Method for enhancing treatment of high salinity nitrogen methyl pyrrolidone wastewater by using salt-tolerant bacteria-algae symbiotic sludge system

Abstract

The application discloses a method for reinforcing treatment of high-salinity N-methylpyrrolidone wastewater by using a salt-tolerant bacteria-algae symbiotic sludge system. Chlorella sorokiniana FACHB-275 is used as a target microalgae, and activated sludge is taken from a secondary sedimentation tank of a chemical wastewater treatment plant.The bacteria-algae symbiotic sludge system in the application has excellent salt tolerance, the system uses dissolved oxygen generated by microalgae photosynthesis as an electron acceptor to reinforce degradation of NMP, CO2 and ammonia nitrogen generated by NMP degradation are used for microalgae growth, the high-salinity NMP wastewater can be reinforced treated under the condition of no aeration, and the high-efficient and stable treatment effect can be maintained under the high-salinity condition.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of biological treatment of organic contaminated wastewater, and relates to a method for treating high-salinity N-methylpyrrolidone wastewater by using a salt-tolerant bacterial algal symbiotic sludge system. BACKGROUND

[0002] N-methylpyrrolidone (NMP) is widely used as an organic solvent in the petroleum processing, pharmaceutical, microelectronics and lithium battery industries. With the rapid development of industrial production, the amount of NMP-containing industrial wastewater discharged is increasing. Since NMP has obvious biological toxicity, improper disposal will seriously threaten human health and the ecological environment. Actual NMP wastewater usually has the characteristics of high salinity. Unprocessed high-salinity wastewater discharge may cause serious environmental pollution and affect aquatic organisms, drinking water and agricultural production.

[0003] Physical and chemical technologies are widely used in the treatment of high-salinity industrial wastewater, mainly including evaporation, membrane technologies such as reverse osmosis and nanofiltration (NF), ion exchange, advanced oxidation processes and electrochemical technologies. However, physical and chemical technologies are limited due to low mineralization rate and easy secondary pollution. Wastewater treatment technologies dominated by biological treatment have the advantages of environmental friendliness, low investment and low operating cost. However, traditional aerobic biological treatment technologies face the defects of high energy consumption, serious carbon emission and pollutant volatilization due to the use of mechanical bubble aeration for oxygen supply. In addition, the content of salt-tolerant bacteria in ordinary activated sludge is low, which makes it difficult to adapt to high-salinity environments. Therefore, it is urgent to develop low-carbon and efficient technologies that can efficiently and stably treat NMP wastewater in high-salinity environments.

[0004] Zhang B, Piet N.L, Shi W, et al. Enhancement of aerobic granulation and nutrient removal by an algal-bacterial consortium in a lab-scale photobioreactor [J]. Chemical Engineering Journal, 2018, 334(Pt. 2): 2373-2382. Zhou Y, Chen S, Guo N, et al, Evaluating the role of algae in algal-bacterial granular sludge: Nutrient removal, microbial community and granular characteristics [J], Bioresource Technology, 2022, 365, 128165.For example, in document 3, Dong et al. studied the effect of high salinity (1%-3%) stress on the algal-bacterial granular sludge in low-toxicity high-nutrient wastewater. The results showed that the system did not collapse under high salinity shock, and could recover its performance after the removal of high salinity stress, but the pollutant removal efficiency decreased significantly when the system was subjected to high salinity shock (Dong X, Zhao Z, Yang X, et al. Response and recovery of mature algal-bacterial aerobic granular sludge to sudden salinity disturbance in influent wastewater: Granule characteristics and nutrients removal / accumulation [J]. Bioresource Technology, 2021, 321: 124492.). However, the cultivation of granular sludge usually requires a long period and high aeration energy consumption, which is contrary to the low-carbon advantage of the algal-bacterial symbiotic system. In addition, in the treatment of high-salinity NMP wastewater, the EPS secretion of microorganisms in the algal-bacterial symbiotic system composed of freshwater microalgae is not clear, and whether the system can withstand high-salinity stress and shock and maintain high-efficiency photosynthesis oxygen production efficiency and pollutant degradation performance has not been reported. SUMMARY

[0005] The present application provides a method for strengthening the treatment of high-salinity N-methyl pyrrolidone wastewater by using a salt-tolerant bacterial-algal symbiotic sludge system. The present application constructs an algal-bacterial symbiotic sludge system, and finds that Chlorella has self-adaptive recovery ability when facing high-salinity stress. At the same time, under the condition of no aeration, the DO produced by Chlorella through photosynthesis can be coupled with NMP-degrading functional bacteria to strengthen the degradation of NMP, a kind of toxic and volatile refractory organic matter. During the operation of the continuous-flow photobioreactor, the constructed algal-bacterial symbiotic sludge system has stronger salt tolerance and degradation efficiency when subjected to high-salinity and pollutant shock.

[0006] The technical solutions of the present application are as follows:

[0007] The method for strengthening the treatment of high-salinity N-methyl pyrrolidone wastewater by using a salt-tolerant bacterial-algal symbiotic sludge system comprises the following steps:

[0008] (1) Construction of salt-tolerant bacterial-algal symbiotic sludge system:

[0009] After expanding culture of Chlorella sorokiniana FACHB-275, centrifuging the liquid algae, removing residual nutrients by washing, and centrifuging again to obtain algae sediment as microalgae inoculum, the microalgae inoculum is inoculated into activated sludge taken from a secondary sedimentation tank of a sewage plant, and a high-salinity NMP-containing simulated wastewater is used for culture to construct a salt-tolerant bacterial-algal symbiotic sludge system.

[0010] (2) Treatment of high-salinity NMP-containing wastewater:

[0011] The salt-tolerant bacterial-algal symbiotic sludge system is inoculated into a photobioreactor, the reactor is operated, and high-salinity NMP-containing wastewater is introduced for biodegradation treatment.

[0012] The Chlorella sorokiniana FACHB-275 described in the application is from the Chinese Academy of Sciences Freshwater Algae Culture Collection (FACHB), and the algae strain has strong photosynthesis and oxygen production efficiency, and can reach a dissolved oxygen concentration of more than 5 mg / L within 24 h.

[0013] Further, in step (1), the salinity of the high-salinity NMP-containing simulated wastewater is 1% to 3%, and the concentration of NMP is 200 mg / L.

[0014] Further, in step (1), the culture medium of Chlorella sorokiniana FACHB-275 is BG-11 medium, the centrifugation speed is 8000 rpm, the centrifugation time is 10 min, and the washing liquid is a phosphate buffer solution.

[0015] Further, in step (1), the dry weight ratio of the microalgae inoculum to the activated sludge is 1:50, and the biomass concentration inoculated in the culture reactor is 1000 mg / L.

[0016] Further, in step (1), during the culture process, the light intensity used is 6000 lux, the light cycle is light / dark=12 h / 12 h, and the culture temperature is 26.0±0.5℃.

[0017] Further, in step (2), the photobioreactor is an upflow continuous-flow photobioreactor. In the specific embodiment of the application, the upflow continuous-flow photobioreactor is made of transparent organic glass, has an effective volume of 2.5 L, a height-diameter ratio of 3:1, and a stirring speed of 100 rpm.

[0018] Further, in step (2), the biomass concentration inoculated in the reactor is 1000 mg / L.

[0019] Further, in step (2), the hydraulic retention time is 24 h, and the influent NMP load is 200 mg / L / d.

[0020] Further, in step (2), the light intensity is set to 6000 lux, and the light cycle is set to light / dark = 12 h / 12 h.

[0021] Compared with the prior art, the present application has the following remarkable advantages:

[0022] (1) The salt-tolerant bacteria-algal symbiotic sludge system proposed by the present application can efficiently treat high-salinity NMP wastewater under the condition of no aeration, avoiding the problems of high energy consumption cost, greenhouse gas emission and pollutant volatilization caused by mechanical bubble aeration. The dissolved oxygen (DO) produced by the photosynthesis of microalgae can enhance the degradation of NMP, and the CO2 and ammonia nitrogen produced by the degradation of NMP can be utilized for the growth of microalgae. Under the condition of 2% salinity, 250 mg / L of NMP can be completely degraded within 48 h.

[0023] (2) Compared with the traditional activated sludge system, the bacteria-algal symbiotic sludge system performs more efficiently and stably in degrading and mineralizing NMP as the salinity increases. Under the condition of 2% salinity and continuous flow mode operation, the NMP removal rate of the bacteria-algal symbiotic system can still remain above 80%, while the degradation rate of the sludge system is almost less than 60%. In addition, the bacteria-algal symbiotic sludge system shows stronger impact resistance in the face of increasing influent organic load. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the change of photosynthetic activity of microalgae in the bacteria-algal symbiotic sludge system when treating NMP wastewater with different salinities, wherein (a) is the change of maximum photochemical efficiency, (b) is the change of actual light energy conversion efficiency, and (c) is the change of relative photosynthetic electron transport rate;

[0025] Figure 2 is the NMP degradation rate (a), total organic carbon (TOC) removal rate (b) and ammonia nitrogen concentration (c) of the bacteria-algal symbiotic sludge system and the activated sludge system when treating NMP wastewater with different salinities;

[0026] Figure 3 is the NMP degradation rate (a), TOC removal rate (b) and effluent ammonia nitrogen concentration (c) of the pure algal system, activated sludge system and bacteria-algal symbiotic sludge system in the continuous flow reactor under different salinities;

[0027] Figure 4 is the NMP removal rate (a), TOC removal rate (b) and effluent ammonia nitrogen concentration of the reactor under different HRT conditions, wherein R1: pure algal system, R2: activated sludge system, R3: bacteria-algal symbiotic sludge system;

[0028] Figure 5 are the EPS contents of pure algal system, activated sludge system and bacteria-algal symbiotic sludge system under different salinity. DETAILED DESCRIPTION

[0029] The application will be further described in detail below with reference to specific examples and drawings, but the embodiments of the application are not limited thereto. For the process parameters not specifically mentioned, the conventional techniques can be referred to.

[0030] Example 1

[0031] This example is used to illustrate the self-adaptability of microalgae in the constructed bacteria-algal symbiotic sludge system under high salinity stress, and the enhanced degradation performance of the system on high salinity NMP wastewater.

[0032] (1) Preparation of microalgae inoculum: Chlorella sorokiniana FACHB-275 was cultured in BG-11 medium and placed on a light incubator, with a temperature of 27.0℃ and a light intensity of 6000 lux, and a light / dark cycle ratio of 12h / 12h. After 72h of culture under the above conditions, the Chlorella sorokiniana FACHB-275 solution was centrifuged at 25℃ and 8000 rpm for 10 min to obtain the microalgae inoculum.

[0033] (2) Cultivation of salt-tolerant bacteria-algal symbiotic sludge system for enhanced treatment of high salinity NMP wastewater: The microalgae inoculum was inoculated into activated sludge taken from the secondary sedimentation tank of a sewage plant and mixed with wastewater containing NMP. The dry weight ratio of microalgae inoculum to activated sludge was 1:50, the biomass concentration in the culture reactor was 1000mg / L, the light intensity used was 6000 lux, the light cycle was light / dark = 12h / 12h, and the culture temperature was 26.0±0.5℃.

[0034] The composition of BG-11 medium is as follows: NaNO31500mg / L, KH2PO4·3H2O 40mg / L, MgCl2·7H2O 0.16g / L, CaCl2·2H2O 36mg / L, EDTA 1mg / L, Na2CO320mg / L, ferric citrate 6mg / L, ammonium ferric citrate 6mg / L, trace elements A5+Co 1mL / L (A5+Co stock solution is H3BO32.86g / L, MnCl2·4H2O 1.81g / L, ZnSO4·7H2O 0.222g / L, CuSO4·5H2O 0.079g / L, NaMoO4·2H2O 0.390g / L, Co(NO3)2·6H2O 0.0494g / L).

[0035] The NMP-containing wastewater has the following composition: NaCl 0-20 g / L, NMP 200 mg / L, Na2HPO4·12H2O 1.53 g / L, KH2PO4 0.38 g / L, KH2PO4·3H2O 40 mg / L, MgCl2·7H2O 0.16 g / L, CaCl2·2H2O 36 mg / L, EDTA 1 mg / L, Na2CO3 20 mg / L, ferric citrate 6 mg / L, ferric ammonium citrate 6 mg / L, trace element A5+Co 1 mL / L (A5+Co stock solution: H3BO3 2.86 g / L, MnCl2·4H2O 1.81 g / L, ZnSO4·7H2O 0.222 g / L, CuSO4·5H2O 0.079 g / L, NaMoO4·2H2O 0.390 g / L, Co(NO3)2·6H2O 0.0494 g / L).

[0036] Figure 1 (a) is the change of the maximum photochemical efficiency (Fv / Fm) of microalgae in the bacteria-algae symbiotic sludge system when treating wastewater with different salinity. When the salinity is 0%, the Fv / Fm value rises from 0.69 to 0.75 within 10 days. When the salinity rises to 1%, the Fv / Fm value decreases from 0.692 to 0.626. When the salinity rises to 2%, the Fv / Fm value decreases from 0.692 to 0.558 within 3 days, and then gradually rises to 0.626 at the 10th day. Figure 1 (b) is the change of the actual light energy conversion efficiency (Y(II)) of microalgae. When the salinity is 0%, the Y(II) value rises from 0.15 to 0.359 within 10 days. When the salinity is 1% and 2%, the Y(II) value decreases from 0.15 to 0.053 and 0.008 within 4 days, respectively, and then slowly rises to 0.218 and 0.224 at the 10th day, respectively. Figure 1 (c) is the change of the relative photosynthetic electron transport rate (ETRm) of microalgae. When the salinity is 0%, the ETRm value rises from 17.92 to 60.81 within 10 days. When the salinity rises to 1% and 2%, the ETRm value decreases from 17.92 to 8.11 and 4.70 within 4 days, respectively, and then slowly rises to 32.28 and 28.68 at the 10th day, respectively. The above results show that under the impact of high salinity, the photosynthetic activity of microalgae in the bacteria-algae symbiotic sludge system is temporarily inhibited, however, after 3-4 days of adaptation time, the photosynthetic activity of microalgae gradually recovers to a higher level. Therefore, Chlorella can maintain photosynthetic activity by self-adaptation under the impact of 0%-2% salinity.

[0037] Figure 2(a) is the NMP degradation rate of the bacteria-algae symbiotic sludge system and the activated sludge system when treating wastewater with different salinity. Under the condition of 0% salinity, the NMP degradation rate of the bacteria-algae symbiotic sludge system reaches 100% within 32h, and the NMP degradation rate of the activated sludge system is only 77%. When the salinity is increased to 1% and 2%, the bacteria-algae symbiotic sludge system can completely degrade NMP in the system within 48h, and the NMP degradation rate of the activated sludge system is only 63% and 89%. Figure 2 (b) is the TOC removal rate of the bacteria-algae symbiotic sludge system and the activated sludge system under different salinity. Under the conditions of 0%, 1% and 2% salinity, the TOC removal rates of the bacteria-algae symbiotic sludge system at 48h are 92.07%, 76.34% and 73.05% respectively, and the TOC removal rates of the activated sludge system at 48h are 89.29%, 81.69% and 71.52% respectively. Through the above results analysis, when treating high salinity NMP wastewater, the salt-tolerant bacteria-algae symbiotic sludge system constructed by the present application significantly enhances the degradation and mineralization of NMP. Figure 2 (c) is the change of ammonia nitrogen concentration in the bacteria-algae symbiotic sludge system and the activated sludge system under different salinity. Under the conditions of 0%, 1% and 2% salinity, the ammonia nitrogen concentrations in the bacteria-algae symbiotic sludge system at 48h are 4.86mg / L, 0.79mg / L and 2.25mg / L respectively, and the ammonia nitrogen concentrations in the activated sludge system at 48h are 19.18mg / L, 7.54mg / L and 1.45mg / L respectively. The above results show that when treating high salinity NMP wastewater, the bacteria-algae symbiotic sludge system significantly enhances the removal of ammonia nitrogen. In summary, the bacteria-algae symbiotic sludge system of the present application has strong salt tolerance, can significantly enhance the degradation and mineralization of NMP under the condition of no aeration, and realize simultaneous denitrification.

[0038] Example 2

[0039] This example is used to illustrate the efficiency and stability of the salt-tolerant bacteria-algae symbiotic sludge system in treating high salinity NMP wastewater under continuous flow operation mode.

[0040] (1) The above cultured bacteria-algae symbiotic sludge system was inoculated into a continuous flow photobioreactor for operation, the biomass concentration inoculated in the reactor was 1000mg / L, the hydraulic retention time was set to 24h, and the NMP loading of the influent was 200mg / L / d. The light intensity was set to 6000lux, and the light cycle was set to light / dark=12h / 12h. A pure algae (Chlorella) system and an activated sludge system were set as control groups.

[0041] (2) Effect of salinity on the treatment efficiency of the zooglea-algal symbiotic sludge system The effect was embodied by gradually increasing the salinity of NMP wastewater, and the removal effect of water quality was monitored. In the first stage, the salinity of NMP wastewater was 0%; in the second stage, the salinity of NMP wastewater was 1%; in the third stage, the salinity of NMP wastewater was 1.5%; and in the fourth stage, the salinity of NMP wastewater was 2%.

[0042] (3) Effect of influent organic load on the treatment efficiency of the zooglea-algal symbiotic sludge system The effect was embodied by changing the HRT, and the removal effect of water quality was monitored. The salinity of simulated NMP wastewater was controlled at 1.5%. In the first stage, the HRT was 24 h; in the second stage, the HRT was 18 h; and in the third stage, the HRT was 12 h.

[0043] Figure 3 is the NMP degradation rate, TOC removal rate and effluent ammonia nitrogen concentration in the pure algal system, activated sludge system and zooglea-algal symbiotic sludge system under different salinities. As shown in Figure 3 (a) and (b), under the condition of 0% salinity, when the influent NMP load was 200 mg / L / d, the NMP degradation rate and TOC removal rate in the zooglea-algal symbiotic sludge system reached more than 98% and 85% respectively, the NMP degradation rate and TOC removal rate in the activated sludge system were about 80% and 78% respectively, and the pure algal system did not have the ability to biodegrade NMP. Under the condition of 2% salinity, the NMP degradation rate and TOC removal rate in the zooglea-algal symbiotic sludge system remained above 80% and 75% respectively, while the NMP degradation rate and TOC removal rate in the activated sludge system were about 58% and 45% respectively. During the operation of the continuous flow photobioreactor, the zooglea-algal symbiotic sludge system significantly enhanced the degradation and mineralization of NMP, and had long-term running stability. Facing the impact of high salinity wastewater, the zooglea-algal symbiotic sludge system had stronger salt tolerance and maintained high NMP degradation and denitrification performance. As shown in Figure 3 (c), under the condition of 0% salinity, the effluent ammonia nitrogen concentration in the zooglea-algal symbiotic sludge system was 5.25±1.45 mg / L, while the effluent ammonia nitrogen concentration in the activated sludge system was 7.60±1.15 mg / L, and the pure algal system did not produce ammonia nitrogen due to the inability of chlorella to degrade NMP. The zooglea-algal symbiotic system promoted microbial activity, and the assimilation of microalgae also enhanced the denitrification capacity of the system. Under the condition of 2% salinity, the effluent ammonia nitrogen concentration in the zooglea-algal symbiotic system was 4.49±0.51 mg / L, and the effluent ammonia nitrogen concentration in the activated sludge system was 5.64±1.08 mg / L. Nitrate and nitrite were not detected during the experiment. Due to the salt tolerance of the zooglea-algal symbiotic sludge system, synchronous enhanced denitrification was achieved under high salinity stress. In summary, the zooglea-algal symbiotic sludge system enhanced the NMP degradation and denitrification performance, and had long-term running stability and impact resistance.

[0044] Figure 4 NMP degradation rate, TOC removal rate and effluent ammonia concentration of the reactors under different HRT conditions at 1.5% salinity (R1: pure algal system, R2: activated sludge system, R3: bacteria-algae symbiotic sludge system). As shown in Figure 4 As shown in (a) and (b), the pure algal system does not have the ability to degrade NMP. Under the condition of HRT of 24h (NMP load of 200mg / L / d), the NMP degradation rate and TOC removal rate of the bacteria-algae symbiotic sludge system are 93.16% and 81.56%, respectively, and the NMP degradation rate and TOC removal rate of the activated sludge system are 80.14% and 69.60%, respectively. When HRT is reduced to 18h (NMP load of 267mg / L / d), the NMP degradation rate and TOC removal rate of the bacteria-algae symbiotic sludge system are 78.17% and 60.91%, respectively, and the NMP degradation rate and TOC removal rate of the activated sludge system are 62.03% and 38.51%, respectively. When HRT is reduced to 12h (NMP load of 400mg / L / d), the NMP degradation rate and TOC removal rate of the bacteria-algae symbiotic sludge system are 52.06% and 38.80%, respectively, and the NMP degradation rate and TOC removal rate of the activated sludge system are 33.44% and 24.61%, respectively. As shown in Figure 4 (c), there is no ammonia production because the pure algal system cannot degrade NMP. Under the condition of HRT of 24h (NMP load of 200mg / L / d), the effluent ammonia concentrations of the bacteria-algae symbiotic sludge system and the activated sludge system are 6.92mg / L and 7.89mg / L, respectively. When HRT is reduced to 12h (NMP load of 400mg / L / d), the effluent ammonia concentrations of the bacteria-algae symbiotic sludge system and the activated sludge system are 2.97mg / L and 5.04mg / L, respectively, and no nitrate and nitrite nitrogen is detected during the experiment. The above results show that the bacteria-algae symbiotic sludge system has strong stability and impact resistance in the face of the impact of NMP load increase.

[0045] Figure 5 Effect of different salinities on EPS of pure algal system, activated sludge system and bacteria-algae symbiotic sludge system. As shown in Figure 5(a) As shown in FIG. 2(a), under the condition of 0% salinity, the content of loosely bound extracellular polymeric substances (LB-EPS) in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system was 83.13 mg / (g MLVSS), 36.88 mg / (g MLVSS) and 29.10 mg / (g MLVSS), respectively. With the gradual increase of salinity to 2%, the content of LB-EPS in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system gradually increased to 173.92 mg / (g MLVSS), 98.26 mg / (g MLVSS) and 66.88 mg / (g MLVSS), respectively, and the proportion of PS increased significantly. As shown in FIG. 2(b), under the condition of 0% salinity, the content of tightly bound extracellular polymeric substances (TB-EPS) in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system was 116.53 mg / (g MLVSS), 61.47 mg / (g MLVSS) and 33.98 mg / (g MLVSS), respectively. With the gradual increase of salinity to 2%, the content of TB-EPS in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system gradually increased to 220.15 mg / (g MLVSS), 70.69 mg / (g MLVSS) and 26.33 mg / (g MLVSS), respectively. The results showed that under the impact of high salinity environment, the bacterial-algal symbiotic system could secrete more TB-EPS, and the increase of PS was particularly beneficial to enhance the salt tolerance of the system. The results showed that compared with the activated sludge system, the LB-EPS and TB-EPS in the bacterial-algal symbiotic sludge system were significantly increased, which was beneficial to enhance the salt tolerance, stability and impact resistance of the system. Figure 5 (b) As shown in FIG. 2(a), under the condition of 0% salinity, the content of loosely bound extracellular polymeric substances (LB-EPS) in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system was 83.13 mg / (g MLVSS), 36.88 mg / (g MLVSS) and 29.10 mg / (g MLVSS), respectively. With the gradual increase of salinity to 2%, the content of LB-EPS in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system gradually increased to 173.92 mg / (g MLVSS), 98.26 mg / (g MLVSS) and 66.88 mg / (g MLVSS), respectively, and the proportion of PS increased significantly. As shown in FIG. 2(b), under the condition of 0% salinity, the content of tightly bound extracellular polymeric substances (TB-EPS) in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system was 116.53 mg / (g MLVSS), 61.47 mg / (g MLVSS) and 33.98 mg / (g MLVSS), respectively. With the gradual increase of salinity to 2%, the content of TB-EPS in the bacterial-algal symbiotic sludge system, the activated sludge system and the pure algal system gradually increased to 220.15 mg / (g MLVSS), 70.69 mg / (g MLVSS) and 26.33 mg / (g MLVSS), respectively. The results showed that under the impact of high salinity environment, the bacterial-algal symbiotic system could secrete more TB-EPS, and the increase of PS was particularly beneficial to enhance the salt tolerance of the system. The results showed that compared with the activated sludge system, the LB-EPS and TB-EPS

Claims

1. A method for enhancing treatment of high salinity N-methylpyrrolidone wastewater using salt-tolerant bacterial-algal symbiotic sludge system, characterized in that, Comprising the following steps: (1) Construction of salt-tolerant bacteria-algal symbiotic sludge system: Chlorella vulgaris Chlorella sorokiniana After the expansion culture of FACHB-275, the liquid algae was centrifuged, the residual nutrients were removed by washing, and the algae sediment obtained by centrifugation again was used as the microalgae inoculum. The microalgae inoculum was inoculated into the activated sludge taken from the secondary sedimentation tank of a sewage plant, and a salt-tolerant bacterial-algal symbiotic sludge system was constructed by using simulated wastewater containing NMP with high salinity. In the simulated wastewater containing NMP with high salinity, the salinity was 1% to 3%, and the concentration of NMP was 200 mg / L. (2) Treatment of high-salinity N-methylpyrrolidone wastewater: Inoculate the salt-tolerant bacteria-algal symbiotic sludge system into a photobioreactor, run the reactor, and input high-salinity NMP wastewater for biodegradation treatment.

2. The method of claim 1, wherein, In step (1), Chlorella vulgaris Chorella sorokiniana The medium for FACHB-275 was BG-11 medium, the centrifugation speed was 8000 rpm, the centrifugation time was 10 min, and the washing solution was phosphate buffer solution.

3. The method of claim 1, wherein, In step (1), the dry weight ratio of microalgae inoculum to activated sludge was 1:50, and the biomass concentration inoculated in the culture reactor was 1000 mg / L.

4. The method of claim 1, wherein, In step (1), the light intensity used during cultivation was 6000 lux, the light cycle was light / dark=12 h / 12 h, and the cultivation temperature was 26.0±0.5℃.

5. The method of claim 1, wherein, In step (2), the photobioreactor was an upflow continuous-flow photobioreactor.

6. The method of claim 5, wherein, The upflow continuous-flow photobioreactor was made of transparent organic glass, with an effective volume of 2.5 L, a height-diameter ratio of 3:1, and a stirring speed setting of 100 revolutions / minute.

7. The method of claim 1, wherein, In step (2), the biomass concentration inoculated in the reactor was 1000 mg / L.

8. The method of claim 1, wherein, In step (2), the hydraulic retention time was 24 h, and the influent NMP load was 200 mg / L / d.

9. The method of claim 1, wherein, In step (2), the light intensity was set to 6000 lux, and the light cycle was set to light / dark=12 h / 12 h.

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