Device and method for improving sewage biochemical treatment efficiency under PFAS stress

Abstract

The invention relates to a device and a method for improving sewage biochemical treatment efficiency under PFAS stress, and belongs to the field of wastewater biological treatment. The device comprises an SBR reaction device, a magnetic stirrer, an aeration system and an ultrasonic generator, the SBR reaction device is provided with a water inlet and a water outlet, the water inlet is connected with a water inlet barrel through a peristaltic pump, and the water outlet is connected with a water outlet barrel through a water outlet valve; activated sludge is added into the SBR reaction device; a stirring rod of the magnetic stirrer is placed in the SBR reaction device; the aeration system comprises an aeration disc and an aeration device, and the aeration disc is located at the bottom in the SBR reaction device and connected with the aeration device; and an ultrasonic vibration rod of the ultrasonic generator is placed in the SBR reaction device. According to the device, the organic matter degradation efficiency under the PFASs stress can be improved. The method is simple and easy to operate, efficient treatment of organic matters can be realized, and the water quality standard of discharged water is improved.

Description

Technical Field

[0001] The present invention relates to the field of wastewater biological treatment, and in particular to a device and method for improving the biochemical treatment efficiency of wastewater under PFASs stress. Background Art

[0002] Wastewater discharged from households, industrial facilities, hospitals, hotels, and other commercial complexes in urban centers contains a variety of chemical pollutants, including antibiotics, pesticides, perfluorinated substances and their substitutes (PFASs), and pharmaceuticals. These substances are discharged into urban sewage networks and ultimately into sewage treatment plants. Although the concentrations of these pollutants in wastewater are generally low, they can still have toxic effects on microorganisms. These pollutants may affect microbial communities through various mechanisms, including inhibiting microbial activity, interfering with cell wall synthesis, reducing membrane permeability, inhibiting key enzyme activities, and causing DNA damage. These effects may not only weaken the growth and metabolic capacity of microorganisms but also further reduce the removal efficiency of chemical oxygen demand (COD), nitrogen, phosphorus, and toxic organic pollutants in sewage treatment plants, affecting the overall stability and operational effectiveness of sewage treatment systems.

[0003] As the most widely used wastewater treatment technology in the world, the activated sludge process relies on the activity and metabolic function of microorganisms for its operational stability. The presence of PFASs will destroy the microbial ecological balance of the sludge system, thereby affecting the removal efficiency of organic matter and pollutants such as nitrogen and phosphorus in the wastewater.

[0004] Experimental data showed that when the PFOA concentration increased from 0 to 0.1 mg / L, the COD removal rate in the SBR system decreased from 86.3% to 73.2%, and the total nitrogen (TN) removal rate decreased from 81.2% to 69.8%. This result shows that even at relatively low concentrations, PFASs can still have a significant adverse impact on sewage treatment systems. The persistence and recalcitrance of PFASs make it difficult for them to be effectively removed by traditional biodegradation methods during sewage treatment. At the same time, their adsorption characteristics may affect the sedimentation and flocculation characteristics of sludge particles, further reducing the treatment stability of the system. In addition, studies have shown that PFASs can directly interfere with the composition and function of microbial communities, inhibit the growth of key degrading bacteria, and lead to a decrease in the efficiency of organic matter degradation and biological nitrogen and phosphorus removal.

[0005] As a sound wave with a frequency higher than 20 kHz, ultrasound forms tiny bubbles through periodic compression and expansion when propagating in a liquid medium. When these bubbles reach a critical size, they undergo violent collapse, releasing instantaneous high pressure and high temperature, accompanied by strongly active free radicals, which trigger a series of physical and chemical reactions. In the field of organic wastewater treatment, ultrasonic technology has shown broad application prospects due to its high efficiency in degrading pollutants without introducing secondary pollution. Through the cavitation effect and free radical generation of weak ultrasound, it is possible to promote denitrification, organic matter degradation, and reduce sludge production without causing secondary pollution. In addition, ultrasonic technology can also improve microbial metabolic activity and enhance treatment efficiency. Summary of the Invention

[0006] In order to solve the problem of the inhibitory effect of existing PFASs on the efficiency of activated sludge in treating organic matter in wastewater under stress, the present invention starts from SBR and weak ultrasonic device to provide a device and method for improving the efficiency of biochemical treatment of wastewater under PFAS stress, in order to provide technical guidance and theoretical basis for improving the degradation efficiency of activated sludge on organic matter and its practical application.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A device for improving the biochemical treatment efficiency of sewage under PFAS stress, comprising an SBR reaction device, a magnetic stirrer, an aeration system, and an ultrasonic generator;

[0009] The SBR reaction device is provided with a water inlet and a water outlet, wherein the water inlet is connected to the water inlet bucket via a peristaltic pump, and the water outlet is connected to the water outlet bucket via a water outlet valve; activated sludge is added to the SBR reaction device;

[0010] The stirring rod of the magnetic stirrer is placed in the SBR reaction device;

[0011] The aeration system includes an aeration plate and an aeration device, wherein the aeration plate is located at the bottom of the SBR reaction device and is connected to the aeration device;

[0012] The ultrasonic vibration rod of the ultrasonic generator is placed in the SBR reaction device.

[0013] A method for improving the biochemical treatment efficiency of sewage under PFAS stress, comprising the following steps:

[0014] (1) Adding activated sludge and wastewater containing PFAS into the SBR reactor;

[0015] (2) Immerse the ultrasonic vibrator in water, start the ultrasonic generator and aeration device, and let them work for a certain period of time. Then, turn off the ultrasonic generator and aeration device, start the magnetic stirrer, stir for a certain period of time, let it stand, and then drain the water.

[0016] (3) Repeat steps (1)-(3).

[0017] Furthermore, in step (2), the ultrasonic frequency is 40 kHz, and the ultrasonic energy density is 9-11 W / L.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a weak ultrasonic coupling SBR device that can provide a reference for engineering applications. The device can improve the degradation efficiency of organic matter under PFASs stress. The present invention is simple and easy to operate, can achieve efficient treatment of organic matter, and improve the water quality standards of discharged water. It has been verified that the device of the present invention can increase the COD and ammonia nitrogen removal rates in wastewater compared to ordinary SBR devices, and typical difficult-to-degrade organic matter such as quinoline, furan, phenols and other substances are almost completely degraded, confirming that the device has a good deep treatment effect on difficult-to-degrade organic matter in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the device of the present invention.

[0021] In the figure, 1. SBR reaction device, 2. magnetic stirrer, 3. ultrasonic generator, 4. aeration plate, 5. peristaltic pump, 6. water inlet bucket, 7. water outlet bucket, 8. water outlet valve, 9. aeration device. DETAILED DESCRIPTION

[0022] The technical solutions and effects of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0023] Under the influence of PFASs, the efficiency of activated sludge in treating wastewater organic matter decreases significantly. Therefore, the present invention provides a device and method for improving the biochemical treatment efficiency of wastewater under PFAS stress. This device and method not only fills a gap in the field of PFAS treatment but also provides new insights for optimizing wastewater treatment technology, aligning with the principles of environmental protection and sustainable development. The research results will provide new technical means for controlling PFAS contamination and provide a scientific basis for optimizing future wastewater treatment systems and policy formulation.

[0024] Example 1

[0025] like Figure 1 As shown, a device for improving the biochemical treatment efficiency of sewage under PFAS stress in this embodiment includes an SBR reaction device 1, a magnetic stirrer 2, an aeration system, and an ultrasonic generator 3;

[0026] The SBR reaction device 1 is provided with a water inlet and a water outlet, wherein the water inlet is connected to a water inlet bucket 6 via a peristaltic pump 5, and the water outlet is connected to a water outlet bucket 7 via a water outlet valve 8; activated sludge is added to the SBR reaction device 1;

[0027] The stirring rod of the magnetic stirrer 2 is placed in the SBR reaction device;

[0028] The aeration system includes an aeration plate 4 and an aeration device 9. The aeration plate 4 is located at the bottom of the SBR reaction device and is connected to the aeration device 9.

[0029] The ultrasonic vibration rod of the ultrasonic generator 3 is placed in the SBR reaction device 1.

[0030] According to the above device, this embodiment also provides a method for improving the efficiency of biochemical treatment of sewage under PFAS stress, comprising the following steps:

[0031] (1) Adding activated sludge and wastewater containing PFAS into the SBR reactor;

[0032] (2) Immerse the ultrasonic vibrator in water, start the ultrasonic generator and aeration device, and let them work for a certain period of time. Then, turn off the ultrasonic generator and aeration device, start the magnetic stirrer, stir for a certain period of time, let it stand, and then drain the water.

[0033] (3) Repeat steps (1)-(3).

[0034] In this embodiment, the ultrasonic frequency is 40 kHz, and the ultrasonic sound energy density is 9-11 W / L.

[0035] As a specific implementation method, the activated sludge comes from the secondary sedimentation tank of the Shangjie Sewage Treatment Plant in Zhengzhou City, Henan Province, and the wastewater comes from the water after passing through the screen of the sewage treatment plant. The COD concentration is 200 mg / L, the total nitrogen concentration is 64 mg / L, and the ammonia nitrogen is 50 mg / L. Two types of PFASs wastewater are prepared respectively, with the concentrations of perfluorobutane sulfonic acid (PFBS) and perfluorooctanoic acid (PFOA) being 100 mg / L.

[0036] The biochemical treatment methods for these two types of wastewater are:

[0037] (1) Add activated sludge and wastewater containing PFAS into the SBR reactor and allow the water to flow for 10 minutes;

[0038] (2) Immerse the ultrasonic vibrator in water, start the ultrasonic generator and aeration device, with an ultrasonic sound energy density of 9.68 W / L, act for 10 minutes, aerate for 6 hours, then turn off the ultrasonic generator and aeration device, start the magnetic stirrer, stir for 4 hours, and then let it stand for 100 minutes to allow the sludge and water to reach a layer below the outlet valve, and then drain for 10 minutes; in this step, the ultrasonic frequency can be selected as 40 kHz;

[0039] (3) Repeat steps (1) to (3) for 10 days.

[0040] In this embodiment, the amount of activated sludge added is 1.5 L, the amount of wastewater added is 5 L, and the water exchange rate is 60%.

[0041] The water quality without ultrasound was used as the control and was shown in Table 1 after 10 days.

[0042] Table 1 Effluent quality after 10 days

[0043]

[0044] Results showed that at a PFOA concentration of 100 mg / L, COD removal reached 78.4%, a nearly 12.5% ​​improvement compared to the previous treatment, while ammonia nitrogen removal reached 36% and 79%, respectively. These improvements were approximately 18% compared to the treatment without ultrasound. Weak ultrasound treatment significantly improved the performance of the SBR system.

[0045] The method described in this paper utilizes a sequencing batch activated sludge process (SBR) to enhance pollutant degradation under PFAS stress through the cavitation effect of weak ultrasound (9.68 W / L, 10 minutes). Ultrasonic microfluidics and free radicals enhance microbial cell membrane permeability, accelerating PFAS desorption and intracellular metabolic enzyme activation. High-frequency mechanical vibration optimizes sludge floc structure and enhances mass transfer efficiency. Ultrasonication upregulates ATP synthase and catalase gene expression, restoring TCA cycle flux and reversing PFAS inhibition of the gluconeogenesis pathway.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A device for improving the biochemical treatment efficiency of sewage under PFAS stress, characterized in that: The device includes an SBR reaction device, a magnetic stirrer, an aeration system, and an ultrasonic generator; The SBR reaction device is provided with a water inlet and a water outlet, wherein the water inlet is connected to the water inlet bucket via a peristaltic pump, and the water outlet is connected to the water outlet bucket via a water outlet valve; activated sludge is added to the SBR reaction device; The stirring rod of the magnetic stirrer is placed in the SBR reaction device; The aeration system includes an aeration plate and an aeration device, wherein the aeration plate is located at the bottom of the SBR reaction device and is connected to the aeration device; The ultrasonic vibration rod of the ultrasonic generator is placed in the SBR reaction device.

2. A method for improving the biochemical treatment efficiency of sewage under PFAS stress, characterized in that: The method comprises the following steps: (1) Adding activated sludge and wastewater containing PFAS into the SBR reactor; (2) Immerse the ultrasonic vibrator in water, start the ultrasonic generator and aeration device, and let them work for a certain period of time. Then, turn off the ultrasonic generator and aeration device, start the magnetic stirrer, stir for a certain period of time, let it stand, and then drain the water. (3) Repeat steps (1)-(3).

3. The method for improving the biochemical treatment efficiency of sewage under PFAS stress according to claim 2, characterized in that: In the step (2), the ultrasonic frequency is 40 kHz and the ultrasonic energy density is 9-11 W / L.

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