Method for improving effluent quality of biological activated carbon slow filter

Abstract

The invention discloses a method for improving the effluent quality of a biological filter. The method comprises the step of introducing a to-be-treated water body into a biological activated carbon slow filter tank inoculated with specific microorganisms to carry out enhanced removal of pollutants. The biological activated carbon slow filter tank is filled with a biological activated carbon filter material; the biological activated carbon filter material is inoculated with a mixed flora with a synergistic metabolism effect. According to the method, a microbial population structure in a biological membrane attached to the surface of biological activated carbon is regulated and controlled mainly through inoculation of specific microorganisms, so that the catabolism capability of organic matters, especially natural organic matters which are difficult to degrade, in a water body to be treated is enhanced; no extra chemical reagent needs to be added in the whole process, a water head in the biological activated carbon slow-speed filter is not obviously lowered, and backwashing is not needed. The technology is simple to operate, saves operation cost and human resources, and is a green and sustainable water treatment technology.

Description

Technical Field

[0001] This invention relates to a method for improving the effluent quality of a biological activated carbon slow filter, belonging to the field of water treatment technology. Background Technology

[0002] Biological activated carbon water treatment is a water treatment technology that combines the dual effects of activated carbon adsorption and biodegradation. Its basic principle is to form a biofilm on the surface of activated carbon, thereby removing pollutants from the water by coupling the adsorption of activated carbon with the metabolic activity of microorganisms.

[0003] After pretreatment, the water enters a filter containing activated carbon. Due to its large specific surface area and abundant pore structure, activated carbon has a strong adsorption capacity for organic matter and some inorganic matter in the water. Through physical and chemical adsorption, pollutants in the water are effectively captured. Simultaneously, microorganisms attached to the surface of the activated carbon gradually form a biofilm. These microorganisms further degrade the organic pollutants adsorbed on the activated carbon through metabolic activities, including some recalcitrant organic matter. In this process, activated carbon not only plays a role in physical adsorption but also provides a suitable environment for microbial growth, thereby improving the overall efficiency of water treatment. Because microorganisms can continuously degrade pollutants on the surface of activated carbon, the adsorption capacity of the activated carbon is regenerated, significantly extending its service life.

[0004] However, while bio-activated carbon processes perform well in removing readily biodegradable soluble organic matter, their efficiency in removing recalcitrant organic matter such as natural organic compounds still needs improvement. Natural organic matter, widely found in surface water, mainly includes humic acid, fulvic acid, and other humic substances. These substances have complex molecular structures, limiting the removal efficiency of traditional bio-activated carbon processes. Current methods to improve the removal efficiency of bio-activated carbon for recalcitrant organic matter include modifying activated carbon to enhance its adsorption capacity or combining it with appropriate pretreatment technologies such as ozone oxidation to promote the removal of recalcitrant organic matter. However, these methods often complicate the process and increase operating costs. Therefore, developing innovative methods to improve the removal of recalcitrant organic matter by bio-activated carbon is essential. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the effluent quality of a slow-flow biological activated carbon filter. This is achieved by optimizing the microbial community composition within the biofilm attached to the surface of the biological activated carbon: introducing highly specific and metabolically efficient functional microorganisms to improve the biodegradation and removal efficiency of recalcitrant organic matter (natural organic matter), thereby enhancing the effluent quality. This invention does not alter the water treatment process flow, requires no additional chemical agents or operating costs, and represents a green water purification method.

[0006] The method for improving the effluent quality of a biological activated carbon slow filter provided by the present invention includes the step of passing the water to be treated into a biological activated carbon slow filter inoculated with specific microorganisms for enhanced removal of pollutants.

[0007] In the method of the present invention, the bio-activated carbon slow filter is filled with bio-activated carbon filter media; The bio-activated carbon filter material is inoculated with a mixed microbial community that has synergistic metabolic effects. These microbial species are derived from nature and obtained through specific culture methods, including Proteobacteria. Proteobacteria Actinomycetes Actinobacteriota Acidic bacteria Acidobacteriota Firmicutes Firmicutes Bacteroidetes Bacteroidota Green Curved Fungi Chloroflexi Phylum Myxococci Myxococcota Nitrifying Spirulina Nitrospirota Bacillus phylum Gemmatimonadota Desulfobacteria Desulfobacterota Among them, the most abundant species were Proteobacteria. Proteobacteria Actinomycetes Actinobacteriota Acidic bacteria Acidobacteriota Firmicutes Firmicutes, The abundances were 32.6%, 13.02%, 11.56%, and 10.11%, respectively. The abundances of the remaining bacteria were: Bacteroidetes. Bacteroidota 8.13%, Green Curvature Chloroflexi 5.14%, Myxococcus Myxococcota 4.54%, Nitrifying Spirulina Nitrospirota 3.07%, Bacillus phylum Gemmatimonadota 2.78%, Desulfobacteria Desulfobacterota 1.53% 。

[0008] In the method of the present invention, the step of inoculating the mixed microbial community is as follows: The bacterial solution containing the mixed bacterial flora is mixed with the water to be treated to obtain mixed water, which is then added to the biological activated carbon slow filter, ensuring that its volume can fill all the pores of the biological activated carbon slow filter; the mixed water is circulated in the biological activated carbon slow filter to ensure that all the packing material is in full contact with the water for inoculation.

[0009] In the method of the present invention, the mixed water is circulated in the biological activated carbon slow filter by a bottom-in, top-out method.

[0010] In the method of this invention, when performing enhanced removal of pollutants, the water to be treated is circulated in the biological activated carbon slow filter using a bottom-in, top-out method. Water is introduced through a metering pump, and the influent flow rate is controlled by the metering pump, thereby controlling the hydraulic retention time of the entire biological activated carbon slow filter system.

[0011] In the method of this invention, the bio-activated carbon filter material is coconut shell activated carbon; The biological activated carbon filter media has a particle size of 3-5 mm and a specific surface area of ​​800-1000 m². 2 / g.

[0012] In the method of the present invention, the thickness of the biological activated carbon filter media has a significant impact on the effluent quality of the treated water body, preferably 5~15cm.

[0013] The method of this invention is applicable not only to biological activated carbon but also to ordinary quartz sand filters, but the effect of quartz sand filters is not significantly better than that of activated carbon filters.

[0014] The present invention has the following beneficial technical effects: (1) This invention is the first to adopt a method to improve the effluent quality of a slow-speed biological activated carbon filter by inoculating specific microorganisms. By introducing functional microorganisms with strong specificity and high metabolic capacity, the biodegradation and removal efficiency of recalcitrant organic matter (natural organic matter) is improved, thereby improving the effluent quality.

[0015] (2) Compared with the traditional biological activated carbon slow filter system, the total organic carbon concentration in the effluent of the method of the present invention is reduced by 57%~76% and the formation potential of disinfection byproducts is reduced by 43%~96% compared with the control group. After 200 days of continuous operation, the operating effect is stable. No additional chemical reagents are required. The operation is simple and saves operating costs and human resources. It is a green and sustainable water treatment technology.

[0016] (3) The specific microbial agents selected in this invention are not only applicable to biological activated carbon, but also to ordinary quartz sand filters. However, the effect of quartz sand filters is not significantly better than that of activated carbon filters.

[0017] (4) The specific microorganisms used for inoculation in this invention are not single bacteria but mixed microbial communities with synergistic metabolic effects. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the biological activated carbon system used in Example 1 of the present invention and other comparative examples, including a schematic diagram of the specific microbial inoculation process and a schematic diagram of the operation overview of other control groups.

[0019] Figure 2The total soluble organic matter removal rate of the effluent obtained by the method of Example 1 and other comparative examples is shown in Figure BD, which represents a biological activated carbon slow filter containing activated carbon packing. In Figure B, activated carbon filter media with a height of 5 cm is included; in Figure C, activated carbon filter media with a height of 10 cm is included; and in Figure D, activated carbon filter media with a height of 15 cm is included.

[0020] Figure 3 This is a graph showing the concentration changes of disinfection byproduct precursors in raw water and effluent from different filter beds in Example 1 and other comparative examples of the present invention.

[0021] Figure 4 The figures show a comparison of the microbial community structure attached to the surface of the filter media inside the filter tanks of Example 1 and other comparative examples. Figure a shows the microbial community structure in the control group (i.e., the comparative example), and Figure b shows the microbial community structure in the example.

[0022] Figure 5 Diagram of the specific microbial community structure inoculated into a biological activated carbon filter. Detailed Implementation

[0023] Example 1: Improving the effluent quality of a biological activated carbon slow filter through specific microbial inoculation The biological activated carbon system used in this embodiment consists of a filter tank, a metering pump, biological activated carbon filter media, and specific microorganisms, as shown in the schematic diagram. Figure 1 As shown, the specific steps are as follows: (1) The biological activated carbon slow filter is equipped with a lower inlet and an upper outlet (an organic glass cylinder with a diameter of 50 mm and a height of 500 mm).

[0024] (2) Gradually fill the biological activated carbon slow filter with granular activated carbon (in this embodiment, coconut shell granular activated carbon with a diameter of 3~5 mm and a specific surface area of ​​800~1000 m²) 2 / g), the filling height was based on the control group and different implementation groups, which were 0cm (system A), 5cm (system B), 10cm (system C) and 15cm (system D), respectively. The pore water volume inside the slow filter was approximately 300mL.

[0025] (3) The filter inlet is connected to the water sample tank to be treated, and then connected to the lower inlet of the filter via a metering pump for continuous water intake.

[0026] (4) Inoculation with specific microorganisms: such as Figure 1 As shown in the schematic diagram of the inoculation mode in Figure b, a certain amount of specific microbial stock solution (including Proteobacteria with an abundance of 32.6%) is inoculated. Proteobacteria Actinobacteria with an abundance of 13.02% Actinobacteriota Acidic bacteria with an abundance of 11.56% AcidobacteriotaFirmicutes with an abundance of 10.11%. Firmicutes Wait, see details Figure 5 The sample is dispersed into 1L of water to be treated and circulated into the filter column by a metering pump. The residence time is 12h and the circulation time is 48h.

[0027] The specific inoculated microorganisms in this embodiment were obtained through cultivation and enrichment using a specific method, as follows: Natural riverbed sediment samples were selected, and contamination was minimized. Samples were transferred to the laboratory using sterile tools. The sediment samples were then stored at low temperature, and large impurities were removed by sieving. A diluted natural soil leachate (natural soil to sterile pure water weight ratio 1:100, extracted by constant temperature shaking, followed by centrifugation to collect the supernatant) was used as the culture medium to cultivate sediment microorganisms (1:100). The cultivation process was conducted in sterile culture bottles, protected from light, and at a constant temperature (25 ± 2 ℃) with shaking. The cultivation period was 5 days, and the microbial concentration in the culture medium reached 10-1. 9 -10 11 CFU / mL; the cultured bacterial solution was centrifuged using a high-speed centrifuge to collect the cell pellet; the collected cell pellet was then washed in sterile buffer (phosphate buffer) to remove residual culture medium; the washed cells were resuspended in a small amount of buffer to prepare a concentrated bacterial suspension; the concentrated bacterial suspension was rapidly frozen (-80°C or lower) by pre-freezing, and then the frozen bacterial suspension was placed in a vacuum freeze dryer to sublimate and remove water, obtaining powdered bacterial culture.

[0028] Inflow rate = Filter pore water volume / retention time = 300 mL / 12 h = 25 mL / h.

[0029] The test water body was a natural river in Beijing. The raw water had a total organic carbon (TOC) of 4.51–7.62 mg / L, a conductivity of 722.9–860 μS / cm, a pH of 7.54–8.23, and a temperature of 22±2℃. The raw water was filtered through gauze to remove sediment, stored in a storage tank, and then supplied to a biological activated carbon slow filter system.

[0030] (5) Actual operation: The test water is placed in the water storage tank and the test water is introduced into the biological activated carbon slow filter system through the metering pump in the bottom-in and top-out mode, with a residence time of 20h.

[0031] Inlet flow rate = water volume treated / retention time = 300 mL / 20 h = 15 mL / h.

[0032] Comparative Example 1 Similar to Example 1, except that the treatment system does not contain the specific microorganisms for inoculation.

[0033] Example of effect 1 The experimental water was continuously treated using the methods of Example 1 and Comparative Example 1 for 200 days, and the results are shown in [Figure 1]. Figure 2 .

[0034] Figure 2 Figure A shows the removal rate of total soluble organic matter in the effluent after 200 days of continuous operation of quartz sand filter media. Figures B and D show the slow-flow biological activated carbon filter containing activated carbon packing. In Figure B, activated carbon packing is 5 cm high; in Figure C, it is 10 cm high; and in Figure D, it is 15 cm high. *** (p<0.001) and ** (p<0.01) indicate a significant difference between the two groups according to the Kruskal-Wallis test, while NS indicates no significant difference (p>0.05) according to the Kruskal-Wallis test.

[0035] from Figure 2 As can be seen from the Kruskal-Wallis test results, after inoculation with specific microorganisms, the removal rate of soluble natural organic matter in the bio-activated carbon slow filter was significantly improved, indicating that the inoculated specific microbial population can significantly promote the degradation of soluble natural organic matter.

[0036] The TOC content of the effluent from Example 1 (experimental group) and Comparative Example 1 (control group), as well as the raw water used in this invention, was determined. NaClO solution (the concentration of NaClO was three times the concentration of TOC) was added based on the TOC content, and the process was simulated by chlorination disinfection in a waterworks for 72 hours in the dark. The precursors of disinfection byproducts in the raw water and effluent were measured. The results are shown in […]. Figure 3 .

[0037] from Figure 3 As can be seen, specific microbial inoculation significantly reduced the total disinfection byproduct precursors in the effluent of the biological activated carbon slow filtration system.

[0038] After continuous operation (200 days later), the activated carbon inside Example 1 (experimental group) and Comparative Example 1 (control group) was removed, and the microbial community structure within the biofilm on their surface was measured. The results are as follows: Figure 4 .

[0039] from Figure 4 As can be seen from the data, the slow-speed biological activated carbon filter after inoculation with specific microbial populations ( Figure 4 Figure b) and a slow-flowing bio-activated carbon filter without specific microorganisms (Figure b) Figure 4 The microbial community structure of the biofilm on the surface of bioactivated carbon (Figure a) shows significant differences. Among them, the phylum Phyllostachys (Phyllostachys) is the most prominent. Acidobacteriota ) and Phylum Chlorofexi The abundance of the two components was increased by 2.37 times and 4.31 times, respectively, compared to the control group (system D).

[0040] from Figures 2-3 As can be seen, the method of this invention (specific microbial inoculation) can enhance the degradation and removal capacity of microorganisms for organic pollutants, thereby promoting the reduction of soluble organic carbon in the effluent of the slow filter. Compared with the traditional biological activated carbon system without inoculation, the method of this invention reduces the total organic carbon concentration in the effluent by 57%~76% and the formation potential of disinfection byproducts by 43%~96%. After 200 days of continuous operation, the operating effect remained stable. The biofilm formed by the added specific microbial agent effectively resisted the invasion of miscellaneous bacteria flowing in with the water during long-term operation, ensuring the dominant position of the functional microbial community. No additional chemical reagents are required during the process, making the operation simple and saving operating costs and human resources. It is a green and sustainable water treatment technology.

[0041] Comparative Example 2 Similar to Example 1, except that the biological slow filter does not contain activated carbon, and all packing materials are traditional quartz sand. Figure 1-4 System A in the middle.

[0042] Inlet flow rate = water volume treated / retention time = 300 mL / 20 h = 15 mL / h.

[0043] from Figure 2 and Figure 3 It can be seen that, for quartz sand filters, inoculation with specific microorganisms can promote the reduction of soluble organic matter and total disinfection byproducts in the effluent of the biofilter. However, in terms of the removal of soluble organic matter, from a statistical point of view, it can be seen that the effect of specific microorganism inoculation on quartz sand filters is not significantly greater than that on activated carbon filters (p>0.05).

[0044] Comparative Example 3 Similar to Example 1, except that the thickness of the activated carbon packing in the biological slow filter is changed, decreasing from 15 cm (System D) to 10 cm (System C) and 5 cm (System B).

[0045] Inlet flow rate = water volume treated / retention time = 300 mL / 20 h = 15 mL / h.

[0046] from Figure 2 and Figure 3 It can be seen that when the height of the activated carbon packing is reduced from 15 cm to 10 cm, and then to 5 cm, the DOC removal rate of the biological slow filter gradually decreases. This indicates that in the biological activated carbon slow filter system of the present invention, the thickness of the biological activated carbon filter layer will have a significant impact on the effluent quality of the treated water. In this embodiment, 15 cm is preferred.

[0047] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for improving the effluent water quality of a biological activated carbon slow filter, comprising the step of passing the water body to be treated into a biological activated carbon slow filter inoculated with specific microorganisms for enhanced removal of pollutants.

2. The method of claim 1, wherein: The biological activated carbon slow filter is filled with biological activated carbon filter material; The bioactive carbon filter material is inoculated with a mixed flora with synergistic metabolism, including bacteria of phylum Proteobacteria with an abundance of 32.6% Proteobacteria , bacteria of phylum Actinobacteria with an abundance of 13.02% Actinobacteriota , bacteria of phylum Acidobacteria with an abundance of 11.56% Acidobacteriota , and bacteria of phylum Firmicutes with an abundance of 10.11% Firmicutes .

3. The method according to claim 1 or 2, characterized in that: The inoculation of the mixed flora is carried out as follows: The bacterial solution containing the mixed flora is mixed with the water body to be treated to obtain a mixed water body, which is then added to the biological activated carbon slow filter; the mixed water body is circulated in the biological activated carbon slow filter for inoculation.

4. The method of claim 3, wherein: The mixed water body is circulated in the biological activated carbon slow filter in a top-down manner.

5. The method according to any one of claims 1-4, characterized by: When performing enhanced removal of pollutants, the water body to be treated is circulated in the biological activated carbon slow filter in a top-down manner.

6. The method of any one of claims 1-5, wherein: The biological activated carbon filter material is coconut activated carbon.

7. The method according to any one of claims 1-6, characterized by: The biological activated carbon filter material has a particle size of 3-5 mm, a specific surface area of 800-1000 m 2 / g.

8. The method according to any one of claims 1-7, characterized by: In the biological activated carbon slow filter, the biological activated carbon filter material is laid in a thickness of 5-15 cm.

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