CN-122010328-A - PFAS and microplastic removing device based on micro-nano bubble jet-drip enrichment in drinking water

Abstract

The invention belongs to the technical field of drinking water purification, and particularly relates to a device for removing PFAS and microplastic in drinking water based on micro-nano bubble jet-drip enrichment. The device of the invention captures PFAS and microplastic by utilizing rising bubbles according to the enrichment characteristic of the PFAS and microplastic at a gas-liquid interface and brings the PFAS and microplastic to a liquid level to form injection drops so as to be removed, and particularly comprises a water inlet pretreatment unit, an air supply regulation unit, a core reaction unit, an aerosol capturing unit and an intelligent control cabinet, wherein the water inlet pretreatment unit is used for preliminarily adsorbing the PFAS in a water body, the air supply regulation unit is used for generating a large number of micro-bubbles to rise, the core reaction unit comprises a cylindrical reaction kettle body provided with an aeration assembly, the aerosol capturing unit is used for sucking and condensing and separating injection drops generated by bubble breakage, and the intelligent control cabinet is used for collecting sensor data in real time and regulating the operation states of a pump and a fan.

Inventors

• WANG XIAOFEI
• Ma Xiewen

Assignees

• 复旦大学

Dates

Publication Date

20260512

Application Date

20260124

Claims (5)

1. 1. The device for removing PFAS and microplastic in the micro-nano bubble jet enriched drinking water is characterized in that by utilizing enrichment characteristics of PFAS and microplastic at a gas-liquid interface, when bubbles reach water surface to be ruptured, upward liquid jet formed by cavity collapse induction is broken into jet drops, long-chain PFAS has low surface tension and high surface activity, the long-chain PFAS is extremely easy to enrich at the interface and enter into jet drops, enrichment factors can be thousands times, and meanwhile, rising bubbles can effectively capture the microplastic and bring the microplastic to the interface so as to be convenient to remove, and the device structurally comprises a water inlet pretreatment unit (1), a core reaction unit (6), an air supply regulation unit (24), an aerosol capturing unit (28) and an intelligent control cabinet (34), wherein: The pretreatment unit (1) for inflow water is used for preliminarily adsorbing short-chain PFAS in a water body and comprises a raw water tank (2), an inflow peristaltic pump (3), a pretreatment column (4) and an inflow ball valve (5), wherein the raw water tank (2) is connected to the inflow peristaltic pump (3) through a pipeline, an outlet of the peristaltic pump (3) is connected to a bottom inlet of the pretreatment column (4) through a hose, and an outlet at the top of the pretreatment column (4) is connected to a side water inlet at the bottom of a core reaction unit (6) through a pipeline provided with the inflow ball valve (5); The core reaction unit (6) comprises a vertically placed transparent cylindrical reaction kettle body (7), wherein a detachable micro-nano aeration assembly (8) is arranged at the bottom of the reaction kettle body (7), and comprises a quartz microporous filter plate which is clamped and fixed through an upper flange and a lower flange; The air supply regulation and control unit (24) is used for providing clean air or nitrogen with stable flow for the micro-nano aeration assembly, the air supply regulation and control unit (24) comprises an oil-free air compressor (25) and a gas mass flow controller (26), wherein the oil-free air compressor (25) is used for providing compressed air, the compressed air enters the air inlet chamber (10) at the bottom after being stabilized by the gas mass flow controller (26), and a large number of microbubbles are generated to rise through the quartz microporous filter plate (11); The device comprises an aerosol collecting unit (28), a conical gas collecting cover (29) made of stainless steel, wherein the conical gas collecting cover (29) is buckled on the top opening of the reaction kettle body (7), the bottom diameter of the conical gas collecting cover (29) is the same as that of the kettle body, an NW (25) vacuum flange interface is welded at the top outlet of the conical gas collecting cover, and the conical gas collecting cover is connected to the tangential inlet of an aerosol cyclone separator (31) through a negative pressure resistant connecting hose (30) embedded with a metal wire framework; The intelligent control cabinet (34) is integrated with a PLC (programmable logic controller) and is used for collecting sensor data in real time and regulating and controlling the running states of the pump and the fan.
2. 2. The device according to claim 1, wherein in the core reaction unit (6), a lower flange base (9) is arranged at the bottom of the reaction kettle body (7), a recess is arranged in the center of the lower flange base (9) to form an air inlet chamber (10), a first layer of silica gel sealing gasket (12), a quartz micropore filter plate (11) and a second layer of silica gel sealing gasket (12) are sequentially arranged above the air inlet chamber (10), an upper pressure ring flange (13) is arranged at the uppermost part, and the sandwich type clamping sealing structure ensures that gas can only enter the water above through micropores of the quartz micropore filter plate (11), uniform micro-nano bubbles are generated, and edge leakage is avoided.
3. 3. The device according to claim 2, wherein in the core reaction unit (6), two sensor interfaces, namely an RH sensor probe (16) and a temperature probe (17), are respectively arranged on the side walls of the reaction kettle body (7) at the heights from the bottom 650-700 mm and 350-400 mm in an opening way, the two sensor probes are respectively inserted into the kettle body in a sealing way through waterproof cable connectors (18), and probe signal wires are connected into the intelligent control cabinet (34).
4. 4. The device according to claim 2, wherein in the core reaction unit (6), the reaction kettle body (7) adopts an overflow water outlet mode, specifically, a bottom water outlet (20) is arranged at a position with a distance of 550-600mm from the bottom, a U-shaped adjustable overflow pipe (21) is connected to the outside of the water outlet, the overflow pipe (21) consists of two sections of UPVC pipes connected through a loose joint nut, the height of the highest point of the overflow pipe is adjusted through rotation, the stable liquid level in the reaction kettle body is accurately set, the distance between the liquid level and the lower edge of a top gas collecting hood is ensured to be stable within a range of 3-5cm as required by design, and the treated water flows into a water collecting tank through the overflow pipe.
5. 5. The apparatus of one of claims 1 to 4, wherein the workflow is: the method comprises the steps of initializing a system and setting parameters, switching on a power supply of an intelligent control cabinet (34), enabling the device to enter a standby state, setting operation parameters through a PLC (programmable logic controller) man-machine interaction interface, wherein the operation parameters comprise a flow set value of a water inlet peristaltic pump (3), an initial flow set value of a gas mass flow controller (26) and an air suction rate of a negative pressure suction pump (33); The second step, water inflow and pretreatment are carried out, a peristaltic pump (3) for inflow is started, water to be treated in a raw water tank (2) is pumped into a pretreatment column (4) through a pipeline, water flows through a column filled with strong alkaline anion exchange resin from bottom to top, 80% -90% of PFAS is adsorbed and removed by the resin in the process, pretreated water enters a reaction kettle body (7) from a side water inlet at the bottom of a core reaction unit (6) through a top pipeline and a water inflow ball valve (5), the liquid level in the reaction kettle body gradually rises along with continuous water inflow until reaching the working level set by the highest point of an external U-shaped adjustable overflow pipe (21), and the liquid level is stably kept at 3-5cm from the lower edge of a conical gas collecting hood (29) at the top; The third step, after the liquid level is stable, an intelligent control cabinet (34) sends out a command to start an air supply regulating and controlling unit (24), clean compressed air generated by an oil-free air compressor (25) enters an air inlet chamber (10) of a micro-nano aeration assembly (8) after being stabilized by a one-way valve (27) and a gas mass flow controller (26), after being buffered in the chamber, the air is uniformly pressed to pass through micro-scale pores of a quartz microporous filter plate (11) and is sheared and dispersed instantly above the quartz plate to generate a large number of micro-nano bubbles with average particle size smaller than 50 mu m, and the micro-bubbles are uniformly lifted in a cloud form in a reaction kettle body (7), and in the lifting process, micro-plastic particles in water are efficiently captured by the micro-bubbles, and the residual PFAS of the water body is adsorbed and enriched on the surface of the bubbles; The fourth step, the generation of jet drops and the capture of aerosol, the generation of the collapse of micro bubbles carrying pollutants when the micro bubbles rise to a liquid interface, the rapid collapse of the bubbles at the bottom under the action of surface tension to generate a jet of upward high-speed liquid, the concentration of the pollutants in the liquid drops is far higher than that of a bulk solution due to the high concentration of long-chain PFAS and micro plastics at the interface, at the moment, a relative humidity sensor probe (16) monitors the humidity change in a gas phase space, the relative humidity in the gas phase space is obviously increased due to the ejection of a large number of liquid drops, a high-humidity aerosol environment is formed, meanwhile, an aerosol capturing unit (28) is in an operation state, a negative pressure suction pump (33) forms a negative pressure area in a conical gas collecting hood (29) to rapidly suck the jet drops which are just generated and reach the gas phase space, the liquid drops enter a cyclone separator (31) along the tangential direction through a negative pressure resistant connecting hose (30), the liquid drops are separated from the gas flow under the action of centrifugal force and slide to the pollutant collecting bottle (32) at the bottom along the wall surface to form high-concentration waste liquid, and the air is discharged from the top of the cyclone separator; Fifthly, intelligent feedback regulation and control; in the whole running process of the device, an intelligent control cabinet (34) carries out accurate regulation and control based on sensor feedback, a temperature sensor probe (17) monitors the temperature of a system in real time, once severe fluctuation of the temperature is detected, the viscosity and the surface tension of water can be changed to influence bubble breakage, a PLC immediately sends an alarm or is linked with external temperature control equipment to intervene, meanwhile, a relative humidity sensor probe (16) is responsible for monitoring the stability of aerosol generation, if the relative humidity value is too low, namely, the relative humidity value is close to the ambient humidity, the PLC prompts insufficient liquid drop quantity or overlarge air flow generated by bubble breakage, the PLC instructs the opening of a gas mass flow controller (26) to increase the air bubble flux, and the system automatically optimizes and adjusts the air suction rate according to the condition that the cyclone separation efficiency is reduced due to continuous RH saturation; The sixth step is that the water is discharged and stopped, the purified clean water enters a U-shaped adjustable overflow pipe (21) through a water outlet (20) at the bottom and overflows into an external water collecting tank under the action of gravity to realize continuous water discharge, after the treatment task is finished, the device stops according to preset logic, namely, firstly, a water inlet peristaltic pump (3) and an air supply regulating and controlling unit (24) are closed, a negative pressure suction pump (33) is closed after time delay (30) seconds to ensure that residual aerosol in a pipeline is completely emptied, and finally, a drain valve (22) at the bottom of a reaction kettle body is opened to empty residual water in the kettle, so that one treatment period is completed.

Description

PFAS and microplastic removing device based on micro-nano bubble jet-drip enrichment in drinking water Technical Field The invention belongs to the technical field of drinking water purification, and particularly relates to a device for removing PFAS and microplastic in drinking water based on micro-nano bubble jet-drip enrichment. Background Conventional drinking water treatment plants relying on coagulation, flocculation and precipitation processes are generally ineffective for removing short chain PFAS (carboxylic acid < C8 or sulfonate < C6) and microplastics, often with PFAS removal rates below 50% and even more often with 1-10 μm microplastic removal rates below 2%. In order to solve the above problems, the industry currently attempts to employ a variety of advanced processing techniques, but all face significant technical bottlenecks. Although the Granular Activated Carbon (GAC) has better adsorption effect on long-chain PFAS, the adsorption effect on short-chain PFAS is weaker, so that an adsorption bed layer is penetrated rapidly, and long-term operation performance is greatly reduced. Anion Exchange Resins (AER), while effective in removing short-chain PFAS, are limited by early breakthrough, difficulty in resin regeneration, and high media and operating costs. High pressure membrane processes such as nanofiltration and reverse osmosis, although extremely high in removal rate, are energy intensive and produce wastewater of high concentration which is difficult to treat, and may even release additional microplastic fragments during operation. In addition, the conventional foam separation technology is excellent in high concentration waste liquid treatment, but in the drinking water treatment scene, it is difficult to maintain a stable foam layer due to extremely low surfactant concentration, and the removal efficiency of short chain PFAS is low. Aiming at the limitation of the prior art, the invention provides a novel removal strategy based on the phenomenon of bubble breakage to generate a jet drop. Unlike processes that rely on a stable foam layer, this technique takes advantage of the enrichment properties of PFAS and microplastic at the gas-liquid interface, and when the bubbles reach the water surface to collapse, the upward liquid jet induced by the collapse of the cavity breaks up into droplets. Because long-chain PFAS has low surface tension and high surface activity, the long-chain PFAS is extremely easy to concentrate at an interface and enter into jet liquid drops, the enrichment factor can reach thousands times, and meanwhile, the ascending bubbles can effectively capture micro-plastics and bring the micro-plastics to the interface. Although there have been studies on aerosol-mediated treatments, mostly focused on high ionic strength or wastewater conditions, there is a lack of low cost systematic solutions for the simultaneous removal of PFAS of different chain lengths with microplastic in low concentration environments of potable water. Therefore, developing a purification device which utilizes the interface enrichment principle and is efficient, economical and expandable has important application value Disclosure of Invention The invention aims to provide the PFAS and microplastic removing device in drinking water, which has the advantages of compact structure, stable operation, low energy consumption and high efficiency. The device for removing PFAS and microplastic in the water based on micro-nano bubble jet-drip enrichment provided by the invention utilizes the enrichment characteristic of PFAS and microplastic at a gas-liquid interface, when bubbles reach water surface to be broken, upward liquid jet formed by cavity collapse induction is broken into jet drops, long-chain PFAS (carboxylic acid < C8 or sulfonate < C6) has low surface tension and high surface activity, so that the injection drops are easily enriched at the interface, the enrichment factor can be thousands times, and meanwhile, the ascending bubbles can effectively capture the microplastic and bring the microplastic to the interface so as to be convenient to remove, and the device comprises a water inlet pretreatment unit 1, a core reaction unit 6, an air supply regulation and control unit 24, an aerosol capture unit 28 and an intelligent control cabinet 34, wherein: The inlet water pretreatment unit 1 is used for preliminarily adsorbing short-chain PFAS in a water body and comprises a raw water tank 2, an inlet water peristaltic pump 3, a pretreatment column 4 and an inlet water ball valve 5, wherein the raw water tank 2 is connected to the inlet water peristaltic pump 3 through a pipeline, an outlet of the peristaltic pump 3 is connected to a bottom inlet of the pretreatment column 4 through a hose, and an outlet at the top of the pretreatment column 4 is connected to a side water inlet at the bottom of a core reaction unit 6 through a pipeline provided with the inlet water ball valve 5; the core reaction unit 6 i