Biological enhancement treatment method of eucalyptus chemimechanical pulp high-concentration wastewater

Abstract

The invention discloses a biological enhancement treatment method for eucalyptus chemimechanical pulp high-concentration wastewater, and belongs to the technical field of toxic chemimechanical pulp high-concentration wastewater treatment. According to the method, the eucalyptus chemimechanical pulp high-concentration wastewater is taken as a treatment object, the biodegradability of the wastewater is improved through biological detoxification treatment, low-oxygen treatment is carried out after anaerobic treatment, organic pollutants are degraded under a low dissolved oxygen condition, and aerobic biological enhancement treatment and deep treatment are carried out through a short process, so that the removal rate of chemical oxygen demand is improved. According to the method disclosed by the invention, the biological detoxification tank is arranged before anaerobic treatment, and the toxicity-resistant microbial flora is screened and domesticated, so that refractory organic matters and antibacterial components in the eucalyptus chemithermomechanical pulp wastewater are treated, toxicity in the wastewater is removed, and the biodegradability of the wastewater is improved, so that the efficiency of subsequent biological treatment is optimized; compared with traditional long-time aerobic treatment, the treatment method disclosed by the invention has the advantages that most pollutants can be removed with lower energy consumption, and the energy consumption in the aerobic treatment process is effectively reduced.

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 chemical mechanical pulp is one of the main pulp types that pulp mills at home and abroad focus on developing. The production wastewater of this pulp type is characterized by high chroma, high chemical oxygen demand (COD) concentration and high temperature, and the efficiency of ordinary aerobic treatment is not high. Studies have shown that eucalyptus contains rich monoterpenoid oxygen-containing derivatives, such as eucalyptol, which have a significant impact on the metabolic activities of algae and environmental microorganisms in the water. The inventors analyzed and studied the effluent components of anaerobic treatment and aerobic treatment of eucalyptus chemical mechanical pulp (chemical mechanical pulp) wastewater. The anaerobic treatment effluent mainly contains organic alcohols, aromatic esters and hydrocarbons, among which the main substances are linalool, citronellol, methyl 4-tert-butylphenyl acetate, diethyl phthalate and D-limonene; the aerobic treatment effluent mainly contains organic alcohols, aromatic esters, aldehydes and hydrocarbons, among which the main substances are linalool, methyl 4-tert-butylphenyl acetate, dihydromyrcenol, lily of the valley aldehyde, tert-butyl cyclohexanol, 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] At present, the mainstream process flow of pulp and paper wastewater treatment includes preliminary sedimentation, hydrolysis, anaerobic treatment, aerobic treatment, Fenton reaction and final discharge. When treating eucalyptus chemical mechanical pulp wastewater, COD becomes the main restrictive pollution indicator. Taking the project with an annual output of 200,000 tons of eucalyptus chemical mechanical pulp as an example, in the primary sedimentation stage, the effluent COD concentration fluctuates between 6500mg / L and 8100mg / L, with an average of 7279mg / L. After anaerobic treatment, the effluent COD concentration fluctuates between 2900mg / L and 3350mg / L, with an average value of 3101mg / L, and an average COD removal rate of 57.4%. After aerobic treatment, the effluent COD concentration fluctuates between 1550mg / L and 1950mg / L, with an average of 1776mg / L, and an average COD removal rate of 42.7%. In order to reduce the COD concentration from about 1176mg / L to below the emission standard of 50mg / L, subsequent deep treatment faces huge challenges, which is not only technically difficult but also costly. In actual operation, two-stage Fenton treatment is usually used. The first-stage treatment reduces COD to about 300mg / L, and the second-stage treatment further reduces COD to 40mg / L to 50mg / L. The cost of Fenton treatment is about 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 within 3 months, wastewater treatment generally faces the problem of low biological treatment efficiency, which increases the burden of subsequent deep treatment and leads to high environmental protection costs.

[0004] At present, the improvement of eucalyptus chemical-mechanical pulping wastewater treatment is mainly focused on catalytic oxidation treatment technology, which achieves wastewater detoxification through photocatalytic oxidation, improves the aerobic treatment effect of eucalyptus chemical-mechanical pulping wastewater, and reduces the use of Fenton reagent in the deep treatment process. However, there is no relevant public report on the use of biological detoxification, low-oxygen decarbonization and aerobic enhancement process combination to synergistically 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 of eucalyptus chemical mechanical pulp, 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 solution adopted by the present invention is as follows:

[0007] A method for bio-enhanced treatment of eucalyptus chemical mechanical pulp high-concentration wastewater, taking eucalyptus chemical mechanical pulp high-concentration wastewater as the treatment object, improving the biodegradability of the eucalyptus chemical mechanical pulp high-concentration wastewater through biological detoxification treatment, performing low-oxygen treatment after anaerobic treatment, utilizing low dissolved oxygen conditions to degrade organic pollutants, and performing 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 0.3~1.0mg / 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 dextran, 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 is Thauera linaloolentis 47LolT, and the Clostridium is Clostridium acetobutylicum, which together with the domesticated activated sludge form a mixed microbial community including a variety of yeasts, bacteria and other microorganisms, and the various microorganisms work together to transform and degrade antibacterial components such as linalool.

[0012] The bio-enhanced 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 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, where microorganisms and activated sludge are inoculated, and polysaccharides, vitamins and enzyme active substances are added to screen and domesticate toxic-resistant microorganisms 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;

[0014] 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;

[0015] 3) The wastewater treated 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 treated in the aerobic treatment tank enters the tertiary sedimentation tank, and the collected sludge enters the sludge concentration tank;

[0016] 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.

[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 specific 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 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.

[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) The present invention sets up a biological detoxification pool before anaerobic treatment to screen and domesticate toxic-resistant microbial flora to treat the refractory organic matter and antibacterial components (such as terpene compounds such as linalool) in eucalyptus chemical-mechanical pulping wastewater, remove the toxicity in the wastewater, and improve its biodegradability, thereby optimizing the efficiency of subsequent biological treatment;

[0025] 2) The present 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 pool, the metabolic activity of microorganisms can be further optimized to ensure efficient removal of pollutants; compared with traditional long-term aerobic treatment, the treatment method of the present invention can remove most pollutants with lower energy consumption, effectively reducing energy consumption in the aerobic treatment process;

[0026] 3) The present invention introduces biologically active carrier materials in the aerobic stage, which can significantly promote the synergistic effect between microorganisms and pollutants and effectively improve the mass transfer efficiency during the degradation process, so that the ideal treatment effect can be achieved in a shorter time, thereby greatly shortening the time required for aerobic treatment;

[0027] 4) The present invention adopts 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, a 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 impact 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 scheme and advantages of the present invention clearer, the present invention is further described below in conjunction with specific embodiments. In the following examples, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they 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, SS 642 mg / L.

[0033] In the following examples, 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 including a variety of yeasts, bacteria and other microorganisms. The various 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 microorganisms and activated sludge from the hydrolysis tank of the plant are inoculated, and active substances such as polysaccharides, vitamins and enzymes are added to screen and domesticate toxic-resistant microorganisms with actual wastewater. Through biological detoxification, the inhibitory effect of wastewater on subsequent microorganisms is reduced, thereby improving the biodegradability of 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;

[0037] 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;

[0038] 3) The wastewater treated 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, improve mass transfer efficiency, significantly improve treatment effects, and reduce the concentrations of indicators such as COD, ammonia nitrogen and chromaticity in the effluent; the wastewater treated in the aerobic treatment tank enters the tertiary sedimentation tank for further removal of suspended matter and solid particles to improve the clarity of the wastewater, and the collected sludge enters the sludge thickening tank;

[0039] 4) The wastewater after treatment in the three sedimentation tanks enters the deep treatment tank and is treated with Fenton oxidation coagulation using deep treatment agents. The Fenton treatment process conditions are as follows: reaction pH 3.0-3.5, reaction time 30 min, FeSO4·7H2O dosage 2.25 g / L, H2O2 (27.5%) dosage 1.3 g / L. The wastewater after deep treatment is introduced into the final sedimentation tank for treatment. After the solid-liquid separation step, the obtained supernatant can meet the discharge requirements of GB3544-2008 standard. 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-enhanced treatment methods for high-concentration eucalyptus chemical mechanical pulp wastewater in the following Examples 2-4 are all carried out in the treatment process flow of this example.

[0041] Example 2

[0042] A bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical 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°C, 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; 100 mg / L of Thauera linaloolentis 47LolT bacteria was added to the biological detoxification tank; 10 mg / L of glucan was added; 1 mg / L of complex vitamin B, 0.2 mg / L of vitamin E, and 3 mg / L of lyase and lipase with single enzyme activity above 1000 U / mg were added, and toxic-resistant microorganisms were screened and domesticated. 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 phosphate are added to the hypoxic treatment tank in 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 treated in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are as follows: water temperature 30-35°C, 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, and 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 obtained 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 Inlet and outlet water 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-enhanced treatment method for high-concentration wastewater from eucalyptus chemical 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 is added to the biological detoxification tank; 15 mg / L of glucan is added; 2 mg / L of complex vitamin B, 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, and toxic-resistant microorganisms are screened and domesticated. 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) 24h. Ammonium gluconate and diammonium phosphate are added to the hypoxic treatment tank in 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 treated in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are as follows: water temperature 25-30°C, 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) 8 h; 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 obtained 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 3-4 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-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping comprises the following steps:

[0065] (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 35-40℃, pH 6.5-7.5, dissolved oxygen (DO) ≤ 0.3 mg / L, activated sludge concentration (MLSS) 20g / L, hydraulic retention time (HRT) 6h; Thauera linaloolentis 47LolT bacteria 100mg / L and acetobutylic acid Clostridium 100mg / L are added to the biological detoxification tank; 20mg / L of glucan is added; the addition amount of vitamin B complex is 5mg / L, the addition amount of vitamin E is 0.8mg / L, and the single enzyme activity of lyase and lipase is 10mg / L above 1000U / mg, and toxic-resistant microorganisms are screened and domesticated. The remaining sludge is 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 phosphate are added to the hypoxic treatment tank in 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 treated in the secondary sedimentation tank enters the aerobic treatment tank for aerobic biological treatment. The operating process parameters of the aerobic treatment tank are as follows: 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, hydraulic retention time (HRT) 8 h; 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 obtained 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 5-6 below.

[0070] Table 5 Inlet and outlet water 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] The conventional process of "anaerobic-aerobic-Fenton treatment" was used for comparative test. The anaerobic section was operated with the same operating parameters as in Example 2, with a hydraulic retention time (HRT) of 24h. The aerobic section was operated with a common activated sludge method, and the operating process parameters were: water temperature 20-40°C, pH 6.5-8.0, dissolved oxygen (DO) 2.0-4.0mg / L, activated sludge concentration (MLSS) 8 g / L, and hydraulic retention time (HRT) 36h. The process conditions of Fenton treatment were: reaction pH 3.0-3.5, reaction 30min, FeSO4·7H2O dosage 2.25g / L, and H2O2 (27.5%) dosage 1.3g / L.

[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 7-8 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] The COD of each effluent in the treatment process of Examples 2 to 4 and Comparative Example 1 was tested using a small test platform to determine the treatment effect of the treatment process. The detoxified sludge was taken from the hydrolysis tank of the pulp mill, the anaerobic granular sludge was taken from the IC tower, and the hypoxic sludge and aerobic activated sludge were taken from the aerobic tank of the same plant. The results are shown in Table 9.

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

[0084]

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

[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 principle of the present invention. These improvements and modifications should also be regarded as 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: Taking eucalyptus chemical mechanical pulp high-concentration wastewater as the treatment object, the biodegradability of eucalyptus chemical mechanical pulp high-concentration wastewater is improved through biological detoxification treatment, low oxygen treatment is carried out after anaerobic treatment, and organic pollutants are degraded under low dissolved oxygen conditions. Aerobic bio-enhanced treatment and deep treatment are carried out through a short process to improve the removal rate of chemical oxygen demand; among them, the concentration of low dissolved oxygen is 0.3~1.0mg / L.

2. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1 is characterized in that: 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.

3. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 2 is characterized in that: The microorganism is selected from any one or more of Delftia microorganisms and Clostridium microorganisms, the polysaccharide is dextran, 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.

4. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 3 is characterized in that: The added amount of the Delftia microorganism is 100 mg / L, the added amount of the Clostridium microorganism is 100 mg / L, the added amount of the glucan is no more than 20 mg / L, the added amount of the vitamin B complex is no more than 5 mg / L, the added amount of the vitamin E is no more than 1 mg / L, and the added amount of the enzyme is 3-10 mg / L.

5. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulp according to claim 1, 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, where microorganisms and activated sludge are inoculated, and polysaccharides, vitamins and enzyme active substances are added to screen and domesticate toxic-resistant microorganisms 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.

6. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 5, 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.

7. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 5, 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.

8. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 5, 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.

9. The bio-enhanced treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 8, 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.

10. The bio-augmented treatment method for high-concentration wastewater from eucalyptus chemical mechanical pulping according to claim 5, 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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