Method and system for enhancing denitrification and decarburization of refractory industrial wastewater

Abstract

The present application relates to a kind of treatment method and system of strengthening the denitrification and carbon removal of refractory industrial wastewater.The method comprises: electrically enhanced hydrolytic acidification treatment step and denitrification and carbon removal treatment step;Wherein, in the electrically enhanced hydrolytic acidification treatment step, industrial wastewater is introduced into electrically enhanced hydrolytic acidification unit for hydrolytic acidification treatment, so that refractory organic matter is converted into easily degradable organic matter;In the denitrification and carbon removal treatment step, the industrial wastewater flowing out of the electrically enhanced hydrolytic acidification unit is subjected to nitrification and denitrification denitrification and organic matter degradation in the packing type two-stage A / O membrane bioreactor.The treatment method provided by the present application can improve the biodegradability of industrial wastewater, promote the conversion of organic carbon and nitrogen, simultaneously remove organic pollutants and ammonia nitrogen, and save operation cost.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method and system for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater. Background Technology

[0002] Recalcitrant organic industrial wastewater mainly originates from pharmaceutical, petrochemical, papermaking, printing and dyeing, and textile industries. This type of wastewater is generally characterized by high concentrations of organic nitrogen pollutants, strong biotoxicity, poor biodegradability, and difficulty in ammoniation. Once discharged into receiving water bodies, it will inevitably pose a significant threat to human health and the sustainable development of the ecological environment. Therefore, the treatment of recalcitrant organic nitrogen wastewater has received widespread attention from researchers both domestically and internationally.

[0003] Currently, nitrogen-containing wastewater treatment methods mainly include physicochemical methods (such as sedimentation, filtration, electrokinetic remediation, ion exchange, and chemical reduction) and biological methods (such as anaerobic and aerobic biological methods). In practical engineering, biological technologies are often used for the pretreatment of recalcitrant organic nitrogen wastewater. However, microorganisms in biological treatment units are easily inhibited by the toxicity of recalcitrant organic nitrogen pollutants, limiting the conversion of organic nitrogen to ammonia nitrogen and leaving residual organic nitrogen in the effluent, thus causing the total nitrogen in the effluent to fail to meet standards. The ammonification of organic nitrogen is the initial step in biological denitrification, and its completeness directly affects the denitrification effect of subsequent wastewater. Therefore, how to rapidly, efficiently, and stably convert recalcitrant organic nitrogen into ammonia nitrogen has become one of the key issues that urgently need to be addressed in nitrogen-containing wastewater treatment research.

[0004] In recent years, to overcome the problems of poor resistance to shock loads and unstable treatment efficiency in the pretreatment of recalcitrant organic nitrogen ammoniation using traditional biotechnology, researchers at home and abroad have attempted a series of studies on enhanced biological treatment of wastewater containing organic nitrogen. For example, adding electron donors to the reaction system or applying measures that can generate electron donors / accelerate electron transfer; applying micro-electric fields to bioreactors to enhance the decomposition of recalcitrant pollutants; and introducing a micro-aerobic environment into the reactor system to enrich the microbial population and improve the removal of recalcitrant pollutants.

[0005] Reference 1 discloses a pilot-scale study of a zero-valent iron-carbon-copper coupled biological method for treating chemical wastewater. This method involves preparing a certain proportion of zero-valent iron-carbon-copper (MFe-C-Cu) mixed packing material and coupling it with A… 2A three-month continuous flow pilot test was conducted using the O-biochemical process to treat centralized mixed chemical wastewater. The results showed that when the influent quality of the centralized chemical wastewater treatment plant met the plant's acceptance standards (COD ≤ 500 mg / L, ammonia nitrogen ≤ 50 mg / L, TN ≤ 80 mg / L), the MFe-C-Cu coupled hydrolysis acidification improved the ammonification rate of organic nitrogen by more than 15%. Compared with the original effluent quality, the COD removal rate increased by 10%, the ammonia nitrogen removal rate increased by 20%, and the TN removal rate increased by more than 10%.

[0006] Reference 2 discloses an electro-enhanced anaerobic process to enhance the biodegradation of pyridine in wastewater. The results show that under the application of 0.3 mA DC current, the biodegradation performance and stability of pyridine in the anaerobic reactor are significantly improved, with pyridine and total organic carbon removal efficiencies of 100.0%, 96.1±1.2%, and ammonia nitrogen formation rates of 60.1±2.1%, respectively.

[0007] Reference 3 discloses a micro-electric field-zero-valent iron (ZVFI) enhanced anaerobic hydrolysis acidification process. This process improves the hydrolysis acidification effect by adding ZVFI and increasing the micro-electric field, thereby improving the biodegradability of mixed industrial wastewater (TOC concentration 190 mg / L, COD concentration 490 mg / L, BOD5 concentration 72 mg / L, ammonia nitrogen 45 mg / L). The experiment was conducted simultaneously in four reactors: a micro-electric field-ZVFI anaerobic reactor, a micro-electric field anaerobic reactor, a ZVFI anaerobic reactor, and a conventional anaerobic reactor. The results showed that the micro-electric field-zero-valent iron had a significant promoting effect on hydrolysis acidification. When the hydraulic retention time was 81 h, the TOC removal rate reached 70%, the BOD5 / COD ratio increased from 0.15 to 0.41, and the biodegradability of the wastewater was significantly improved. The ammonia nitrogen concentration in the effluent of the micro-electric field-zero-valent iron enhanced hydrolysis acidification reactor (86.69 mg / L) was 32.9% higher than that of the ordinary anaerobic reactor (58.16 mg / L).

[0008] Reference 4 discloses a sequencing batch reactor (SBR) under intermittent microaerobic or anaerobic conditions to remove different concentrations of pyridine from synthetic wastewater. The results show that the intermittent microaerobic SBR process enhances the conversion of pyridine to ammonia nitrogen, achieving an ammonification rate higher than 60%, and its effluent pH is significantly higher than that under anaerobic conditions.

[0009] Reference 5 discloses an electrochemical-biological combined denitrification reactor. However, the electrobioreactor operates in a single environment, namely, under aerobic conditions, with nitrification as the main reaction. Although total nitrogen (TN) is removed under applied voltage, the main reaction still relies solely on the traditional biofilm method for denitrification. The aerobic environment affects the TN removal rate. In addition, the anode is a metal rod with a small surface area, placed in the center of the reactor, resulting in extremely limited contact with the particle electrode. The effective range gradually weakens around the anode, affecting the enrichment of electrogenic microorganisms. Furthermore, it is only applied to simulated wastewater (COD concentration 45 mg / L, ammonia nitrogen 30 mg / L, total nitrogen 40 mg / L) without experimental research on actual wastewater.

[0010] Reference 6 discloses an electro-enhanced bioreactor and a method for treating COD and TN in wastewater. Wastewater (COD concentration 230 mg / L, total nitrogen 24 mg / L) enters from the bottom of the electro-enhanced bioreactor and sequentially passes through a hydrolysis-acidification zone, an aeration zone, and an aerobic zone. Denitrification and decomposition of macromolecular organic matter are completed in the hydrolysis-acidification zone, while nitrification and organic matter degradation are completed in the aerobic zone, thus achieving deep removal of COD and TN from the wastewater. Calculations show that the COD removal rate is below 83%.

[0011] Although numerous studies have been conducted on wastewater treatment, especially on nitrogen-containing organic wastewater, and the aforementioned enhanced biotechnology has greatly improved the decomposition efficiency of recalcitrant organic nitrogen through various enhancement methods, most of the research has been concentrated in the laboratory stage and often uses self-prepared water. Research on some industrial wastewater containing recalcitrant organic nitrogen, such as pharmaceutical, petrochemical, and dyeing industrial wastewater, is limited.

[0012] Industrial wastewater differs from laboratory-prepared water in that it has a larger discharge volume, more complex composition, and more severe pollution. Conventional water quality indicators such as COD and TN are much higher in industrial wastewater than in laboratory-prepared water, making it difficult for traditional A / O processes to meet the requirements. Therefore, there is an urgent need to develop a new, stable, efficient, and low-cost process for treating recalcitrant organic industrial wastewater.

[0013] References:

[0014] Reference 1: Bian Weilin, Dai Jianjun, Dai Honggang. Pilot-scale study on zero-valent iron-carbon-copper coupled biological method for treating chemical wastewater [J]. Industrial Water Treatment, 2016, 36(09):25-28.

[0015] Cited literature 2: Jiang X, Shen J, Xu K, et al. Substantial enhancement ofanaerobic pyridine bio-mineralization by electrical stimulation[J]. WaterResearch, 2018, 130: 291-299.

[0016] Reference 3: Wang Jingxin, Cui Kangping. Micro-electric field-zero valent iron enhanced anaerobic hydrolysis acidification performance [J]. Journal of Environmental Engineering, 2014, 8(10): 4191-4195.

[0017] Cited literature 4: Sun G, Wan J, Sun Y, et al. Enhanced biodegradation of pyridineusing sequencing batch biofilm reactor under intermittent micro-aerobiccondition[J]. Environmental Technology, 2020, 41(8): 1034-1043.

[0018] Reference 5: CN101857309A

[0019] Reference 6: CN115893680A Summary of the Invention

[0020] The problem the invention aims to solve

[0021] To address the aforementioned technical problems, this invention provides a method and system for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater. By coupling an electro-enhanced hydrolysis acidification unit with a built-in nested electrode assembly to a packing-type two-stage A / O membrane bioreactor, the biodegradability of industrial wastewater can be effectively improved, organic nitrogen conversion can be promoted, and organic pollutants and ammonia nitrogen can be removed simultaneously without the need for additional carbon sources.

[0022] Solution for solving the problem

[0023] It has been found that the above-mentioned technical problems can be solved by implementing the following technical solutions:

[0024] [1]. This invention first provides a method for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater, the method comprising: an electro-enhanced hydrolysis acidification treatment step and a denitrification and carbon removal treatment step;

[0025] in,

[0026] In the electro-enhanced hydrolysis acidification treatment step, industrial wastewater is fed into the electro-enhanced hydrolysis acidification unit for hydrolysis acidification treatment, so as to convert recalcitrant organic matter into easily degradable organic matter.

[0027] In the denitrification and decarbonization treatment step, the industrial wastewater flowing out of the electro-enhanced hydrolysis acidification unit is subjected to nitrification-denitrification denitrification and organic matter degradation in a packed two-stage A / O membrane bioreactor.

[0028] The packed-type two-stage A / O membrane bioreactor includes a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence. The first aerobic unit (O1) is filled with microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor.

[0029] At least a portion of the industrial wastewater after the electro-enhanced hydrolysis acidification treatment is recirculated from the second anoxic unit (A2) to the first anoxic unit (A1) and from the second aerobic unit (O2) to the first aerobic unit (O1).

[0030] [2]. According to the processing method described in [1], the electro-enhanced hydrolysis acidification unit is provided with a nested electrode assembly, the electrode assembly including an inner biological cathode and an outer biological anode.

[0031] [3]. According to the processing method described in [2], wherein,

[0032] The biocathode includes one or more of the following: carbon felt, carbon paper, carbon cloth, and carbon brush.

[0033] The bioanode includes one or more of carbon felt, carbon paper, carbon cloth, and carbon brush.

[0034] [4]. The treatment method according to any one of [1] to [3], wherein the electro-enhanced hydrolysis acidification treatment step further includes micro-voltage application and micro-oxygen aeration treatment during the hydrolysis acidification treatment process.

[0035] [5]. According to the processing method described in [4], wherein,

[0036] The applied voltage is 0.2–0.8V; the aeration rate of the micro-oxygen aeration is 10–20 mL / min.

[0037] [6]. The processing method according to any one of [1] to [5], wherein,

[0038] The microbial carrier packing material accounts for 20% to 60% of the volume of the first aerobic unit (O1);

[0039] The microbial carrier packing material includes one or more of the following: polyester cotton, polyethylene plastic doped with ammonia nitrogen adsorbent (M-10), polyethylene plastic doped with manganese (M-Mn), and polyethylene plastic doped with iron tetroxide (M-Fe3O4).

[0040] [7]. The processing method according to any one of [1] to [6], wherein,

[0041] The hydraulic retention time in the electro-enhanced hydrolysis acidification unit is 12–36 h;

[0042] The hydraulic retention time in the packed-type two-stage A / O membrane bioreactor is 48–96 h.

[0043] The reflux ratio of the anoxic unit to the aerobic unit in the packed-type two-stage A / O membrane bioreactor is 100% to 200%.

[0044] [8]. The processing method according to any one of [1] to [7], wherein,

[0045] The dissolved oxygen concentration in the electro-enhanced hydrolysis acidification unit is 0.1–0.8 mg / L;

[0046] The dissolved oxygen concentration in the first anoxic unit (A1) is less than 0.1 mg / L;

[0047] The dissolved oxygen concentration in the first aerobic unit (O1) is 0.5–2 mg / L;

[0048] The dissolved oxygen concentration in the second anoxic unit (A2) is less than 0.1 mg / L;

[0049] The dissolved oxygen concentration of the second aerobic unit (O2) is 2-5 mg / L.

[0050] [9]. Furthermore, the present invention also provides a system for implementing the treatment method described in any one of [1] to [8], wherein the system comprises an electro-enhanced hydrolysis acidification unit, a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence, and the first aerobic unit (O1) is filled with microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor.

[0051]

[10] . According to the system described in [9], the electro-enhanced hydrolysis acidification unit is provided with a nested electrode assembly, the electrode assembly including an inner biological cathode and an outer biological anode.

[0052] The effects of the invention

[0053] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0054] 1) The industrial wastewater denitrification and carbon removal method provided by the present invention adopts an electro-enhanced hydrolysis acidification pretreatment coupled with a two-stage A / O membrane bioreactor (first anoxic unit A1, packed aerobic unit O1, second anoxic unit A2, and aerobic MBR unit O2) for synergistic treatment, which greatly improves the biodegradability of industrial wastewater, promotes the conversion of organic nitrogen, and can simultaneously remove organic pollutants and ammonia nitrogen.

[0055] 2) The method of this invention introduces industrial wastewater into the hydrolysis acidification zone from the bottom of the electro-enhanced hydrolysis acidification unit. Utilizing the stimulation and induction effect of the electric field, it enhances the activity of microorganisms and enzymes, domesticates and enriches functional microorganisms with special adaptability, improves the efficiency of converting recalcitrant pollutants into readily degradable substances, and increases the biodegradability of the wastewater. The suitable packing materials and structure in the packing-type aerobic unit provide a good attachment carrier for microorganisms, promotes the enrichment of environmentally sensitive and slow-growing microorganisms, improves the hydraulic conditions of the reactor, mitigates membrane fouling, and greatly enhances the overall removal efficiency and resistance to shock loads of the system. Simultaneously, by combining and fully utilizing the advantages of the two technical units, efficient and stable operation is achieved.

[0056] 3) The method of the present invention can efficiently and stably remove recalcitrant organic matter from industrial wastewater, resulting in COD levels below 100 mg / L, ammonia nitrogen levels below 10 mg / L, and total nitrogen levels below 60 mg / L in the effluent. This achieves a COD removal rate of over 99%, an ammonia nitrogen removal rate of over 97%, and a total nitrogen removal rate of over 88%. It also has significant advantages in reducing facility investment and operating costs, enhancing operational stability, and simplifying maintenance workload. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the process for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater according to an embodiment of the present invention.

[0058] Figure 2 This is a diagram showing the water quality indicators of each process unit in Embodiment 1 of the present invention;

[0059] Figure 3 This is a diagram showing the water quality indicators of each process unit in Embodiment 2 of the present invention. Detailed Implementation

[0060] The present invention will now be described in detail. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples.

[0061] It should be noted that:

[0062] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0063] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0064] In this specification, “Da” is used to represent the unit of molecular weight, “Dalton”.

[0065] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0066] In this specification, the terms "substantially" or "truly" mean that the error compared to the relevant perfect or theoretical standard is less than 1%, or less than 0.8%, or less than 0.6%. Furthermore, when "all" or "entire" is used in this specification, it also means "all" or "entire" in the sense of "substantially" or "truly".

[0067] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0068] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0069] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, or may occur in any of the circumstances described, and the description includes both the occurrence and non-occurrence of the event.

[0070] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0071] In this specification, the terms “comprising” and / or “including” are used to indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0072] In this instruction manual, "normal temperature" or "room temperature" refers to an indoor ambient temperature of "23±2℃".

[0073] <First Aspect>

[0074] In a first aspect, the present invention provides a method for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater, the method comprising sequentially performing an electro-enhanced hydrolysis acidification treatment step and a denitrification and carbon removal treatment step.

[0075] Industrial wastewater

[0076] The industrial wastewater of the present invention mainly contains recalcitrant organic matter, and in some specific embodiments, the industrial wastewater contains recalcitrant organic nitrogen and organic carbon.

[0077] In some specific embodiments, the recalcitrant organic compounds in the industrial wastewater are preferably macromolecular organic compounds with a molecular weight of 1000-10000 kDa and an aromatic structure, such as one or more aryl groups, including phenyl and heterocyclic aryl groups. Furthermore, in some preferred embodiments of the present invention, the recalcitrant organic compounds include aryl esters, amines, and phenols.

[0078] Furthermore, the industrial wastewater of the present invention also contains inorganic nitrogen. In some preferred embodiments of the present invention, the amount of inorganic nitrogen present in the industrial wastewater of the present invention, calculated as ammonia nitrogen, is 60 mg / L or more, preferably 70 mg / L or more, and more preferably 75 mg / L or more.

[0079] Furthermore, there are no particular requirements in principle for the total nitrogen value of the industrial wastewater of this invention, as it is related to its source. In some preferred embodiments of this invention, the total nitrogen concentration is 400 mg / L or more, preferably 420 mg / L or more, and more preferably 450 mg / L or more.

[0080] Furthermore, there are no special requirements in principle regarding the COD value of the industrial wastewater of this invention, as it is related to its source. In some specific embodiments of this invention, the organic matter content of the industrial wastewater is a COD value greater than 5000 mg / L.

[0081] Furthermore, there are no particular restrictions on the source of the industrial wastewater of this invention. For example, it can be wastewater discharged during the production process of certain industrial sectors, such as wastewater from oil extraction and wastewater discharged from the printing and dyeing, papermaking, pharmaceutical, chemical and pesticide industries.

[0082] Electro-enhanced hydrolysis acidification treatment steps

[0083] The electro-enhanced hydrolysis acidification treatment step of the present invention mainly involves passing industrial wastewater into an electro-enhanced hydrolysis acidification unit for hydrolysis acidification treatment, so as to convert recalcitrant organic matter into readily degradable organic matter.

[0084] In some specific embodiments, the readily degradable organic matter is preferably a small molecule organic matter with a molecular weight of less than 10 kDa, such as one or more of acids, amines, amides, phenols, alkanes, etc.

[0085] Specifically, the electro-enhanced hydrolysis acidification unit of the present invention is an upflow anaerobic sludge bed reactor (UASB) configuration, that is, industrial wastewater enters from the bottom of the electro-enhanced hydrolysis acidification unit, overflows after passing through the settling zone at the top, and by selecting this configuration of the electro-enhanced hydrolysis acidification unit, the loss of microorganisms can be reduced, and the effluent turbidity is low, which reduces the interference with subsequent treatment processes.

[0086] In some specific embodiments of the present invention, the electro-enhanced hydrolysis acidification unit is provided with a nested electrode assembly, the electrode assembly including an inner biological cathode and an outer biological anode.

[0087] There are no particular limitations in principle regarding the biocathode of this invention. In some preferred embodiments of this invention, the biocathode is a carbon material, which may include one or more of carbon felt (carbon fiber felt), carbon paper, carbon cloth, and carbon brushes. The biocathode of this invention does not require the use of chemical catalysts, thus reducing operating costs.

[0088] There are no particular limitations in principle regarding the bioanode of this invention. In some preferred embodiments of this invention, the bioanode is a carbon material, which may include one or more of carbon felt (carbon fiber felt), carbon paper, carbon cloth, and carbon brush. The bioanode of this invention has good electrical conductivity, a large specific surface area, and is easy for microorganisms to attach. It can also utilize microorganisms (e.g., electroactive microorganisms such as Shewanella and Geobacterium) to promote electricity generation, while simultaneously removing pollutants from wastewater.

[0089] In some preferred embodiments of the present invention, the hydrolysis acidification process further includes the application of a micro-voltage and micro-oxygen aeration. By applying a certain micro-voltage to the inner biological cathode and the outer biological anode, and providing a trace amount of oxygen aeration to the cathode, the activity of microorganisms and enzymes is enhanced, promoting the oxidative degradation of organic matter.

[0090] In some specific embodiments of the present invention, the applied voltage value is 0.2 to 0.8V, preferably 0.3 to 0.8V, more preferably 0.4 to 0.7V, for example, it can be 0.25V, 0.35V, 0.45V, 0.5V, 0.55V, 0.6V, 0.65V, 0.75V, etc.

[0091] In some specific embodiments of the present invention, the aeration rate of the micro-aerobic aeration is 10-20 mL / min, preferably 12-19 mL / min, more preferably 13-18 mL / min, for example, it can be 11 mL / min, 13 mL / min, 15 mL / min, 17 mL / min, etc.

[0092] There are no particular limitations on the operation method of micro-aerobic aeration in this invention. In some specific embodiments of this invention, for example, an aeration pipe can be installed in the electro-enhanced hydrolysis acidification unit, and micro-aerobic aeration can be carried out under the action of an air pump.

[0093] In some specific embodiments of the present invention, the dissolved oxygen concentration of the electro-enhanced hydrolysis acidification unit is 0.1-0.8 mg / L, preferably 0.2-0.8 mg / L, more preferably 0.3-0.8 mg / L, for example, 0.4 mg / L, 0.5 mg / L, 0.6 mg / L, 0.7 mg / L, etc.

[0094] In some preferred embodiments of the present invention, the biocathode is an aerobic biocathode, which mainly uses oxygen molecules (O2) as electron acceptors.

[0095] In this invention, the hydraulic retention time (HRT) of industrial wastewater in the electro-enhanced hydrolysis acidification unit can be selected according to the different types of industrial wastewater. In some specific embodiments of this invention, the hydraulic retention time of pharmaceutical wastewater in the electro-enhanced hydrolysis acidification unit can be 12–36 h, preferably 16–32 h, more preferably 20–28 h, for example, 14 h, 18 h, 22 h, 24 h, 26 h, 30 h, 35 h, etc. Insufficient hydraulic retention time will directly lead to a deterioration in effluent quality; excessive hydraulic retention time will not only fail to improve hydrolysis acidification efficiency, but will also lead to unnecessary consumption of manpower and resources, reduce overall process efficiency, and increase operating costs. By controlling the hydraulic retention time in the electro-enhanced hydrolysis acidification unit to 12–36 h, not only can the hydrolysis acidification efficiency be improved, but the effluent quality parameters can also be ensured to reach the ideal range.

[0096] The electro-enhanced hydrolysis acidification unit of this invention utilizes the stimulation and induction effect of an electric field to enhance the activity of microorganisms and enzymes, domesticate and enrich functional microorganisms with special adaptability, improve the efficiency of converting recalcitrant pollutants into easily degradable substances, and degrade macromolecular organic matter into small molecule organic matter, remove part of COD, and improve the biodegradability of wastewater.

[0097] Denitrification and decarbonization treatment steps

[0098] The denitrification and decarbonization process of this invention mainly involves nitrification, denitrification, and organic matter degradation of the industrial wastewater flowing out of the electro-enhanced hydrolysis acidification unit in a packed-type two-stage A / O membrane bioreactor.

[0099] Specifically, the packing-type two-stage A / O membrane bioreactor of the present invention includes a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence. The first aerobic unit (O1) is filled with microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor.

[0100] In some specific embodiments of the present invention, at least a portion of the industrial wastewater after the electro-enhanced hydrolysis acidification treatment is refluxed from the second anoxic unit (A2) to the first anoxic unit (A1) and from the second aerobic unit (O2) to the first aerobic unit (O1).

[0101] In some specific embodiments of the present invention, the reflux ratio of the anoxic unit and the aerobic unit in the packed-type two-stage A / O membrane bioreactor is 100% to 200%, for example, it can be 100%, 120%, 150%, 180%, 200%, etc.

[0102] In some specific embodiments of the present invention, the dissolved oxygen concentration of the first anoxic unit (A1) is less than 0.1 mg / L, preferably less than 0.08 mg / L, more preferably less than 0.06 mg / L, and even more preferably less than 0.05 mg / L. For example, it can be 0.01 mg / L, 0.02 mg / L, 0.03 mg / L, 0.04 mg / L, 0.045 mg / L, 0.049 mg / L, etc. Since excessively high oxygen concentrations will inhibit the activity of denitrifying bacteria, the present invention controls the dissolved oxygen concentration of the first anoxic unit (A1) to be less than 0.1 mg / L, so as to facilitate anaerobic or facultative anaerobic bacteria to use the organic matter in the incoming water as a carbon source to denitrify the NO in the nitrate solution returned from the aerobic unit. X -N is reduced to N2, achieving the effect of denitrification.

[0103] In some specific embodiments of the present invention, the dissolved oxygen concentration of the first aerobic unit (O1) is 0.5–2 mg / L, preferably 0.6–1.5 mg / L, more preferably 0.8–1.2 mg / L, for example, it can be 0.6 mg / L, 0.7 mg / L, 0.9 mg / L, 1.0 mg / L, 1.2 mg / L, 1.6 mg / L, 1.8 mg / L, 1.9 mg / L, etc.; by controlling the dissolved oxygen concentration of the first aerobic unit (O1) at 0.5–2 mg / L, the present invention facilitates the nitrifying bacteria to convert NH4+ into nitrogen oxides. + -N is oxidized to NO X-N and decarbonizing bacteria oxidize and decompose organic matter into water and carbon dioxide, thus achieving the effect of carbon removal.

[0104] In some specific embodiments of the present invention, the microbial carrier packing material accounts for 20% to 60% of the volume percentage of the first aerobic unit (O1), preferably 25% to 55%, more preferably 30% to 50%, for example, 24%, 28%, 32%, 36%, 40%, 44%, 48%, 52%, 56%, etc.; the packing material in the present invention, as a carrier of microorganisms, is in a fluidized state by relying on aeration and water flow. Microorganisms are attached to the surface and interior of the packing material and move randomly in the system with the packing material, thereby making more full contact with wastewater and achieving the purpose of water purification. At the same time, the packing material can also reduce the escape of air from the water and reduce the aeration amount.

[0105] In some specific embodiments of the present invention, the microbial carrier packing includes one or more of polyester cotton, polyethylene plastic doped with ammonia nitrogen adsorbent (M-10), polyethylene plastic doped with manganese (M-Mn), and polyethylene plastic doped with iron tetroxide (M-Fe3O4). The microbial carrier packing of the present invention can provide sufficient attachment space for microbial cells and their secreted extracellular polymers. The attachment of microorganisms inside and on the surface of the packing will greatly increase the biomass of the process, thereby improving the system's shock resistance. At the same time, due to the different concentration distribution of dissolved oxygen (DO) in the carrier packing, an oxygen concentration gradient is formed. An aerobic environment is formed outside the carrier packing, and an anoxic environment is formed inside. In this way, simultaneous nitrification and denitrification reactions can occur on the carrier packing, which improves the TN removal effect to a certain extent.

[0106] In the first aerobic unit (O1), the addition of microbial carrier packing material results in the activated sludge in the reactor being composed of both suspended and attached states. This significantly increases the overall sludge volume. The attached activated sludge is more stable, which can prevent the loss of slow-growing nitrifying bacteria, improve nitrification efficiency, increase the system's shock resistance, and reduce excess sludge production. At the same time, the first aerobic unit (O1) also has a certain denitrification effect, enhancing the nitrogen and carbon removal capabilities of the A / O process.

[0107] In some specific embodiments of the present invention, the dissolved oxygen concentration of the second anoxic unit (A2) is less than 0.1 mg / L, preferably less than 0.08 mg / L, more preferably less than 0.06 mg / L, and even more preferably less than 0.05 mg / L. For example, it can be 0.01 mg / L, 0.02 mg / L, 0.03 mg / L, 0.04 mg / L, 0.05 mg / L, 0.07 mg / L, 0.08 mg / L, etc. Since excessively high oxygen concentrations will inhibit the activity of denitrifying bacteria, the present invention controls the dissolved oxygen concentration of the second anoxic unit (A2) to less than 0.1 mg / L, further enabling anaerobic or facultative anaerobic bacteria to utilize the organic matter in the incoming water as a carbon source to denitrify the NO in the nitrate solution returned from the aerobic unit. X -N is reduced to N2, improving the denitrification effect.

[0108] In some specific embodiments of the present invention, the dissolved oxygen concentration of the second aerobic unit (O2) is 2-5 mg / L, preferably 2.5-5 mg / L, more preferably 3-5 mg / L, for example, it can be 2.2 mg / L, 2.4 mg / L, 2.8 mg / L, 3 mg / L, 3.5 mg / L, 4 mg / L, 4.5 mg / L, 4.8 mg / L, etc.; by controlling the dissolved oxygen concentration of the second aerobic unit (O2) at 2-5 mg / L, the present invention facilitates nitrifying bacteria to further nitrate NH4+. + -N is oxidized to NO X -N and decarbonizing bacteria oxidize and decompose organic matter into water and carbon dioxide, further improving the carbon removal effect.

[0109] In this invention, the membrane bioreactor is placed at the end of the biochemical treatment process. Due to the membrane's retention effect, the effluent turbidity can be greatly reduced, and sludge loss can be minimized. The sludge is then re-entered into the system via reflux, increasing sludge retention time and, in particular, enriching slow-growing nitrifying bacteria, thus improving nitrification efficiency. Based on the membrane pore size, membranes can be categorized as ultrafiltration, microfiltration, nanofiltration, and reverse osmosis membranes. Smaller pore sizes result in better retention, but also more severe membrane fouling and higher operating costs. In some specific embodiments of this invention, when the effluent meets certain standards, microfiltration ceramic membranes or hollow fiber membranes made of polyvinylidene fluoride (PVDF) are preferred.

[0110] In some specific embodiments of the present invention, the hydraulic retention time in the packing-type two-stage A / O membrane bioreactor is 48–96 h, preferably 55–90 h, more preferably 60–80 h, for example, 54 h, 58 h, 62 h, 66 h, 72 h, 78 h, 82 h, 86 h, etc.; by controlling the hydraulic retention time in the packing-type two-stage A / O membrane bioreactor to 48–96 h, not only can the denitrification and carbon removal efficiency be improved, but also the effluent water quality parameters can be guaranteed to reach the ideal range.

[0111] By implementing the above-described treatment method, the present invention can reduce COD in the effluent to below 100 mg / L, ammonia nitrogen to below 10 mg / L, and total nitrogen to below 60 mg / L.

[0112] <Second aspect>

[0113] In a second aspect of the present invention, a system for implementing the processing method described in the first aspect is provided. The system includes an electro-enhanced hydrolysis acidification unit, a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence. The first aerobic unit (O1) is filled with a microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor.

[0114] In some specific implementations, the electro-enhanced hydrolysis acidification unit is provided with a nested electrode assembly, which includes an inner biocathode and an outer bioanode, respectively connected to the negative and positive terminals of an external regulated DC power supply. Both the inner biocathode and the outer bioanode are in the form of annular columnar structures. A vertical microporous aeration pipe is installed in the annular columnar inner biocathode, and a trace amount of oxygen is provided by an air pump.

[0115] Example

[0116] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0117] Example 1

[0118] The composition of pharmaceutical wastewater is shown in Table 1 (where BOD5 / COD = 0.094 ± 0.005). Figure 1 As shown, the electro-enhanced hydrolysis acidification unit is an upflow anaerobic sludge blanket (UASB) configuration. Nested electrode assemblies are installed at the bottom of the unit. The internal biocathode (carbon fiber felt material) and external bioanode (carbon fiber felt material) are connected to the negative and positive terminals of an external regulated DC power supply, respectively. Both the internal and external biocathodes are annular columnar structures. Vertical microporous aeration pipes are installed in the annular columnar internal biocathode, and a trace amount of oxygen is supplied by an air pump. The packed aerobic unit (O1) is filled with 1.5cm × 1.5cm × 1.5cm polyester cotton, with a filling rate of 40%, and is equipped with aeration pipes. The membrane assembly in the aerobic membrane bioreactor (MBR) unit (O2) is a ceramic membrane.

[0119] In this process, pharmaceutical wastewater is fed into an electro-enhanced hydrolysis and acidification unit. The hydraulic retention time (HRT) in the electro-enhanced hydrolysis and acidification unit is 24 hours, a voltage of 0.5V is applied, and the micro-aerobic aeration rate is 15mL / min to maintain the dissolved oxygen concentration in the electro-enhanced hydrolysis and acidification unit at 0.5mg / L. The effluent from the electro-enhanced hydrolysis and acidification unit (with BOD5 / COD = 0.33±0.01) is fed into a two-stage A / O membrane bioreactor (passing sequentially through the first anoxic unit A1, the packed-type aerobic unit O1, and the second anoxic unit A / O). Unit A2 and the aerobic MBR unit O2, in a two-stage A / O membrane bioreactor with a packed bed, had a total hydraulic retention time (HRT) of 72 hours. The dissolved oxygen concentration in the packed bed aerobic unit (O1) was 1 mg / L, the dissolved oxygen concentration in the aerobic MBR unit (O2) was 3 mg / L, and the dissolved oxygen concentration in the first anoxic unit (A1) and the second anoxic unit (A2) was less than 0.05 mg / L. A2 was refluxed to A1, and O2 was refluxed to O1, with a reflux ratio of 100% between the anoxic and aerobic units. Effluent from the electro-enhanced hydrolysis acidification unit, the first anoxic unit (A1), the packed bed aerobic unit (O1), the second anoxic unit (A2), and the aerobic MBR unit (O2) was collected daily for relevant index testing, for a total of 47 days. The test results are as follows: Figure 2 As shown.

[0120] Example 2

[0121] The composition of the pharmaceutical wastewater is shown in Table 1 (where BOD5 / COD = 0.094 ± 0.005). The electro-enhanced hydrolysis acidification unit is a UASB configuration. Nested electrode assemblies are installed at the bottom of the unit. The internal biocathode (carbon fiber felt material) and external bioanode (carbon fiber felt material) are connected to the negative and positive terminals of an external regulated DC power supply, respectively. Both the internal and external biocathodes are annular columnar structures. Vertical microporous aeration pipes are installed in the annular columnar internal biocathode, and a trace amount of oxygen is supplied by an air pump. The packed aerobic unit (O1) is filled with 3cm diameter polyethylene plastic doped with ammonia nitrogen adsorbent (M-10), with a filling rate of 40%. The membrane assembly in the aerobic MBR unit (O2) is a ceramic membrane.

[0122] The treatment method in Example 2 was the same as that in Example 1. Water samples were taken daily from the electro-enhanced hydrolysis acidification unit, the first anoxic unit (A1), the packing-type aerobic unit (O1), the second anoxic unit (A2), and the aerobic MBR unit (O2) for relevant index testing, for a total of 47 days. The test results are as follows: Figure 3 As shown.

[0123] Comparative Example 1

[0124] The composition of pharmaceutical wastewater is shown in Table 1 (where BOD5 / COD = 0.094 ± 0.005). The wastewater is treated using a conventional hydrolysis-acidification reactor and a two-stage A / O membrane bioreactor. The hydrolysis-acidification reactor is a UASB configuration and contains no electrode components or micro-aerobic aeration. The first aerobic unit of the two-stage A / O membrane bioreactor has no microbial carrier packing material, and the membrane module in the aerobic MBR unit is a ceramic membrane.

[0125] Pharmaceutical wastewater is fed into a hydrolysis-acidification reactor with a hydraulic retention time (HRT) of 24 hours. The effluent from the hydrolysis-acidification reactor (with BOD5 / COD = 0.22 ± 0.02) is fed into a two-stage A / O membrane bioreactor (passing sequentially through a first anoxic unit, a first aerobic unit, a second anoxic unit, and an aerobic MBR unit). The total HRT in the two-stage A / O membrane bioreactor is 72 hours. The dissolved oxygen concentration in the first aerobic unit is 1 mg / L, the dissolved oxygen concentration in the aerobic MBR unit is 3 mg / L, and the dissolved oxygen concentration in the first and second anoxic units is less than 0.05 mg / L. The second anoxic unit is refluxed back to the first anoxic unit, and the aerobic MBR unit is refluxed back to the first aerobic unit, with a reflux ratio of 100% between the anoxic and aerobic units. Every day, water samples were taken from the hydrolysis acidification reactor, the first anoxic unit, the first aerobic unit, the second anoxic unit, and the aerobic MBR unit for relevant index testing, for a total of 47 days.

[0126] The test results of the pharmaceutical wastewater before and after treatment in Examples 1-2 and Comparative Example 1 are shown in Table 1:

[0127] Table 1

[0128]

[0129] As shown in Table 1, after treatment by the methods provided by this invention (Examples 1 and 2), the effluent COD concentration of pharmaceutical wastewater is less than 100 mg / L and the effluent total nitrogen concentration is less than 60 mg / L, which are far lower than the effluent COD concentration (1053 mg / L) and effluent total nitrogen concentration (104 mg / L) after treatment by the traditional treatment method (Comparative Example 1). This indicates that the treatment method of this invention has excellent denitrification and carbon removal performance for pharmaceutical wastewater and can effectively remove pollutants from the water.

[0130] The contribution rates of each unit in the two-stage A / O membrane bioreactor for pollutant removal (referring to pollutants in the wastewater treated by the electro-enhanced hydrolysis and acidification unit) of the pharmaceutical wastewater in Examples 1 and 2 are as follows: Figure 2 and Figure 3 As shown.

[0131] Depend on Figure 2 It can be seen that in Example 1, the packing-type aerobic unit (O1) contributed 45.3% to the removal of chemical oxygen demand (COD) and 45.3% to the removal of ammonia nitrogen (NH4). + The contribution rate of total nitrogen (TN) removal was 67.6%, and the contribution rate of the first anoxic unit (A1) to the removal of total nitrogen (TN) was 54.6%.

[0132] Depend on Figure 3 It can be seen that in Example 2, the first anoxic unit (A1) contributed 37.4% to COD removal and 53.2% to TN removal, while the packing-type aerobic unit (O1) contributed 75.7% to ammonia nitrogen removal.

[0133] In summary, COD and NH4 + Nitrogen (N) is primarily removed in the packed aerobic unit (O1), while nitrogen (TN) is primarily removed in the first anoxic unit (A1). This demonstrates that the packed aerobic unit (O1) not only performs COD removal but also achieves simultaneous denitrification through the localized zones formed by the microbial carrier packing. The addition of packing material to the aerobic unit can remove nitrogen through simultaneous nitrification and denitrification.

[0134] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0135] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for enhancing the denitrification and carbon removal of recalcitrant industrial wastewater, characterized in that, The method includes: an electro-enhanced hydrolysis acidification treatment step and a denitrification and decarbonization treatment step; in, In the electro-enhanced hydrolysis acidification treatment step, industrial wastewater is fed into the electro-enhanced hydrolysis acidification unit for hydrolysis acidification treatment, so as to convert recalcitrant organic matter into easily degradable organic matter. In the denitrification and decarbonization treatment step, the industrial wastewater flowing out of the electro-enhanced hydrolysis acidification unit is subjected to nitrification-denitrification denitrification and organic matter degradation in a packed two-stage A / O membrane bioreactor. The packed-type two-stage A / O membrane bioreactor includes a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence. The first aerobic unit (O1) is filled with microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor. At least a portion of the industrial wastewater after the electro-enhanced hydrolysis acidification treatment is recirculated from the second anoxic unit (A2) to the first anoxic unit (A1) and from the second aerobic unit (O2) to the first aerobic unit (O1); The electro-enhanced hydrolysis acidification unit is equipped with a nested electrode assembly, which includes an inner biological cathode and an outer biological anode. The biocathode includes one or more of the following: carbon felt, carbon paper, carbon cloth, and carbon brush. The bioanode includes one or more of carbon felt, carbon paper, carbon cloth, and carbon brush; The microbial carrier packing material includes one or more of the following: polyester cotton, polyethylene plastic doped with ammonia nitrogen adsorbent (M-10), polyethylene plastic doped with manganese (M-Mn), and polyethylene plastic doped with iron tetroxide (M-Fe3O4).

2. The processing method according to claim 1, characterized in that, The electro-enhanced hydrolysis acidification treatment step further includes applying a micro-voltage and micro-oxygen aeration during the hydrolysis acidification process.

3. The processing method according to claim 2, characterized in that, The applied voltage is 0.2–0.8V; the aeration rate of the micro-oxygen aeration is 10–20 mL / min.

4. The processing method according to any one of claims 1 to 3, characterized in that, The microbial carrier packing material accounts for 20% to 60% of the volume of the first aerobic unit (O1).

5. The processing method according to any one of claims 1 to 3, characterized in that, The hydraulic retention time in the electro-enhanced hydrolysis acidification unit is 12–36 h; The hydraulic retention time in the packed-type two-stage A / O membrane bioreactor is 48–96 h. The reflux ratio of the anoxic unit to the aerobic unit in the packed-type two-stage A / O membrane bioreactor is 100% to 200%.

6. The processing method according to any one of claims 1 to 3, characterized in that, The dissolved oxygen concentration in the electro-enhanced hydrolysis acidification unit is 0.1–0.8 mg / L; The dissolved oxygen concentration in the first anoxic unit (A1) is less than 0.1 mg / L; The dissolved oxygen concentration in the first aerobic unit (O1) is 0.5–2 mg / L; The dissolved oxygen concentration in the second anoxic unit (A2) is less than 0.1 mg / L; The dissolved oxygen concentration of the second aerobic unit (O2) is 2-5 mg / L.

7. A system for implementing the processing method according to any one of claims 1 to 6, characterized in that, The system includes an electro-enhanced hydrolysis acidification unit, a first anoxic unit (A1), a first aerobic unit (O1), a second anoxic unit (A2), and a second aerobic unit (O2) connected in sequence. The first aerobic unit (O1) is filled with microbial carrier packing material, and the second aerobic unit (O2) is a membrane bioreactor.

8. The system according to claim 7, characterized in that, The electro-enhanced hydrolysis acidification unit is equipped with a nested electrode assembly, which includes an inner biological cathode and an outer biological anode.

Images