A system and method for treating wastewater and promoting sludge granulation using a combination of a granulation fluidized bed-bioreactor process

Abstract

A granulation fluidized bed-bioreactor process combined system and method for treating wastewater and promoting sludge granulation, the system comprising: a first inlet end of a rapid stirring pool is communicated with sewage, a second inlet end of the rapid stirring pool is communicated with a PAC dosing barrel through a PAC dosing pump, outlet ends of the rapid stirring pool and the PAM dosing barrel are both communicated with a fluidized bed water inlet of a granulation fluidized bed, the granulation fluidized bed is provided with a reflux port at the top, and a fluidized bed water outlet is communicated with a bioreactor; sewage enters the rapid stirring pool, a PAC dosing barrel injects PAC reagent into the rapid stirring pool to destabilize raw water, the destabilized raw water flows into the granulation fluidized bed, mixes with PAM reagent injected into the granulation fluidized bed by a PAM dosing barrel, and realizes solid-liquid separation, supernatant of the granulation fluidized bed enters the bioreactor for reaction; carbon-rich products after separation are collected for carbon recovery; the two processes are combined to realize rapid granulation and stable operation under the condition of ensuring water quality.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a system and method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process. Background Technology

[0002] Granulated fluidized bed (FPB) systems, as a chemically enhanced treatment process (CEPT), exhibit good removal efficiency for particulate and colloidal substances, and offer advantages such as short retention time (small footprint). However, due to the presence of large amounts of dissolved COD and ammonia nitrogen in water, which are non-coagulable, FPB systems alone face challenges in treating these substances and are therefore typically used as a pretreatment measure. On the other hand, aerobic granular sludge systems (AGS) demonstrate good performance in treating dissolved substances due to their small footprint and low energy consumption. However, they are insufficient in removing particulate and colloidal substances, which may even affect the stability of the granular sludge.

[0003] For example, Chinese patent application CN202010209535.5 discloses a landfill leachate treatment system and method. The method introduces wastewater that has undergone a pretreatment stage into an anaerobic fluidized bed reactor to reduce ammonia nitrogen and COD and improve biodegradability before it enters a bioreactor for further treatment. However, the method does not explain how the combined process can achieve stable operation of granular sludge in the bioreactor, and it does not describe how the method is applied in the wastewater treatment process. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a granulation fluidized bed-bioreactor process combined with a system and method for treating wastewater and promoting sludge granulation. By strengthening the pretreatment at the front end, using reagents and seed crystals to screen the raw water, and controlling the composition of the influent in the bioreactor, a suitable environment for the growth of granular sludge is created. At the same time, the fluidized bed is used to enrich and recover insoluble substances that are difficult to treat biologically at the front end. The present invention has the advantages of rapid granulation, resource recovery, and easy in-situ modification.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A granulation fluidized bed-bioreactor combined process for treating wastewater and promoting sludge granulation includes a rapid mixing tank 2. The first inlet 2-1 of the rapid mixing tank 2 is connected to sewage. The second inlet 2-2 of the rapid mixing tank 2 is connected to a PAC dosing tank 3 via a PAC dosing pump 4. The outlet 2-3 of the rapid mixing tank 2 and the outlet 6-1 of the PAC dosing tank 6 are both connected to the fluidized bed inlet 8-1 of the granulation fluidized bed 8. The fluidized bed outlet 8-2 of the granulation fluidized bed 8 is connected to the bioreactor 11.

[0007] The outlet end 2-3 of the rapid mixing tank 2 is connected to the fluidized bed inlet 8-1 of the granulation fluidized bed 8 via the fluidized bed inlet pump 5; the outlet end 6-1 of the PAM dosing tank 6 is connected to the fluidized bed inlet 8-1 of the granulation fluidized bed 8 via the PAM dosing pump 7.

[0008] The fluidized bed outlet 8-2 of the granulation fluidized bed 8 is connected to the inlet 9-1 of the water storage tank 9, and the outlet 9-2 of the water storage tank 9 is connected to the bioreactor 11 through the bioreactor dosing pump 10.

[0009] A reflux port is provided above the granulation fluidized bed 8.

[0010] A method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process includes the following steps:

[0011] Step 1: Wastewater enters the rapid mixing tank 2 through the mixing tank inlet pump 1. At the same time, PAC dosing tank 3 injects PAC agent into the rapid mixing tank 2 through PAC dosing pump 4 to destabilize the raw water. The destabilization time is 1-10 minutes.

[0012] Step 2: The destabilized raw water flows out from the rapid mixing tank 2 and enters the granulation fluidized bed 8 through the fluidized bed inlet pump 5. The PAM agent in the PAM dosing tank 6 is mixed with the raw water in the granulation fluidized bed 8 through the PAM dosing pump 7 and then the solid-liquid separation is carried out.

[0013] Step 3: Solid-liquid separation is achieved in the granulation fluidized bed 8 by the impact of the reagent and the upward flow velocity. At the same time, the supernatant is refluxed inside the granulation fluidized bed 8 to increase the upward flow velocity. The supernatant in the effluent enters the bioreactor 11 for reaction.

[0014] Step 4: Collect the carbon enrichment products separated in the granulation fluidized bed 8 for carbon recovery.

[0015] The concentration of PAC agent in step 1 is 10-100 mg / L.

[0016] In step 2, the dosage of PAM agent is 0.5-10 mg / L.

[0017] In step 2, different types of crystal nuclei can be added to the granulation fluidized bed 8 to screen the raw water.

[0018] In step 3, the upflow velocity of the granulation fluidized bed 8 is 0.2-4 mm / s.

[0019] In step 3, the reflux ratio of the granulation fluidized bed 8 is 0.1-0.9.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. Stable operation of granular sludge. The aerobic granular sludge used in this invention, due to the screening of organic matter types, eliminates hydrolytic bacteria that feed on insoluble organic matter, thus ensuring the long-term stability of the granular sludge.

[0022] 2. Dual Granulation Capabilities. Existing aerobic granular sludge treatment technologies, using actual wastewater for granulation, generally suffer from long granulation cycles and poor particle stability. In this invention, the front-end granulation fluidized bed 8, through coagulation and seed adsorption, can form particles with inorganic cores. Simultaneously, by regulating the wastewater composition through the front-end granulation fluidized bed 8, the composition of the bioreactor influent is controlled, retaining readily biodegradable dissolved organic matter, creating a stable influent environment, and accelerating particle formation.

[0023] 3. Carbon recovery and utilization saves resources. The granules formed in the granulation fluidized bed 8 contain abundant carbon sources because they capture many particulate and colloidal organic matter. The carbon sources inside the granulation fluidized bed 8 can be discharged and collected for use in methanogenesis, anaerobic digestion, and cogeneration.

[0024] 4. The combined use of the reaction tanks: fluidized beds have a shorter HRT (Heat Reduction Time), which allows them to meet the treatment capacity while occupying a smaller area. AGS (Automatic Gas Storage System) also has the advantages of small footprint and low energy consumption. The combined use of the two can greatly reduce the land area occupied by the water plant and save land.

[0025] In summary, the present invention, through the combined fluidized bed-bioreactor process, has the advantages of rapid granulation, resource recovery, and easy in-situ modification. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system of the present invention.

[0027] Figure 2 This is a process flow diagram of the present invention.

[0028] Figure 3 shows the water treatment capacity of the combined process; Figure 3(a) shows the changes in ammonia nitrogen in the influent and effluent, Figure 3(b) shows the changes in COD in the influent and effluent, and Figure 3(c) shows the proportion of dissolved COD in the raw water and the fluidized bed treated effluent.

[0029] Figure 4 shows the changes in sedimentation performance during the bioreactor cultivation process, representing SV5 and SV6. 30 The variation diagrams are shown in Figure 4(a), which is the SV settlement diagram of a single process, and Figure 4(b) is the SV settlement diagram of a combined process.

[0030] Figure 5 shows the changes in particle size of activated sludge in the bioreactor system; Figure 5(a) shows the proportion of particle size distribution of granular sludge during single-process cultivation, and Figure 5(b) shows the changes in granular sludge over time during combined-process cultivation.

[0031] Figure 6 The images show gene sequencing data before and after particle formation in the two reactors; the main data are phylum-level species abundance maps.

[0032] The components are as follows: 1. Mixed tank inlet pump; 2. Rapid mixing tank; 2-1 First inlet end; 2-2 Second inlet end; 2-3 Outlet end; 3. PAC dosing tank; 4. PAC dosing pump; 5. Fluidized bed inlet pump; 6. PAM dosing tank; 6-1 Dosing outlet; 7. PAM dosing pump; 8. Granulating fluidized bed; 8-1 Fluidized bed inlet; 8-2 Fluidized bed outlet; 9. Reservoir; 10. Bioreactor inlet pump; 11. Bioreactor. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] This invention proposes a combined granulation fluidized bed-bioreactor process for wastewater treatment and to promote sludge granulation. The granulation fluidized bed 8 achieves solid-liquid separation, with the front-end removing particulate and colloidal substances, and the rear-end aerobic granular sludge removing and absorbing dissolved substances. This combined approach effectively reduces land occupation and achieves process intensification. Furthermore, the combined process accelerates particle formation, achieving a synergistic effect (1+1>2), demonstrating promising application prospects.

[0035] like Figure 1 As shown, a granulation fluidized bed-bioreactor process combined with wastewater treatment and sludge granulation system includes a rapid mixing tank 2. The first inlet end 2-1 of the rapid mixing tank 2 is connected to sewage through a mixing tank inlet pump 1. The second inlet end 2-2 of the rapid mixing tank 2 is connected to a PAC dosing tank 3 through a PAC dosing pump 4. The outlet end 2-3 of the rapid mixing tank 2 is connected to a pipeline through a fluidized bed inlet pump 5 and the outlet 6-1 of the PAC dosing tank 6 is connected to a PAC dosing pump 7. The end of the pipeline is connected to the fluidized bed inlet 8-1 of the granulation fluidized bed 8. The granulation fluidized bed 8 is connected to an internal reflux channel, that is, a reflux port is set at the top of the granulation fluidized bed 8 to return the liquid to the bottom. The fluidized bed outlet end 8-2 of the granulation fluidized bed 8 is connected to the inlet end 9-1 of a water storage tank 9. The outlet end 9-2 of the water storage tank 9 is connected to a bioreactor 11 through a bioreactor dosing pump 10.

[0036] Rapid mixing tank 2 is mainly used for rapid destabilization of raw water. The tank is equipped with a stirring device. As the raw water and PAC agent are injected into the mixing tank, they are stirred and mixed rapidly at a speed of 200rpm-1200rpm.

[0037] The granulation fluidized bed 8 is mainly used to achieve solid-liquid separation. After the raw water is destabilized in the rapid stirring tank, it is pumped into the granulation fluidized bed together with the PAM reagent. The fluidized bed is equipped with a stirring device to slowly mix at 10rpm-100rpm. The sludge settles at the bottom of the fluidized bed. A return port is set above the fluidized bed to return the supernatant and micro flocs to the bottom of the device to increase the upward flow rate and extend the reaction time.

[0038] Bioreactor 11 is primarily designed for the biological removal of pollutants. Its interior mainly consists of activated sludge, but can also be a biofilm. It operates in both intermittent and continuous modes and includes internal stirring and aeration equipment. Various chemicals can be added as needed.

[0039] A method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process includes the following steps:

[0040] Step 1: Wastewater flows into the first inlet 2-1 of the rapid mixing tank 2 through the mixing tank inlet pump 1. At the same time, PAC dosing tank 3 injects PAC agent into the second inlet 2-2 of the rapid mixing tank 2 through PAC dosing pump 4. The concentration of PAC agent is 10-100mg / L to destabilize the raw water. The destabilization time is between 1-10min.

[0041] Step 2: After destabilization, the raw water flows out from the outlet 2-3 of the rapid mixing tank 2 and is pumped into the pipeline by the fluidized bed inlet pump 5. Then, the PAM reagent in the PAM dosing tank 6 is mixed with the raw water in the pipeline at a dosage of 0.5-10 mg / L through the PAM dosing pump 7 from the outlet 6-1. After mixing, it enters from the fluidized bed inlet 8-1 of the fluidized bed 8 for solid-liquid separation. Different types of crystal nuclei can also be added to the fluidized bed 8 to achieve screening of the raw water.

[0042] Step 3: In the granulation fluidized bed 8, the destabilized raw water achieves solid-liquid separation through chemical coagulation and physical adsorption, removing a large amount of insoluble organic matter. At the same time, the supernatant is refluxed inside the granulation fluidized bed 8 to increase the upward flow velocity. The reflux ratio of the granulation fluidized bed 8 is 0.1-0.9, ensuring that the upward flow velocity of the fluidized bed is 0.2-4 mm / s. Then, the supernatant is collected in the water storage tank 9 through the fluidized bed outlet 8-2, and then pumped into the bioreactor 11 by the bioreactor inlet pump 10 for treatment. The supernatant flowing out through the fluidized bed outlet 8-2 basically does not contain insoluble organic matter, the proportion of biological degradation of complex organic matter in the sludge decreases, and the granulation speed is accelerated.

[0043] Step 4: Collect the carbon enrichment products separated in the granulation fluidized bed 8 for carbon recovery.

[0044] like Figure 1 As shown, the combined process includes: a rapid mixing tank 2, through which wastewater flows in from the first inlet end 2-1 using a mixing tank inlet pump 1; and a PAC dosing tank 3, through a PAC dosing pump 4, injects PAC reagent into the second inlet end 2-2 for destabilization. The destabilized raw water flows out from the outlet end 2-3 of the rapid mixing tank 2. The destabilized raw water is then mixed with PAM reagent in the PAM dosing tank 6 via a pipeline through a fluidized bed inlet pump 5 and a PAM dosing pump 7. After mixing, the raw water enters the granulation fluidized bed 8 from the fluidized bed inlet 8-1 for solid-liquid separation. The raw water achieves solid-liquid separation in the granulation fluidized bed 8, and then the supernatant is collected in the storage tank 9 through the fluidized bed outlet end 8-2 of the granulation fluidized bed 8. Finally, it is injected into the bioreactor 11 by the bioreactor dosing pump 10.

[0045] This invention utilizes PAC dosing tank 3 and PAM dosing tank 6 to coagulate solid substances and achieve solid-liquid separation.

[0046] After a series of pretreatments, the influent is pumped into the bioreactor 11 to treat pollutants using biological processes. The bioreactor used for biological processes is not limited to a single type of reactor; it is applicable to other water treatment processes.

[0047] The method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process as described in this invention is not limited to adding reagents to achieve solid-liquid separation in the fluidized bed. Seed crystal addition and other measures to control the fluidized bed sludge should also be included in the scope of protection of this invention.

[0048] Example

[0049] A method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process includes the following steps:

[0050] Step 1: Wastewater flows into the first inlet 2-1 of the rapid mixing tank 2 through the mixing tank inlet pump 1. At the same time, PAC dosing tank 3 injects PAC agent into the second inlet 2-2 of the rapid mixing tank 2 through PAC dosing pump 4. The concentration of PAC agent is 60 mg / L, and the raw water is destabilized for 4 minutes.

[0051] Step 2: After destabilization, the raw water flows out from the outlet 2-3 of the rapid mixing tank 2 and is pumped into the pipeline by the fluidized bed inlet pump 5. Then, the PAM reagent in the PAM dosing tank 6 is mixed with the raw water in the pipeline at a dosage of 6 mg / L through the PAM dosing pump 7 from the outlet 6-1. The mixture then enters from the fluidized bed inlet 8-1 of the fluidized bed 8 for solid-liquid separation. Different types of crystal nuclei can also be added to the fluidized bed 8 to achieve screening of the raw water.

[0052] Step 3: In the granulation fluidized bed 8, the destabilized raw water achieves solid-liquid separation through chemical coagulation and physical adsorption, removing a large amount of insoluble organic matter. At the same time, the supernatant is refluxed inside the granulation fluidized bed 8 to increase the upward flow velocity. The reflux ratio of the granulation fluidized bed 8 is 0.5, ensuring that the upward flow velocity of the fluidized bed is 0.4 mm / s. Then, the supernatant is collected in the water storage tank 9 through the fluidized bed outlet 8-2, and then pumped into the bioreactor 11 by the bioreactor inlet pump 10 for treatment. The supernatant flowing out through the fluidized bed outlet 8-2 basically does not contain insoluble organic matter, the proportion of biological degradation of complex organic matter in the sludge decreases, and the granulation speed is accelerated.

[0053] Step 4: Collect the carbon enrichment products separated in the granulation fluidized bed 8 for carbon recovery.

[0054] Experimental Analysis

[0055] First, the bioreactor 11 in this embodiment of the invention is an SBR bioreactor. The SBR bioreactor is the most suitable process for cultivating granular sludge in the prior art. Therefore, the granulation fluidized bed 8+SBR bioreactor is selected to demonstrate the granulation and treatment effects.

[0056] The inoculum sludge for the SBR system was taken from the return sludge of the DE oxidation ditch process at a municipal wastewater treatment plant in Xi'an, with an MLSS of approximately 8.72 g·L⁻¹. -1 SVI is 126 mL·g -1 Dilute to approximately 4 g / L. -1 The wastewater was then fed into the SBR system for cultivation, and the combined process directly connected the effluent from the aerated grit chamber to the reactor feedwater. A separate control group was also established, where wastewater was fed directly into the SBR reactor without undergoing fluidized bed treatment.

[0057] The entire system's reaction tanks are made of plexiglass, and the system consists of a rapid stirring tank 2, a granulating fluidized bed 8, and an SBR bioreactor. The control group is a single SBR reactor.

[0058] Table 1. Parameters and operating conditions of the rapid mixing tank 2

[0059] Effective volume (ml) 250 PAC0 dosage (mg / L) 90 Hydraulic residence time (min) 4 Inlet flow rate (ml / min) 60.9

[0060] Table 2. Parameters and operating conditions of granulation fluidized bed

[0061]

[0062] Table 3 SBR bioreactor and its operating conditions

[0063]

[0064] The operating parameters of the combined process are the same as those of the single process.

[0065] The sludge is divided into three stages during the granulation process.

[0066] Table 3. Three stages of granular sludge cultivation:

[0067]

[0068] 1) Acclimatization period (1–9 days)

[0069] After being aerated for 24 hours, the sludge was introduced into bioreactor 11. Anhydrous sodium acetate at a concentration of 255 mg / L was added as an external carbon source. After about a week of acclimatization, the sludge adapted to the current water quality, and the effluent ammonia nitrogen and COD met the Class A standard.

[0070] 2) Culture period (9–40 days)

[0071] During the granular sludge cultivation period, the settling properties of the combined process continuously improved, while the settling properties of the reactor directly connected to the actual wastewater were poor, and sludge bulking occurred midway.

[0072] 3) Granulation period (after 41 days)

[0073] On day 41, the SV5 / SV30 of the combined process was 1, which is less than 1.2, thus achieving granularity.

[0074] The following methods were used to measure various indicators of activated sludge:

[0075] Ammonia nitrogen was determined by Nessler's reagent spectrophotometric method "Determination of Ammonium in Water by Nessler's Reagent Colorimetric Method" (GB7479-87).

[0076] The respiration rate was measured using the respiration metering method, which involved long-term manual sampling and monitoring of the activated sludge to evaluate changes in microbial activity within the reactor.

[0077] A laser particle size analyzer (LS230 / SVM, Beckman Coulter, USA) was used to measure the size of sludge samples, with a detection range of 0.04-2000 μm.

[0078] The mixed liquor suspended solids concentration (MLSS) and conventional water quality indicators of the sludge were determined according to national standard methods.

[0079] Furthermore, the experimental results were analyzed.

[0080] 1) Water quality analysis

[0081] As shown in Figure 3(a), after the acclimatization period, both the combined process and the single process could basically meet the ammonia nitrogen treatment requirements. However, because the single process lacked fluidized bed pretreatment to stabilize the influent, the effluent ammonia nitrogen reached 6.37 mg·L⁻¹ on Day 19. -1 On Day 37, the ammonia nitrogen level in the effluent was 4.07 mg / L. -1 The combined process of granulation fluidized bed 8 and SBR bioreactor showed very stable ammonia nitrogen treatment, maintaining a level of 2 mg / L. -1 Below 250-350 mg / L, as shown in Figure 3(b), the influent COD was maintained at 250-350 mg / L. -1 The COD concentration after treatment with granulation fluidized bed 8 was between 100 (mg·L⁻¹). -1 The COD of the effluent from the combined process and the single process remained at around 50 mg / L. -1 The following conditions are met, and the processing requirements are met.

[0082] As shown in Figure 3(c), after fluidized bed treatment, the proportion of dissolved COD is over 80%. In other words, in single-process cultivation, the proportion of dissolved COD is only 60-70%, while in combined processes, the proportion of dissolved COD is 80-90%. Therefore, the high proportion of dissolved COD is beneficial to reactor operation and granulation.

[0083] Therefore, the combined process of granulated fluidized bed 8 and SBR bioreactor can meet the daily operation requirements of water plants in terms of wastewater treatment capacity. At the same time, the pretreatment of the granulated fluidized bed 8 at the front end can stabilize the influent of the SBR bioreactor, making it less affected by shock loads.

[0084] 2) Sludge settling properties analysis

[0085] As shown in Figure 4(a), for the single process, the sludge settling performance has been consistently poor. SV5 remained above 90 until 20 days prior. After the settling performance improved, the SV5 / SV ratio decreased. 30 The SV5 remained above 1.5, while in Figure 4(b), the combined process maintained SV5 below 30 after 17 days, and at 39 days, the SV5 / SV5 ratio was... 30 It was changed to 1.2, which basically achieved granularity.

[0086] 3) Sludge particle size analysis

[0087] As shown in Figure 5(a), the sludge particle size distribution reflects the changes in sludge morphology and structure within the SBR bioreactor. It can be observed that during the cultivation process, in both the combined and single-process reactors, sludge smaller than 50 μm accounted for over 71% on day 17. By day 24, the proportion of sludge smaller than 50 μm in the combined process decreased to 39%, and dense, yellowish-brown granular sludge appeared within the SBR bioreactor. As cultivation progressed, from day 37 onwards, particles larger than 100 μm accounted for 23%, and significant sludge-water stratification was observed during settling, with very distinct particles. In contrast, the single-process reactor still primarily consisted of flocculent sludge with poor settling properties. Figure 5(b) also shows that the particle size increase rate was slower in the early stages of the combined process, but accelerated after day 37. This is because the formed granular sludge acted as a core, aggregating surrounding flocculents, leading to a faster particle size increase.

[0088] 4) Population abundance analysis

[0089] like Figure 6 As shown, at the phylum level, the dominant species in the granular sludge cultivated by the two processes are basically the same. The main difference lies in the proportion of Actinobacteria. Actinobacteria can decompose complex organic matter in wastewater by producing various secondary metabolites and are the main microorganisms for decomposing recalcitrant organic matter in wastewater. On day 40, the proportion of Actinobacteria in the sludge cultivated by the single process was 15.31%, while that in the combined process was 3.11%. It can be seen that under the same conditions, the activity of hydrolytic microorganisms was greatly inhibited. Therefore, it can be considered that the inhibition of hydrolytic bacteria promoted the granulation process.

[0090] Based on the above experimental data, it can be concluded that the combined use of granulation fluidized bed 8 and bioreactor 11 can not only meet the actual wastewater treatment requirements, but also accelerate the formation of granular sludge.

[0091] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The combined use of a granulating fluidized bed 8 and a bioreactor 11 utilizes physicochemical techniques to distinguish between dissolved and non-dissolved organic matter in water for wastewater treatment and granular sludge cultivation. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this invention should be included within the scope of protection of this invention.

[0092] This invention utilizes a fluidized bed reactor to distinguish between dissolved and undissolved organic matter in actual wastewater. The fluidized bed exhibits excellent solid-liquid separation, effectively removing sparingly soluble organic matter from the wastewater. This alters the dominant microorganisms in the bioreactor that degrade organic matter, filtering out microorganisms capable of hydrolyzing sparingly soluble substances and reducing the likelihood of these microorganisms degrading the granules themselves. This achieves stable operation of the granular sludge.

Claims

1. A method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process, characterized in that: Includes the following steps: Step 1: Wastewater enters the rapid mixing tank (2) through the mixing tank inlet pump (1). At the same time, the PAC dosing tank (3) injects PAC agent into the rapid mixing tank (2) through the PAC dosing pump (4) to destabilize the raw water. The destabilization time is 1-10 minutes. Step 2: The destabilized raw water flows out from the rapid mixing tank (2) and enters the granulation fluidized bed (8) through the fluidized bed inlet pump (5). The PAM agent in the PAM dosing tank (6) is mixed with the raw water in the granulation fluidized bed (8) through the PAM dosing pump (7) and then the solid-liquid separation is carried out. Step 3: Solid-liquid separation is carried out in the granulation fluidized bed (8) by the impact of the reagent and the upward flow velocity. At the same time, the supernatant is refluxed in the granulation fluidized bed (8) to increase the upward flow velocity. The supernatant in the effluent enters the bioreactor (11) for reaction. The bioreactor (11) is an SBR reactor. Then, granular sludge is generated in the SBR reactor. Step 4: Collect the carbon enrichment products separated in the granulation fluidized bed (8) and perform carbon recovery; The wastewater treatment and sludge granulation method is based on a wastewater treatment and sludge granulation system, which includes a rapid mixing tank (2). The first inlet (2-1) of the rapid mixing tank (2) is connected to sewage. The second inlet (2-2) of the rapid mixing tank (2) is connected to the PAC dosing tank (3) via a PAC dosing pump (4). The outlet (2-3) of the rapid mixing tank (2) and the outlet (6-1) of the PAM dosing tank (6) are both connected to the fluidized bed inlet (8-1) of the granulation fluidized bed (8). The fluidized bed outlet (8-2) of the granulation fluidized bed (8) is connected to the bioreactor (11).

2. The method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process according to claim 1, characterized in that: The outlet end (2-3) of the rapid mixing tank (2) is connected to the fluidized bed inlet (8-1) of the granulation fluidized bed (8) via the fluidized bed inlet pump (5); the outlet end (6-1) of the PAM dosing tank (6) is connected to the fluidized bed inlet (8-1) of the granulation fluidized bed (8) via the PAM dosing pump (7).

3. The method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process according to claim 1, characterized in that: The fluidized bed outlet (8-2) of the granulation fluidized bed (8) is connected to the inlet (9-1) of the water storage tank (9), and the outlet (9-2) of the water storage tank (9) is connected to the bioreactor (11) through the bioreactor dosing pump (10).

4. The method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process according to claim 1, characterized in that: A reflux port is provided above the granulation fluidized bed (8).

5. The method for treating wastewater and promoting sludge granulation using a combined granulation fluidized bed-bioreactor process according to claim 1, characterized in that: The concentration of PAC agent in step 1 is 10-100 mg / L.

6. The method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process according to claim 1, characterized in that: In step 2, the dosage of PAM agent is 0.5-10 mg / L.

7. The method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process according to claim 1, characterized in that: In step 2, different types of crystal nuclei are added to the granulation fluidized bed (8) to screen the raw water.

8. The method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process according to claim 1, characterized in that: The upward flow velocity of the granulation fluidized bed (8) in step 3 is 0.2-4 mm / s.

9. A method for treating wastewater and promoting sludge granulation using a granulation fluidized bed-bioreactor process according to claim 1, characterized in that: The reflux ratio of the granulation fluidized bed (8) in step 3 is 0.1-0.9.

Images