Simultaneous treatment device and method for secondary effluent and excess sludge of sewage treatment plant

Abstract

This invention relates to a device and method for simultaneous treatment of secondary effluent and excess sludge in a wastewater treatment plant. The device includes a cathode chamber and an anode chamber, connected by an external circuit. A load is installed on the external circuit. The cathode chamber and anode chamber are separated by an anion exchange membrane. The outer shell of the cathode chamber is made of transparent material, and a light source is installed on its outer side. The anode chamber has a sludge inlet, a sludge outlet, a sludge circulation inlet, and a sludge circulation outlet. The sludge circulation inlet and outlet are connected by an external circulation pipe, on which a circulation pump is installed. The cathode chamber has a sludge inlet and an effluent outlet. Worms and electrogenic bacteria are attached to the surface of the anode material. CO2 is introduced into the conductive aeration membrane of the cathode material, with autotrophic denitrifying bacteria attached to the inner layer and a microalgae biofilm attached to the outer layer. This invention is simple to operate, easy to control, has low operating costs, and high wastewater treatment efficiency, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to a wastewater treatment technology, specifically a device and method for the simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant. Background Technology

[0002] With the increasing amount of wastewater generated from industrial production and daily life, the wastewater treatment industry has developed rapidly, with both treatment capacity and treatment rate steadily improving. However, with the increase in wastewater treatment capacity and increasingly stringent effluent discharge standards from wastewater treatment plants, the production of excess sludge will also continue to increase.

[0003] Wastewater sludge is a byproduct of wastewater purification using activated sludge. It contains various environmentally hazardous pollutants, including persistent organic pollutants that can cause cancer, birth defects, and gene mutations, as well as pathogenic microorganisms and heavy metals. Direct discharge into the environment can severely pollute soil, air, and rivers, indirectly impacting human development and community richness. Furthermore, the complex composition and high water content of wastewater sludge increase the difficulty of treatment and raise disposal costs for wastewater treatment plants.

[0004] Current wastewater treatment technologies mainly include physical, chemical, and biological treatment, with biological treatment accounting for a larger proportion. Microbial wastewater treatment is a green and environmentally friendly method, less prone to secondary pollution. The most commonly used microbial treatment method in wastewater treatment plants is the activated sludge process, which is typically used to remove organic pollutants from water but neglects the removal of nitrogen and phosphorus. This results in secondary effluent from wastewater treatment plants containing low concentrations of organic matter and certain amounts of nitrogen and phosphorus, failing to meet wastewater discharge standards, thus requiring further advanced treatment. In addition, the activated sludge process generates a large amount of excess sludge, leading to a continuous increase in operating costs.

[0005] Therefore, there is a need to develop a new technology that is low-cost, easy to operate, and can achieve efficient removal of nitrogen and phosphorus with good operating results for the treatment of secondary effluent and residual sludge from wastewater treatment plants. Summary of the Invention

[0006] The purpose of this invention is to provide a device and method for simultaneous treatment of secondary effluent and excess sludge from wastewater treatment plants, in order to solve the problems of large amounts of excess sludge generated by current wastewater treatment plants and high nitrogen and phosphorus content in secondary effluent.

[0007] This invention is implemented as follows: A device for simultaneous treatment of secondary effluent and residual sludge in a wastewater treatment plant includes a cathode chamber and an anode chamber. An anode material is disposed in the anode chamber, and a cathode material is disposed in the cathode chamber. The anode and cathode materials are connected by an external circuit, on which a load is installed. The cathode and anode chambers are separated by an anion exchange membrane. The outer shell of the cathode chamber is made of a transparent material, and a light source is disposed on the outside of the cathode chamber. The anode chamber has a sludge inlet, a sludge outlet, a sludge circulation inlet, and a sludge circulation outlet. The sludge circulation inlet and outlet are connected by an external circulation pipe, on which a circulation pump is installed. The cathode chamber has a water inlet and a water outlet. Worms and electrogenic bacteria are attached to the surface of the anode material. Autotrophic denitrifying bacteria are attached to the inner layer of the cathode material, and a microalgae biofilm is attached to the outer layer. The cathode material is a conductive aeration membrane, and an air inlet is disposed on the conductive aeration membrane.

[0008] There are several anode materials, and all anode materials are interconnected by conductive wires.

[0009] The air inlet is connected to the CO2 supply device via an air inlet pipe.

[0010] The sludge inlet is connected to a residual sludge storage tank via a sludge inlet pipe, and a sludge pump is installed on the sludge inlet pipe.

[0011] The water inlet is connected to the secondary water storage tank via an inlet pipe, and an inlet pump is installed on the inlet pipe.

[0012] A method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant includes the following steps.

[0013] a. Establish a device for simultaneous treatment of secondary effluent and residual sludge from a wastewater treatment plant.

[0014] b. Inject the remaining sludge into the anode chamber through the sludge inlet, and inject secondary effluent into the cathode chamber through the water inlet pump.

[0015] c. Start the circulation pump to circulate the remaining sludge in the anode chamber, turn on the CO2 gas supply device to input CO2 gas into the conductive aeration membrane, and turn on the light source outside the cathode chamber.

[0016] d. Electrogenic bacteria utilize the residual sludge in the anode chamber as an organic substrate, generating electrons that are transferred to the anode material. These electrons are then transferred to the cathode via an external circuit. The autotrophic denitrifying bacteria on the inner layer of the cathode surface accept these electrons to denitrify nitrates in the secondary effluent from the cathode chamber. Simultaneously, they use CO2 released from the conductive aeration membrane pores as an inorganic carbon source. Worms prey on the residual sludge, reducing its volume. The worms accelerate the breakdown of sludge cells, causing organic matter to dissolve from the sludge and enhancing electrogenic performance. Microalgae on the outer layer of the cathode surface perform photosynthesis under light irradiation, absorbing CO2 transferred from the inner layer of the conductive aeration membrane as an inorganic carbon source and consuming nitrogen and phosphorus in the secondary effluent. Unremoved NO3 in the cathode chamber... - and NO2 - Driven by the electric field, the ions are transferred through the anion exchange membrane to the anode chamber, where they are further reduced to N2 by denitrifying bacteria and removed.

[0017] e. The treated residual sludge is discharged from the sludge outlet, and the treated secondary effluent is discharged from the effluent outlet.

[0018] The sludge inlet is connected to a residual sludge storage tank via a sludge inlet pipe. A sludge inlet pump is installed on the sludge inlet pipe, and the speed at which the residual sludge is transported to the anode chamber is controlled by the sludge inlet pump.

[0019] The inlet is connected to the secondary outlet water storage tank through an inlet pipe. An inlet pump is installed on the inlet pipe to control the speed at which the secondary outlet water is transported to the cathode chamber.

[0020] The remaining sludge entering the anode chamber is circulated between the external circulation pipe and the anode chamber for 4 days by the circulation pump. After 4 days, all the remaining sludge in the anode chamber is discharged from the sludge outlet, and the remaining sludge is reinjected into the anode chamber from the sludge inlet.

[0021] Adjust the speed of the inlet pump so that the hydraulic residence time of the secondary effluent entering the cathode chamber is 1 day.

[0022] The anode and cathode chambers in this invention serve to reduce and utilize excess sludge and to perform deep nitrogen and phosphorus removal, respectively. The combined action of the two reaction chambers enables simultaneous treatment and resource utilization of secondary effluent and excess sludge from wastewater treatment plants. In the anode chamber, worms accelerate cell breakdown, dissolving organic matter from the sludge. Electrogenic bacteria in the anode chamber effectively degrade this organic matter and generate electricity. This generated electricity further enhances the disturbance effect of the worms and increases their metabolic rate. In the cathode chamber, autoaerobic denitrifying bacteria receive electrons from the electrogenic bacteria in the anode chamber. Simultaneously, CO2 released from the conductive aeration membrane in the cathode creates an anaerobic environment for the biofilm formed by the autoaerobic denitrifying bacteria on the inner surface, preventing the migration of oxygen produced by microalgae to the biofilm formed by the autotrophic denitrifying bacteria. This improves the efficiency of nitrate denitrification in the cathode chamber, thereby enhancing the nitrogen removal effect. The secondary effluent in the cathode chamber contains a certain amount of nitrogen and phosphorus. Simultaneously, the CO2 released from the conductive aeration membrane provides an inorganic carbon source for the microalgae. The metabolism of the microalgae on the carbon felt enables efficient removal of nitrogen and phosphorus pollutants from the secondary effluent. The electric field generated between the cathode and anode materials also stimulates the microalgae, increasing their activity and thus enhancing the removal efficiency of nitrogen and phosphorus. The anode and cathode chambers are separated by an anion exchange membrane. Unremoved NO3 in the cathode chamber... - and NO2 - Driven by the electric field, it will be transferred to the anode chamber, where it will be further reduced by anaerobic denitrifying bacteria and removed.

[0023] The anode chamber utilizes electrogenic bacteria to convert organic matter in the sludge into clean electrical energy, which is then used as the electron source for the autotrophic denitrification process on the cathode surface in the cathode chamber, thus achieving deep denitrification of the secondary effluent.

[0024] The conductive aeration membrane has an inner layer of autotrophic denitrifying bacteria and an outer layer of microalgae biofilm. CO2 is introduced into the membrane, providing ample inorganic carbon for both the outer layer of microalgae and the inner layer of autotrophic denitrifying bacteria. This reduces competition from the inner layer of heterotrophic denitrifying bacteria for the autotrophic denitrifying bacteria, while also minimizing O2 diffusion into the inner biofilm. This ensures the thickness and biomass of the inner anaerobic autotrophic denitrifying bacteria biofilm and inhibits the exchange of O2 and NO3 within the inner biofilm at the cathode. - and NO2 - The competition for electrons between them enhances the utilization rate of electrode electrons in the cathode denitrification process.

[0025] This invention is simple to operate, easy to control, and has low operating costs, providing an effective way to simultaneously treat and utilize secondary effluent and excess sludge from wastewater treatment plants. Attached Figure Description

[0026] Figure 1This is a structural diagram of the wastewater treatment plant secondary effluent and residual sludge simultaneous treatment device of the present invention.

[0027] In the diagram: 1. Residual sludge storage tank; 2. Sludge inlet pump; 3. Sludge circulation inlet; 4. Sludge inlet; 5. Anode material; 6. Anode chamber; 7. Sludge outlet; 8. Circulation pump; 9. Sludge circulation outlet; 10. Anion exchange membrane; 11. Cathode chamber; 12. Cathode material; 13. Water inlet; 14. Water outlet; 15. Light source; 16. Water inlet pump; 17. Secondary effluent storage tank; 18. External circuit; 19. Load; 20. Paperless recorder; 21. CO2 gas supply device; 22. Air inlet; 23. External circulation pipe. Detailed Implementation

[0028] like Figure 1 As shown, the wastewater treatment plant secondary effluent and residual sludge simultaneous treatment device of the present invention includes a cathode chamber 11 and an anode chamber 6. An anode material 5 is disposed in the anode chamber 6, and a cathode material 12 is disposed in the cathode chamber 11. The anode material 5 and the cathode material 12 are connected by an external circuit 18, and a load 19 is disposed on the external circuit 18.

[0029] The cathode chamber 11 and the anode chamber 6 are separated by an anion exchange membrane 10. The outer shell of the cathode chamber 11 is made of transparent material, and a light source 15 is installed on the outside of the cathode chamber 11. The anode chamber 6 is provided with a sludge inlet 4, a sludge outlet 7, a sludge circulation inlet 3, and a sludge circulation outlet 9. The sludge circulation inlet 3 and the sludge circulation outlet 9 are connected by an external circulation pipe 23, and a circulation pump 8 is installed on the external circulation pipe 23. The cathode chamber 11 is provided with a water inlet 13 and a water outlet 14.

[0030] Worms and electrogenic bacteria are attached to the surface of the anode material 5, and autotrophic denitrifying bacteria are attached to the inner layer of the cathode material 12, while microalgae biofilm is attached to the outer layer.

[0031] The cathode material 12 is a conductive aeration membrane, and an air inlet 22 is provided on the conductive aeration membrane.

[0032] The air inlet 22 is used to introduce CO2 into the conductive aeration membrane.

[0033] The air inlet 22 is connected to the CO2 supply device 21 via an air inlet pipe. The CO2 supply device 21 is used to supply CO2 gas. The CO2 supply device 21 can be a high-pressure CO2 cylinder.

[0034] A paperless recorder 20 is installed on the external circuit to record the output voltage readings.

[0035] The sludge inlet 4 and sludge circulation inlet 3 are located at the top of the anode chamber 6, while the sludge outlet 7 and sludge circulation outlet 9 are located at the bottom of the anode chamber 6.

[0036] The inlet 13 is located at the bottom of the cathode chamber 11, and the outlet 14 is located at the top of the cathode chamber 11.

[0037] The anode chamber 6 and the cathode chamber 11 are both made of plexiglass.

[0038] Specifically, the volume of both the anode chamber 6 and the cathode chamber 11 is 5 liters.

[0039] There are several anode materials 5, and all anode materials 5 are interconnected by conductive wires.

[0040] Among them, the anode material 5 can be carbon cloth, carbon felt, carbon paper, or graphite plate.

[0041] Specifically, the anode chamber 6 is equipped with 4 carbon felts.

[0042] Conductive wires can be made of materials with conductive properties, such as titanium wire.

[0043] The sludge inlet 4 is connected to the residual sludge storage tank 1 through the sludge inlet pipe, and the sludge inlet pump 2 is installed on the sludge inlet pipe.

[0044] The inlet 13 is connected to the secondary outlet storage tank 17 via an inlet pipe, and an inlet pump 16 is installed on the inlet pipe.

[0045] Using microalgae to treat secondary effluent from wastewater treatment plants can achieve highly efficient removal of nitrogen and phosphorus, and the microalgae can also be harvested for biodiesel production. However, due to the suspended nature of microalgae, a certain amount of microalgae remains in the effluent, making it difficult to separate the microalgae from the water, resulting in microalgae loss. To overcome these challenges, this invention attaches microalgae to a carrier, removing nitrogen and phosphorus from the secondary effluent while simultaneously solving the problem of difficult separation between microalgae and water. Using microalgae to treat urban secondary effluent opens up a new avenue for waste-to-waste treatment, energy conservation, and wastewater management. It is of great significance for sustainable economic development and ensuring the safety of aquatic ecosystems.

[0046] This invention uses a sludge pump 2 to pump the remaining sludge from the remaining sludge storage tank 1 into the anode chamber 6 through the sludge inlet 4. The surface of the anode material 5 in the anode chamber 6 is covered with worms that prey on the remaining sludge, accelerating cell breakdown, thereby treating and recycling the remaining sludge. The electrogenic bacteria attached to the surface also degrade the organic matter in the remaining sludge to generate electricity, thus achieving the effect of reducing the amount of sludge.

[0047] The electrons generated by the electrogenic bacteria first pass through the anode material 5, and then through the external circuit 18 to the cathode material 12 to form an electric current. An electric field is formed between the anode material 5 and the cathode material 12. The generated electric field will further enhance the disturbance effect of the worm and also enhance the metabolic rate of the worm.

[0048] The inlet pump 16 pumps the secondary effluent from the secondary effluent storage tank 17 into the cathode chamber 11 through the inlet 13. The cathode material 12 inside the cathode chamber 11 is covered with autoaerobic denitrifying bacteria, which receive electrons generated by the electrogenic bacteria at the anode. At the same time, the CO2 released from the cathode conductive aeration membrane 12 creates an anaerobic environment for the biofilm formed by the autoaerobic denitrifying bacteria on the inner surface, preventing the oxygen produced by the microalgae from migrating to the biofilm formed by the autoaerobic denitrifying bacteria, thereby improving the treatment efficiency of nitrate denitrification in the cathode chamber and achieving the effect of nitrogen removal.

[0049] The secondary effluent in cathode chamber 11 contains a certain amount of nitrogen and phosphorus. Simultaneously, CO2 released from the conductive aeration membrane provides an inorganic carbon source for microalgae. Microalgae on cathode material 12 perform photosynthesis under the condition of light source 15, consuming the nitrogen and phosphorus in the secondary effluent. The electric field generated between anode material 5 and cathode material 12 also stimulates microalgae, increasing their activity and thus enhancing the removal efficiency of nitrogen and phosphorus.

[0050] In addition, unreacted NO3 in cathode chamber 11 - and NO2 - Under the influence of the electric field, NO3 will pass through the anion exchange membrane 10 and enter the anode chamber 6. - and NO2 - The algae will then be removed by anaerobic denitrification. The microalgae collected by this system can be used for the production of biodiesel, realizing the resource utilization of nitrogen and phosphorus pollutants in the secondary effluent.

[0051] The present invention also discloses a method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant, comprising the following steps.

[0052] a. Establish a device for simultaneous treatment of secondary effluent and residual sludge from a wastewater treatment plant.

[0053] b. Inject the remaining sludge into the anode chamber 6 through the sludge inlet 4, and inject secondary effluent into the cathode chamber 11 through the water inlet pump 16.

[0054] c. Start the circulation pump to circulate the remaining sludge in the anode chamber, turn on the CO2 gas supply device to input CO2 gas into the conductive aeration membrane, and turn on the light source outside the cathode chamber.

[0055] d. Electrogenic bacteria utilize the residual sludge in the anode chamber as an organic substrate, generating electrons that are transferred to the anode material. These electrons are then transferred to the cathode via an external circuit. The autotrophic denitrifying bacteria on the inner layer of the cathode surface accept these electrons to denitrify nitrates in the secondary effluent from the cathode chamber. Simultaneously, they use CO2 released from the conductive aeration membrane pores as an inorganic carbon source. Worms prey on the residual sludge, reducing its volume. The worms accelerate the breakdown of sludge cells, causing organic matter to dissolve from the sludge and enhancing electrogenic performance. Microalgae on the outer layer of the cathode surface perform photosynthesis under light irradiation, absorbing CO2 transferred from the inner layer of the conductive aeration membrane as an inorganic carbon source and consuming nitrogen and phosphorus in the secondary effluent. Unremoved NO3 in the cathode chamber... - and NO2 - Driven by the electric field, the ions are transferred through the anion exchange membrane to the anode chamber, where they are further reduced to N2 by denitrifying bacteria and removed.

[0056] e. The treated residual sludge is discharged from sludge outlet 7, and the treated secondary effluent is discharged from effluent outlet 14.

[0057] The sludge inlet 4 is connected to the residual sludge storage tank 1 through the sludge inlet pipe. The sludge inlet pump 2 is installed on the sludge inlet pipe, and the speed at which the residual sludge is transported to the anode chamber 6 is controlled by the sludge inlet pump 2.

[0058] The inlet 13 is connected to the secondary outlet water storage tank 17 through the inlet pipe. An inlet pump 16 is installed on the inlet pipe to control the speed at which the secondary outlet water is delivered to the cathode chamber 11.

[0059] The remaining sludge entering the anode chamber 6 is circulated between the external circulation pipe 23 and the anode chamber 6 for 4 days under the action of the circulation pump 8. After 4 days, the remaining sludge in the anode chamber 6 is completely discharged from the sludge outlet 7, and the remaining sludge is reinjected into the anode chamber 6 from the sludge inlet 4.

[0060] Adjust the speed of the inlet pump 16 so that the hydraulic residence time of the secondary effluent entering the cathode chamber 11 is 1 day.

[0061] In this embodiment, since the volume of the cathode chamber 11 is 5 liters, in order to ensure that the hydraulic residence time of the secondary effluent in the cathode chamber 11 is 1 day, the flow rate of the inlet pump 16 is set to 3.5 ml / min.

[0062] The simultaneous treatment method for secondary effluent and residual sludge of wastewater treatment plants according to the present invention can achieve continuous treatment of residual sludge and secondary effluent from wastewater treatment plants.

Claims

1. A device for simultaneous treatment of secondary effluent and residual sludge in a wastewater treatment plant, comprising a cathode chamber and an anode chamber, wherein an anode material is disposed in the anode chamber, and a cathode material is disposed in the cathode chamber, the anode material and the cathode material are connected by an external circuit, and a load is disposed on the external circuit, characterized in that, The cathode chamber and anode chamber are separated by anion exchange membrane. The outer shell of the cathode chamber is made of transparent material, and a light source is installed on the outside of the cathode chamber. The anode chamber is equipped with a sludge inlet, a sludge outlet, a sludge circulation inlet, and a sludge circulation outlet. The sludge circulation inlet and outlet are connected by an external circulation pipe, and a circulation pump is installed on the external circulation pipe. The sludge inlet is connected to a residual sludge storage tank through a sludge inlet pipe, and a sludge inlet pump is installed on the sludge inlet pipe. The cathode chamber is equipped with a water inlet and a water outlet. There are several anode materials, and all anode materials are interconnected by conductive wires. Worms and electrogenic bacteria are attached to the surface of the anode materials. Autotrophic denitrifying bacteria are attached to the inner layer of the cathode material surface, and a microalgae biofilm is attached to the outer layer. The cathode material is a conductive aeration membrane, and an air inlet is provided on the conductive aeration membrane. The air inlet is connected to a CO2 supply device through an air inlet pipe.

2. The wastewater treatment plant secondary effluent and excess sludge simultaneous treatment device according to claim 1, characterized in that, The water inlet is connected to the secondary water storage tank via an inlet pipe, and an inlet pump is installed on the inlet pipe.

3. A method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant, characterized in that, Includes the following steps: a. Establish a wastewater treatment plant secondary effluent and residual sludge simultaneous treatment device as described in claim 1; b. Inject excess sludge into the anode chamber through the sludge inlet, and inject secondary effluent into the cathode chamber through the inlet pump; The sludge inlet is connected to a residual sludge storage tank via a sludge inlet pipe. A sludge inlet pump is installed on the sludge inlet pipe, and the speed at which the residual sludge is transported to the anode chamber is controlled by the sludge inlet pump. c. Start the circulation pump to circulate the remaining sludge in the anode chamber, turn on the CO2 gas supply device to input CO2 gas into the conductive aeration membrane, and turn on the light source outside the cathode chamber. d. Electrogenic bacteria utilize the residual sludge in the anode chamber as an organic substrate, generating electrons that are transferred to the anode material. These electrons are then transferred to the cathode via an external circuit. The autotrophic denitrifying bacteria on the inner layer of the cathode surface accept these electrons to denitrify nitrates in the secondary effluent from the cathode chamber. Simultaneously, they use CO2 released from the conductive aeration membrane pores as an inorganic carbon source. Worms prey on the residual sludge, reducing its volume. The worms accelerate the breakdown of sludge cells, causing organic matter to dissolve from the sludge and enhancing electrogenic performance. Microalgae on the outer layer of the cathode surface perform photosynthesis under light irradiation, absorbing CO2 transferred from the inner layer of the conductive aeration membrane as an inorganic carbon source and consuming nitrogen and phosphorus in the secondary effluent. Unremoved NO3 in the cathode chamber... - and NO2 - Driven by an electric field, the ions are transferred through the anion exchange membrane to the anode chamber, where they are further reduced to N2 by denitrifying bacteria and removed. e. The treated residual sludge is discharged from the sludge outlet, and the treated secondary effluent is discharged from the effluent outlet.

4. The method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant according to claim 3, characterized in that, The inlet is connected to the secondary outlet water storage tank through an inlet pipe. An inlet pump is installed on the inlet pipe to control the speed at which the secondary outlet water is transported to the cathode chamber.

5. The method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant according to claim 3, characterized in that, The remaining sludge entering the anode chamber is circulated between the external circulation pipe and the anode chamber for 4 days by the circulation pump. After 4 days, all the remaining sludge in the anode chamber is discharged from the sludge outlet, and the remaining sludge is reinjected into the anode chamber from the sludge inlet.

6. The method for simultaneous treatment of secondary effluent and excess sludge from a wastewater treatment plant according to claim 3, characterized in that, Adjust the speed of the inlet pump so that the hydraulic residence time of the secondary effluent entering the cathode chamber is 1 day.

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