Method for biologically removing toxicity inhibition and intensively degrading typical medical organic wastewater under salt stress

Abstract

The invention provides a method for biologically removing toxicity inhibition and intensively degrading typical medical organic wastewater under salt stress, and belongs to the technical field of sewage treatment. According to the method, efficient degradation of the high-salt medical organic wastewater is achieved by taking measures such as combination of salt-tolerant nascent-state functional flora and cofactor strengthening, the salt-tolerant nascent-state functional flora comprises obligate COD degradation anaerobic granular sludge and sludge domesticated by gradient salinity pressure of medical wastewater, and the cofactor is betaine, glutamic acid, trehalose or potassium chloride. According to the method, the anaerobic methanogenesis efficiency and TOC removal of organic matters in a degradation system under salt stress can be promoted, the inhibition effect of salt on flora can be relieved and broken through the addition of cofactors, effective metabolism of pollutant nitrogen heterocyclic rings and alkane substances is promoted, refractory characteristic components of wastewater are eliminated, and the biodegradability of the wastewater is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress. Background Art

[0002] As a representative high-salt organic wastewater, pharmaceutical industry wastewater is a typical difficult-to-degrade wastewater with high salt content, multiple types of pollutants, and complex inhibitory components. Therefore, it has become a difficult point in wastewater treatment. Due to the complex composition, many toxic and harmful substances, and poor biodegradability of pharmaceutical wastewater, an effective wastewater treatment system has not yet been formed. Existing methods such as physical and chemical methods and traditional biochemical methods have problems such as high cost and unstable treatment effect. It has become a bottleneck problem in the current pharmaceutical wastewater treatment and one of the main factors restricting the development of many pharmaceutical companies. How to treat the high-salt organic wastewater of pharmaceutical chemical industry while balancing economic and environmental benefits to the greatest extent has become a difficult problem that must be overcome.

[0003] Biological treatment of saline pharmaceutical wastewater utilizes the metabolic function of microorganisms to degrade and transform organic pollutants. Compared with physical and chemical methods, it is efficient, economical, and harmless. However, the salt and toxic and harmful substances in wastewater inhibit the growth and metabolism of microorganisms. The removal of difficult-to-biodegrade substances in high-salt environments is still a difficult point in the field of environmental engineering. Therefore, identifying characteristic pollutants in pharmaceutical wastewater and studying the stress response of inhibitory factors to microorganisms, thereby regulating the efficient detoxification of inhibitory components, has important practical significance for the development of technologies for reducing difficult-to-degrade organic matter and biological detoxification of wastewater. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress.

[0005] To achieve the above-mentioned purpose, the present invention provides a method for biologically removing inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress, inoculating salt-tolerant new ecological functional sludge into high-salt pharmaceutical organic wastewater, and achieving efficient degradation of organic matter in high-salt pharmaceutical wastewater by adding cofactors to enhance measures; The salt-tolerant new ecological functional sludge includes specific COD degradation anaerobic granular sludge and sludge acclimated with pharmaceutical wastewater; The cofactor is at least one of betaine, glutamic acid, trehalose and potassium chloride (KCl).

[0006] Furthermore, the salt concentration in the high-salt pharmaceutical wastewater system is 30 g / L~50 g / L.

[0007] Furthermore, the inoculation amount of the salt-tolerant new ecological functional sludge is 8-12%, preferably 10 wt%.

[0008] Furthermore, the amount of betaine, glutamic acid or trehalose added to the pharmaceutical wastewater is 3-6 mol / L, preferably 5 mmol / L, and the amount of potassium chloride added to the pharmaceutical wastewater is 0.1-0.5 wt%, preferably 0.2 wt%.

[0009] Preferably, the salt-tolerant new ecological functional sludge includes specific COD-degrading anaerobic granular sludge and sludge acclimated with pharmaceutical wastewater, wherein the specific COD-degrading anaerobic granular sludge accounts for 25-75wt% of the salt-tolerant new ecological functional sludge, preferably 50%.

[0010] Furthermore, the specific COD-degrading anaerobic granular sludge is sludge produced in a chemical plant production process and has a volatile suspended solids content of 25-35 g / L, preferably 29.44 g / L.

[0011] Furthermore, the domesticated sludge of the pharmaceutical wastewater is obtained by controlling conditions such as hydraulic retention time, wastewater organic matter concentration, salinity, etc.

[0012] Furthermore, the method for acclimating sludge from pharmaceutical wastewater comprises the following steps: The sludge is placed in an anaerobic fermentation tank, and the hydraulic retention time (HRT) of the diluted wastewater is gradually shortened according to a gradient, and then the hydraulic retention time is maintained for at least 3 days. The dilution multiple of the added wastewater is changed in turn. During this period, the internal temperature of the anaerobic fermentation tank is controlled to be constant by water circulation, specifically 37°C. After the operation, the acclimated sludge of the pharmaceutical wastewater is obtained.

[0013] Furthermore, the sludge load in the anaerobic fermentation tank is not less than 10 kg VSS / m 3 .

[0014] Furthermore, the organic matter in the typical pharmaceutical organic wastewater includes heterocyclics, lipids, ketones, amides and long-chain alkanes.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: The method of the present invention for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress can promote anaerobic methanogenesis efficiency and TOC (total organic carbon) removal in the degradation system under salt stress. The addition of cofactors can alleviate the stress inhibition of salt on microbial growth metabolism, promote the effective metabolism of nitrogen heterocyclic and alkane pollutants, and avoid the large accumulation of VFAs (volatile fatty acids). Therefore, the method can eliminate the difficult-to-degrade characteristic components in high-salt wastewater and improve the biodegradability of the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 Comparison results of the degradation of typical pharmaceutical wastewater by different sludges S1, S2, and S3 at 3% salinity, where (a) is the total organic carbon concentration and total organic carbon removal rate at the beginning and end, (b) is the change of total organic carbon and methane production over time, (c) is the comparison of total organic carbon removal rate and average methane content, and (d) is the production of acetic acid and butyrate; Figure 2 The results of the degradation experiment of typical pharmaceutical wastewater at 3% salinity by mixing S1 and S2 sludge, where (a) is the change of TOC (total organic carbon) concentration over time, and (b) is the change of methane content over time; Figure 3 The results of VFAs analysis of typical pharmaceutical wastewater degradation enhanced by adding cofactors under 3% salt stress, where (a) shows the changes in total VFAs accumulation over time, and (b) shows the box plot of different small molecular organic acids; Figure 4 The results of methane analysis of typical pharmaceutical wastewater degradation enhanced by adding cofactors under 3% salt stress, where (a) shows the change of methane content over time, and (b) shows the box plot of methane content; Figure 5 The results of the analysis of COD changes in typical pharmaceutical wastewater under 3% salt stress by adding cofactors to enhance degradation, where (a) is the change of COD concentration over time, and (b) is the comparison of COD removal rates; Figure 6 To enhance the efficiency of various indicators of typical pharmaceutical wastewater degradation under 3% salt stress by adding different cofactors; Figure 7 The percentage change results of organic component categories of typical pharmaceutical wastewater under salt stress before and after bio-augmentation; Figure 8 The results are as follows: the changes in the composition of nitrogen heterocyclic substances in typical pharmaceutical wastewater under salt stress before and after bioaugmentation; Fig. 9 (a) shows the changes in significant components in typical pharmaceutical wastewater before and after bioaugmentation under salt stress, and (b) shows the main metabolic changes in typical pharmaceutical wastewater under salt stress. DETAILED DESCRIPTION

[0017] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0019] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0020] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] The sludge used in the acclimation process of the pharmaceutical wastewater in the embodiment of the present invention (VSS is 32.38 g / L, S2) was taken from the hydrolysis acidified sludge of a sewage treatment plant in Bozhou, Anhui. The activated sludge was first settled for 2 days and then the supernatant was discarded. The sludge was simply washed to remove the organic matter in the original sludge to avoid the interference of the original substrate on the anaerobic degradation process. The sludge TSS (total suspended solids) was 8.144 g / L, the ash content was 1.84 g / L, the VSS (volatile suspended solids) was 6.304 g / L, and VSS / TSS=0.774; the wastewater used in the acclimation process was taken from the antibiotic pharmaceutical wastewater of Xianju Pharmaceutical, and its original indicators TDS was 10.7 g / L, COD was 106100 mg / L, TN was 488.70 mg / L, TP was 52.19 mg / L, NH4 + -N is 1475.5 mg / L.

[0023] The specific COD-degrading anaerobic granular sludge (S1) used in the embodiment of the present invention was taken from a chemical plant producing citric acid, with a VSS of 29.44 g / L and an effective sludge particle size of >70%; the ordinary anaerobic sludge (S3) was taken from a sewage treatment plant in Bozhou, Anhui, with a VSS of 14.42 g / L.

[0024] The cofactors betaine, glutamic acid, trehalose or potassium chloride (KCl) used in the embodiments of the present invention are all commercially available.

[0025] The gas chromatograph-mass spectrometer (GC-MS) of the Institute of Process Engineering of the Chinese Academy of Sciences used in the performance test of the present invention is Agilent 7890AGC-5975CMS. The solid phase microextraction device used is a manual SPME injector, and the extraction needle is a 50 / 30 μm PDMS / CAR / DVB (2 cm) extraction fiber head, Supelco, USA.

[0026] The technical solution of the present invention is further illustrated by the following embodiments.

[0027] Example 1 Step 1: Preparation of acclimatized sludge from pharmaceutical wastewater An anaerobic fermentation tank with an effective volume of 1 L was used as the biological selector, and the sludge load in the anaerobic fermentation tank was 10 kg VSS / m 3 The startup phase is to dilute the wastewater 20 times, which allows the sludge to grow rapidly. Then, during the hydraulic selection period, the dominant bacteria are screened by continuously shortening the HRT and increasing the organic load OLR. After that, it is the concentration selection phase. The hydraulic retention time HRT is set to 3 d. The dilution multiple of the wastewater is continuously reduced to increase the proportion of raw water in the influent, so that the sludge gradually adapts to the wastewater. Microorganisms that cannot adapt to the environment are eliminated. During this period, the internal temperature of the reactor is controlled at 37°C through water circulation. A total of 6 stages are run to obtain the acclimated sludge (S2) of pharmaceutical wastewater. The conditions of each operation stage are shown in Table 1.

[0028] Table 1 Condition settings for each operating stage in the anaerobic fermentation tank

[0029] Step 2: Degradation of pharmaceutical wastewater NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the sludge was inoculated at an inoculation rate of 10wt%, and cofactors (betaine, glutamic acid, trehalose or KCl) were added to achieve the degradation of pharmaceutical wastewater.

[0030] a. Screening of sludge types NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the sludge was inoculated at an inoculation rate of 10wt%. Every 5 days, the wastewater in the system was drained and an equal amount of fresh wastewater was added. During the water change, the whole process was operated in an anaerobic glove box. The reaction was carried out for 5 cycles and the experiment lasted for 26 days. Samples were taken regularly during the period. The detection indicators included gas production, VFAs, and TOC. Three parallels were made for each condition.

[0031] The type of inoculated sludge is set as: S1: specific COD degradation anaerobic granular sludge; S2: domesticated sludge from pharmaceutical wastewater; S3: normal anaerobic sludge; 25%S1+75%S2: Specific COD degradation anaerobic granular sludge and domesticated sludge of pharmaceutical wastewater with a mass ratio of 1:3; 50%S1+50%S2: 1:1 mass ratio of specific COD degradation anaerobic granular sludge and domesticated sludge of pharmaceutical wastewater; 75%S1+25%S2: Specific COD degradation anaerobic granular sludge and domesticated sludge of pharmaceutical wastewater with a mass ratio of 3:1; Test results: (1) Analysis of the enhanced degradation effect of sludge on typical pharmaceutical wastewater under salt stress S1, S2, and S3 were used to conduct periodic anaerobic biodegradation experiments on typical pharmaceutical wastewater (3% salinity) diluted 10 times. The comparison of the degradation effects of different sludges S1, S2, and S3 on typical pharmaceutical wastewater at 3% salinity is shown in Figure 1 , Figure 1 (a) shows the TOC concentration and TOC removal rate at the beginning and end, (b) shows the change of TOC and methane content over time, (c) shows the comparison of TOC removal rate and average methane content, and (d) shows the production of acetic acid and butyric acid. It can be seen that in the first three cycles of the reaction, the TOC concentration of the diluted wastewater continued to decrease, and the TOC removal rate of the three sludges gradually increased ( Figure 1 In (a), at 13 days, the TOC removal rates of S1, S2, and S3 increased to 64.97%, 60.88%, and 59.29%, respectively. After that, the average TOC removal rates of the three were 80.11%, 72.26%, and 65.60%, respectively. The rate of decline of organic concentration in wastewater slowed down in the last two cycles. From the results, S1 has the best TOC removal efficiency for wastewater at 3% salinity, S3 sludge has the worst degradation effect, and S2 sludge is between the two.

[0032] Depend on Figure 1It was observed in (b) that only the S1 sludge produced a large amount of methane gas, and the methanogenesis did not occur immediately, but increased sharply and was detected after the first cycle. Methane production is the final stage in anaerobic fermentation. Only a small amount of methane was detected in the S2 sludge in the later stage of the experiment, and almost no methane was detected in the S3 sludge, indicating that the anaerobic methanogenesis process of wastewater degradation in the S3 sludge at 3% salinity was significantly inhibited. On the contrary, a large amount of acetic acid and butyric acid were produced in all three sludge systems. The accumulation of these small molecular organic acids indicates that the hydrolysis and acidification stage of the anaerobic process was not inhibited. The S1 sludge had the best TOC removal rate and the highest methane production efficiency ( Figure 1 (c)). It can be inferred that the methanogenic stage in the anaerobic digestion process is the limiting step of anaerobic degradation under salt stress. Moreover, based on the law of methanogenic content and time, it is believed that TOC degradation and methanogenicity in the reaction system have a synergistic effect ( Figure 1 in (d).

[0033] The above experiments found that the degradation effect of selective domesticated sludge on typical pharmaceutical wastewater is better than that of ordinary anaerobic sludge. The performance of the constructed new ecological functional bacterial community is better than that of ordinary sludge bacterial community, but lower than that of specialized sludge. Its degradation performance in salt environment can be further improved. S1 sludge has the best effect on TOC removal, and S1 sludge promotes the anaerobic methanogenesis stage in the degradation system under salt stress. Therefore, an attempt was made to improve the performance of the selective sludge by adding S1 sludge to the selective salt-tolerant sludge S2 and mixing it with it. The experimental results of the degradation of typical pharmaceutical wastewater at 3% salinity by the mixed ratio of S1 and S2 sludge are shown in Figure 2 , Figure 2 (a) shows the change of TOC concentration over time, and (b) shows the change of methane content over time. It can be seen that in the three groups of S1 and S2 sludge ratios, the TOC decrease is greater than that of the single S2 and S3 sludges, and the methane production is also significantly increased. The three combinations all promote the degradation of wastewater and the methane production process. Among them, adding 50% S1 sludge has achieved a more obvious enhancement effect. Finally, 50% S1 + 50% S2 sludge ratio was selected to carry out further bio-enhanced degradation of typical pharmaceutical wastewater experiments.

[0034] b. Experiment on enhancing wastewater degradation under salt stress by adding cofactors NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L (3% salt stress). After nitrogen blowing, the mixed sludge (50% S1 + 50% S2) was inoculated at an inoculation amount of 10 wt%, and then betaine, glutamic acid, trehalose and KCl were added respectively, wherein the amount of betaine, glutamic acid or trehalose added to the pharmaceutical wastewater was 5 mmol / L, and the amount of KCl added to the pharmaceutical wastewater was 0.2 wt%, respectively recorded as salinity 3% + trehalose, salinity 3% + glutamic acid, salinity 3% + betaine and salinity 3% + KCl. A control group without adding NaCl (salinity 0%) and without adding cofactors (Salinity 3%) was also set up, the same below. The experiment was set up in three parallels.

[0035] Hydrolysis of acidified sludge can degrade nutrients such as glucose into VFAs (acetic acid + butyric acid + valeric acid + hexanoic acid). VFAs are important intermediates in the anaerobic digestion process. At the same time, methanogens mainly use VFAs to form methane. The formation of methane is inseparable from the formation of VFAs, but higher VFAs concentrations have an adverse effect on the activity of methanogens. The accumulation of VFAs inhibits the activity of methanogens. The analysis results of VFAs produced by adding cofactors to enhance the degradation of typical pharmaceutical wastewater under 3% salt stress are shown in Figure 3 , Figure 3 (a) shows the change of total VFAs accumulation over time, and (b) shows the box plot of different small molecule organic acids. Figure 3 It can be seen that the amount of volatile organic acids detected under salinity of 3% is higher than the total amount of organic acids under salt-free conditions. After the anaerobic reaction system is subjected to salinity shock, the VFA in the effluent increases significantly. Combined with previous research results, it is analyzed that under saline conditions, the activity of methanogens in anaerobic sludge is inhibited, thereby reducing the ability to utilize VFA, resulting in the accumulation of organic acids in the system.

[0036] In addition, by Figure 3As can be seen in (a), the concentration of total VFAs (acetic acid + butyric acid + valeric acid + hexanoic acid) at different sampling times under various conditions during the anaerobic degradation of wastewater. From the graph of VFAs concentration over time, it was found that the concentration surged on the first day, and the concentrations of salinity 0% (Salinity0%, i.e., the control group without adding NaCl), salinity 3% (Salinity3%, i.e., the control group without adding cofactors), salinity 3% + KCl (Salinity3% + KCl), salinity 3% + trehalose (Salinity3% + trehalose), salinity 3% + glutamate (Salinity3% + glutamate), and salinity 3% + betaine (Salinity3% + betaine) reached 0.561 g / L, 1.21 g / L, 1.19 g / L, 0.700 g / L, 1.00 g / L, and 0.862 g / L, respectively, indicating that the hydrolysis and acidification process dominated in the initial stage of the reaction, and the sludge quickly produced acid. After that, the VFAs concentration decreased and remained at a stable stage, and the consumption process of organic acids occurred in each group. In the later stage, the VFAs concentration slowly increased again, and organic acids were continuously produced and consumed during the reaction. At the end of the reaction, the total VFAs concentration in the control group with a salinity of 3% was 0.584 g / L, and the VFAs concentrations in the groups with added KCl, trehalose, glutamic acid, and betaine were 0.421 g / L, 0.491 g / L, 0.516 g / L, and 0.463 g / L, respectively, which were all lower than the accumulation of small molecule organic acids in the control group.

[0037] from Figure 3 It can also be clearly seen in (b) that the concentration of organic acids in each group is not much different. There is a certain accumulation of VFAs in all cases, and the accumulation of small molecular acetic acid and butyric acid is greater, indicating that salinity does not cause a strong inhibition on the hydrolysis and acidification stage during the anaerobic digestion of pharmaceutical wastewater. In addition, when cofactors such as KCl are added at 3% salinity, the accumulation of VFAs is between salt-free and 3% salinity. Taking butyric acid as an example, the median butyric acid concentrations of the control group at 0% salinity and 3% salinity are 0.215 g / L and 0.258 g / L, respectively. Under 3% salt stress, the median butyric acid concentrations of KCl, trehalose, glutamic acid, and betaine are 0.225 g / L, 0.235 g / L, 0.229 g / L, and 0.225 g / L, respectively. The accumulation of organic acids when cofactors are added is slightly lower than that when containing 3% salt. This phenomenon shows that the addition of cofactors can appropriately alleviate the accumulation of VFAs. K + Osmotic factors and three compatible solutes can promote the consumption of organic acids, avoid the massive accumulation of VFAs, and alleviate the inhibition of high concentrations of organic acids on methanogens, thus helping the anaerobic methanogenesis process.

[0038] c. Analysis of methane production by adding different cofactors to enhance degradation of typical pharmaceutical wastewater under salt stress The methanogenic stage is the final stage of anaerobic digestion and the final stage where pollutants are completely degraded or mineralized. The VFAs produced in the previous stage are converted into methane or CO2 under the action of methanogens. The gas production in the anaerobic process is a key indicator for measuring the effect of anaerobic reaction. The results of the analysis of methanogenicity of typical pharmaceutical wastewater by adding cofactors to enhance the degradation under 3% salt stress are shown in Figure 4 , Figure 4 (a) shows the change of methane production over time, and (b) is a box plot of methane production (the upper and lower whiskers extend from the upper and lower edges of the box, respectively, to data that do not exceed 1.5× the interquartile range).

[0039] Depend on Figure 4 It can be seen that the methane production detected under salinity of 3% is greatly reduced (9.31%), which is much lower than the methane content under salt-free conditions (49.2%), indicating that the methane production of the anaerobic reaction system is significantly reduced after being impacted by salinity. Previous studies have reported that methane production gradually decreases with the increase of salt concentration, which indicates that with the increase of salt concentration, the anaerobic methanogenesis stage is significantly inhibited, which in turn causes the anaerobic gas production capacity to decrease. From the line graph of methane production over time, it can be seen that anaerobic sludge methane production is different from the rapid production of a large number of volatile organic acids, and anaerobic degradation of wastewater produces methane more slowly. Methane production did not rise rapidly in the initial stage, but showed a trend of gradual increase. This is because the methanogens mainly involved in the reaction at this stage are more sensitive to high-salt environments than hydrolytic acidogenic bacteria. They have a slow growth rate, a long generation time, and strict requirements on environmental conditions such as temperature, pH, absolute anaerobicity, and inhibitors. Therefore, the anaerobic methanogenesis stage is more sensitive to the influence of salinity than the hydrolytic acidification stage.

[0040] Except for the control group with 0% salinity, the methane production ratio of each group under salt stress was below 30% ( Figure 4In (b), the methane ratios of salinity 3%, salinity 3% + KCl, salinity 3% + trehalose, salinity 3% + glutamic acid, and salinity 3% + betaine were between 4.45% and 7.40%, 4.40% and 10.4%, 4.20% and 6.75%, 5.50% and 7.00%, and 5.10% and 7.45%, respectively, with average values ​​of 9.31%, 23.1%, 10.3%, 23.5%, and 17.9%, respectively. It can be seen that the methane production under the condition of exogenous addition of cofactors is significantly higher than that without the addition of cofactors, which significantly promotes the methane production process under salt stress. Among them, KCl, trehalose, glutamic acid, and betaine increased the methane production by 134%, 4.11%, 138%, and 81.6%, respectively, compared with the methane production under the condition of only 3% salinity. Potassium chloride and glutamic acid more than doubled the efficiency of promoting methane production, effectively relieving the inhibition of salt on gas and methane production in the anaerobic degradation process.

[0041] d. Effect of adding cofactors to enhance the removal rate of organic matter in typical pharmaceutical wastewater under salt stress The results of the analysis of COD changes in typical pharmaceutical wastewater under 3% salt stress by adding cofactors to enhance degradation are shown in Figure 5 , where (a) is the change of COD concentration over time, and (b) is the comparison of COD removal rate. Figure 5 It can be seen that under no salt stress, the COD concentration of the wastewater decreased the most and fastest. At 20 days, the COD concentration of the wastewater decreased from 35096 mg / L to 7788 mg / L, and the COD removal rate was as high as 77.8%. Under 3% NaCl salinity, COD slowly decreased in the concentration range of 20118-34862 mg / L. At the 20th day, the COD concentration was 20312 mg / L, and the removal rate was only 43.6%. The addition of the four cofactors under 3% salinity stress increased the COD removal rate. Among them, the exogenous addition of betaine had the highest COD removal rate among all groups. The average COD removal rate after 5 days was 57.4%, which was more than twice that of the control group without betaine under 3% salinity. The removal rate reached 65.6% at the 20th day. In addition, the KCl addition group also achieved good removal effects. The removal rate reached 50.9% on the 5th day, and then stabilized between 53.6% and 64.1%. The corresponding COD concentration fluctuated between 12951 and 16694 mg / L. The COD removal rate was 61.4% on the 20th day, which was 40.8% higher than the removal rate without adding KCl at 3% salinity. From the above analysis, it can be seen that the added cofactors all played a certain role in de-inhibition. The exogenous addition of KCl osmotic factors and compatible solutes such as trehalose promoted the degradation of typical pharmaceutical wastewater under salt stress. The order of the improvement effect of these four cofactors on COD removal is betaine>KCl>glutamic acid>trehalose.

[0042] The results of the enhanced efficiency of adding different cofactors on the degradation of various indicators of typical pharmaceutical wastewater under 3% salt stress are shown in Figure 6 As can be seen from the figure, the sludge VSS, methane production, COD removal rate (remocal rate), and BOD reduction rate have all been significantly improved. After the sludge VSS was measured after the reaction, it was found that KCl had the most obvious enhancement effect on sludge activity (174.07%). In terms of methane production and COD removal rate, the improvement efficiency of KCl was 162.25% and 40.80%, respectively. At the same time, the BOD after enhanced treatment was monitored and the B / C ratio was calculated. In the KCl group, the BOD removal rate increased by 32%, the B / C ratio increased by 58.8%, and the biodegradability of the wastewater was improved. Comprehensive analysis shows that among the four cofactors, KCl has the best enhancement effect, and glutamic acid has the lowest enhancement effect.

[0043] e. Analysis of changes in organic components in typical pharmaceutical wastewater under enhanced degradation under salt stress Organic pollutants in typical pharmaceutical wastewater diluted 10 times before and after bio-augmentation were analyzed by GC-MS. 92 organic substances were detected in the original diluted wastewater. These organic substances were classified into nitrogen heterocyclics, alkanes and benzene rings, as well as a small amount of esters, phenols, amines, polycyclic aromatic hydrocarbons, aldehydes, acids, alcohols, ketones, other types and nitrous oxide. Organic substances related to pre-treatment for on-machine testing were also detected. Among them, benzene ring compounds do not include phenol, aromatic acids, aromatic aldehydes, etc. Acid compounds are mainly composed of fatty acids and aromatic acids, and amine compounds include fatty amines and aromatic amines.

[0044] The percentage changes of organic components in typical pharmaceutical wastewater under salt stress before and after bioaugmentation are shown in Figure 7 .Depend on Figure 7It can be seen that before bio-augmentation, the main pollutants in the wastewater were nitrogen heterocycles (28.9%) and alkanes (26.3%), and the sum of the two accounted for as high as 55.2%, exceeding the sum of other types of organic matter in the wastewater. The proportions of the remaining benzene rings, esters, phenols, amines, aldehydes, polycyclic aromatic hydrocarbons, acids, alcohols, ketones, N2O and other types in the wastewater were 11.1%, 6.82%, 2.00%, 1.48%, 0.760%, 1.02%, 0.6%, 0.54%, 0.46%, 2.46% and 2.13%, respectively. After anaerobic degradation, the proportions of these two types of inhibitory components decreased significantly, with nitrogen heterocycles decreasing from 28.9% to 8.37% and alkanes decreasing from 26.3% to 14.9%, which preliminarily showed that nitrogen heterocycles and alkanes had been effectively transformed and removed after bio-augmentation treatment of the wastewater. The proportion of benzene ring substances also decreased after the reaction. At the same time, the proportion of amines in the wastewater increased significantly, from 1.48% to 23.4%, aldehydes increased from 0.76% to 8.59%, and the proportion of phenols and esters also increased, to 3.51% and 3.46% respectively. This shows that typical pharmaceutical wastewater produces more amines, aldehydes, phenols and ester compounds during anaerobic digestion, and similar intermediates are produced during the degradation and transformation of nitrogen heterocycles and long-chain aliphatic hydrocarbons. At the same time, intermediates such as those with benzene rings combine with each other to generate complex aldehydes and amines. Another thing worth noting is the change in N2O. The proportion of N2O before and after bioaugmentation treatment was 2.16% and 10.9% respectively. The significant increase in the proportion of N2O may be due to the ring cleavage, denitrification and a series of anaerobic reactions of nitrogen heterocycles.

[0045] The changes in the composition of nitrogen heterocyclic substances in typical pharmaceutical wastewater under salt stress before and after bioaugmentation are shown in Figure 8 .from Figure 8 It can be seen intuitively that the composition of nitrogen heterocyclic substances in wastewater has changed significantly before and after bioaugmentation. The main component has changed from pyrazine compounds (with methyl and other groups) (accounting for 74.9% in nitrogen heterocyclics) to pyridine compounds (accounting for 76.9% in nitrogen heterocyclics). This shows that the significant decrease in the proportion of nitrogen heterocyclic substances in wastewater is caused by the decrease in pyrazine organic compounds. Under 3% salt stress, pyrazine substances in typical pharmaceutical wastewater are transformed and degraded (from 21.6% to 0), while the proportion of pyridine substances increases (from 5.48% to 6.44%). In the typical pollutant inhibition experiment, the biodegradability of nitrogen heterocyclic substances is: pyridine> pyrazine> quinoline. It can be seen that the content of pyridine, which is more easily degraded in wastewater, has increased slightly, which has improved the biodegradability of wastewater to a certain extent. In addition, the content of pyrimidine has also decreased slightly, and a small amount of pyrans, indoles, and imidazoles have not been detected in the effluent treated by bioaugmentation.

[0046] Further analysis of another major category of organic matter in the original wastewater, alkanes, revealed that the alkanes in the wastewater are mainly composed of n-hexane and cyclohexane, accounting for 15.3% and 8.15% of the wastewater, respectively. After biological treatment, the proportions of the two decreased to 11.0% and 1.46%, respectively. This shows that cyclohexane is more easily degraded and transformed than n-hexane, and the removal of cyclohexane is the main reason for the decrease in the proportion of alkanes in the wastewater after bio-augmentation.

[0047] By comparing the amine compounds before and after the reaction, it was found that the types and contents of amide substances increased significantly after bioaugmentation treatment, and N,N-dibutylformamide was the main substance, accounting for as much as 21.77%. A large number of intermediates produced during the anaerobic degradation of wastewater combined with each other to lead to the formation of amide substances. N,N-dibutylformamide is an important intermediate product in the degradation of nitrogen heterocyclic substances. The substance was not detected in the original wastewater before treatment, which proves that it was produced during the degradation reaction due to the cleavage of nitrogen heterocyclic rings. The increase in amide substances while the reduction of nitrogen heterocyclic substances verified the occurrence of degradation metabolism of nitrogen heterocyclic inhibitory components.

[0048] Fig. 9 (a) shows the changes in significant components in typical pharmaceutical wastewater before and after bioaugmentation under salt stress, and (b) shows the main metabolic changes in typical pharmaceutical wastewater under salt stress. Fig. 9 The data in the figure show that similar to the above analysis results, pyrazine compounds (with methyl groups) and cyclohexane were effectively degraded, with removal rates of 100% and 82.1%, respectively. However, pyridine and n-hexane compounds were not effectively removed, which is the rate-limiting step in wastewater degradation under salt stress. The increase in phenol content may be due to the degradation and conversion of other high molecular weight organic compounds into phenol. The large amount of N,N-dibutylformamide substances appearing in the effluent of bioaugmentation treatment is an intermediate product of the metabolism of nitrogen heterocyclic compounds.

[0049] Hydroxylation at the C2 position is a key step in the production of heterocyclic substances such as pyridine and quinoline. Many studies have shown that aerobic and anaerobic biodegradation of pyridine and quinoline are initiated by C2 hydroxylation near the N-heteroatom. When the hydroxyl group is oxidized, a hydrogenation reaction occurs at the N position. Then a series of reactions such as CC bond cleavage, hydroxylation, and oxidation reactions will occur to produce amides or amide derivatives. The experiment detected N,N-dibutylformamide, whose CN bond further breaks, which may produce malondialdehyde, which is then converted into malonic acid. When the CN bond of formamide breaks, aminoformic acid is released, and then NH4 is produced. +. The biodegradation of pyrazine-type nitrogen-containing heterocyclic substances will be converted into intermediate products such as amides, aldehydes, and acids. At the same time, the degradation process is accompanied by the generation and degradation of benzene homologues including phenol. The anaerobic biodegradation of cyclohexane will produce methane, fatty acids and a series of hydrocarbons. The generation of nitrous oxide is a common by-product in the biological treatment of sewage, mainly from nitrification and denitrification in wastewater denitrification. From the above analysis, we can conclude that most of the organic pollutants in typical pharmaceutical wastewater containing mainly nitrogen heterocyclic rings and alkanes can be metabolized and transformed under 3% NaCl salt stress. The main degradation products of the wastewater are pyridine, n-hexane, N,N-dibutylformamide and N2O ( Fig. 9 (b) in the figure.

[0050] In summary, the mixed sludge with a ratio of 50% S1 + 50% S2 as the inoculated sludge promoted the anaerobic methanogenesis efficiency and TOC removal in the degradation system under salt stress. The addition of cofactors can avoid the large accumulation of VFAs. The exogenous addition of cofactors, especially glutamic acid and KCl, significantly promoted the methane content. After the enhanced treatment of typical pharmaceutical wastewater, the main pollutants, nitrogen heterocycles and alkanes, were effectively metabolized, and decreased from 28.9% to 8.37% and from 26.3% to 14.9%, respectively. Therefore, the bio-enhanced treatment of the present invention alleviates salt stress, eliminates the difficult-to-degrade characteristic components of wastewater, and improves the biodegradability of wastewater.

[0051] The medical wastewater in Example 1 was degraded using the technical solutions of Examples 2-5, and the results are as follows:

[0052] Example 2 NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the salt-tolerant new ecological functional sludge was inoculated at an inoculation rate of 8wt% (the specific COD-degrading anaerobic granular sludge accounted for 75wt% of the salt-tolerant new ecological functional sludge, and the preparation method was the same as above), and cofactors (betaine, added in amounts of 3 mmol / L, 4 mmol / L, 5 mmol / L and 6 mol / L, respectively) were added to achieve the degradation of pharmaceutical wastewater.

[0053] The degradation results are as follows: The specific COD degradation anaerobic granular sludge has the most significant effect on TOC removal. At the same time, the degradation effect of domesticated sludge on typical pharmaceutical wastewater is also better than that of ordinary anaerobic sludge. In order to improve the degradation rate of TOC, the specific COD degradation anaerobic granular sludge was also improved when constructing the new ecological functional bacteria. The inoculation amount of salt-tolerant new ecological functional sludge was 8 wt%. When only salt-tolerant new ecological functional sludge was inoculated, the COD removal rate in the system could reach 40.3%. After further adding different concentrations of betaine, the COD removal rate reached 52.5%~73.6%.

[0054] Example 3 NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the salt-tolerant new ecological functional sludge was inoculated at an inoculation rate of 12wt% (the specific COD-degrading anaerobic granular sludge accounted for 25wt% of the salt-tolerant new ecological functional sludge, and the preparation method was the same as above), and cofactors (trehalose, added in amounts of 3 mmol / L, 4 mmol / L, 5 mmol / L and 6 mol / L, respectively) were added to achieve the degradation of pharmaceutical wastewater.

[0055] The degradation results are as follows: The inoculation amount of sludge is crucial for the degradation of COD in high-salt systems. The inoculation amount of salt-tolerant new ecological functional sludge was further increased to 12wt%. When only salt-tolerant new ecological functional sludge was inoculated, the COD removal rate in the system was also increased to 48.5%. After further adding different concentrations of trehalose, the COD removal rate reached 50.2%~70.3%.

[0056] Example 4 NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the salt-tolerant new ecological functional sludge was inoculated at an inoculation rate of 12wt% (the specific COD-degrading anaerobic granular sludge accounted for 75wt% of the salt-tolerant new ecological functional sludge, and the preparation method was the same as above), and a cofactor (KCl, added in an amount of 0.1 wt%) was added to achieve the degradation of pharmaceutical wastewater.

[0057] The degradation results are as follows: Adding 0.1 wt% KCl also promoted the degradation of COD to a certain extent, and the COD removal rate reached 60.5%.

[0058] Example 5 NaCl was added to the pharmaceutical wastewater to adjust the salt concentration in the degradation system to 30 g / L. After nitrogen blowing, the salt-tolerant new ecological functional sludge was inoculated at an inoculation rate of 12wt% (the specific COD-degrading anaerobic granular sludge accounted for 25wt% of the salt-tolerant new ecological functional sludge, and the preparation method was the same as above), and a cofactor (KCl, added in an amount of 0.5 wt%) was added to achieve the degradation of pharmaceutical wastewater.

[0059] The degradation results are as follows: When the addition amount of KCl was increased to 0.5 wt%, it was found that the COD removal efficiency reached 69.8%.

[0060] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress, characterized in that: Inoculate salt-tolerant new ecological functional sludge and add cofactors to high-salinity pharmaceutical organic wastewater to achieve efficient degradation of organic matter in high-salinity pharmaceutical wastewater; The salt-tolerant new ecological functional sludge includes specific COD degradation anaerobic granular sludge and sludge acclimated with pharmaceutical wastewater; The cofactor is at least one of betaine, glutamic acid, trehalose and potassium chloride.

2. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 1, characterized in that: The salt concentration in the high-salt pharmaceutical wastewater system is 30 g / L~50 g / L.

3. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 1, characterized in that: The inoculation amount of the salt-tolerant new ecological functional sludge is 8-12 wt%.

4. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 1, characterized in that: The amount of betaine, glutamic acid or trehalose added to the pharmaceutical wastewater is 3-6 mmol / L, and the amount of potassium chloride added to the pharmaceutical wastewater is 0.1-0.5 wt%.

5. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 1, characterized in that: The salt-tolerant new ecological functional sludge includes specific COD-degrading anaerobic granular sludge and sludge acclimated with pharmaceutical wastewater, wherein the specific COD-degrading anaerobic granular sludge accounts for 25-75 wt% of the salt-tolerant new ecological functional sludge.

6. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 5, characterized in that: The specific COD-degrading anaerobic granular sludge is sludge with a volatile suspended solid content of 25-35 g / L generated in the production process of a chemical plant.

7. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 5, characterized in that: The sludge domesticated from the pharmaceutical wastewater is obtained by selective domestication through controlling the hydraulic retention time, wastewater concentration and salinity.

8. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 7, characterized in that: The method for acclimating sludge from pharmaceutical wastewater comprises the following steps: The sludge is placed in an anaerobic fermentation tank, and the hydraulic retention time of the diluted wastewater is gradually shortened according to a gradient, and then the hydraulic retention time is maintained for at least 3 days. The dilution multiple of the added wastewater is changed in sequence according to the gradient. During this period, the internal temperature of the anaerobic fermentation tank is controlled to remain constant through water circulation, and after the operation is completed, the acclimated sludge of the pharmaceutical wastewater is obtained.

9. The method for biologically removing toxic inhibition and enhancing degradation of typical pharmaceutical organic wastewater under salt stress according to claim 8, characterized in that: The organic matter in the typical pharmaceutical organic wastewater includes heterocyclics, lipids, ketones, amides and long-chain alkanes.

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