A wastewater treatment system and a wastewater treatment process

Abstract

The present invention provides a wastewater treatment system and a wastewater treatment process, belonging to the technical field of wastewater treatment. The wastewater treatment system provided by the present invention uses activated sludge combined with quartz sand and an algal-bacterial symbiont, which can overcome the problems in the prior art that sludge bulking affects the effluent water quality and harms the operation of the biochemical system, and can also improve the wastewater remediation effect. The wastewater treatment process provided by the present invention can significantly reduce the chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids (SS) in the wastewater to be treated. The removal rate of chemical oxygen demand (COD) can reach 94.87% within 4 h, the removal rate of biochemical oxygen demand (BOD) can reach 96.60%, and the removal rate of suspended solids (SS) can reach 96.58%. The best removal efficiency can be achieved in a relatively short treatment time, which is beneficial to accelerating the wastewater treatment process.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a wastewater treatment system and a wastewater treatment process. Background Art

[0002] For a long time, the secondary biological treatment of urban domestic sewage mostly adopts the activated sludge method. It is the most widely used secondary biological treatment process at present, with advantages such as high treatment capacity and good effluent quality. However, it generally has problems such as high capital construction cost, high operation cost, high energy consumption, complex management, easy occurrence of sludge bulking and sludge floating, and cannot remove inorganic nutrients such as nitrogen and phosphorus, resulting in low operation efficiency.

[0003] CN201810461965.9 discloses a method for removing nitrogen and phosphorus in aquaculture wastewater by combining immobilized chlorella and activated sludge. The chlorella (and activated sludge) is embedded and fixed with sodium alginate and put into aquaculture wastewater. However, this method using immobilized embedding materials will increase additional costs and cannot avoid the situation of sludge bulking. Summary of the Invention

[0004] The purpose of the present invention is to provide a wastewater treatment system and a wastewater treatment process to solve the problem that sludge bulking affects the effluent quality and endangers the operation of the biochemical system, and can also improve the wastewater repair effect.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a wastewater treatment system, including a base material and an algal-bacterial symbiont. The base material includes activated sludge and quartz sand;

[0007] The algal-bacterial symbiont contains nostoc algal solution, microcystis aeruginosa algal solution and halomonas denitrificans bacterial solution;

[0008] The weight ratio of the activated sludge to the quartz sand is 1:2 to 3;

[0009] The mass-volume ratio of the base material to the algal-bacterial symbiont is 1 kg:0.8 to 1.2 mL.

[0010] Preferably, the volume ratio of the nostoc algal solution, the microcystis aeruginosa algal solution and the halomonas denitrificans bacterial solution in the algal-bacterial symbiont is 1:0.8 to 1.2:0.8 to 1.2.

[0011] Preferably, the initial cell concentration of the nostoc algal solution in the algal-bacterial symbiont is 10 5 ~10 7 cells / mL;

[0012] The initial cell concentration of the microcystis aeruginosa algal solution in the algal-bacterial symbiont is 105 ~10 7 cells / mL;

[0013] The initial cell concentration of the Nitrosomonas eutropha solution in the algal-bacterial symbiont is 10 7 ~10 9 cells / mL.

[0014] Preferably, the particle size of the activated sludge is 0.3 - 3 mm.

[0015] Preferably, the particle size of the quartz sand is below 4 mm.

[0016] Preferably, the preparation method of the Nostoc sp. algal solution is: inoculating Nostoc sp. in BG11 medium and culturing to obtain it;

[0017] The preparation method of the Microcystis aeruginosa algal solution is: inoculating Microcystis aeruginosa in BG11 medium and culturing to obtain it;

[0018] The preparation method of the Nitrosomonas eutropha solution is: inoculating Nitrosomonas eutropha in R2A medium and culturing to obtain it.

[0019] The present invention also provides a wastewater treatment process, including the following steps:

[0020] Placing the above wastewater treatment system in an aeration tank, introducing the wastewater to be treated, and achieving wastewater remediation after aeration treatment.

[0021] Preferably, the volume ratio of the wastewater treatment system to the wastewater to be treated is 1:2 - 5.

[0022] Preferably, the time of the aeration treatment is 4 h or more.

[0023] The technical effects and advantages of the present invention:

[0024] In the present invention, the activated sludge combined with quartz sand and algal-bacterial symbiont can effectively prevent the situation of sludge bulking caused by excessive soluble low-molecular components and miscellaneous strains in the sludge, ensuring the continuous progress of the wastewater treatment process. The wastewater treatment process provided by the present invention can significantly reduce the chemical oxygen demand (COD), biochemical oxygen demand (BOD), and suspended solids (SS) in the wastewater to be treated. The removal rate of chemical oxygen demand (COD) can reach 94.87% within 4 h, the removal rate of biochemical oxygen demand (BOD) can reach 96.60%, and the removal rate of suspended solids (SS) can reach 96.58%. It can achieve the best removal efficiency in a relatively short treatment time, which is beneficial to accelerating the wastewater treatment process. Specific embodiments

[0025] The present invention provides a wastewater treatment system, comprising a base material and an algae-bacteria symbiotic body. The base material includes activated sludge and quartz sand, and the weight ratio of the activated sludge to the quartz sand is 1:2 - 3, preferably 1:2.3 - 2.7. The particle size of the activated sludge is preferably 0.3 - 3 mm, and the particle size of the quartz sand is preferably below 4 mm. The algae-bacteria symbiotic body contains nostoc algal solution, microcystis aeruginosa algal solution and halomonas denitrificans bacterial solution. The volume ratio of the nostoc algal solution, microcystis aeruginosa algal solution and halomonas denitrificans bacterial solution in the algae-bacteria symbiotic body is preferably 1:0.8 - 1.2:0.8 - 1.2, more preferably 1:0.9 - 1.1:0.9 - 1.1. The mass-volume ratio of the base material to the algae-bacteria symbiotic body is 1 kg:0.8 - 1.2 mL, preferably 1 kg:0.9 - 1.1 mL. The initial cell concentration of the nostoc algal solution in the algae-bacteria symbiotic body is preferably 10 5 - 10 7 cells / mL, more preferably 5×10 5 - 5×10 6 cells / mL. The preparation method of the nostoc algal solution is: inoculating nostoc into BG11 medium for cultivation. The initial cell concentration of the microcystis aeruginosa algal solution in the algae-bacteria symbiotic body is preferably 10 5 - 10 7 cells / mL, more preferably 5×10 5 - 5×10 6 cells / mL. The preparation method of the microcystis aeruginosa algal solution is: inoculating microcystis aeruginosa into BG11 medium for cultivation. The initial cell concentration of the halomonas denitrificans bacterial solution in the algae-bacteria symbiotic body is preferably 10 7 - 10 9 cells / mL, more preferably 5×10 7 - 5×10 8 cells / mL. The preparation method of the halomonas denitrificans bacterial solution is: inoculating halomonas denitrificans into R2A medium for cultivation.

[0026] The present invention also provides a wastewater treatment process, comprising the following steps: placing the above wastewater treatment system in an aeration tank, introducing the wastewater to be treated, and realizing the repair of the wastewater after aeration treatment. The volume ratio of the wastewater treatment system to the wastewater to be treated is preferably 1:2 - 5, more preferably 1:3 - 4. The time of the aeration treatment is preferably more than 4 h, more preferably more than 6 h.

[0027] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0028] The granular activated sludge was purchased from Shanghai Biruncheng Biotechnology Engineering Co., Ltd.;

[0029] Nostoc sp. (FACHB-95); Microcystis aeruginosa (FACHB-526); Chlorella sorokiniana (FACHB-24), all of which were purchased from the Freshwater Algae Culture Collection of the Chinese Academy of Sciences;

[0030] Halomonas nitrativorans MCCC 1K06330 was purchased from the China Center for Marine Microbial Culture Collection.

[0031] Example 1

[0032] Nostoc sp. was cultured in BG11 medium to 10 6 cells / mL, Microcystis aeruginosa was cultured in BG11 medium to 10 6 cells / mL, Halomonas nitrativorans was cultured in R2A liquid medium to 10 8 cells / mL. The cultured Nostoc sp. algal solution, Microcystis aeruginosa algal solution and Halomonas nitrativorans bacterial solution were mixed at a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0033] The granular activated sludge with a particle size specification of 0.3 - 3 mm was mixed with quartz sand (removing large particles) sieved through 4 meshes at a weight ratio of 3:7 and placed into a 100 m 3 aeration tank, and the above-prepared algal-bacterial symbiont was inoculated at an inoculation ratio of 500 kg:500 mL.

[0034] Example 2

[0035] Nostoc sp. was cultured in BG11 medium to 10 5 cells / mL, Microcystis aeruginosa was cultured in BG11 medium to 10 5 cells / mL, Halomonas nitrativorans was cultured in R2A liquid medium to 10 7 cells / mL. The cultured Nostoc sp. algal solution, Microcystis aeruginosa algal solution and Halomonas nitrativorans bacterial solution were mixed at a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0036] The granular activated sludge with a particle size specification of 0.3 - 3 mm was mixed with quartz sand (removing large particles) sieved through 4 meshes at a weight ratio of 1:2 and placed into a 100 m 3 aeration tank, and the above-prepared algal-bacterial symbiont was inoculated at an inoculation ratio of 500 kg:400 mL.

[0037] Example 3

[0038] Cultivate Nostoc sp. in BG11 medium until it reaches 10 7 cells / mL, cultivate Microcystis aeruginosa in BG11 medium until it reaches 10 7 cells / mL, cultivate Halomonas nitrativorans in R2A liquid medium until it reaches 10 9 cells / mL. Mix the cultivated Nostoc sp. algal solution, Microcystis aeruginosa algal solution and Halomonas nitrativorans bacterial solution in a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0039] Mix granular activated sludge with a particle size specification of 0.3 - 3 mm and quartz sand (removing large particles) sieved through 4 meshes in a weight ratio of 1:3 and place it into a 100 m 3 aeration tank, and inoculate the above-prepared algal-bacterial symbiont according to an inoculation ratio of 500 kg:600 mL.

[0040] Control Example 1

[0041] Cultivate Chlorella sorokiniana in BG11 medium until it reaches 10 6 cells / mL, cultivate Microcystis aeruginosa in BG11 medium until it reaches 10 6 cells / mL, cultivate Halomonas nitrativorans in R2A liquid medium until it reaches 10 8 cells / mL. Mix the cultivated Nostoc sp. algal solution, Microcystis aeruginosa algal solution and Halomonas nitrativorans bacterial solution in a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0042] Mix granular activated sludge with a particle size specification of 0.3 - 3 mm and quartz sand (removing large particles) sieved through 4 meshes in a weight ratio of 3:7 and place it into a 100 m 3 aeration tank, and inoculate the above-prepared algal-bacterial symbiont according to an inoculation ratio of 500 kg:500 mL.

[0043] Control Example 2

[0044] Cultivate Nostoc sp. in BG11 medium until it reaches 10 6 cells / mL, cultivate Chlorella sorokiniana in BG11 medium until it reaches 10 6 cells / mL, cultivate Halomonas nitrativorans in R2A liquid medium until it reaches 10 8 cells / mL. Mix the cultivated Nostoc sp. algal solution, Microcystis aeruginosa algal solution and Halomonas nitrativorans bacterial solution in a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0045] Mix granular activated sludge with a particle size specification of 0.3 - 3 mm and quartz sand (removing large particles) sieved through 4 meshes in a weight ratio of 3:7 and place it into a 100 m3 In the aeration tank, the above-prepared algal-bacterial symbiont was inoculated at an inoculation ratio of 500 kg:500 mL.

[0046] Comparative Example 3

[0047] Nostoc was cultured in BG11 medium to 10 6 cells / mL, and Microcystis aeruginosa was cultured in BG11 medium to 10 6 cells / mL. The cultured Nostoc algal solution and Microcystis aeruginosa algal solution were mixed at a volume ratio of 1:1 to obtain a composite algal solution.

[0048] Particulate activated sludge with a particle size specification of 0.3 - 3 mm and quartz sand (removing large particles) after passing through a 4-mesh sieve were mixed at a weight ratio of 3:7 and placed into a 100 m 3 aeration tank. The above-prepared composite algal solution was inoculated at an inoculation ratio of 500 kg:500 mL.

[0049] Comparative Example 4

[0050] Nostoc was cultured in BG11 medium to 10 6 cells / mL, Microcystis aeruginosa was cultured in BG11 medium to 10 6 cells / mL, and Halomonas nitrativorans was cultured in R2A liquid medium to 10 8 cells / mL. The cultured Nostoc algal solution, Microcystis aeruginosa algal solution, and Halomonas nitrativorans bacterial solution were mixed at a volume ratio of 1:1:1 to obtain an algal-bacterial symbiont.

[0051] Particulate activated sludge with a particle size specification of 0.3 - 3 mm was placed into a 100 m 3 aeration tank. The above-prepared algal-bacterial symbiont was inoculated at an inoculation ratio of 500 kg:500 mL.

[0052] Wastewater treatment effect of Experimental Example 1

[0053] Experiments were conducted using the wastewater treatment systems in Example 1 and Comparative Examples 1 - 4 as follows:

[0054] The experiments were carried out in a blower aeration tank to test the purification efficiency of each system. A total of 500 L of the wastewater treatment system and 1500 L of urban sewage were put into the aeration tank for each group of experiments. The aeration time was set to 4 h, and samples were taken after discharging.

[0055] The discharge standards refer to the Class B standards of the "Pollutant Discharge Standards for Municipal Wastewater Treatment Plants: GB 18918-2002", and the three indicators are Chemical Oxygen Demand (COD): 60 mg / L, Biochemical Oxygen Demand (BOD): 20 mg / L, and Suspended Solids (SS): 20 mg / L.

[0056] Chemical Oxygen Demand (COD) is determined by the dichromate method, and the determination method refers to GB11914-89; Biochemical Oxygen Demand (BOD) is determined by the dilution and inoculation method, and the determination method refers to GB7488-87; Suspended Solids (SS) is determined by the gravimetric method, and the determination method refers to GB11901-89.

[0057] Before discharging urban sewage, water quality samples are taken at the discharge outlet at the end of the aeration tank after aeration treatment to measure the three groups of indicators and calculate the average value, as shown in Tables 1 to 3 below:

[0058] Table 1 Changes in Chemical Oxygen Demand (COD) before and after treatment

[0059]

[0060] Table 2 Changes in Biochemical Oxygen Demand (BOD) before and after treatment

[0061]

[0062] Table 3 Changes in Suspended Solids (SS) before and after treatment

[0063]

[0064] From the treatment results, it can be seen that the wastewater treatment process provided by the present invention can significantly reduce the Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), and Suspended Solids (SS) in the wastewater to be treated. In Example 1, the removal rate of Chemical Oxygen Demand (COD) can reach 94.87% within 4 hours, the removal rate of Biochemical Oxygen Demand (BOD) can reach 96.60%, and the removal rate of Suspended Solids (SS) can reach 96.58%. Compared with other implementation schemes, Example 1 provided by the present invention achieves the best removal efficiency in a shorter treatment time, which is beneficial to accelerating the wastewater treatment process.

[0065] System state after treatment in Experimental Example 2

[0066] Five sewage treatment operation management personnel with experience in patrolling the aeration tank are selected to record and score the system state after treatment respectively. The scoring criteria are shown in Table 4 below:

[0067] Table 4 Scoring criteria for system state after treatment

[0068]

[0069] The average value of the scoring results for each group is taken, and the final results are shown in Table 5 below:

[0070] Table 5 System status after treatment

[0071] Grouping System odor Supernatant color Sludge floating condition Total score Example 1 27.87 28.27 37.17 93.31 Comparative example 1 25.70 23.77 19.56 69.03 Comparative example 2 11.07 15.26 7.24 33.57 Comparative example 3 14.27 15.68 10.03 39.98 Comparative example 4 26.88 19.89 24.90 71.67

[0072] The earthy smell of the sludge often indicates a certain microbial activity in the system. When the smell is strong, it means that the sludge in the system has basically lost its activity and no longer has the ability to treat wastewater. The color of the supernatant and the condition of the floating sludge can correspond to the treatment degree. When the supernatant is clear and transparent and the sludge does not expand or float, it means that the wastewater treatment system can continue to operate normally. When the supernatant is turbid, it represents a poor treatment effect of the sludge, and the organic matter in the wastewater has not been fully decomposed. The sludge expansion or floating is caused by the deterioration of the sludge sedimentation performance, which in turn destroys the normal process operation and directly affects the effluent quality. In the present invention, the activated sludge combined with quartz sand and the algal-bacterial symbiont can effectively prevent the situation of sludge expansion caused by excessive soluble low-molecular components and miscellaneous strains in the sludge, and ensure the continuous progress of the wastewater treatment process.

[0073] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A wastewater treatment system, characterized in that, It includes a base material and an algal-bacterial symbiont, and the base material includes activated sludge and quartz sand; The algal-bacterial symbiont contains Nostoc sphaeroides algal solution, Microcystis aeruginosa algal solution and Halomonas nitrificans bacterial solution; The weight ratio of the activated sludge to the quartz sand is 1:2 - 3; The mass-volume ratio of the base material to the algal-bacterial symbiont is 1 kg:0.8 - 1.2 mL.

2. The wastewater treatment system according to claim 1, characterized in that, The volume ratio of the Nostoc sphaeroides algal solution, Microcystis aeruginosa algal solution and Halomonas nitrificans bacterial solution in the algal-bacterial symbiont is 1:0.8 - 1.2:0.8 - 1.

2.

3. The wastewater treatment system according to claim 2, characterized in that, The initial cell concentration of the Nostoc algal solution in the algal-bacterial symbiont is 10 5 ~10 7 cells / mL; The initial cell concentration of Microcystis aeruginosa algal solution in the algal-bacterial symbiont is 10 5 ~10 7 cells / mL; The initial cell concentration of Nitrosomonas eutropha bacteria solution in the algal-bacterial symbiont is 10 7 ~10 9 cells / mL.

4. The wastewater treatment system according to claim 3, characterized in that, The particle size of the activated sludge is 0.3 - 3 mm.

5. The wastewater treatment system according to claim 4, characterized in that, The particle size of the quartz sand is below 4 mm.

6. The wastewater treatment system according to claim 5, characterized in that, The preparation method of the Nostoc sphaeroides algal solution is: inoculating Nostoc sphaeroides in BG11 medium and culturing to obtain it; The preparation method of the Microcystis aeruginosa algal solution is: inoculating Microcystis aeruginosa in BG11 medium and culturing to obtain it; The preparation method of the Halomonas nitrificans bacterial solution is: inoculating Halomonas nitrificans in R2A medium and culturing to obtain it.

7. A wastewater treatment process, characterized in that, It includes the following steps: Placing the wastewater treatment system according to any one of claims 1 - 6 in an aeration tank, introducing the wastewater to be treated, and achieving wastewater restoration after aeration treatment.

8. The wastewater treatment process according to claim 7, characterized in that, The volume ratio of the wastewater treatment system to the wastewater to be treated is 1:2 - 5.

9. The wastewater treatment process according to claim 8, characterized in that, The time of the aeration treatment is 4 h or more.

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