewater is adjusted to 6 and the temperature is 25°C. The aerobic biological reactor 3 has been inoculated and cultured in advance to OD 600 =0.8 denitrifying sulfur-oxidizing bacteria, with a bacterial inoculum size of 1% of the effective volume of the aerobic bioreactor 3. The aerobic bioreactor is aerated, with a DO value controlled at 0.8 mg / L. A stirring device is provided at the bottom, with a stirring rate controlled at 60 rpm. The hydraulic retention time for the aerobic bioreactor is 150 h. After the aerobic treatment is completed, the effluent water quality parameters are tested (liquid phase testing) at the aerobic reactor outlet. Discharge is only allowed after meeting the "Pollutant Discharge Standard for Municipal Wastewater Treatment Plants (GB18919-2002)". Sewage that does not meet the standards is deoxygenated in the return water tank 5 using nitrogen generated in the aerobic bioreactor, and then re-circulated to the anaerobic bioreactor 2 for treatment until it meets the standards and is discharged.

[0054] The same batch of wastewater was treated using a conventional A / O process as a control, and the treatment results were compared with those of the improved A / O process of the present invention. The sulfur content in the wastewater was measured using the iodine titration method (HJ / T60-2000). The results, shown in Table 1, demonstrate that the improved A / O process is capable of effectively treating petroleum industry wastewater with a high sulfur content, achieving a desulfurization rate of 97.8%. Furthermore, the improved A / O process significantly outperformed the conventional A / O process in desulfurizing sulfur-containing wastewater, demonstrating its significant practicality and superiority in treating wastewater with a high sulfur content.

[0055] Table 1 Desulfurization effect of improved A / O process on sulfur-containing petroleum wastewater from a refinery in Qilu

[0056]

[0057] Example 3 Application of the Improved A / O Process in Treating Sulfur-Containing Petroleum Wastewater from a Jinling Refinery

[0058] This example uses the modified A / O process of the present invention to treat petroleum wastewater from a Jinling refinery with a relatively medium sulfur content. The sulfide (oxidized sulfur) content is 1725 mg / L, and the nitrate nitrogen content is 1000-1200 mg / L. The specific steps are as follows:

[0059] After simple filtration through the grid pool (grid spacing 20mm), the petroleum wastewater is introduced into the anaerobic bioreactor 2, and the wastewater pH is adjusted to 7 and the temperature is 30℃. The anaerobic bioreactor 2 has been inoculated and cultured in advance to OD 600 =0.2 of sulfate-reducing bacteria, Desulfovibrio sulfuricans, with an inoculum size of 2% of the effective volume of anaerobic bioreactor 2. The hydraulic retention time for anaerobic treatment is 120 hours. The bottom of anaerobic bioreactor 2 is designed in a funnel shape to facilitate solid-liquid separation and to precipitate and remove metal sulfides generated during the anaerobic bioreactor process.

[0060] The wastewater after anaerobic biological treatment flows into the biological aerobic reactor 3, and the pH of the wastewater is adjusted to 7 and the temperature is 30°C. The aerobic biological reactor 3 has been inoculated and cultured in advance to OD 600 =0.8 denitrifying sulfur-oxidizing bacteria, with the bacterial inoculum size accounting for 2% of the effective volume of the aerobic bioreactor 3. During the advanced treatment process, the hydraulic retention time (HRT) for aerobic treatment is 150 hours. The bioaerobic reactor is aerated, with a DO value controlled at 1.0 mg / L. A stirring device is installed at the bottom, with a stirring rate controlled at 80 rpm. After aerobic treatment is completed, the effluent water quality parameters are tested (liquid phase testing) at the aerobic reactor outlet. Discharge is only permitted if it meets national wastewater discharge standards. Any wastewater that does not meet these standards is deoxygenated in the return tank 5 using nitrogen generated in the aerobic bioreactor, then recirculated to the anaerobic bioreactor 2 for treatment until it meets the standards for discharge.

[0061] The same batch of wastewater was treated using a conventional A / O process as a control, and the treatment results were compared with those of the improved A / O process of the present invention. The sulfur content in the wastewater was measured using the iodine titration method (HJ / T60-2000). The results, shown in Table 2, demonstrate that the improved A / O process can effectively treat petroleum industry wastewater with a medium sulfur content, achieving a desulfurization rate of 96.3%. Furthermore, the improved A / O process significantly outperformed the conventional A / O process in desulfurizing sulfur-containing wastewater, demonstrating its significant practicality and superiority in treating wastewater with a medium sulfur content.

[0062] Table 2 Desulfurization effect of improved A / O process on sulfur-containing petroleum wastewater from a refinery in Jinling

[0063]

[0064] Example 4 Application of the Improved A / O Process in Treating Sulfur-Containing Petroleum Wastewater from a Daqing Refinery

[0065] This example uses the improved A / O process of the present invention to treat petroleum wastewater from a Daqing refinery with a relatively low sulfur content. The sulfide (oxidized sulfur) content is 779 mg / L, and the nitrate nitrogen content is 400-600 mg / L. The specific steps are as follows:

[0066] The petroleum wastewater after simple filtration in the grid pool (grid spacing 20mm) is passed into the anaerobic biological reactor 2, and the wastewater pH is adjusted to 8 and the temperature is 40℃. The anaerobic biological reactor 2 has been inoculated and cultured in advance to OD 600 =0.2 of sulfate-reducing bacteria, Desulfovibrio sulfatum, with an inoculum volume of 3% of the effective volume of anaerobic bioreactor 2. The hydraulic retention time for anaerobic bioreactor 2 is 150 hours. The bottom of anaerobic bioreactor 2 is designed in a funnel shape to facilitate solid-liquid separation and to precipitate and remove metal sulfides generated during the anaerobic bioreactor process.

[0067] The wastewater after anaerobic biological treatment flows into the aerobic biological reactor 3, and the pH of the wastewater is adjusted to 8 and the temperature is 35°C. The aerobic biological reactor 3 has been inoculated and cultured in advance to OD 600 =0.8 denitrifying sulfur-oxidizing bacteria, and the bacterial liquid inoculation amount is 3% of the effective volume of the aerobic bioreactor 3. The aerobic bioreactor is aerated, and the DO value is controlled at 1.2 mg / L. A stirring device is provided at the bottom, and the stirring rate is controlled at 100 rpm. The hydraulic retention time of the aerobic biological treatment is 120 hours. After the aerobic treatment is completed, the water quality parameters of the effluent are tested (liquid phase testing) at the aerobic reactor outlet. If it meets the "Pollutant Discharge Standard for Municipal Wastewater Treatment Plants (GB18919-2002)", it is discharged. The sewage that does not meet the standard is deoxygenated in the return water tank 5 with nitrogen generated in the aerobic bioreactor, and then re-circulated to the anaerobic bioreactor 2 for treatment until it meets the standard and is discharged.

[0068] The same batch of wastewater was treated using a conventional A / O process as a control, and the treatment results were compared with those of the improved A / O process of the present invention. The sulfur content in the wastewater was measured using the iodine titration method (HJ / T60-2000). The results, shown in Table 3, demonstrate that the improved A / O process can effectively treat petroleum industry wastewater with a low sulfur content, achieving a desulfurization rate of 92.8%. Furthermore, the improved A / O process significantly outperformed the conventional A / O process in desulfurizing sulfur-containing wastewater, demonstrating its significant practicality and superiority in treating wastewater with a high sulfur content.

[0069] Table 3 Desulfurization effect of improved A / O process on sulfur-containing petroleum wastewater from a refinery in Daqing

[0070]

[0071] The present invention provides a concept and method for an improved A / O device and process for treating sulfur-containing petroleum wastewater. While there are numerous methods and approaches for implementing this technical solution, the foregoing description represents only a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. An improved A / O device for treating sulfur-containing petroleum wastewater, characterized in that: It includes a grid pool (1), an anaerobic biological reaction pool (2), an aerobic biological reaction pool (3), a spray device (4), a return water pool (5) and a return system; The grid pool (1), the anaerobic biological reaction pool (2), the aerobic biological reaction pool (3) and the reflow water pool (5) are connected in sequence through pipelines; The spraying device (4) is provided with a spraying liquid inlet, a hydrogen sulfide gas inlet, and an absorption liquid outlet; the anaerobic biological reaction tank (2) is provided with a hydrogen sulfide gas outlet, and the hydrogen sulfide gas outlet is connected to the hydrogen sulfide gas inlet of the spraying device (4) through a pipeline; the aerobic biological reaction tank (3) is provided with an absorption liquid inlet, and the absorption liquid inlet is connected to the absorption liquid outlet of the spraying device (4) through a pipeline; The aerobic biological reaction tank (3) is provided with a nitrogen outlet, and the recirculation water tank (5) is provided with a nitrogen inlet, and the nitrogen outlet of the aerobic biological reaction tank (3) and the nitrogen inlet of the recirculation water tank (5) are connected through a pipeline; The reflux system consists of a reflux pipe and a reflux pump arranged on the reflux pipe; the reflux water pool (5) is provided with a reflux liquid outlet, and the reflux liquid outlet is connected to the anaerobic biological reaction tank (2) through the reflux pipe.

2. The improved A / O device for treating sulfur-containing petroleum wastewater according to claim 1, characterized in that: A one-way valve is provided at the hydrogen sulfide gas outlet of the anaerobic biological reaction tank (2).

3. The improved A / O device for treating sulfur-containing petroleum wastewater according to claim 1, characterized in that: The spray device (4) is provided with an S-shaped channel formed by a partition, and an S-shaped pipe with a liquid nozzle is provided in the S-shaped channel; the spray liquid inlet is connected to the S-shaped pipe; the hydrogen sulfide gas inlet is connected to the S-shaped channel; and the bottom of the spray device is set as an inclined surface.

4. The improved A / O device for treating sulfur-containing petroleum wastewater according to claim 1, characterized in that: A stirring device is provided at the bottom of the anaerobic biological reaction tank (2) and the aerobic biological reaction tank (3), and the bottoms of the tanks are both configured in a funnel shape.

5. A method for treating sulfur-containing petroleum wastewater using the improved A / O device for treating sulfur-containing petroleum wastewater according to any one of claims 1 to 4.

6. An improved A / O process for treating sulfur-containing petroleum wastewater, characterized in that: The following steps are involved: Step 1: the sulfur-containing petroleum wastewater is filtered through a grid pool and then subjected to anaerobic biological treatment with sulfate-reducing bacteria to produce anaerobic treated wastewater, H2S gas and metal sulfide precipitate, and the metal sulfide precipitate is discharged after deposition; Step 2: The H2S gas generated in step 1 is absorbed by alkaline solution to form an absorption liquid, which is subjected to aerobic biological treatment with denitrifying sulfur-oxidizing bacteria together with the anaerobic treated wastewater generated in step 1 to produce aerobic treated wastewater, elemental sulfur and nitrogen. The wastewater that meets the standards after aerobic treatment is discharged to the outside, and the wastewater that does not meet the standards is subjected to step 3, and the elemental sulfur is precipitated and then discharged; In step 3, the nitrogen generated in step 2 is introduced into the wastewater that does not meet the standards in step 2 for deoxygenation. The deoxygenated wastewater is returned and mixed with the sulfur-containing petroleum wastewater filtered through the grid pool, and then step 1 is performed together.

7. The improved A / O process for treating sulfur-containing petroleum wastewater according to claim 6, characterized in that: In step 1, the inoculation amount of the sulfate-reducing bacteria is 1-3% of the effective volume of the reaction tank for anaerobic biological treatment. The inoculated sulfate-reducing bacteria are in the logarithmic growth phase and their OD 600 The pH value during the anaerobic biological treatment is 6.0-8.0, the temperature is 25-40° C., and the hydraulic retention time is 120-150 h.

8. The improved A / O process for treating sulfur-containing petroleum wastewater according to claim 6, characterized in that: In step 2, the inoculation amount of the denitrifying sulfur oxidizing bacteria group is 1-3% of the effective volume of the reaction tank for aerobic biological treatment. The inoculated denitrifying sulfur oxidizing bacteria group is in the logarithmic growth phase and its OD 600 The dissolved oxygen during the aerobic biological treatment is 0.8-1.2 mg / L, the stirring rate is 60-100 rpm, the pH value is 6.0-8.0, the temperature is 25-35°C, and the hydraulic retention time is 120-150 h.

9. The improved A / O process for treating sulfur-containing petroleum wastewater according to claim 6 or 7, characterized in that: The sulfate-reducing bacteria is Desulfovibrio.

10. The improved A / O process for treating sulfur-containing petroleum wastewater according to claim 6 or 8, characterized in that: The denitrifying sulfur oxidizing bacteria group is a mixed bacteria group consisting of Thiobacillus thiosulfurans and Ochrobacterium hominis.

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