Method for recycling of failed activated carbon from waterworks in sewage plant

Abstract

The present application discloses a method for resource utilization of failed activated carbon in waterworks in sewage treatment plant, and relates to the field of sewage treatment.The method comprises the following steps: (1) hatching the failed activated carbon A with raw water of the sewage treatment plant; (2) domesticating the activated carbon A with effluent of the aerobic tank of the sewage treatment plant + sludge anaerobic digestion biogas liquid, or effluent of the aerobic tank of the sewage treatment plant + sludge hydrothermal supernatant, or mixed liquid of effluent of the aerobic tank of the sewage treatment plant + sludge anaerobic digestion biogas liquid and sludge hydrothermal supernatant, and centrifugal dewatering to obtain activated carbon B; (3) domesticating the activated carbon A with effluent of the secondary sedimentation tank of the sewage treatment plant + nutrient elements, and centrifugal dewatering to obtain activated carbon C; (4) adding the activated carbon B to the aerobic tank, strengthening the nitrification capacity of the aerobic tank, the COD removal rate of the whole sewage treatment process and the denitrification capacity, and finally adding the activated carbon B to the subsequent treatment and disposal link by enriching into the residual sludge; (5) filling the activated carbon C into a filter column, and passing the effluent of the secondary sedimentation tank of the sewage treatment plant into the filter column for treating and removing pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a method for resource utilization of failed activated carbon in a waterworks in a sewage treatment plant. BACKGROUND

[0002] With the increasingly stringent water treatment effluent standards, and activated carbon as a kind of efficient, economical and practical pollutant removal material, its use in waterworks is increasing. However, the activated carbon adsorbs the pollutants in water and gradually saturates. Generally, the activated carbon used for 6 months to 1 year has reached the upper limit of adsorption, and if the water quality is poor, the time will be further shortened. However, the replacement of all new activated carbon will increase the operating cost, and the treatment and disposal of waste activated carbon will cause energy consumption and secondary pollution problems.

[0003] Currently, the activated carbon regeneration technologies mainly include thermal regeneration method, solvent regeneration method, chemical regeneration method, electrochemical regeneration method and biological regeneration method. However, the loss of activated carbon in the thermal regeneration method is large, about 5% to 15%, and the mechanical strength of the activated carbon after regeneration is reduced; the electrochemical regeneration method consumes a large amount of electric energy; the solvent regeneration method uses organic solvents such as acetone, methanol, ethanol and n-pentane, most of which are toxic solvents; the chemical regeneration method such as photocatalysis and wet oxidation regeneration method requires high equipment and harsh reaction conditions. When the amount of waste activated carbon is small, some enterprises will also incinerate and dispose of it.

[0004] Therefore, the current various activated carbon regeneration technologies and the incineration of waste activated carbon will consume a large amount of energy in the treatment and disposal process, use chemical substances harmful to the environment, have high carbon emissions, and the adsorption efficiency of the activated carbon after repeated regeneration will also decrease significantly, which will not meet the high standard requirements of waterworks. Therefore, it is necessary to seek other resource utilization schemes for failed activated carbon in waterworks and find a waste activated carbon treatment method that can reduce costs and does not consume a large amount of energy and cause secondary pollution. SUMMARY

[0005] The purpose of the present application is to solve the problems of low regeneration efficiency, high disposal energy consumption and low resource utilization rate of failed activated carbon in waterworks, and to provide a method for resource utilization of failed activated carbon in waterworks in a sewage treatment plant.

[0006] The present application can utilize the failed activated carbon in waterworks as a resource, avoid high-cost regeneration, is simple to operate, significantly enhances the function of the sewage treatment system, increases the removal rate of ammonia nitrogen in the aerobic tank of the sewage treatment plant by 20% to 30%, increases the removal rate of COD by 20% to 40%, and increases the removal rate of micro-pollutants in the liquid phase by 20% to 30%, reduces the COD in the effluent of the secondary sedimentation tank by 40% to 60%, reduces the TN by 5% to 20%, and reduces the NH4+ -N reduces 40-60%, TP reduces 10-30%, the concentration of typical micro-pollutants reduces more than 90%, and the efficiency of subsequent treatment and disposal of residual sludge is strengthened.

[0007] The object of the application is achieved by the following technical solutions:

[0008] A method for recycling failed activated carbon in a waterworks in a sewage plant, comprising the following steps:

[0009] S1, the failed activated carbon is filled into an activated carbon filter column, and is incubated with raw water in the sewage plant for 2-7 days to obtain activated carbon A;

[0010] S2, the activated carbon A in S1 is subjected to alternating-gradient acclimation using liquid A and liquid B, the acclimation time is 5-10 days, then the acclimated activated carbon is taken out, and centrifugal dewatering is performed to obtain activated carbon B;

[0011] The liquid A is effluent from an aerobic tank in the sewage plant;

[0012] The liquid B is supernatant of sludge hydrothermal treatment or sludge anaerobic digestion biogas liquid;

[0013] S3, nutrient elements are added to the effluent from the secondary sedimentation tank in the sewage plant to acclimate the activated carbon A in S1, the acclimation time is 10-30 days, then the acclimated activated carbon is taken out, and centrifugal dewatering is performed to obtain activated carbon C;

[0014] The activated carbon B is suitable for the aerobic tank in the sewage plant;

[0015] The activated carbon C is suitable for the secondary sedimentation tank in the sewage plant.

[0016] The working principle of the application is that the surface of the failed activated carbon in the waterworks is rich in biofilm, and after incubation and acclimation under different influent water qualities, different functional microbial populations can be established, and the activated carbon has the ability of physical adsorption and microbial removal of pollutants, thereby strengthening the function of the traditional activated sludge sewage treatment system.

[0017] In the application, the flow rate and incubation time during the incubation of raw water in the sewage plant are important factors affecting the activity of microorganisms in the failed activated carbon in the waterworks, when the flow rate is too large, the flushing is too large, which is not conducive to the enrichment of microorganisms, when the flow rate is too small, it is easy to be blocked and difficult to backwash, when the incubation time is too long, the failed activated carbon in the waterworks will adsorb a large amount of pollutants in the raw water, affecting the subsequent advanced treatment, and when the incubation time is too short, the microorganisms in the failed activated carbon in the waterworks cannot adapt to the sewage conditions, and it is difficult to establish new microbial populations.

[0018] Further, the failed activated carbon in step S1 is activated carbon in an activated carbon filter with a COD removal rate of less than or equal to 20% in the waterworks which has been used continuously for more than 1 year. Mn activated carbon in an activated carbon filter with a COD removal rate of less than or equal to 20% in the waterworks which has been used continuously for more than 1 year.

[0019] Further, the raw water of the sewage plant in step S1 refers to the sewage after the grid and the primary sedimentation tank of the domestic sewage treatment plant adopting the activated sludge method.

[0020] Further, the gravel layer of 5-12 cm is arranged at the bottom of the activated carbon filter column in step S1.

[0021] Further, the up-flow water inlet mode is adopted during the incubation in step S1, the flow rate is 1.0-2.0 mL / cm 2 / min, the operation is performed for 15-20 h per day, the tap water is backwashed once every 3-5 h, and the incubation is performed under the normal temperature condition.

[0022] In the present application, the flow rate and the time during the domestication are important factors affecting the activity of the microorganisms in the failed activated carbon of the tap water plant, when the flow rate is too large, the scouring is too large, and the microorganisms are not conducive to enrichment, when the flow rate is too small, the backwashing is difficult; when the domestication time is too long, the failed activated carbon of the tap water plant can absorb a large amount of pollutants in the sewage, affecting the treatment, and when the domestication time is too short, the microorganisms in the failed activated carbon of the tap water plant are not adapted to the conditions of the effluent of the aerobic tank and the high nitrogen-containing heterocyclic substances, and it is difficult to establish a new microbial population.

[0023] In the present application, the characteristics of the biogas slurry and the sludge water heat supernatant selected by the sludge anaerobic digestion are important factors affecting the selection of the microorganisms on the sludge surface of the failed activated carbon of the tap water plant resistant to nitrogen-containing heterocyclic substances, when the total nitrogen and humus content are too high, the growth of the surface microorganisms is directly inhibited, and the domestication fails, and when the content is too low, it is difficult to establish the tolerance of the microorganisms.

[0024] Further, the sludge water heat supernatant in step S2 refers to the supernatant separated after the residual sludge is hydrolyzed by hot water at a temperature of 120-160 ℃ for 30-60 min.

[0025] Further, the total nitrogen concentration of the sludge water heat supernatant in step S2 is 800-1500 mg / L, the humus content is 1800-2200 mg / L, and the protein peak, the fulvic acid peak and the humic acid peak can be seen through the three-dimensional fluorescence detection.

[0026] Further, the sludge anaerobic digestion biogas in step S2 is the supernatant separated after the sludge in the sludge anaerobic digestion project is treated by the mesophilic (35-37 ℃) anaerobic digestion for 10-30 d.

[0027] Further, the total nitrogen concentration of the sludge anaerobic digestion biogas in step S2 is 80-150 mg / L, the humus content is 180-220 mg / L, and the protein peak, the fulvic acid peak and the humic acid peak can be seen through the three-dimensional fluorescence detection.

[0028] Further, the flow rate of the alternate-gradient acclimation in step S2 is 1.0-2.0 mL / cm 2 / min.

[0029] Further, the temperature of the alternate-gradient acclimation in step S2 is 23-30℃.

[0030] Further, the upward flow mode is used in the alternate-gradient acclimation in step S2.

[0031] Further, the alternate-gradient acclimation in step S2 is operated for 15-20 h per day, and the tap water is used for backwashing once every 3-5 h.

[0032] Further, the alternate in the alternate-gradient acclimation in step S2 refers to the acclimation using the effluent of the aerobic tank first, and then the acclimation using the supernatant of the sludge water heat or the sludge anaerobic digestion liquid;

[0033] After the acclimation using the two kinds of liquids is completed, it is called one-time alternate acclimation.

[0034] Further, the number of times of the alternate acclimation per day in the alternate-gradient acclimation in step S2 is 3-5 times.

[0035] Further, the gradient acclimation in the alternate-gradient acclimation in step S2 refers to that, in the whole alternate acclimation process, the total volume ratio of the effluent of the aerobic tank and the supernatant of the sludge water heat or the sludge anaerobic digestion liquid gradually decreases with the increase of the number of times of the alternate acclimation.

[0036] Further, the volume ratio of liquid A and liquid B in the gradient acclimation in the alternate-gradient acclimation in step S2 gradually decreases from 8-10:1 to 4-5:1.

[0037] In the present application, the concentration of the added nutrient element is an important factor affecting the acclimation of the microorganisms on the surface of the failed activated carbon. If the concentration is too high, the biofilm grows too fast, is easy to be blocked, and the metabolic products are easy to produce inhibition. If the concentration is too low, it is not conducive to the growth of microorganisms.

[0038] Further, the acclimation in step S3 refers to the acclimation of the activated carbon A under the condition of room temperature and using the upward flow mode, at a flow rate of 1.0-2.0 mL / cm 2 / min, and the operation is performed for 15-20 h per day, and the tap water is used for backwashing once every 3-5 h during the acclimation.

[0039] Further, the added nutrient element in step S3 includes nitrogen and easily biodegradable organic matter.

[0040] Further, the added concentration of the nitrogen is 1-2 mg / L NH 4+ -N.

[0041] Further, the concentration of the added biodegradable organic matter is 2-10 mg / L TOC.

[0042] Preferably, the nitrogen source is ammonium salt.

[0043] Preferably, the biodegradable organic matter is one or more of ethanol, methanol or glucose.

[0044] The application provides the resource-utilizable activated carbon B or activated carbon C prepared by the above method.

[0045] The application provides the application of the resource-utilizable activated carbon in the field of sewage treatment and environmental protection.

[0046] The application provides the application of the prepared resource-utilizable activated carbon in the aerobic tank of a sewage treatment plant, including the following steps:

[0047] The activated carbon B prepared by the above method is added to the aerobic tank of the sewage treatment plant at a ratio of 100-500 mg / L every 5-10 days, and the added activated carbon B can enter the subsequent sludge treatment and disposal links including sludge dewatering, anaerobic digestion, aerobic fermentation, drying and incineration.

[0048] In the application, the adding concentration and frequency of the activated carbon B are important factors affecting the nitrification capacity of the aerobic tank, the adsorption and microbial degradation and removal capacity of organic matter, and the adsorption and microbial degradation and removal capacity of micro-pollutants.

[0049] The application provides the application of the prepared resource-utilizable activated carbon in the secondary sedimentation tank of a sewage plant, including the following steps:

[0050] The activated carbon C prepared by the above method is filled into a new filter column, and the effluent of the secondary sedimentation tank of the sewage plant is introduced into the filter column for deep treatment.

[0051] Preferably, the bottom of the new filter column is provided with a 5-12 cm gravel layer support, and the filter column is operated for 15-20 h every day in an upward flow mode, and is backwashed once every 3-5 h by using tap water at a flow rate of 0.2-1.0 mL / cm 2 / min.

[0052] The main innovation of the application is:

[0053] (1) Innovative method for resource utilization of spent activated carbon from waterworks. Existing activated carbon regeneration and waste activated carbon incineration technologies consume significant amounts of energy and generate high carbon emissions during treatment and disposal. Furthermore, the adsorption efficiency of repeatedly regenerated activated carbon decreases considerably, failing to meet the high standards of waterworks and thus being discarded. However, this invention allows for the specific incubation and acclimatization of spent activated carbon from waterworks, transforming it into activated carbon with specific functions. This activated carbon can then be selectively added to aerobic tanks and advanced treatment stages, significantly enhancing the function of the wastewater treatment system and improving its ability to control COD and NH3 levels. 4+ It has the ability to remove nitrogen and micro-pollutants, while enhancing the efficiency of subsequent treatment and disposal of residual sludge, realizing the transformation from waste to resource, avoiding high-cost regeneration, and is simple to operate with high resource utilization.

[0054] (2) An innovative method for acclimatizing specific functional microbial communities in spent activated carbon from water treatment plants. The original functional microorganisms in spent activated carbon from water treatment plants adapt to the oligotrophic conditions of tap water, playing a dominant role in adsorption. However, their microbial degradation efficiency is low, and they have poor adaptability to wastewater from sewage treatment plants and poor degradation ability for high-concentration pollutants in wastewater. This invention aims to enhance the treatment capacity of aerobic tanks and the advanced treatment capacity of secondary sedimentation tank effluent by selectively screening for adaptable functional microbial communities. By alternating and gradient-coupled acclimation of activated carbon with wastewater rich in nitrogen-containing heterocyclic substances such as humic acid and fulvic acid and effluent from the aerobic tank, compared to direct acclimation with only aerobic tank effluent, or alternation or gradient concentration, this alternating-gradient coupling acclimation can gradually screen microorganisms tolerant to nitrogen-containing heterocyclic substances and adapt them to the physicochemical conditions of the aerobic tank, while also taking advantage of improving the shock resistance of microorganisms in activated carbon. At the same time, using supernatant from anaerobic digestion of sludge or sludge hydrothermal treatment to acclimate the microorganisms treating the wastewater can enhance the homology of the acclimated microbial population compared to nitrogen-containing heterocyclic substances from other sources, avoiding the collapse of the wastewater treatment system caused by disruptive changes in the microbial population.

[0055] (3) The treated spent activated carbon of the present application is added into the aerobic tank, which can increase the tolerance of microorganisms in the aerobic tank to nitrogen-containing heterocyclic substances in wastewater, such as humic acid and fulvic acid, significantly release the inhibition of these substances on the activity of various functional microorganisms in the system, and also adsorb toxic substances such as phenols and heavy metals that inhibit nitrifying bacteria, thereby enhancing the nitrification capacity, adsorption of organic matter, and microbial degradation and removal capacity of the aerobic tank. Finally, the effluent from the secondary sedimentation tank still contains a certain concentration of organic pollutants and micro-pollutants, but the degree of nutrition is low. After the addition of high-concentration nutrients, the spent activated carbon in the waterworks is incubated with the influent of the wastewater treatment plant, and the low-concentration pollutants in the secondary sedimentation tank are domesticated with the added high-concentration nutrients, which can enrich the biological membrane with high tolerance to organic pollutants and micro-pollutants in the secondary sedimentation tank. In addition to the adsorption capacity, the microbial degradation capacity of the microorganisms enriched on the activated carbon is enhanced. The use of such activated carbon for advanced treatment of the effluent from the secondary sedimentation tank can enhance the removal of COD, TN, NH 4+ -N, TP, and micro-pollutants in the effluent from the secondary sedimentation tank. In addition, the activated carbon added into the aerobic tank will be enriched in the excess sludge, which will have a certain degree of strengthening effect on the subsequent dewatering efficiency, anaerobic digestion, aerobic fermentation, and incineration process of the sludge.

[0056] Compared with the prior art, the present application has the following beneficial effects:

[0057] (1) After adding activated carbon B, the removal rate of NH 4+ -N in the aerobic tank of the wastewater treatment plant can be increased by 20-30%, the removal rate of COD can be increased by 20-40%, and the removal rate of micro-pollutants in the liquid phase, including but not limited to diclofenac sodium and tetracycline hydrochloride, can be increased by 20-30%.

[0058] (2) After using activated carbon C for advanced treatment of the effluent from the secondary sedimentation tank, the COD in the effluent from the secondary sedimentation tank is reduced by 40-60%, the TN is reduced by 30-50%, the NH4+-N is reduced by 30-50%, the TP is reduced by 10-30%, and the concentration of typical micro-pollutants, including but not limited to diclofenac sodium and tetracycline hydrochloride, is reduced by more than 90%.

[0059] (3) The present application does not need to regenerate the spent activated carbon in the waterworks at high cost, and the operation is simple. After domestication, the activated carbon can be fully resourceized, and finally goes to the excess sludge. The activated carbon can also strengthen the subsequent dewatering, anaerobic digestion, aerobic fermentation, and incineration process of the sludge. DETAILED DESCRIPTION

[0060] Detection process

[0061] Three-dimensional fluorescence detection: The biogas slurry was passed through a 0.45 μm polyethersulfone membrane and measured using a three-dimensional fluorescence spectrometer. During the three-dimensional fluorescence spectroscopy scan, the PMT scanning voltage was 700 V, the excitation wavelength Ex range was 200–400 nm with a step size of 5 nm, the emission wavelength was 300–500 nm with a step size of 5 nm, and the scanning speed was 12000 nm / min. To eliminate Raman scattering, ultrapure water was used as a blank control. The spectral images were analyzed according to the table below.

[0062] Table 1 Fluorescence spectral parameters of organic matter in simulated wastewater

[0063]

[0064] Source of raw materials

[0065] The depleted activated carbon was taken from activated carbon that had been in operation for more than one year in a waterworks. The COD of this activated carbon was... Mn Removal rate ≤20%.

[0066] Example 1

[0067] S1. Expired activated carbon from a water treatment plant's activated carbon filter, which had been in continuous use for one year, was loaded into an activated carbon filter column. The COD of this activated carbon... Mn The removal rate is 18%. A 12cm gravel layer is installed at the bottom of the filter column for support. The wastewater influent from the wastewater treatment plant is at a concentration of 2.0 mL / cm³. 2 The activated carbon A was obtained by incubating at room temperature for 5 days at a constant rate of / min. During incubation, the water was fed in an upward flow mode for 20 hours per day, and the activated carbon A was backwashed with tap water every 3 hours.

[0068] S2. The remaining sludge was hydrolyzed at 160℃ for 60 minutes, and the supernatant was obtained. The total nitrogen concentration of the supernatant was 1000 mg / L, and the humic content was 2000 mg / L. Three-dimensional fluorescence detection revealed protein-like peaks, fulvic acid-like peaks, and humic acid-like peaks. The effluent from the aerobic tank of the wastewater treatment plant and the supernatant were compared at a concentration of 2.0 mL / cm³. 2 The activated carbon was acclimated for 10 days under alternating conditions of 0.5 rpm and ambient temperature. The effluent and supernatant from the aerobic tank of the wastewater treatment plant were acclimated 5 times a day. The order of each alternation was to first use the effluent from the aerobic tank for acclimation, and then use the supernatant for acclimation. This order was repeated. The total volume ratio of the two types of water decreased successively in each alternation, to 8:1, 7:1, 7:1, 6:1, and 5:1. The plant was operated in an upward flow mode for 20 hours a day, and was backwashed with tap water every 3 hours. After that, the acclimated activated carbon A was taken out and centrifuged at 3000 rpm to obtain activated carbon B-1.

[0069] Example 2

[0070] S1. Expired activated carbon from a water treatment plant's activated carbon filter, which had been in continuous use for one year, was loaded into an activated carbon filter column. The COD of this activated carbon... Mn The removal rate is 18%. A 12cm gravel layer is installed at the bottom of the filter column for support. The wastewater influent from the wastewater treatment plant is at a concentration of 2.0 mL / cm³. 2 The activated carbon A was obtained by incubating at room temperature for 5 days at a constant rate of / min. During incubation, the water was fed in an upward flow mode for 20 hours per day, and the activated carbon A was backwashed with tap water every 3 hours.

[0071] S2. Add ammonium bicarbonate (concentration of 2 mg / L NH4) to the effluent from the secondary sedimentation tank of the wastewater treatment plant. + The system was operated for 20 hours daily using an upflow feed mode, with backwashing with tap water every 3 hours at a concentration of 2.0 mL / cm³. The solution contained 10 mg / L ethanol (N-1) and ethanol (10 mg / L LTOC). 2 Activated carbon A was acclimated with effluent from the secondary sedimentation tank of a wastewater treatment plant at a constant temperature for 30 days. After acclimation, activated carbon A was removed and centrifuged at 3000 r / min for 10 min to obtain activated carbon C-1.

[0072] Example 3

[0073] The activated carbon B-1 prepared in Example 1 was added to the aerobic tank of the wastewater treatment plant at a rate of 500 mg / L once every 5 days. The aerobic tank of the wastewater treatment plant is effective against NH4+. + The removal rate of -N was 58.5%, which was 30% higher than that without the addition of activated carbon B-1 (45.0%). The removal rate of COD was 78.0%, which was 40% higher than that without the addition of activated carbon B-1 (60.0%). The removal rate of tetracycline hydrochloride in the liquid phase increased from 40.0% to 52.0% (+30%). The added activated carbon B-1 was enriched into the excess sludge and entered into subsequent sludge dewatering, aerobic fermentation and land application.

[0074] Table 2. Pollutant removal rate of the aerobic tank.

[0075] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-1 58.5％ 78.0％ 52.0％

[0076] The activated carbon C-1 prepared in Example 2 was packed into a new filter column and fed into the effluent from the secondary sedimentation tank of the wastewater treatment plant for advanced treatment. The new filter column was supported by a 12cm gravel layer and operated in an upward flow mode for 20 hours per day, with backwashing with tap water every 3 hours at a flow rate of 1.0 mL / cm. 2 / min.

[0077] This new filter column can further reduce COD by 60%, TN by 50%, and NH4+ in the secondary sedimentation tank effluent. + -N decreased by 50%, TP decreased by 30%, and the concentration of tetracycline hydrochloride decreased by 95%.

[0078] Table 3 Pollutant concentration (mg / L) of effluent from secondary sedimentation tank and filter column

[0079] COD TN NH4 + -N]]> TP Tetracycline hydrochloride Secondary sedimentation tank effluent 25.0 10.5 4.3 0.1 2.0 Filter column effluent with activated carbon C-1 packed 10.0 5.3 2.2 0.07 0.1

[0080] Example 4

[0081] S1, the spent activated carbon in the activated carbon filter column of the waterworks which has been continuously used for 1 year was filled into the activated carbon filter column, the COD removal rate of the activated carbon was 18%, a 12 cm gravel layer was arranged at the bottom of the filter column for support, and the effluent from the waterworks was used to incubate for 5 days at 2.0 mL / cm Mn / min and normal temperature, an upward flow feeding mode was adopted for 20 h of operation per day, and tap water was used for backwashing once every 3 h, to obtain activated carbon A; 2

[0082] S2, the supernatant separated from the sludge after the sludge was treated by a mesophilic (35-37°C) anaerobic digestion process for 20 d in the sludge anaerobic digestion project was referred to as sludge anaerobic digestion biogas, the total nitrogen concentration of the sludge anaerobic digestion biogas was 120 mg / L, the humus content was 200 mg / L, and the protein-like peak, fulvic acid-like peak and humic acid-like peak could be seen through three-dimensional fluorescence detection, the effluent from the aerobic tank of the sewage plant and the sludge anaerobic digestion biogas were used to be alternately acclimated for 5 days at 1.0 mL / cm 2 / min and normal temperature, the effluent from the aerobic tank of the sewage plant and the sludge anaerobic digestion biogas were alternated 3 times per day, the acclimation sequence of each time was to use the effluent from the aerobic tank first, then use the sludge anaerobic digestion biogas, and then repeat the sequence, the total volume ratio of the two kinds of water in each time of acclimation was 10:1, 9:1 and 8:1 in turn, an upward flow feeding mode was adopted for 15 h of operation per day, tap water was used for backwashing once every 5 h, and the acclimated activated carbon A was taken out and centrifuged for dehydration at 1000 r / min for 5 min, to obtain activated carbon B-2.

[0083] Example 5

[0084] S1, the spent activated carbon in the activated carbon filter column of the waterworks which has been continuously used for 1 year was filled into the activated carbon filter column, the COD removal rate of the activated carbon was 18%, a 12 cm gravel layer was arranged at the bottom of the filter column for support, and the effluent from the waterworks was used to incubate for 5 days at 2.0 mL / cm Mn / min and normal temperature, an upward flow feeding mode was adopted for 20 h of operation per day, and tap water was used for backwashing once every 3 h, to obtain activated carbon A; 2

[0085] S2, the supernatant separated from the sludge after the sludge was treated by a mesophilic (35-37°C) anaerobic digestion process for 20 d in the sludge anaerobic digestion project was referred to as sludge anaerobic digestion biogas, the total nitrogen concentration of the sludge anaerobic digestion biogas was 120 mg / L, the humus content was 200 mg / L, and the protein-like peak, fulvic acid-like peak and humic acid-like peak could be seen through three-dimensional fluorescence detection, the effluent from the aerobic tank of the sewage plant and the sludge anaerobic digestion biogas were used to be alternately acclimated for 5 days at 1.0 mL / cm + ​​The system was operated for 15 hours daily using an upward flow feed mode, with backwashing with tap water every 5 hours at a concentration of 1.0 mL / cm³, containing ethanol (2 mg / L TOC) and nitrogen (N-N). 2 Activated carbon A was acclimated with effluent from the secondary sedimentation tank of a wastewater treatment plant at a constant speed and ambient temperature for 10 days. After acclimation, activated carbon A was removed and centrifuged at 1000 r / min to obtain activated carbon C-2.

[0086] Example 6

[0087] The activated carbon B-2 prepared in Example 4 was added to the aerobic tank of the wastewater treatment plant at a rate of 100 mg / L once every 10 days. The aerobic tank of the wastewater treatment plant is effective against NH4+. + The removal rate of -N was increased by 20% compared with that without the addition of activated carbon B-2, the removal rate of COD was increased by 20% compared with that without the addition of activated carbon B-2, and the removal rate of diclofenac sodium in the liquid phase was increased by 20%. The added activated carbon B-2 was enriched into the remaining sludge and entered into the subsequent sludge dewatering, drying and incineration.

[0088] Table 4. Pollutant removal rate of the aerobic tank.

[0089] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-2 54.0％ 72.0％ 48.0％

[0090] The activated carbon C-2 prepared in Example 5 was packed into a new filter column and fed into the effluent from the secondary sedimentation tank of the wastewater treatment plant for advanced treatment. The new filter column was supported by a 12cm gravel layer and operated in an upward flow mode for 15 hours per day, with backwashing with tap water every 3 hours at a flow rate of 1.0 mL / cm. 2 / min. This new filter column can further reduce COD by 55%, TN by 38%, and NH4+ in the secondary sedimentation tank effluent. + -N decreased by 53%, TP decreased by 30%, and the concentration of diclofenac sodium decreased by 94%.

[0091] Table 5. Pollutant concentrations (mg / L) in the effluent from the secondary sedimentation tank and the filter column.

[0092] COD TN NH4 + -N]]> TP Tetracycline hydrochloride Secondary sedimentation tank effluent 25.0 10.5 4.3 0.1 2.0 Filter column effluent with activated carbon C-2 packed 11.2 6.4 2.0 0.07 0.12

[0093] Comparative Example 1

[0094] The acclimatization method in S2 of Example 1 is modified to use only the effluent from the aerobic tank of the wastewater treatment plant for acclimatization at the same concentration, that is, using the effluent from the aerobic tank of the wastewater treatment plant at 2.0 mL / cm³. 2 The activated carbon was acclimated at room temperature for 10 days, and then run for 20 hours a day in an upward flow mode. It was backwashed with tap water every 3 hours. The acclimated activated carbon A was taken out and centrifuged at 3000 r / min to obtain activated carbon B-D1.

[0095] Referring to Example 3, the obtained activated carbon B-D1 is added into the aerobic tank, and other operations remain unchanged. The removal rates of NH4 + The removal rate of -N is only increased by 10% compared with that without adding the activated carbon B-D1, the removal rate of COD is only increased by 15% compared with that without adding the activated carbon B-D1, and the removal rate of tetracycline hydrochloride in the liquid phase is only increased by 10%. It can be known from Proportion 1 that the alternating-gradient coupling domestication is crucial for improving the function of the activated carbon.

[0096] Table 6: Removal rates of pollutants in the aerobic tank

[0097] NH4 + -N]]> COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-D1 49.5％ 69.0％ 44.0％

[0098] Comparative Example 2

[0099] The domestication mode in S2 in Example 1 is modified to alternating once a day with the effluent and sludge water hot supernatant of the wastewater treatment plant, the total volume ratio of the two kinds of water is fixed as 5:1 in the alternating domestication, other conditions remain unchanged, an upward flow water feeding mode is used to run for 20 hours a day, tap water is used to backwash once every 3 hours, the domesticated activated carbon A is taken out, centrifugal dewatering is performed at 3000 r / min to obtain activated carbon B-D2.

[0100] Other operations remain unchanged. After the obtained activated carbon B-D2 is added into the aerobic tank, the removal rates of NH4 + The removal rate of -N is only increased by 11% compared with that without adding the activated carbon B-D2, the removal rate of COD is only increased by 8.7% compared with that without adding the activated carbon B-D2, and the removal rate of tetracycline hydrochloride in the liquid phase is only increased by 10%. It can be known from Proportion 2 that the alternating times of the alternating-gradient coupling domestication are crucial for improving the function of the activated carbon.

[0101] Table 7: Removal rates of pollutants in the aerobic tank

[0102] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-D2 50.0％ 65.2％ 44.0％

[0103] Comparative Example 3

[0104] The domestication mode in S2 in Example 1 is modified to alternating 5 times a day with the effluent and sludge water hot supernatant of the wastewater treatment plant, the total volume ratio of the two kinds of water is 5:1 in each alternating domestication, other conditions remain unchanged, an upward flow water feeding mode is used to run for 20 hours a day, tap water is used to backwash once every 3 hours, the domesticated activated carbon A is taken out, centrifugal dewatering is performed at 3000 r / min to obtain activated carbon B-D3.

[0105] Other operations remain unchanged. After the obtained activated carbon B-D3 is added into the aerobic tank, the removal rates of NH4 +The removal rate of -N is only increased by 16% compared to when no activated carbon B-D3 is added, the removal rate of COD is only increased by 13% compared to when no activated carbon B-D3 is added, and the removal rate of tetracycline hydrochloride in the liquid phase is only increased by 10%. It can be known from proportion 3 that the concentration gradient in the alternating-gradient coupling domestication is crucial to improving the function of the activated carbon.

[0106] Table 8 Removal rate of pollutants in the aerobic tank

[0107] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-D3 52.3％ 68.0％ 44.0％

[0108] Comparative example 4

[0109] The activated carbon B-1 in example 3 is added to the aerobic tank of the sewage treatment plant at a proportion of 100 mg / L for 10 d once, and other operations remain unchanged. After the activated carbon B-1 is added to the aerobic tank, the removal rates of NH4 + The removal rate of -N is only increased by 8% compared to when no activated carbon B-1 is added, the removal rate of COD is only increased by 10% compared to when no activated carbon B-1 is added, and the removal rate of tetracycline hydrochloride in the liquid phase is only increased by 8%. It can be known from the comparison of comparative example 4 and examples 3 and 6 that the optimal addition amount and optimal addition frequency of the activated carbon after different domestication conditions are different, and therefore the activated carbon under a specific domestication condition is matched with a specific addition amount and addition frequency to achieve the optimal removal effect.

[0110] Table 9 Removal rate of pollutants in the aerobic tank

[0111] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With activated carbon B-1 48.6％ 66.0％ 43.2％

[0112] Comparative example 5

[0113] In example 3, the domesticated activated carbon from the waterworks is not used, but clean and unused activated carbon is directly used, and other conditions remain unchanged. After the addition, the removal rates of NH4 + The removal rate of -N is increased by 16% compared to when no activated carbon is added, the removal rate of COD is increased by 18% compared to when no activated carbon is added, and the removal rate of tetracycline hydrochloride in the liquid phase is increased by 12.5%; the COD in the effluent of the secondary sedimentation tank is reduced by 60.8%, the TN is reduced by 43.8%, the NH4 + -N is reduced by 52%, the TP is reduced by 30%, and the concentration of tetracycline hydrochloride is reduced by 95%. It can be known from comparative example 5 that the improvement of the sewage treatment plant removal capacity by the domesticated activated carbon from the waterworks in example 1 is equivalent to that of the clean and unused activated carbon, and therefore the method provided by the present application is an effective solution to the problems of low regeneration efficiency, high disposal energy consumption, and low resource utilization rate of the activated carbon from the waterworks.

[0114] Table 10 Removal rate of pollutants in the aerobic tank

[0115] NH4 + -N]] COD Tetracycline hydrochloride Without activated carbon 45.0％ 60.0％ 40.0％ With clean activated carbon 52.3％ 71.0％ 50.0％

[0116] Table 11 Pollutant concentrations (mg / L) in effluent from secondary sedimentation tank and filter column

[0117] COD TN NH4 + -N]] TP Tetracycline hydrochloride Secondary sedimentation tank effluent 25.0 10.5 4.3 0.1 2.0 Filter column effluent with clean activated carbon packed 9.8 5.9 2.1 0.07 0.1

[0118] Although the present application has been disclosed in its preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application should be defined by the claims.

Claims

1. A method for resource recycling of failed activated carbon from a waterworks in a sewage plant, characterized by, It comprises the following steps: S1, packing the failed activated carbon into an activated carbon filter column, and incubating with raw water of a sewage plant for 2-7 days to obtain activated carbon A; the failed activated carbon refers to activated carbon that has been used continuously in a water plant for more than 1 year and whose COD Mn removal rate is less than or equal to 20%; S2, using liquid A and liquid B to carry out alternating-gradient acclimation to activated carbon A in S1, the acclimation time is 5-10 days, and then the acclimated activated carbon is taken out and centrifuged to obtain activated carbon B; The liquid A is effluent from an aerobic tank of a sewage plant; The liquid B is supernatant of sludge hydrothermal treatment or supernatant of sludge anaerobic digestion; In the alternating-gradient acclimation, the alternating refers to first acclimation using effluent from an aerobic tank, and then acclimation using supernatant of sludge hydrothermal treatment or supernatant of sludge anaerobic digestion; after the alternating acclimation of the two liquids is completed, it is called one-time alternating acclimation; the number of alternating acclination per day is 3-5 times; the gradient refers to that in the whole acclimation process, the total volume ratio of effluent from an aerobic tank to supernatant of sludge hydrothermal treatment or supernatant of sludge anaerobic digestion gradually decreases with the increase of the number of alternating acclination; the volume ratio of liquid A to liquid B in gradient acclimation gradually decreases from 8-10:1 to 4-5:1; S3, adding nutrient elements into the effluent of the secondary sedimentation tank of the sewage plant to domesticate the activated carbon A in S1, the domestication time is 10-30 days, then the domesticated activated carbon is taken out, centrifuged and dewatered to obtain activated carbon C; the nutrient elements include nitrogen and easily biodegradable organic matter; the addition concentration of the nitrogen is 1-2 mg / L NH4 + -N; the addition concentration of the easily biodegradable organic matter is 2-10 mg / L TOC; The activated carbon B is suitable for an aerobic tank of a sewage plant; The activated carbon C is suitable for a secondary sedimentation tank of a sewage plant.

2. The method as claimed in claim 1, characterized in that In step S1, the raw water of a sewage plant refers to sewage after a grid and a primary sedimentation tank in a domestic sewage treatment plant using activated sludge method; a 5-12 cm gravel layer is arranged at the bottom of the activated carbon filter column in step S1.

3. The method as claimed in claim 1, characterized in that In step S2, the supernatant of sludge hydrothermal treatment refers to supernatant obtained by separating residual sludge after hydrolysis at 120-160℃ for 30-60 min; the supernatant of sludge anaerobic digestion refers to supernatant obtained by separating sludge in sludge anaerobic digestion engineering after anaerobic digestion at 35-37℃ for 10-30 d; the total nitrogen concentration in the supernatant of sludge anaerobic digestion and the supernatant of sludge hydrothermal treatment is 100-1000 mg / L, the humus content is 200-2000 mg / L, and the protein-like peak, fulvic acid-like peak and humic acid-like peak can be seen by three-dimensional fluorescence detection.

4. The resourceable activated carbon B or activated carbon C prepared by the method according to any one of claims 1-3.

5. The resourceable activated carbon B or activated carbon C according to claim 4 is applied in the field of sewage treatment and environmental protection.

6. A method for using a resourceable activated carbon in an aerobic tank of a sewage treatment plant, comprising the following steps: The activated carbon B according to claim 4 is added to the aerobic tank of the sewage treatment plant at a ratio of 100-500 mg / L every 5-10 d, and the added activated carbon can enter subsequent sludge treatment and disposal links including sludge dewatering, anaerobic digestion, aerobic fermentation, drying and incineration.

7. A method of using a resource-usable activated carbon in a secondary sedimentation tank of a sewage treatment plant, characterized in that, The activated carbon C according to claim 4 is filled into a new filter column, and effluent from a secondary sedimentation tank of a sewage plant is introduced to carry out advanced treatment on the effluent from the secondary sedimentation tank. ​

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