A bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping

Abstract

The present invention discloses a method for bio-enhanced treatment of high-concentration wastewater from eucalyptus chemical mechanical pulp, and belongs to the technical field of treatment of high-concentration wastewater from toxic chemical mechanical pulp. The present invention takes high-concentration wastewater from eucalyptus chemical mechanical pulp as the treatment object, improves the biodegradability of the wastewater through biological detoxification treatment, performs low-oxygen treatment after anaerobic treatment, utilizes low dissolved oxygen conditions to degrade organic pollutants, and performs aerobic bio-enhanced treatment and deep treatment through a short process, thereby improving the removal rate of chemical oxygen demand. The present invention sets a biological detoxification pool before anaerobic treatment, screens and domesticates toxic-resistant microbial flora, so as to treat the difficult-to-degrade organic matter and antibacterial components in the eucalyptus chemical mechanical pulp wastewater, remove the toxicity in the wastewater, and improve its biodegradability, thereby optimizing the efficiency of subsequent biological treatment; compared with traditional long-term aerobic treatment, the treatment method of the present invention can remove most of the pollutants with lower energy consumption, effectively reducing the energy consumption in the aerobic treatment process.

Description

Technical Field

[0001] The invention belongs to the technical field of toxic chemical mechanical pulp high-concentration wastewater treatment, and more specifically relates to a bio-enhanced treatment method for eucalyptus chemical mechanical pulp high-concentration wastewater. Background Art

[0002] Eucalyptus chemimechanical pulp (CMP) is one of the main pulp types being developed by pulp mills both domestically and internationally. The wastewater from this pulp production is characterized by high color, high chemical oxygen demand (COD) concentration, and high temperature, making conventional aerobic treatment inefficient. Research indicates that eucalyptus is rich in oxygenated monoterpenoids, such as eucalyptol, which significantly impact the metabolic activity of algae and environmental microorganisms in the water. The inventors analyzed the effluent composition of anaerobic and aerobic treatments of eucalyptus CMP wastewater. The effluent from anaerobic treatment primarily contained organic alcohols, aromatic esters, and hydrocarbons, with the main components being linalool, citronellol, methyl 4-tert-butylphenylacetate, diethyl phthalate, and D-limonene. The effluent from aerobic treatment primarily contained organic alcohols, aromatic esters, aldehydes, and hydrocarbons, with the main components being linalool, methyl 4-tert-butylphenylacetate, dihydromyrcenol, lilysinal, tert-butylcyclohexanol, benzyl alcohol, and citronellol. The residual organic matter after aerobic treatment was mainly aromatic compounds and antibacterial components, showing a certain degree of biodegradability.

[0003] Currently, the mainstream process for treating pulp and paper wastewater includes initial sedimentation, hydrolysis, anaerobic treatment, aerobic treatment, Fenton reaction, and final discharge. When treating eucalyptus chemi-mechanical pulping wastewater, COD becomes the primary limiting pollution indicator. For a 200,000-ton annual eucalyptus chemi-mechanical pulping project, for example, during the initial sedimentation stage, the effluent COD concentration fluctuated between 6,500 mg / L and 8,100 mg / L, with an average of 7,279 mg / L. After anaerobic treatment, the effluent COD concentration fluctuated between 2,900 mg / L and 3,350 mg / L, with an average of 3,101 mg / L, and an average COD removal efficiency of 57.4%. After aerobic treatment, the effluent COD concentration fluctuated between 1,550 mg / L and 1,950 mg / L, with an average of 1,776 mg / L, and an average COD removal efficiency of 42.7%. In order to reduce the COD concentration from approximately 1176 mg / L to below the emission standard of 50 mg / L, subsequent deep treatment faces huge challenges. It is not only technically difficult but also costly. In actual operation, two-stage Fenton treatment is usually used. The first stage treatment reduces the COD to about 300 mg / L, and the second stage treatment further reduces the COD to 40 mg / L to 50 mg / L. The cost of Fenton treatment is approximately 8 yuan / m³ to 11 yuan / m³. When domestic pulp mills use tree species such as eucalyptus or acacia for pulping, especially when using fresh wood chips less than 3 months old, wastewater treatment generally faces the problem of low biological treatment efficiency. This increases the burden of subsequent deep treatment and leads to high environmental protection costs.

[0004] Currently, improvements in the treatment of eucalyptus chemical-mechanical pulping wastewater are primarily focused on catalytic oxidation. Photocatalytic oxidation detoxifies the wastewater, improves aerobic treatment efficiency, and reduces the use of Fenton reagents during advanced treatment. However, there are currently no published reports on the combined use of biological detoxification, low-oxygen decarbonization, and aerobic enhancement processes to treat eucalyptus chemical-mechanical pulping wastewater. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping, which can effectively improve the removal rate of chemical oxygen demand and significantly reduce the energy consumption and cost during the treatment process.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for bio-enhanced treatment of high-concentration eucalyptus chemi-mechanical pulp wastewater is disclosed. The method uses the high-concentration eucalyptus chemi-mechanical pulp wastewater as the treatment object, improves the biodegradability of the high-concentration eucalyptus chemi-mechanical pulp wastewater through biological detoxification treatment, performs low-oxygen treatment after anaerobic treatment, utilizes low dissolved oxygen conditions to degrade organic pollutants, and performs aerobic bio-enhanced treatment and deep treatment through a short process, thereby improving the removal rate of chemical oxygen demand; wherein the concentration of low dissolved oxygen is 0.3-1.0 mg / L.

[0008] The biological detoxification process is as follows: the supernatant after treatment in the primary sedimentation tank is passed into the biological detoxification tank, microorganisms and activated sludge are inoculated into the biological detoxification tank, polysaccharides, vitamins and enzyme active substances are added, and toxic-resistant microorganisms are screened and domesticated.

[0009] Preferably, the microorganism is selected from any one or more of Delftia microorganisms and Clostridium microorganisms, the polysaccharide is glucan, the vitamins are vitamin B complex and vitamin E, and the enzyme is one or two of lyase, isomerase and lipase with a single enzyme activity of more than 1000 U / mg.

[0010] Preferably, the amount of Delftia microorganism added is 100 mg / L, the amount of Clostridium microorganism added is 100 mg / L, the amount of glucan added is no more than 20 mg / L, the amount of vitamin B complex added is no more than 5 mg / L, the amount of vitamin E added is no more than 1 mg / L, and the amount of enzyme added is 3-10 mg / L.

[0011] Preferably, the Delftia species is Thauera linaloolentis 47LolT, and the Clostridium species is Clostridium acetobutylicum, which together with the domesticated activated sludge form a mixed microbial community comprising a variety of yeasts, bacteria and other microorganisms. The multiple microorganisms work together to transform and degrade antibacterial components such as linalool.

[0012] The bio-augmented treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping comprises the following steps:

[0013] 1) After fiber recovery treatment, the eucalyptus chemical-mechanical pulping wastewater undergoes solid-liquid separation in a primary sedimentation tank. The supernatant from the primary sedimentation tank is introduced into a biological detoxification tank, where microorganisms and activated sludge are inoculated, and polysaccharides, vitamins, and enzyme-active substances are added to screen and domesticate toxic-resistant microorganisms, thereby improving the biodegradability of the wastewater. The sludge generated in the primary sedimentation tank and the biological detoxification tank is discharged into a sludge thickening tank for subsequent sludge disposal.

[0014] 2) The biologically detoxified wastewater undergoes conventional anaerobic treatment and is introduced into a hypoxic treatment tank. Ammonium gluconate and diammonium hydrogen phosphate are added to the hypoxic treatment tank at a COD, N, and P mass ratio of 200-300:5:1, respectively, to reduce the concentration of pollutants in the water under hypoxic conditions. The wastewater after hypoxic treatment enters a secondary sedimentation tank, where the effluent from the secondary sedimentation tank is returned to adjust the pH value, dissolved oxygen concentration, and toxic substance concentration of the hypoxic tank. The sludge produced in the secondary sedimentation tank is sent to a sludge thickening tank for further treatment.

[0015] 3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank, where biologically active carrier materials are added to promote the enrichment of microorganisms and pollutants; the wastewater after aerobic treatment enters the tertiary sedimentation tank for treatment, and the collected sludge enters the sludge thickening tank;

[0016] 4) The wastewater after treatment in the three sedimentation tanks enters the deep treatment tank, and is treated with Fenton oxidation coagulation treatment using deep treatment agents. The wastewater after deep treatment is introduced into the final sedimentation tank for treatment. After the solid-liquid separation step, the obtained supernatant is discharged in compliance with the standards, and the separated sludge is sent to the sludge thickening tank for treatment. After the sludge plate and frame dehydration treatment, the sludge is transported out.

[0017] Preferably, in step 1), the operating process parameters of the biological detoxification treatment tank are: water temperature 20-40°C, pH 5-9, dissolved oxygen not more than 0.5 mg / L, activated sludge concentration 10-20 g / L, hydraulic retention time 6-8 h, an independent sludge return system is used for operation, and the remaining sludge is discharged into the sludge thickening tank for subsequent treatment.

[0018] Preferably, in step 2), the operating process parameters of the hypoxic treatment tank are: water temperature 15-40°C, pH 5-9, dissolved oxygen 0.3-1 mg / L, activated sludge concentration 8-15 g / L, and hydraulic retention time 24-36 h.

[0019] Preferably, in step 2), the preparation process of the bioactive carrier material is: loading specialized microorganisms and growth factors on the surface active groups of the carrier by chemical bonding or forming a biofilm to obtain the bioactive carrier material; the carrier is selected from any one or more of diatomaceous earth, biochar, bentonite and activated coke.

[0020] Preferably, the carrier particle size is not less than 100 mesh; the obligate microorganisms are selected from any two or more of white rot fungi, Nocardia, Flavobacterium and Bacillus that degrade lignin, and the loading amount of the obligate microorganisms is not less than 10 billion / g; the growth factor is selected from any one or more of B vitamins, vitamin C or coenzyme R, and the loading amount of the growth factor is 0.01 mg to 0.1 mg / g.

[0021] Preferably, in step 3), the operating process parameters of the aerobic treatment tank are: water temperature 15-40°C, pH 6-9, dissolved oxygen 2-4 mg / L, activated sludge concentration 8-15 g / L, hydraulic retention time 12h-24h, and the dosage of biologically active carrier material 30-60 mg / L.

[0022] Preferably, in step 4), the Fenton treatment process conditions are: reaction pH 3-3.5, reaction time 30 min, FeSO4·7H2O dosage 2.25 g / L, H2O2 (27.5%) dosage 1.3 g / L.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) This invention uses a biological detoxification tank before anaerobic treatment to screen and domesticate toxic-resistant microbial communities to treat refractory organic matter and antibacterial components (such as terpenes like linalool) in eucalyptus chemical-mechanical pulping wastewater, removing toxicity while improving its biodegradability, thereby optimizing the efficiency of subsequent biological treatment.

[0025] 2) This invention uses a low-oxygen treatment method (i.e., a low dissolved oxygen environment with a concentration between 0.3-1.0 mg / L) to degrade carbonaceous pollutants in water. By precisely controlling the dissolved oxygen level in the low-oxygen tank, the metabolic activity of microorganisms can be further optimized, ensuring efficient removal of pollutants. Compared with traditional long-term aerobic treatment, the treatment method of this invention can remove most pollutants with lower energy consumption, effectively reducing energy consumption during the aerobic treatment process.

[0026] 3) The present invention introduces bioactive carrier materials during the aerobic stage, which can significantly promote the synergistic interaction between microorganisms and pollutants, effectively improving the mass transfer efficiency during the degradation process. This allows the ideal treatment effect to be achieved in a relatively short time, thereby significantly shortening the time required for aerobic treatment.

[0027] 4) The present invention uses independent sludge systems in both the biological detoxification tank and the hypoxic treatment tank, which helps to form a stable and efficient microbial community, thereby more efficiently treating organic pollutants in wastewater. In addition, the hypoxic treatment tank is set between the anaerobic treatment tank and the aerobic treatment tank, which can achieve a smooth transition of environmental conditions in different treatment stages, reduce the shock load during the treatment process, and ensure the stable operation of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the treatment process flow of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with specific examples. In the following examples, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art. In the examples, if specific conditions are not specified, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased commercially.

[0030] The determination method in the embodiment refers to the following content:

[0031] COD was tested using the potassium dichromate method (HJ828-2017); pH was determined using the glass electrode method (GB / T6920-1986).

[0032] The fresh eucalyptus chemical mechanical pulp high-concentration wastewater used in the following examples was taken from the effluent of the primary sedimentation tank of a wastewater treatment plant of a large pulp and paper enterprise. The main water quality indicators were: COD 7055 mg / L, BOD 1832 mg / L, pH 7.08, and SS 642 mg / L.

[0033] In the following examples, the Delftia species is Thauera linaloolentis 47LolT, and the Clostridium species is Clostridium acetobutylicum. These species, together with the domesticated activated sludge, form a mixed microbial community comprising a variety of yeasts, bacteria, and other microorganisms. These multiple microorganisms work together to transform and degrade antibacterial components such as linalool.

[0034] Example 1

[0035] A bio-enhanced treatment process for high-concentration wastewater from eucalyptus chemical mechanical pulping, the process flow is as follows Figure 1 As shown, the following steps are included:

[0036] 1) High-concentration wastewater from eucalyptus chemical-mechanical pulp enters the accident pool, undergoes fiber recovery treatment, and then achieves solid-liquid separation in the primary sedimentation tank. The supernatant after treatment in the primary sedimentation tank is introduced into the biological detoxification tank, where it is inoculated with microorganisms and activated sludge from the plant's hydrolysis tank. Active substances such as polysaccharides, vitamins, and enzymes are added to screen and domesticate toxic-resistant microorganisms using actual wastewater. Through biological detoxification, the inhibitory effect of wastewater on subsequent microorganisms is reduced, thereby improving the biodegradability of the wastewater. The sludge generated in the primary sedimentation tank and biological detoxification tank is discharged into the sludge thickening tank for subsequent sludge disposal.

[0037] 2) The biologically detoxified wastewater undergoes conventional anaerobic treatment and is introduced into a hypoxic treatment tank. Ammonium gluconate and diammonium hydrogen phosphate are added to the hypoxic treatment tank at a COD, N, and P mass ratio of 200-300:5:1, respectively, to reduce the concentration of pollutants in the water under hypoxic conditions. The wastewater after hypoxic treatment enters a secondary sedimentation tank, where the effluent from the secondary sedimentation tank is returned to adjust the pH value, dissolved oxygen concentration, and toxic substance concentration of the hypoxic tank. The sludge produced in the secondary sedimentation tank is sent to a sludge thickening tank for further treatment.

[0038] 3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank. The addition of biologically active carrier materials to the aerobic treatment tank promotes the enrichment of microorganisms and pollutants, improves mass transfer efficiency, significantly enhances the treatment effect, and reduces the concentrations of indicators such as COD, ammonia nitrogen and color in the effluent. The wastewater after aerobic treatment enters the tertiary sedimentation tank for further removal of suspended matter and solid particles to improve the clarity of the wastewater. The collected sludge enters the sludge thickening tank.

[0039] 4) After treatment in the three sedimentation tanks, the wastewater enters the advanced treatment tank and undergoes Fenton oxidation coagulation treatment using advanced treatment agents. The Fenton treatment process conditions are: reaction pH 3.0-3.5, reaction time 30 minutes, FeSO4·7H2O dosage 2.25g / L, H2O2 (27.5%) dosage 1.3g / L. The advanced treated wastewater is introduced into the final sedimentation tank for treatment. After the solid-liquid separation step, the resulting supernatant meets the discharge requirements of GB3544-2008. The separated sludge is sent to the sludge thickening tank for treatment. After treatment in the sludge plate and frame dewatering room, the sludge is transported out.

[0040] The bio-augmented treatment methods for high-consistency eucalyptus chemi-mechanical pulping wastewater in the following Examples 2-4 are all carried out within the treatment process flow of this Example.

[0041] Example 2

[0042] A bio-augmented treatment method for high-concentration wastewater from eucalyptus chemi-mechanical pulping comprises the following steps:

[0043] (1) The supernatant after the primary sedimentation tank treatment was introduced into the biological detoxification tank. The operating process parameters of the biological detoxification tank were as follows: water temperature 35℃, pH 6.5-7.0, dissolved oxygen (DO) ≤ 0.2 mg / L, activated sludge concentration (MLSS) 15 g / L, hydraulic retention time (HRT) 6 h. Thauera linaloolentis 47LolT bacteria 100 mg / L, glucan 10 mg / L, vitamin B complex 1 mg / L, vitamin E 0.2 mg / L, and lyase and lipase with single enzyme activity above 1000 U / mg were added to the biological detoxification tank to screen and domesticate toxic-resistant microorganisms. The remaining sludge was discharged into the sludge thickening tank for subsequent sludge disposal.

[0044] (2) After biological detoxification, the wastewater enters the hypoxic treatment stage after 18 hours of anaerobic treatment. The anaerobic operation process parameters are: water temperature 35-37℃, pH 6.5-7.5, organic load 6-7kgCOD / m³・d, sludge concentration (MLSS) 30-35 g / L; the operation process parameters of the hypoxic treatment tank are: water temperature 30-35℃, pH 6.5-8.0, dissolved oxygen (DO) 0.3-0.5 mg / L, activated sludge concentration (MLSS) 10 g / L, hydraulic retention time (HRT) 24h. Ammonium gluconate and diammonium hydrogen phosphate are added to the hypoxic treatment tank at a mass ratio of COD, N and P of 300:5:1, respectively, to degrade pollutants in the water under hypoxic conditions.

[0045] (3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are: water temperature 30-35℃, pH 7.0-8.0, dissolved oxygen (DO) 2.0-3.0 mg / L, activated sludge concentration (MLSS) 8 g / L, hydraulic retention time (HRT) 12 h; 50 mg / L of biologically active carrier material (diatomaceous earth and biochar mixed in a ratio of 1:1) is added to the aerobic treatment tank. The surface active groups of the carrier load specialized microorganisms and growth factors by forming a biofilm; the specialized microorganisms mainly include: white rot fungi that degrade lignin, with a loading of 10 billion / g; the growth factors mainly include: B vitamins, vitamin C and coenzyme R, with a loading of 0.1 mg / g;

[0046] (4) The wastewater after aerobic treatment is treated in three sedimentation tanks, deep treatment tanks and final sedimentation tanks. The supernatant liquid meets the discharge requirements of GB3544-2008 standard. The separated sludge is sent to the sludge thickening tank for treatment. After being treated in the sludge plate and frame dewatering room, the sludge is transported out.

[0047] The inlet and outlet water results of the biological detoxification tank, anaerobic treatment tank, hypoxic treatment tank, aerobic treatment tank, and deep treatment tank operation sections of Example 2 are shown in Tables 1 and 2 below.

[0048] Table 1 Water inlet and outlet results of the operation section of Example 2

[0049]

[0050] Table 2 Pollutant treatment results of the operation section of Example 2

[0051]

[0052] Example 3

[0053] A bio-augmented treatment method for high-concentration wastewater from eucalyptus chemi-mechanical pulping comprises the following steps:

[0054] (1) The supernatant after the primary sedimentation tank treatment is introduced into the biological detoxification tank. The operating process parameters of the biological detoxification tank are as follows: water temperature 25-30℃, pH 6.5-7.0, dissolved oxygen (DO) ≤ 0.5 mg / L, activated sludge concentration (MLSS) 20 g / L, hydraulic retention time (HRT) 8h; 100 mg / L of Clostridium acetobutylicum, 15 mg / L of glucan, 2 mg / L of vitamin B complex, 0.5 mg / L of vitamin E and 5 mg / L of lyase with a single enzyme activity of more than 1000 U / mg are added to the biological detoxification tank to screen and domesticate toxic-resistant microorganisms. The remaining sludge is discharged into the sludge thickening tank for subsequent sludge disposal.

[0055] (2) After biological detoxification, the wastewater enters the hypoxic treatment stage after 16 hours of anaerobic treatment. The anaerobic operation process parameters are: water temperature 35-37℃, pH 6.5-7.5, organic load 6-7kgCOD / m³・d, sludge concentration (MLSS) 30-35 g / L; the operation process parameters of the hypoxic treatment tank are: water temperature 25-30℃, pH 6.5-7.5, dissolved oxygen (DO) 0.5-0.8 mg / L, activated sludge concentration (MLSS) 12-15 g / L, hydraulic retention time (HRT) 24 hours. Ammonium gluconate and diammonium hydrogen phosphate are added to the hypoxic treatment tank at a mass ratio of COD, N and P of 300:5:1, respectively, to degrade pollutants in the water under hypoxic conditions.

[0056] (3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are: water temperature 25-30℃, pH 6.5-8.0, dissolved oxygen (DO) 2.0-4.0 mg / L, activated sludge concentration (MLSS) 10 g / L, hydraulic retention time (HRT) 8h; 80 mg / L of biologically active carrier material (diatomaceous earth and biochar mixed in a ratio of 1:1) is added to the aerobic treatment tank. The surface active groups of the carrier load specialized microorganisms and growth factors by forming a biofilm; the specialized microorganisms mainly include: Nocardia spp. that degrade lignin, with a loading of 10 billion / g; the growth factors mainly include: vitamin C and coenzyme R, with a loading of 0.05 mg / g;

[0057] (4) The wastewater after aerobic treatment is treated in three sedimentation tanks, deep treatment tanks and final sedimentation tanks. The supernatant liquid meets the discharge requirements of GB3544-2008 standard. The separated sludge is sent to the sludge thickening tank for treatment. After being treated in the sludge plate and frame dewatering room, the sludge is transported out.

[0058] The inlet and outlet water results of the biological detoxification tank, anaerobic treatment tank, hypoxic treatment tank, aerobic treatment tank, and deep treatment tank operation sections of Example 3 are shown in Tables 3 and 4 below.

[0059] Table 3 Water inlet and outlet results of the operation section of Example 3

[0060]

[0061] Table 4 Pollutant treatment results of the operation section of Example 3

[0062]

[0063] Example 4

[0064] A bio-augmented treatment method for high-concentration wastewater from eucalyptus chemi-mechanical pulping comprises the following steps:

[0065] (1) The supernatant after the primary sedimentation tank treatment was introduced into the biological detoxification tank. The operating process parameters of the biological detoxification tank were as follows: water temperature 35-40℃, pH 6.5-7.5, dissolved oxygen (DO) ≤ 0.3 mg / L, activated sludge concentration (MLSS) 20 g / L, hydraulic retention time (HRT) 6 h; Thauera linaloolentis 47LolT bacteria 100 mg / L and Clostridium acetobutylicum 100 mg / L were added to the biological detoxification tank; glucan 20 mg / L was added; vitamin B complex was added in an amount of 5 mg / L, vitamin E was added in an amount of 0.8 mg / L, and lyase and lipase with single enzyme activity above 1000 U / mg were added in an amount of 10 mg / L to screen and domesticate toxic-resistant microorganisms. The remaining sludge was discharged into the sludge thickening tank for subsequent sludge disposal;

[0066] (2) After biological detoxification, the wastewater enters the hypoxic treatment stage after 16 hours of anaerobic treatment. The anaerobic operation process parameters are: water temperature 35-37℃, pH 6.5-7.5, organic load 6-7kgCOD / m³・d, sludge concentration (MLSS) 30-35 g / L; the operation process parameters of the hypoxic treatment tank are: water temperature 20-40℃, pH 6.5-8.0, dissolved oxygen (DO) 0.5-1.0 mg / L, activated sludge concentration (MLSS) 15 g / L, hydraulic retention time (HRT) 24h. Ammonium gluconate and diammonium hydrogen phosphate are added to the hypoxic treatment tank at a mass ratio of COD, N and P of 200:5:1, respectively, to degrade pollutants in the water under hypoxic conditions.

[0067] (3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are: water temperature 20-40℃, pH 6.5-8.0, dissolved oxygen (DO) 2.0-4.0 mg / L, activated sludge concentration (MLSS) 8 g / L, hydraulic retention time (HRT) 8h; 100 mg / L of biologically active carrier material (diatomaceous earth and biochar mixed in a ratio of 1:1) is added to the aerobic treatment tank. The surface active groups of the carrier load specialized microorganisms and growth factors by forming a biofilm; the specialized microorganisms mainly include: white rot fungi and Nocardia that degrade lignin, with a loading of 15 billion / g; the growth factors mainly include: vitamin C and coenzyme R, with a loading of 0.08 mg / g;

[0068] (4) The wastewater after aerobic treatment is treated in three sedimentation tanks, deep treatment tanks and final sedimentation tanks. The supernatant liquid meets the discharge requirements of GB3544-2008 standard. The separated sludge is sent to the sludge thickening tank for treatment. After being treated in the sludge plate and frame dewatering room, the sludge is transported out.

[0069] The inlet and outlet water results of the biological detoxification tank, anaerobic treatment tank, hypoxic treatment tank, aerobic treatment tank, and deep treatment tank operation sections of Example 4 are shown in Tables 5 and 6 below.

[0070] Table 5 Water inlet and outlet results of the operation section of Example 4

[0071]

[0072] Table 6 Changes of main pollutants in each section of Example 4

[0073]

[0074] Comparative Example 1

[0075] A comparative experiment was conducted using a conventional anaerobic-aerobic-Fenton treatment process. The anaerobic process followed the same operating parameters as in Example 2, with a hydraulic retention time (HRT) of 24 hours. The aerobic process employed a conventional activated sludge process with the following operating parameters: water temperature 20-40°C, pH 6.5-8.0, dissolved oxygen (DO) 2.0-4.0 mg / L, activated sludge concentration (MLSS) 8 g / L, and a hydraulic retention time (HRT) of 36 hours. Fenton treatment conditions included a reaction pH of 3.0-3.5, a reaction time of 30 minutes, a dosage of 2.25 g / L of FeSO₄·7H₂O, and 1.3 g / L of H₂O (27.5%).

[0076] The inlet and outlet water results of the anaerobic treatment tank, aerobic treatment tank and deep treatment tank operation sections of Comparative Example 1 are shown in Tables 7 and 8 below.

[0077] Table 7 Inlet and outlet water results of the operation section of Comparative Example 1

[0078]

[0079] Table 8 Pollutant treatment results of the operation section of Comparative Example 1

[0080]

[0081] Example 5

[0082] A pilot test platform was used to measure the COD content of the effluent from each stage of the treatment process in Examples 2-4 and Comparative Example 1 to assess the treatment effectiveness. Detoxified sludge was collected from the pulp mill's hydrolysis tank, anaerobic granular sludge was collected from the IC tower, and hypoxic sludge and aerobic activated sludge were collected from the mill's aerobic tank. The results are shown in Table 9.

[0083] Table 9 COD removal effect of bio-augmented treatment of eucalyptus chemical-mechanical pulping wastewater

[0084]

[0085] As shown in Table 9, after biological detoxification treatment, the effluent COD removal rates in the anaerobic treatment stage of Examples 2 to 4 increased to 67.07%, 63.44%, and 71.47%, respectively, compared to 55.08% in the control group; in the aerobic treatment stage, the effluent COD removal rates also increased from 80.62% in the control group to 84.59%, 82.14%, and 87.03%, respectively. These data indicate that the efficiency of subsequent biological treatment, whether anaerobic or aerobic, has been improved to varying degrees. Biological detoxification treatment effectively degrades the biotoxicity in the wastewater and reduces the negative impact on subsequent biological treatment processes.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping, characterized in that: The following steps are involved: 1) After fiber recovery treatment, the eucalyptus chemical mechanical pulp wastewater is separated into solid and liquid in the primary sedimentation tank. The supernatant after treatment in the primary sedimentation tank is introduced into the biological detoxification tank. Microorganisms and activated sludge are inoculated in the biological detoxification tank. The microorganisms are selected from any one or more of Thauera linaloolentis 47LolT bacteria and Clostridium acetobutylicum. Glucan, complex vitamin B, vitamin E and enzyme active substances are added. The enzyme is one or two of lyase, isomerase and lipase with a single enzyme activity of more than 1000U / mg. Toxin-resistant microorganisms are screened and domesticated to improve the biodegradability of the wastewater. The sludge produced in the primary sedimentation tank and the biological detoxification tank is discharged into the sludge thickening tank for subsequent sludge disposal. 2) The wastewater after biological detoxification is subjected to conventional anaerobic treatment. The wastewater after anaerobic treatment is introduced into the low oxygen treatment tank. According to the mass ratio of COD, N and P of 200~300:5:1, ammonium gluconate and diammonium hydrogen phosphate are added to the low oxygen treatment tank respectively to reduce the concentration of pollutants in the water under low oxygen conditions; the wastewater after low oxygen treatment enters the secondary sedimentation tank, and the pH value, dissolved oxygen concentration and toxic substance concentration of the low oxygen tank are adjusted by the effluent return of the secondary sedimentation tank. The sludge produced in the secondary sedimentation tank is sent to the sludge thickening tank for further treatment; 3) The wastewater after treatment in the secondary sedimentation tank enters the aerobic treatment tank, and biologically active carrier materials are added to the aerobic treatment tank to promote the enrichment of microorganisms and pollutants; The wastewater after aerobic treatment enters the three sedimentation tanks for treatment, and the collected sludge enters the sludge thickening tank; 4) The wastewater treated in the three sedimentation tanks enters the deep treatment tank, where it is treated with Fenton oxidation coagulation treatment using deep treatment agents. The wastewater after deep treatment is introduced into the final sedimentation tank for treatment. After the solid-liquid separation step, the resulting supernatant is discharged in compliance with the standards, and the separated sludge is sent to the sludge thickening tank for treatment. After the sludge plate and frame dehydration treatment, the sludge is transported out.

2. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1 is characterized in that: In the step 1), when the microorganism is Thauera linaloolentis 47LolT, the addition amount of Thauera linaloolentis 47LolT is 100 mg / L, and 10 mg / L of glucan, 1 mg / L of vitamin B complex, 0.2 mg / L of vitamin E, and 3 mg / L of lyase and lipase with single enzyme activity above 1000 U / mg are added.

3. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1, characterized in that: In the step 1), when the microorganism is Clostridium acetobutylicum, the amount of Clostridium acetobutylicum added is 100 mg / L, and 15 mg / L of dextran, 2 mg / L of vitamin B complex, 0.5 mg / L of vitamin E, and 5 mg / L of lyase with a single enzyme activity of more than 1000 U / mg are added.

4. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1, characterized in that: In the step 1), when the microorganisms are Thauera linaloolentis 47LolT and Clostridium acetobutylicum, the addition amount of Thauera linaloolentis 47LolT is 100 mg / L, the addition amount of Clostridium acetobutylicum is 100 mg / L, and 20 mg / L of dextran, 5 mg / L of vitamin B complex, 0.8 mg / L of vitamin E, and 10 mg / L of lyase and lipase with single enzyme activity above 1000 U / mg are added.

5. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1, characterized in that: In the step 1), the operating process parameters of the biological detoxification treatment tank are: water temperature 20-40°C, pH 5-9, dissolved oxygen not more than 0.5 mg / L, activated sludge concentration 10-20 g / L, hydraulic retention time 6-8 hours, an independent sludge return system is used for operation, and the remaining sludge is discharged into the sludge thickening tank for subsequent treatment.

6. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 1, characterized in that: In the step 2), the operating process parameters of the hypoxic treatment tank are: water temperature 15-40°C, pH 5-9, dissolved oxygen 0.3-1 mg / L, activated sludge concentration 8-15 g / L, and hydraulic retention time 24-36 h.

7. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1, characterized in that: In the step 2), the preparation process of the bioactive carrier material is as follows: loading specific microorganisms and growth factors on the active groups on the surface of the carrier by chemical bonding or forming a biofilm to obtain the bioactive carrier material; the carrier is selected from any one or more of diatomaceous earth, biochar, bentonite and activated coke.

8. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 7, characterized in that: The carrier particle size is not less than 100 meshes; the dedicated microorganisms are selected from any two or more of white rot fungi, Nocardia, Flavobacterium and Bacillus that degrade lignin, and the loading amount of the dedicated microorganisms is not less than 10 billion / g; the growth factors are selected from any one or more of B vitamins, vitamin C or coenzyme R, and the loading amount of the growth factors is 0.01 mg to 0.1 mg / g.

9. The bio-augmented treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 1, characterized in that: In step 3), the operating process parameters of the aerobic treatment tank are: water temperature 15-40°C, pH 6-9, dissolved oxygen 2-4 mg / L, activated sludge concentration 8-15 g / L, hydraulic retention time 12h-24h, and the addition amount of biologically active carrier material 30-60 mg / L.

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