Method for treating nitrobenzene high-salinity wastewater by using sulfur-modified zero-valent iron reinforced anaerobic organisms

Abstract

The invention discloses a method for treating nitrobenzene high-salinity wastewater by using sulfur-modified zero-valent iron reinforced anaerobic organisms. The sulfur-modified zero-valent iron is introduced into a traditional high-salt anaerobic reduction system, so that the direct interspecific electron transfer efficiency of microorganisms is enhanced, the activity of the microorganisms is improved, the tolerance of anaerobic sludge to a high-salt environment is enhanced, meanwhile, the nitrobenzene degradation capacity of the anaerobic sludge in the high-salt wastewater can be effectively improved, and the high-salt wastewater treatment efficiency is improved. The method has a wide application prospect in wastewater treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial wastewater treatment and relates to a method for treating nitrobenzene high-salt wastewater by strengthening anaerobic biology using sulfur-modified zero-valent iron. Background Art

[0002] Food processing wastewater, pharmaceutical industrial wastewater, landfill leachate wastewater, fishery wastewater, aquatic wastewater, fur wastewater, fossil fuel wastewater, etc. contain a large amount of inorganic salt ions and difficult-to-degrade pollutants, which are called high-salt organic wastewater. The high-salt wastewater treatment methods currently used mainly include physical, chemical and biological methods. Although physical and chemical methods have certain effects on the treatment of high-salt wastewater, they also have problems such as high equipment investment and operation investment, easy to cause secondary pollution and difficult to promote on a large scale in practical applications. Biological methods have the advantages of high efficiency, low treatment cost and low secondary pollution. They have great research value and application prospects in the treatment of high-salt organic wastewater. However, high salt content will seriously inhibit the activity of microorganisms and even cause cell decomposition and death. Therefore, for the biological treatment of high-salt wastewater, how to enable microorganisms to maintain sufficient activity and exert their effectiveness in a high-salt environment is the key.

[0003] By introducing exogenous conductive materials into the microbial system, direct electron transfer (DIET) can be promoted, thereby improving the efficiency of electron exchange between microorganisms. For pollutants that are difficult to degrade, the DIET process can be enhanced by adding conductive materials, thereby improving the degradation efficiency of pollutants. Iron-based materials stand out among many conductive materials due to their large specific surface area, strong reducing activity and low cost. Studies have shown that iron-based materials can replace cytochrome c as a bridge connecting bacteria and methanogens to achieve direct electron transfer. At the same time, the added iron element can also promote the metabolism of microorganisms and enhance their activity.

[0004] However, common iron-based materials, such as nano-zero-valent iron (nZVI), are prone to agglomeration, oxidation, and passivation during storage and on-site repair, and have poor electron transfer selectivity. To overcome these problems, researchers have often sulfided the surface of nZVI (Cao Z, Liu X, Xu J, et al. Removal of Antibiotic Florfenicol by Sulfide-Modified Nanoscale Zero-Valent Iron[J]. Environmental Science & Technology, 2017, 51: 11269-11277.) to generate sulfidated zero-valent iron (S-ZVI). Sulfidation not only enhances the dispersibility and stability of nanoparticles, but also effectively inhibits the release of hydrogen from nZVI, making more electrons available for the removal of target pollutants (Xu J, Wang Y, Weng C, et al. Reactivity, Selectivity, and Long-Term Performance of Sulfidized Nanoscale Zerovalent Iron with Different Properties [J]. Environmental Science & Technology, 2019, 53: 5936-5945.). Compared with other modification methods, the research focus of sulfidation modification is to enhance the electron selectivity of nZVI for specific reactions and achieve directional degradation of target pollutants. Therefore, the application of S-ZVI in the field of environmental governance and remediation has become a hot topic of research.

[0005] S-ZVI can be used as a reducing agent to reduce various organic pollutants. At the same time, due to the hydrophobicity of FeS on its surface, it is more conducive to reacting with highly hydrophobic organic matter. Li et al. conducted a study on the use of zero-valent iron sulfide in water treatment and found that S-ZVI can transfer electrons more effectively and is more hydrophobic than ZVI, so it is easier to bind to hydrophobic organic pollutants (Li JX, Zhang XY, Sun YK, et al. Advances in Sulfidation of Zerovalent Iron for Water Decontamination [J]. Environmental Science & Technology, 2017, 51, (23), 13533-13544.). Dai et al. found that zero-valent iron sulfide enhanced the reduction and degradation of chloramphenicol and found that the FeS generated on the surface xIt can directly participate in the reduction of pollutants (Dai YS, Du WY, Jiang C, et al. Enhanced reductive degradation of chloramphenicol by sulfidated microscale zero-valent iron: Sulfur-induced mechanism, competitive kinetics, and new transformation pathway[J]. Water research, 2023, 233: 119743.).

[0006] Nitrobenzene (NB) has been listed as a priority pollutant by many countries due to its tertiary effects, difficulty in degradation and environmental accumulation trend. At present, the main treatment methods for high-salinity nitrobenzene wastewater are mainly physical and chemical methods, such as resin adsorption, activated carbon adsorption, Fenton oxidation, iron-carbon reduction, etc., or aerobic biological treatment. These methods not only have high treatment costs and are difficult to achieve pretreatment goals, but may also cause secondary pollution. Therefore, if a method based on biological methods can be designed to efficiently degrade high-salinity nitrobenzene wastewater under anaerobic conditions, it will be able to effectively reduce process investment costs and operating costs. However, halophilic strains are expensive and have limited application ranges, and the domestication of salt-tolerant microorganisms often takes a long time. Therefore, it is a very meaningful research task to find a low-cost method that can improve the tolerance of microorganisms to high-salinity environments in a short period of time and improve their efficiency in degrading pollutants in high-salinity wastewater. Summary of the invention

[0007] The purpose of the present invention is to provide a method for strengthening anaerobic biological treatment of nitrobenzene high-salinity wastewater using sulfur-modified zero-valent iron. The method adds sulfur-modified zero-valent iron to nitrobenzene high-salinity wastewater, using sulfur-modified zero-valent iron to act as a conductive medium, establishes a direct interspecies electron transfer process, enhances the efficiency of microbial electron transfer, and thus enhances the salt tolerance of anaerobic sludge. At the same time, sulfur-modified zero-valent iron can also act as an electron donor to provide additional electrons, further strengthening the anaerobic biological treatment of nitrobenzene that is difficult to degrade in nitrobenzene high-salinity wastewater.

[0008] The technical solution for achieving the purpose of the present invention is as follows:

[0009] The method for treating nitrobenzene high-salinity wastewater by using sulfur-modified zero-valent iron to strengthen anaerobic biology comprises the following steps:

[0010] Step 1, adding simulated wastewater with a nitrobenzene concentration of 40-60 mg / L into anaerobic sludge, and after the nitrobenzene in the simulated wastewater is completely degraded, gradually increasing the nitrobenzene concentration in the wastewater to 100 mg / L, and completing the sludge acclimation after the effluent water quality is stable;

[0011] Step 2: Passing the acclimated anaerobic sludge into nitrobenzene high-salt wastewater, and adding sulfur-modified zero-valent iron to biodegrade nitrobenzene, wherein the concentration of NaCl in the nitrobenzene high-salt wastewater is above 10 g / L.

[0012] Preferably, in step 1, in addition to nitrobenzene, the simulated wastewater also contains: 1.02 g / L NH4Cl, 0.252 g / L NaH2PO4·2H2O, 1.5 g / L NaHCO3, and 1 g / L glucose.

[0013] Preferably, in step 1, the sludge concentration is 2 g VSS L -1 (VSS: Volatile Suspended Solids).

[0014] Preferably, in step 2, the concentration of NaCl in the nitrobenzene high-salt wastewater is 10 to 60 g / L.

[0015] Preferably, in step 2, the sulfur-modified zero-valent iron is prepared by ball milling to a particle size of 100 nm.

[0016] Preferably, in step 2, the dosage of sulfur-modified zero-valent iron is 0.5 g / L.

[0017] Preferably, in step 1 or 2, the operating temperature of the biodegradation system is 25°C to 35°C.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention uses sulfur-modified zero-valent iron as an additive added to the nitrobenzene high-salt wastewater biodegradation system. The sulfur-modified zero-valent iron can enhance the efficiency of microbial electron transfer, improve the salt tolerance of sludge, alleviate salt stress, and achieve effective degradation of nitrobenzene, a toxic pollutant in high-salt wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Figure 2 shows the nitrobenzene removal rate (a) and aniline generation rate (b) in the anaerobic sludge reduction of nitrobenzene system (Bio), the sulfur-modified zero-valent iron chemical reduction of nitrobenzene system (S-ZVI), and the sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI) under different salinity stresses.

[0021] Figure 2 The figure shows the effect of sulfur-modified zero-valent iron on the redox potential (a) and pH (b) of the anaerobic system under different salinities.

[0022] Figure 3 This graph shows the effect of sulfur-modified zero-valent iron on microbial electron transfer activity under different salinities.

[0023] Figure 4 XPS spectra of S-ZVI (a, b, c); XPS spectra of sulfur-modified zero-valent iron chemical reduction of nitrobenzene system (S-ZVI) after reaction at 0 g / L (d, e, f) and 20 g / L (g, h, i) salinities; and XPS spectra of sulfur-modified zero-valent iron after reaction at 0 g / L (j, k, l) and 20 g / L (m, n, o) salinities in sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI).

[0024] Figure 5 These are SEM images of the morphology of microorganisms after reaction in the anaerobic sludge reduction of nitrobenzene system (Bio) (a, b, c, d, e) and the sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI) (f, g, h, i, j) at salinity of 0 g / L ~ 60 g / L.

[0025] Figure 6 (a) The nitrobenzene removal rate and (b) aniline generation rate of different iron-based materials at 0 g / L and 20 g / L salinity. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments and drawings.

[0027] The target pollutant of the present invention is nitrobenzene. Due to the electron-withdrawing property of -NO2, the electron cloud density on the benzene ring decreases, thereby hindering the electrophilic attack of the oxidase, resulting in the difficulty of aerobic degradation of nitrobenzene. -NO2 nucleophilic reaction is easier. Under anaerobic conditions, nitrobenzene can be reduced to aniline through a series of electron gains and losses and protonation. Aniline can be further degraded under aerobic conditions, which can overcome the shortcomings of aerobic degradation of nitrobenzene. Therefore, the biological treatment of nitrobenzene usually uses anaerobic conditions to degrade nitrobenzene.

[0028] In the following examples, the zero-valent iron used was purchased from Aladdin Reagent (Shanghai) Co., Ltd. and prepared according to the sulfur-modified zero-valent iron reference (Sun Y, Zheng K, Du X, et al. Insights into the contrasting effects of sulfidation on dechlorination of chlorinated aliphatic hydrocarbons by zero-valent iron[J]. Water research, 2024, 255: 121494.).

[0029] Example 1

[0030] 1. Acclimation of anaerobic sludge:

[0031] The anaerobic sludge used in this batch experiment was taken from a chemical plant sewage treatment plant. The anaerobic sludge was placed in a 2L upflow anaerobic bioreactor and fed with simulated wastewater for acclimatization. The simulated wastewater with a nitrobenzene concentration of 40-60mg / L was added to the anaerobic sludge. After the nitrobenzene in the simulated wastewater could be completely degraded, the nitrobenzene concentration in the wastewater was gradually increased to 100mg / L. After the effluent water quality was stable, the sludge acclimatization was completed. The simulated wastewater composition was: 40-60mg / L nitrobenzene, 1.02g / L NH4Cl, 0.252g / L NaH2PO4·2H2O, 1.5g / L NaHCO3, 1g / L glucose.

[0032] The difficult-to-degrade organic pollutant targeted by the present invention is nitrobenzene. The batch experiment of nitrobenzene degradation is carried out in a 100mL serum bottle. During the experiment, the serum bottle under each condition contains 80mL of simulated wastewater, and the same volume of anaerobic sludge acclimated with nitrobenzene is added to each serum bottle, and the sludge concentration in the serum bottle is controlled to be 2g VSS / L. The serum bottle is placed at a constant speed of 180rmin -1 The reaction was carried out at a constant temperature of 35°C in a full-temperature shaking incubator.

[0033] 2. Experiment on degradation of nitrobenzene wastewater with different salinities by acclimated sludge

[0034] Simulated wastewater with salinities of 0 g / L, 10 g / L, 20 g / L, 35 g / L and 60 g / L and a nitrobenzene concentration of 120.53 mg / L was introduced respectively, and domesticated sludge was added to construct an anaerobic sludge nitrobenzene degradation system at different salinities (Bio).

[0035] Figure 1 Figure (a) shows the removal rate of nitrobenzene under different salinity stresses. As the salt concentration increases, the removal rate of nitrobenzene decreases significantly. Without the addition of NaCl, the degradation time of 120.53 mg / L nitrobenzene is less than 22 h. When the NaCl concentration is 20 g L -1 At the same time, in the experimental groups with salt concentrations of 35 g / L and 60 g / L, the degradation rates of nitrobenzene after 28 h were 52.27±0.20% and 50.40±5.72%, respectively.

[0036] The above results show that the increase in salt concentration significantly inhibits the degradation of nitrobenzene by anaerobic microorganisms. High salinity increases the osmotic pressure inside and outside the cells, causes cell dehydration, inhibits enzyme activity, and ultimately reduces the biological activity of bacteria.

[0037] Example 2

[0038] The anaerobic sludge after acclimation in Example 1 was introduced into nitrobenzene wastewater with salinities of 0 g / L, 10 g / L, 20 g / L, 35 g / L and 60 g / L, respectively, and 0.5 g / L of sulfur-modified zero-valent iron was added to construct a sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI). In addition, an anaerobic sludge reduction of nitrobenzene system (Bio) and a sulfur-modified zero-valent iron chemical reduction of nitrobenzene system (S-ZVI) were set up to synergistically analyze the enhancing effect of sulfur-modified zero-valent iron on anaerobic reduction of nitrobenzene under high salinity.

[0039] from Figure 1 It can be seen that as the salinity increases from 0g / L to 60g / L, the nitrobenzene removal rates of the Bio+S-ZVI system at 6h are 94.75±5.48%, 93.1±8.25%, 99.38±5.38%, 81.57±3.89%, 76.14±2.40%, and the aniline generation rates are 94.2±7.91%, 87.52±9.99%, 80.67±8.99%, 51.07±10.74%, 47.2±0.77%, respectively. As the salt concentration increases, the nitrobenzene removal first increases and then decreases, and the aniline generation shows a downward trend with the increase of salinity, indicating that a certain increase in salinity will promote the removal of nitrobenzene to a certain extent, but too high salinity will inhibit the removal of nitrobenzene. The production of aniline decreased with the increase of salinity. By observing the production of aniline in the Bio system and the S-ZVI system at the same time, it was found that at salt concentrations of 0g / L and 10g / L, the aniline production rate of the Bio system was 100±3.23% and 97.39±0.33% after the experiment, which was significantly higher than that of S-ZVI 45.85±4.25% and 41.67±3.09%.

[0040] The above results show that S-ZVI can significantly enhance the anaerobic reduction of nitrobenzene under high salt conditions, and enhance the pollutant removal effect by enhancing the reduction of nitrobenzene.

[0041] Figure 2 This is a graph showing the effect of sulfur-modified zero-valent iron on the redox potential and pH of the anaerobic system under different salinities.

[0042] The ORP and pH of the system after the reaction of Bio, S-ZVI, and Bio+S-ZVI were shown. It can be found that the ORP of Bio gradually decreases with the increase of salinity, indicating that salinity has a strong inhibitory effect on microorganisms and reduces the reaction activity of the system. The ORP in the S-ZVI chemical reduction system first increases and then decreases, indicating that a certain salinity can enhance the corrosion of S-ZVI and improve its ability as an electron donor, but higher salinity may cause its passivation and weaken its reaction activity. The ORP in the Bio+S-ZVI enhanced system is higher than that of Bio and S-ZVI at different salinities, indicating that the synergistic effect of organisms and materials can significantly reduce the ORP of the system. At the same time, studies have shown that the coupling system of materials and organisms is conducive to the electron outflow of materials and improves the removal efficiency of pollutants. In the Bio anaerobic system, the pH gradually decreases with the increase of salinity. Salinity will inhibit the activity of anaerobic microorganisms and lead to acidification. In the S-ZVI chemical reduction system, the pH gradually increases with the increase of salinity, and the corrosion of iron will cause the alkalinity of the system to increase. The pH in the Bio+S-ZVI enhanced system remained at a stable level as the salinity increased (7.41±0.02, 7.18±0.05, 7.11±0.01, 7.11±0.01, 7.07±0.01), indicating that the synergistic effect of materials and organisms is conducive to maintaining the stability of the pH in the system and maintaining a high level of microbial activity.

[0043] Figure 3 The figure shows the effect of sulfur-modified zero-valent iron on the electron transfer activity of microorganisms under different salinities. The microbial metabolic activity can be reflected by measuring ETS (microbial electron transfer activity) in the system. It uses INT reagent to react with the electron transfer chain of microorganisms, and uses part of the electrons to reduce and discolor the INT reagent, thereby indirectly reflecting the electron transfer activity of activated sludge.

[0044] The relative activity of ETS is based on the ETS activity in the Bio anaerobic system at 0g / L salt concentration, and then the changes in ETS activity of the remaining groups relative to the control group are observed, which can more intuitively reflect the effects of different conditions on ETS. Figure 3 As shown in the results, in the Bio anaerobic system, with the increase of salinity, the relative activity of ETS decreased. Salinity has a strong stress effect on microorganisms, affecting their osmotic balance, destroying cell structure, inhibiting cell activity, and thus reducing the activity of intercellular electron transfer. At a salt concentration of 60g / L, the relative activity of ETS was only 35.24±1.07%. In the Bio+S-ZVI enhanced system, at salt concentrations of 10g / L, 20g / L, and 35g / L, the relative activity of ETS remained at a high level of 124.22±0.27%, 136.06±3.29%, and 109.93±0.01%, indicating that the addition of S-ZVI can effectively alleviate the stress of salinity on microorganisms, accelerate the metabolic process between microorganisms, and improve the activity of electron transfer.

[0045] Example 3

[0046] XPS analysis of the valence state of the S-ZVI material after Example 2 demonstrated that S-ZVI had excellent performance in enhancing the anaerobic reduction of nitrobenzene under high salt conditions. Figure 4 These are the XPS spectra of sulfur-modified zero-valent iron before and after the reaction in the sulfur-modified zero-valent iron chemical reduction of nitrobenzene system (S-ZVI) and the sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI) at salinity of 0 g / L and 20 g / L.

[0047] XPS was used to analyze the elemental composition of S-ZVI itself and the material after the reaction, and the elemental changes on the surface of the material after the reaction were observed. The results are as follows: Figure 4 As shown. The XPS spectrum of the S2p region is Figure 4 (b, e, h, k, n), 162.2±0.3 eV is assigned to S 2- +1.18 eV corresponds to the 2p 3 / 2 orbital; 164.05 ± 0.3 eV is assigned to S - The 2p 3 / 2 orbital, +1.18 eV corresponds to its 1 / 2 orbital; 168.0 ± 0.3 eV is assigned to SO4 2- The 2p 3 / 2 orbital, +1.18eV corresponds to its 1 / 2 orbital. First, the material itself was analyzed and it was found that the surface of the material had a FeS shell, indicating that the material was effectively modified by sulfur. At the same time, the S-ZVI chemical reduction system is compared with the Bio+S-ZVI enhanced system SO4 2- The corresponding peak area is larger, indicating that the degree of sulfur corrosion in the Bio+S-ZVI enhanced system is higher, indicating that the S-ZVI enhanced pollutant removal ability is stronger under the enhanced system. 2- The corresponding peak area is larger, indicating that a certain salinity is conducive to material corrosion and enhances the electron transfer ability. The XPS spectrum of the material in the Fe2p region is as follows Figure 4 (a, d, j, g, m), where 710.6 ± 0.3 eV is assigned to Fe 2+ The 2p 3 / 2 orbital of , +13.6eV corresponds to its 1 / 2 orbital; 712.5±0.3eV is assigned to Fe 3+ The 2p 3 / 2 orbital of the 2p, +13.6eV corresponds to its 1 / 2 orbital; 717±0.3eV and 733±0.3eV are assigned to the satellite peaks. It can be observed that as the reaction ends, the Fe 2+The corresponding peak areas are enhanced, and the materials participate in the removal of pollutants. At the same time, the corrosion degree of the materials in the S-ZVI chemical reduction system is significantly higher than that in the Bio+S-ZVI enhanced system, indicating that the materials are easily passivated under a certain salinity, resulting in a decrease in reaction activity, and the coupling of organisms and materials can alleviate the passivation phenomenon. At the same time, under a certain salinity, the reaction degree of the materials is further improved, indicating that it is more conducive to pollutant removal.

[0048] Example 4

[0049] Analysis of the surface morphology of the microorganisms after Example 2 showed that the addition of S-ZVI could alleviate the stress of salinity on the microorganisms, maintain the cell morphology, and ensure the cell activity. Figure 5 These are SEM images of the morphology of microorganisms after reaction in the anaerobic sludge reduction of nitrobenzene system (Bio) and the sulfur-modified zero-valent iron enhanced anaerobic sludge reduction of nitrobenzene system (Bio+S-ZVI) at different salinities.

[0050] Salinity has a significant stress effect on microorganisms, which will change the cell osmotic pressure, cause the cells to shrink, destroy their cell structure, reduce biological activity, and affect their normal metabolic function. By characterizing the morphology of the cell surface by SEM, the tolerance of cells under different salinities can be observed. In the Bio anaerobic system, microbial cells show obvious shrinkage as salinity increases. When the salt concentration is 60g / L, the cells rupture, indicating that the cell osmotic pressure is significantly unbalanced and the cell activity is significantly reduced, which is consistent with the pollutant removal situation in Example 2. In the Bio+S-ZVI enhanced system, as the salinity increases, the cells show a slight shrinkage phenomenon, but the degree of shrinkage is much lower than that of the Bio anaerobic system, indicating that the addition of S-ZVI is conducive to alleviating the stress effect of salinity on microorganisms, so that microorganisms can still maintain physiological metabolic functions under a certain salinity, and enhance the ability of microorganisms to anaerobic reduction of pollutants under high salt.

[0051] Example 5

[0052] The three iron-based materials (ZVI, S-ZVI, Fe3O4) and two iron ions (Fe 2+ , Fe 3+ ) Enhanced anaerobic reduction performance of nitrobenzene under high salt conditions. The material dosage maintained the same Fe atomic concentration and the dosage was 8.95 mmol L -1 Conduct batch experiments.

[0053] The removal of nitrobenzene and the formation of aniline are as follows Figure 6As shown in the results, S-ZVI has excellent performance in enhancing the removal of nitrobenzene and the generation of aniline. Under a salinity of 20 g / L, the nitrobenzene removal rate was 99.12±0.88% and the aniline generation rate was 65.87±3.64% at 4 h, which were significantly higher than those of the ZVI group (68.49±0.49% and 16.39±1.38%), the Fe3O4 group (60.33±0.30% and 9.39±0.72%) and the control group (64.1±0.24% and 9.32±0.33%). The results showed that both S-ZVI and ZVI could significantly promote the anaerobic reduction of nitrobenzene under high salt conditions, which may be because they can act as electron donors to provide the electrons required for the reduction of nitrobenzene, and at the same time, as electron transfer media between microorganisms, they promote the direct interspecies electron transfer process of microorganisms and improve the removal efficiency of nitrobenzene. Compared with the control group, the Fe3O4 group had a slightly lower nitrobenzene removal rate and a slightly higher aniline generation rate. The results showed that Fe3O4 did not have the ability to enhance nitrobenzene removal. However, some studies have shown that Fe3O4 can enhance the direct interspecies electron transfer process, which can explain why the aniline generation rate was slightly higher than that of the control group. 2+ Group and Fe 3+ The results showed that when Fe was added at 20 g / L salinity 2 + , Fe 3+ The removal of nitrobenzene and the formation of aniline were inhibited, which may be due to the fact that a large amount of Fe ions destroyed the integrity of microbial cells and inhibited microbial activity. Under high salt conditions, S-ZVI has a significant advantage in enhancing the anaerobic reduction of nitrobenzene.

Claims

1. A method for treating nitrobenzene high-salinity wastewater by using sulfur-modified zero-valent iron to strengthen anaerobic biology, characterized in that: The following steps are involved: Step 1, adding simulated wastewater with a nitrobenzene concentration of 40-60 mg / L into anaerobic sludge, and after the nitrobenzene in the simulated wastewater is completely degraded, gradually increasing the nitrobenzene concentration in the wastewater to 100 mg / L, and completing the sludge acclimation after the effluent water quality is stable; Step 2: Passing the acclimated anaerobic sludge into nitrobenzene high-salt wastewater, and adding sulfur-modified zero-valent iron to biodegrade nitrobenzene, wherein the concentration of NaCl in the nitrobenzene high-salt wastewater is above 10 g / L.

2. The method according to claim 1, characterized in that In step 1, in addition to nitrobenzene, the simulated wastewater also contained: 1.02 g / L NH4Cl, 0.252 g / L NaH2PO4·2H2O, 1.5 g / L NaHCO3, and 1 g / L glucose.

3. The method according to claim 1, characterized in that In step 1, the sludge concentration was 2 g VSS L -1 .

4. The method according to claim 1, characterized in that In step 2, the concentration of NaCl in the nitrobenzene high-salt wastewater is 10-60 g / L.

5. The method according to claim 1, characterized in that In step 2, the sulfur-modified zero-valent iron is prepared into a particle size of 100 nm by ball milling.

6. The method according to claim 1, characterized in that In step 2, the dosage of sulfur-modified zero-valent iron is 0.5 g / L.

7. The method according to claim 1, characterized in that In step 1 or 2, the operating temperature of the biodegradation system is 25°C to 35°C.

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