Salt-containing wastewater treatment process for aramid fiber material production

Abstract

The invention provides a salt-containing wastewater treatment process for aramid fiber material production, and relates to the technical field of wastewater treatment.The salt-containing wastewater treatment process comprises the following steps of flocculation pretreatment, electrocatalytic oxidation treatment, salt-tolerant microbiological treatment, filter membrane separation and resource recycling.The salt-containing wastewater treatment process has the beneficial effects that organic pollutants and salt can be efficiently removed, the water quality can reach the national discharge standard, and environmental pollution is avoided. The environmental pollution is reduced. Through anaerobic fermentation methane production, reverse osmosis produced water reuse and crystalline salt recovery, resource recycling is realized, and the production cost is reduced. By adopting salt-tolerant microbial flora and an electrocatalytic oxidation technology, the stability and high efficiency of the treatment process under a high-salt condition are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a salt-containing wastewater treatment process for aramid material production. BACKGROUND

[0002] Aramid material, as a high-performance fiber, plays a key role in many high-end fields. However, aramid production inevitably produces a large amount of salt-containing wastewater. Such wastewater not only contains high concentrations of sodium chloride, potassium chloride and other salts, but also contains p-xylylenediamine and other refractory organic pollutants. Direct discharge of these wastewaters not only seriously pollutes the soil and water bodies, destroys the ecological balance, but also causes a great waste of water resources.

[0003] Currently, the traditional treatment process of simple physical sedimentation method cannot remove soluble salts and most organic pollutants; chemical precipitation method can remove part of heavy metal ions, but has limited effect on organic pollutants, and produces a large amount of chemical sludge, increasing the subsequent treatment cost; the conventional biological treatment process cannot efficiently degrade organic pollutants due to the inhibition of microbial activity in high-salt environment, resulting in that the water quality after treatment is difficult to meet the standard. SUMMARY

[0004] The purpose of the present application is to provide a salt-containing wastewater treatment process for aramid material production, which can efficiently remove salts and organic pollutants in wastewater, realize purification and resource recovery of wastewater, reduce treatment cost and reduce environmental pollution.

[0005] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the present application is as follows: a salt-containing wastewater treatment process for aramid material production, comprising the following steps: step 1, flocculation pretreatment: introducing aramid production salt-containing wastewater into a conditioning tank, ensuring uniform water quality by stirring equipment, adding sulfuric acid or sodium hydroxide by using a pH automatic adjusting system to adjust the pH value of the wastewater to 7-8, adding a composite flocculant composed of polyaluminum chloride (PAC) and polyacrylamide (PAM) in a specific ratio to the adjusted wastewater, and after flocculation reaction, the wastewater enters an inclined tube sedimentation tank for solid-liquid separation;

[0006] Step 2, electro-catalytic oxidation treatment: the flocculated and precipitated wastewater flows into an electro-catalytic oxidation reactor, boron-doped diamond (BDD) is used as anode and titanium plate is used as cathode, and the reaction is carried out under the action of direct current electric field, hydrogen evolution reaction occurs in the cathode area, the gas floatation effect of the generated hydrogen micro-bubbles is used to separate suspended impurities, and the alkaline environment formed near the cathode is used to remove heavy metal impurities;

[0007] Step 3, salt-tolerant microbial treatment: after electro-catalytic oxidation, the wastewater enters an anaerobic baffled reactor (ABR) inoculated with acclimated salt-tolerant anaerobic microbial flora, and the temperature in the reactor (ABR) is adjusted for reaction; the effluent from the reactor (ABR) enters a sequencing batch biofilm reactor (SBBR), and oxygen is provided by an aeration system; the reactor (SBBR) runs in cycles, including water feeding, aeration, sedimentation, and water draining stages;

[0008] Step 4, filtration membrane separation and resource recovery: the treated wastewater passes through an ultrafiltration membrane assembly, the ultrafiltration membrane is an external pressure type polyvinylidene fluoride (PVDF) membrane, the ultrafiltration product water enters a reverse osmosis device, the reverse osmosis device uses an anti-fouling composite membrane, the product water recovery rate reaches 70-80%, the reverse osmosis product water is recycled for production, and the reverse osmosis concentrated water enters a multi-effect evaporation crystallizer for evaporation and concentration, and the crystallized salt is separated by centrifugation, washed, dried, and then recycled as industrial salt.

[0009] As an improvement, the complex ratio of polyaluminum chloride (PAC) and polyacrylamide (PAM) in the composite flocculant is determined according to the wastewater quality and through experiments.

[0010] As an improvement, during the operation of the electro-catalytic oxidation reactor, the organic pollutant concentration in the wastewater and the current efficiency are monitored, and the current density and reaction time are adjusted in a timely manner.

[0011] As an improvement, during the operation of the sequencing batch biofilm reactor (SBBR), the organic matter concentration, ammonia nitrogen concentration, and other indicators in the wastewater are monitored, and the aeration time and sedimentation time operating parameters are optimized.

[0012] As an improvement, during the operation of the reverse osmosis device, the membrane assembly is periodically chemically cleaned to maintain the product water flux and desalination rate.

[0013] The beneficial effects of the present application are: efficient removal of organic pollutants and salt, water quality meeting national discharge standards, and reduction of environmental pollution; resource recycling and utilization, and reduction of production costs through anaerobic fermentation to produce methane, reverse osmosis product water reuse, and crystallized salt recovery; stable and efficient treatment process under high salt conditions by using salt-tolerant microbial flora and electro-catalytic oxidation technology. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a framework diagram of a salt-containing wastewater treatment process for aramid material production. DETAILED DESCRIPTION

[0015] In order to make the content of the present application more easily understood, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0016] AsFigure 1 As shown, a salt-containing wastewater treatment process for aramid material production includes the following steps:

[0017] Step 1, flocculation pretreatment: introduce aramid production salt-containing wastewater into a conditioning tank, ensure uniform water quality through stirring equipment, adjust the pH value of the wastewater to 7-8 by adding sulfuric acid or sodium hydroxide using an automatic pH adjustment system, add a composite flocculant composed of polyaluminum chloride (PAC) and polyacrylamide (PAM) in a specific ratio to the adjusted wastewater, and after flocculation, the wastewater enters an inclined tube sedimentation tank for solid-liquid separation.

[0018] Step 2, electro-catalytic oxidation treatment: the flocculated and precipitated wastewater flows into an electro-catalytic oxidation reactor, boron-doped diamond (BDD) is used as the anode and titanium plate as the cathode, and the reaction is carried out under the action of a direct current electric field. Hydrogen evolution reaction occurs in the cathode area, and the gas flotation effect of the generated hydrogen micro-bubbles is used to separate suspended impurities, while the alkaline environment formed near the cathode is used to remove heavy metal impurities.

[0019] Step 3, salt-tolerant microbial treatment: the electro-catalytic oxidation treated wastewater enters an anaerobic baffled reactor (ABR) inoculated with domesticated salt-tolerant anaerobic microbial flora, adjusts the temperature in the reactor (ABR) for reaction, and the reactor (ABR) effluent enters a sequencing batch biofilm reactor (SBBR), which provides oxygen through an aeration system. The reactor (SBBR) operating cycle includes the stages of water inflow, aeration, sedimentation, and water discharge.

[0020] Step 4, membrane filtration separation and resource recovery: the treated wastewater passes through a ultrafiltration membrane assembly, the ultrafiltration membrane uses external pressure type polyvinylidene fluoride (PVDF) membrane, the ultrafiltration product water enters a reverse osmosis device, the reverse osmosis device uses anti-pollution composite membrane, the product water recovery rate reaches 70-80%, the reverse osmosis product water is recycled for production, and the reverse osmosis concentrated water enters a evaporation crystallization system, the reverse osmosis concentrated water is evaporated and concentrated in a multi-effect evaporation crystallizer, and the crystallized salt is separated by centrifugation, washed, dried, and then recycled as industrial salt.

[0021] The compounding ratio of polyaluminum chloride (PAC) and polyacrylamide (PAM) in the composite flocculant is determined according to the wastewater quality and through experiments.

[0022] During the operation of the electro-catalytic oxidation reactor, the concentration of organic pollutants in the wastewater and the current efficiency are monitored, and the current density and reaction time are adjusted in a timely manner.

[0023] During the operation of the sequencing batch biofilm reactor (SBBR), the concentration of organic matter, ammonia nitrogen, and other indicators in the wastewater are monitored, and the aeration time and sedimentation time operating parameters are optimized.

[0024] During the operation of the reverse osmosis device, the membrane assembly is periodically chemically cleaned to maintain the product water flux and desalination rate.

[0025] In actual use, the application determines the compounding ratio of PAC and PAM according to the wastewater quality condition, realizes the maximization of flocculation effect, reduces the risk of blockage of subsequent treatment equipment, guarantees the smoothness of the treatment process, in the electro-catalytic oxidation treatment stage, the automatic monitoring system continuously tracks the organic pollutant concentration and current efficiency, without frequent manual intervention, the current density and reaction time can be adjusted in time, to ensure that the oxidation reaction is always in an efficient state, effectively reduce the cost of wastewater treatment, the salt-tolerant microbial flora in the ABR reactor and the SBBR reactor can exhibit good treatment effect on wastewater containing salt with different concentrations, through accurate regulation of the temperature, dissolved oxygen and other parameters in the reactor, the metabolic activity of microorganisms can be further strengthened, the treated wastewater is treated by the ultrafiltration membrane assembly, the ultrafiltration water is treated by the reverse osmosis device, to generate reverse osmosis concentrated water, the reverse osmosis concentrated water enters the evaporation crystallization system, the reverse osmosis concentrated water is evaporated and concentrated in the multi-effect evaporation crystallizer, the crystallized salt is separated by centrifugation, washed and dried, and then recycled as industrial salt.

[0026] The above only describes the preferred embodiments of the present application patent, and is not intended to limit the present application patent, any modification, equivalent replacement and improvement made within the spirit and principle of the present application patent should be included in the protection scope of the present application patent.

Claims

1. A process for treating salt-containing wastewater from aramid material production, characterized by, The method comprises the following steps: Step 1, flocculation pretreatment: the aramid production salt-containing wastewater is introduced into a conditioning tank, water quality is ensured to be uniform through a stirring device, sulfuric acid or sodium hydroxide is added by using a pH automatic adjusting system to adjust the pH value of the wastewater to 7-8, a composite flocculant compounded by polyaluminum chloride (PAC) and polyacrylamide (PAM) in a specific ratio is added to the conditioned wastewater, and after flocculation reaction, the wastewater enters an inclined tube sedimentation tank for solid-liquid separation; Step 2, electro-catalytic oxidation treatment: the flocculation and precipitation wastewater flows into an electro-catalytic oxidation reactor, boron-doped diamond (BDD) is used as an anode, a titanium plate is used as a cathode, and reaction is carried out under the action of a direct current electric field, hydrogen evolution reaction occurs in the cathode area, hydrogen gas micro-bubbles are used to separate suspended impurities through air floatation, and heavy metal impurities are removed by using the alkaline environment formed near the cathode; Step 3, salt-tolerant microbial treatment: the electro-catalytic oxidation wastewater enters an anaerobic baffled reactor (ABR), is inoculated with domesticated salt-tolerant anaerobic microbial flora, and is adjusted to react at a temperature in the reactor (ABR), and the reactor (ABR) effluent enters a sequencing batch biofilm reactor (SBBR), oxygen is provided through an aeration system, and the reactor (SBBR) runs in a cycle, including the water inlet, aeration, sedimentation and drainage stages; Step 4, filter membrane separation and resource recovery: the treated wastewater passes through an ultrafiltration membrane assembly, the ultrafiltration membrane is an external pressure type polyvinylidene fluoride (PVDF) membrane, the ultrafiltration product water enters a reverse osmosis device, the reverse osmosis device adopts an anti-pollution composite membrane, the product water recovery rate reaches 70-80%, the reverse osmosis product water is recycled for production, and the reverse osmosis concentrated water enters a multi-effect evaporation crystallizer, the reverse osmosis concentrated water is evaporated and concentrated in the multi-effect evaporation crystallizer, and the crystallized salt is separated by centrifugation, washed, dried and recycled as industrial salt.

2. The salt-containing wastewater treatment process for aramid material production according to claim 1, characterized in that, The compounding ratio of polyaluminum chloride (PAC) and polyacrylamide (PAM) in the composite flocculant is determined according to the wastewater quality and through experiments.

3. The salt-containing wastewater treatment process for aramid material production according to claim 1, characterized in that, During the operation of the electro-catalytic oxidation reactor, the organic pollutant concentration and current efficiency in the wastewater are monitored, and the current density and reaction time are adjusted in a timely manner.

4. The salt-containing wastewater treatment process for aramid material production according to claim 1, characterized in that, During the operation of the sequencing batch biofilm reactor (SBBR), the organic matter concentration, ammonia nitrogen concentration and other indicators in the wastewater are monitored, and the aeration time and sedimentation time operation parameters are optimized.

5. The salt-containing wastewater treatment process for aramid material production according to claim 1, characterized in that, During the operation of the reverse osmosis device, the membrane assembly is regularly chemically cleaned to maintain the product water flux and desalination rate.

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