Treatment process for cylindrospora in waterworks

Abstract

The invention relates to the technical field of water treatment in waterworks, in particular to a treatment process for cylindrospora in waterworks, which comprises the steps of pre-oxidation, flocculation, air floatation and coagulation aid, and realizes efficient treatment by optimizing parameters and flexibly adjusting sequence. According to the process, aiming at the scene that the concentration of raw water cylindrotheca is 1.0 * 10 < 6 >-6.0 * 10 < 8 > cells / L, the cell structure of the cylindrotheca is damaged through pre-oxidation of sodium hypochlorite, then the frond is preferentially removed in combination with air flotation, and the removal effect is improved through cooperation with the synergistic effect of flocculation and coagulation aid. Under optimal conditions, the dosage of PAC can be reduced by 30%-50%, the algae removal rate exceeds 98%, and the concentration of algal toxin is lower than 1 microgram / L. According to the application, the medicament consumption and the operation cost can be remarkably reduced, meanwhile, the strict water quality requirement is met, and the method is suitable for high-concentration cylindrocarpon treatment scenes.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a treatment process for Cylindrospermum spp. in a waterworks. Background Art

[0002] During the water treatment process at waterworks, the presence of Cylindrosperma algae poses a significant threat to water quality. This algae not only reproduces rapidly but can also release algal toxins, impacting the safety and stability of the water supply. Traditional water treatment processes typically employ single oxidation, flocculation, or flotation technologies, but these methods have limitations when dealing with high concentrations of Cylindrosperma algae. For example, pre-oxidation alone may not adequately destroy the algal cell structure, while flocculation may result in poor flocculent floating due to the low algae density. Furthermore, flotation processes must be combined with other treatment steps to achieve the desired effect when removing algae, otherwise unstable treatment efficiency may occur.

[0003] In recent years, composite treatment technologies for Cylindrospora spp. have gradually attracted attention. By organically combining multiple steps such as pre-oxidation, flocculation, flotation, and coagulant aid, treatment efficiency can be effectively improved. However, existing composite processes still face some challenges in practical application. For example, improper control of pre-oxidant dosage may lead to increased by-product formation; the matching relationship between flocculant dosage and algae concentration is not clear, which can easily lead to agent waste or substandard treatment effect; insufficient optimization of microbubble particle size and surface load parameters in the flotation process may also limit overall treatment performance. These problems make it difficult for existing technologies to achieve both high efficiency and economic efficiency when treating high-concentration Cylindrospora spp. raw water.

[0004] The present invention optimizes the combination of pre-oxidation, flocculation, flotation and coagulant aid steps and introduces a flexible process sequence adjustment strategy, thereby improving the removal rate of Pseudospondylosporium while reducing reagent consumption. It is a water treatment process improvement scheme with high practical value.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a treatment process for Cylindrospermum spp. in a waterworks, thereby solving the problems raised in the above-mentioned background technology.

[0007] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0008] A treatment process for Cylindrospermum spp. in a waterworks comprises the following steps:

[0009] Step 1: Pre-oxidation treatment: Sodium hypochlorite (NaClO) is added to the raw water for pre-oxidation, and the NaClO dosage is controlled to be 3-6 mg / L, and the reaction time is 10-15 min;

[0010] Step 2, flocculation treatment: add polyaluminium chloride (PAC) as a flocculant, control the PAC dosage to 10-25 mg / L, stir quickly (200-300 r / min) for 1-2 minutes, and then stir slowly (60-80 r / min) for 15-20 minutes;

[0011] Step 3, flotation treatment: adopt dissolved air flotation process, control the flotation time to 5-15min, the dissolved air pressure to 0.35-0.4MPa, and separate and remove the scum after flotation;

[0012] Step 4, coagulant treatment: add polyacrylamide (PAM) as a coagulant, control the PAM dosage to 1-4 mg / L, the stirring speed to 40-60 r / min, and the reaction time to 5-10 min;

[0013] In the process, step 3 flotation treatment can be performed before step 2 flocculation treatment, or after steps 1, 2, and 4 combined treatment.

[0014] Preferably, in step 1, the dosage of NaClO is controlled to be 3-5 mg / L, and the pre-oxidation reaction time is 15 min to ensure the destruction effect on the cell structure of Cylindrospermum cylindricum.

[0015] Preferably, the amount of PAC added in step 2 is adjusted according to the concentration of Cylindrospermum spp.: when the algae concentration is 1.0×10 6 -4.0×10 6 cells / L, the PAC dosage is 10-15 mg / L; when the algae concentration is 3.0×10 8 -6.0×10 8 cells / L, the PAC dosage is 20-25 mg / L. This adjustment strategy can avoid reagent waste and improve flocculation effect.

[0016] Preferably, when flotation treatment in step 3 takes precedence over flocculation treatment in step 2, the flotation time is 5-10 minutes. After flotation, the algae concentration is reduced to 10%-20% of the original concentration, and then PAC is added for flocculation. This order adjustment can reduce the subsequent flocculant dosage and improve the overall treatment efficiency.

[0017] Preferably, in step 4, anionic polyacrylamide is used as PAM, the dosage is 1-2 mg / L, the stirring speed is 50 r / min, and the reaction time is 7 min. This parameter setting can further promote floc formation and enhance the precipitation effect.

[0018] Preferably, the process also includes sedimentation and filtration steps: after flotation or flocculation, the water is settled in an inclined plate sedimentation tank for 1-2 hours, and then filtered through a quartz sand filter at a filtration rate of 8-10 m / h. This step can effectively remove residual fine particles and further improve water quality.

[0019] Preferably, when steps 1, 2, and 4 are combined, NaClO is added first for pre-oxidation, PAC is added for flocculation, and PAM is added as a coagulant aid. The interval between the addition of the three steps is less than 5 minutes. This operation flow can ensure the synergistic effect between the steps.

[0020] Preferably, the process has a removal rate of more than 98% for Cylindrospermum spp., and the algal toxin concentration in the treated water is less than 1 μg / L. This result verifies the overall effectiveness of the process.

[0021] Preferably, the microbubble particle size generated by the dissolved air flotation process is 20-30 μm, and the surface load of the flotation tank is 5-10 m 3 / (m 2 h). This parameter range can ensure the stability and efficiency of the flotation process.

[0022] Preferably, the process is applied to the raw water with a concentration of 1.0×10 6 -6.0×10 8 cells / L water plants, and by adopting a flotation-followed-flocculation process sequence, the PAC dosage can be reduced by 30%-50%. This optimization strategy significantly reduces the cost of chemicals.

[0023] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described below at the same time:

[0024] By optimizing the parameters and sequence of the pre-oxidation, flocculation, flotation, and coagulation-assisted steps, this method demonstrates significant advantages in treating high-concentration Cylindrospermum algae. The pre-oxidation step disrupts the algal cell structure, reducing the release of algal toxins; the flotation step preferentially removes the majority of the algae, alleviating the burden of subsequent flocculation; and the synergistic effect of the flocculation and coagulation-assisted steps further enhances removal efficiency. Furthermore, by rationally controlling the parameters of each step, the dosage of reagents is reduced, lowering operating costs while meeting stringent water quality requirements.

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described below are only some embodiments. A person skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0027] Figure 1 This is the flocculation effect diagram of low-concentration Cylindrospermum for 5 minutes;

[0028] Figure 2 This is the flocculation effect diagram of high concentration Cylindrospermum sp. in 5 minutes;

[0029] Figure 3 This is the change diagram of the removal rate of Cylindrospermum serrata under different PAC dosages;

[0030] Figure 4 This is the flocculation effect diagram of the combined treatment of 5-min low-concentration Cylindrospermum pre-chlorination and PAC;

[0031] Figure 5 This is the flocculation effect diagram of the combined treatment of 5-min high-concentration Cylindrospermum pre-chlorination and PAC;

[0032] Figure 6 This is a graph showing the change in removal rate of Cylindrospermum spp. under the combined treatment of NaClO and PAC; (the left graph shows low concentration of Cylindrospermum spp., and the right graph shows high concentration of Cylindrospermum spp.);

[0033] Figure 7 This is the flocculation effect diagram of the combined treatment of low-concentration Cylindrospermum PAC and PAM for 5 minutes;

[0034] Figure 8 This is the flocculation effect diagram of the combined treatment of high-concentration Cylindrospermum PAC and PAM for 5 minutes;

[0035] Figure 9 This is a graph showing the change in removal rate of Cylindrospermum spp. under the combined treatment of PAC and PAM; (the left graph shows low concentration of Cylindrospermum spp., and the right graph shows high concentration of Cylindrospermum spp.);

[0036] Figure 10 This is the flocculation effect diagram of the combined treatment of low-concentration Cylindrospermum NaCLO, PAC and PAM for 5 minutes;

[0037] Figure 11 This is the flocculation effect diagram of the combined treatment of high concentration NaCLO, 15mg / LPAC and PAM for 5 minutes;

[0038] Figure 12 This is a graph showing the resuspension of flocs in some treatment groups at 120 min;

[0039] Figure 13 This is a graph showing the changes in the removal rate of low-concentration Cylindrospermum spp. under the combined treatment of NaClO, PAC and PAM; (A: 5 mg / LPAC treatment group; B: 10 mg / LPAC treatment group);

[0040] Figure 14This is a graph showing the changes in removal rates of high-concentration Cylindrospermum spp. under the combined treatment of NaClO, PAC, and PAM (A: 10 mg / L PAC treatment group; B: 15 mg / L PAC treatment group; C: 20 mg / L PAC treatment group);

[0041] Figure 15 The figure is a flow chart of a treatment process for Cylindrospermum spp. in a waterworks.

[0042] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0043] The present invention will now be described in further detail with reference to the accompanying drawings.

[0044] See also Figure 1-15 As shown, in this embodiment, a treatment process for Cylindrospermum spp. in a water plant is provided, comprising the following steps:

[0045] First, in the pre-oxidation treatment step 1, sodium hypochlorite (NaClO) is added to the raw water as an oxidant, and its dosage is controlled in the range of 3-6 mg / L, and the reaction time is 10-15 minutes. The main function of this step is to destroy the cell structure of Cylindrospermum spp., thereby reducing the release of algal toxins. To ensure operational consistency, the NaClO solution is evenly added to the raw water pipeline through a metering pump and fully mixed with the raw water through a static mixer. Subsequently, the mixed solution enters a reaction tank with a stirring device. The reaction tank is equipped with a stirring paddle, and the stirring speed is maintained at 100-150 r / min to ensure that NaClO is fully in contact with the Cylindrospermum spp. in the raw water and reacts. According to actual test results, when the NaClO dosage is 3-5 mg / L and the reaction time is 15 minutes, the optimal cell destruction effect can be achieved while avoiding the formation of by-products caused by excessive addition.

[0046] Next, the raw water after pre-oxidation treatment enters the flocculation treatment step 2; in this step, polyaluminium chloride (PAC) is added to the raw water as a flocculant, and its dosage is dynamically adjusted according to the concentration of Pseudomonas aeruginosa. When the concentration of Pseudomonas aeruginosa is 1.0×10 6 -4.0×10 6 cells / L, the PAC dosage is 10-15 mg / L, the algae removal rate can reach 93.60%; when the concentration is 3.0×10 8 -6.0×10 8cells / L, the dosage is increased to 20-25 mg / L; the algae removal rate can reach 97.12%; the PAC solution is also added to the pipeline through a metering pump and mixed with the raw water through a static mixer before entering the flocculation reaction tank; the flocculation reaction tank is equipped with two sets of stirring devices, the first set of stirring devices has a speed of 200-300 r / min and a running time of 1-2 minutes to quickly disperse the PAC; the second set of stirring devices has a speed of 60-80 r / min and a running time of 15-20 minutes to promote floc formation. Through the above design, the flocculation treatment step 2 not only achieves effective capture of Pseudomonas aeruginosa, but also reduces the waste of reagents.

[0047] In some cases, flotation treatment step 3 may be performed before flocculation treatment step 2, depending on the concentration of Cylindrospermum in the raw water and the treatment requirements. When the order of flotation first and flocculation later is adopted, the raw water directly enters the flotation tank, which is equipped with a dissolved air system. The air is dissolved in the water by a high-pressure pump to form microbubbles. The particle size of the microbubbles is controlled within the range of 20-30μm. The surface load of the flotation tank is set to 5-10m 3 / (m 2 h), with a flotation time of 5-10 minutes. During this process, most of the Pseudospondias cylindrica is separated and removed along with the scum, reducing the algae concentration in the remaining raw water to 10%-20% of the original concentration. In situ experiments have verified that 5 minutes of flotation can reduce the algae concentration to 15% of the raw water concentration. Subsequently, only 5 mg / L of PAC is required to achieve a 99.76% removal rate, reducing PAC dosage by 50%. This sequential adjustment not only reduces the subsequent flocculant dosage but also improves overall treatment efficiency. A sludge discharge pipe is installed at the bottom of the flotation tank for regular discharge of sediment, and a scraper is installed at the top to remove scum.

[0048] After flotation or flocculation treatment, the raw water enters the coagulant treatment step 4; in this step, polyacrylamide (PAM) is added to the raw water as a coagulant aid, and its dosage is 1-4 mg / L; preferably, anionic polyacrylamide is selected, the dosage is 1-2 mg / L, the stirring speed is 40-60 r / min, and the reaction time is 5-10 minutes; PAM must be strictly controlled to be ≤ 2 mg / L, and excessive addition (such as 4 mg / L) will cause algal cells to be stabilized again, reducing the removal rate from 94.35% to 86.59%; PAM solution is added to the pipeline through a metering pump and mixed with the raw water through a static mixer before entering the coagulant reaction tank; a low-speed stirring device is provided in the coagulant reaction tank with a rotation speed of 50 r / min and a running time of 7 minutes; at this time, the floc sedimentation rate is increased by 40%, and there is no risk of floc resuspension; this step further promotes the formation and growth of flocs, providing a good foundation for subsequent precipitation and filtration;

[0049] After completing the above core steps, the raw water enters the sedimentation and filtration stage; the sedimentation process is carried out in the inclined plate sedimentation tank, and the sedimentation time is 1-2 hours; the design of the inclined plate sedimentation tank allows the water to flow slowly along the inclined plate, thereby accelerating the sedimentation of particulate matter; the supernatant after precipitation enters the quartz sand filter for filtration, and the filtration rate is controlled at 8-10m / h; the quartz sand filter is filled with quartz sand layers of different particle sizes, from top to bottom, coarse sand layer, fine sand layer and support layer to ensure the filtration effect; the water quality of the filtered water meets the drinking water standard, and the removal rate of Pseudomonas aeruginosa exceeds 100%. The removal rate of cylindrocystis spp. was over 98%, and the algal toxin concentration was less than 1 μg / L. After the optimized process (3 mg / L NaClO + 15 mg / L PAC), the algal toxin concentration in the sedimentation tank was 0.43 μg / L, far below the limit of the "Sanitary Standard for Drinking Water". In the Dasha River Water Plant, after reducing NaClO from 6 mg / L to 3 mg / L and PAC from 20 mg / L to 15 mg / L, the removal rate of Pseudospondylosporium increased from 51.77% to 98.39% (an increase of 46.62%), and the cost of reagents was reduced by more than 30%.

[0050] Furthermore, when the flocculation-followed flotation sequence is adopted, the raw water undergoes pre-oxidation treatment step 1, flocculation treatment step 2, coagulant-assisted treatment step 4, and finally enters flotation treatment step 3. In this case, the flotation time is 5-15 minutes, and the dissolved air pressure is 0.35-0.4 MPa. By rationally controlling the parameters of each step, especially the flotation time and dissolved air pressure, the stability and efficiency of the flotation process can be ensured. Experimental data show that when this sequence is adopted, the PAC dosage can be reduced by 30%-50%, significantly saving reagent costs.

[0051] Throughout the entire process, the various steps are closely connected and organized. For example, the pre-oxidation step 1 is connected to the flocculation step 2 via a pipeline, which is equipped with a flow meter and an online monitor for real-time monitoring of raw water flow and water quality changes. The flocculation step 2 is connected to the flotation step 3 via a lift pump, with a pressure gauge and valve installed at the lift pump outlet for regulating flow and pressure. The flotation step 3 is connected to the coagulation-assisted treatment step 4 via an overflow weir, the height of which can be adjusted according to actual needs to ensure a smooth transition of water flow. The coagulation-assisted treatment step 4 is connected to the sedimentation tank via gravity flow, and a sludge discharge valve is installed at the bottom of the sedimentation tank for regular sludge removal.

[0052] To further improve the automation level of the process, the present invention also introduces an intelligent control system; the control system includes a PLC controller, sensors, and actuators. The sensors are used to monitor key parameters such as raw water flow, reagent dosage, reaction time, and flotation tank surface load, while the actuators are responsible for controlling the operating status of the metering pump, agitator, and scraper. The PLC controller collects and analyzes various parameters in real time, enabling automatic adjustment and optimization of the process flow.

[0053] The experimental method of the present invention:

[0054] 1) PAC flocculation

[0055] The optimal PAC dosage concentration range for removing different abundances of Pseudospondylospora was determined through preliminary experiments. 1L of algae solution was taken into a beaker, and different amounts of PAC were added according to the abundance of algae. The solution was stirred slowly with a glass rod for 1 minute, then stopped stirring and allowed to settle. After standing for 5 minutes, the formation of flocs and the speed of sedimentation were observed and photographed. The flocculation time in a water plant is generally about 20 minutes. Therefore, after standing for 20 minutes, water samples were taken at a fixed value of 4 cm below the liquid surface to count the abundance of Pseudospondylospora. In order to examine the stability of the flocs and better evaluate the flocculation effect and floc stability, samples were taken again after standing for 120 minutes to calculate the abundance of Pseudospondylospora. Three parallel experiments were set up for each group.

[0056]

[0057] Table 1

[0058] 2) Combined treatment of pre-chlorination and PAC flocculation

[0059] Take 1L of algae solution into a beaker, first add different amounts of NaClO (including available chlorine concentration), stir with a glass rod for 1 minute and let it stand for 15 minutes, then add different amounts of PAC, stir slowly with a glass rod for 1 minute, stop stirring, and let it stand to settle; the recording time and sampling time are the same as above

[0060]

[0061] Table 2

[0062] 3) PAC and PAM combined processing

[0063] The approximate PAM concentration range for coagulant effect was determined through preliminary experiments. 1 L of algae solution was placed in a beaker, and different amounts of PAC were first added. The mixture was stirred with a glass rod for 1 minute. Subsequently, different amounts of PAM were added. The mixture was stirred slowly with a glass rod for 1 minute, then the stirring was stopped and the mixture was allowed to settle. The recording and sampling times were the same as above.

[0064]

[0065] Table 3

[0066] 4) Pre-chlorination combined with PAC and PAM treatment

[0067] Take 1L of algae liquid into a beaker, first add different amounts of NaClO (containing available chlorine concentration), stir with a glass rod for 1 minute, and then let it stand for 15 minutes; then add different amounts of PAC, stir with a glass rod for 1 minute; then add different amounts of PAM, stir slowly with a glass rod for 1 minute, stop stirring, and let it stand to settle; the recording time and sampling time are the same as above.

[0068]

[0069] Table 4

[0070] In order to better enable relevant personnel in this technical field to fully understand and implement the present invention, the specific implementation principle of the present invention is supplemented below with reference to a specific application scenario.

[0071] In the actual operation of a water plant, the concentration of Cylindrospermum spp. in the raw water was 3.0×10 8 cells / L, and the water quality presents high turbidity; for this scenario, the treatment process provided by the present invention is adopted, and the attached Figure 1 Execute each step in the process order in sequence;

[0072] First, in the pre-oxidation treatment step 1, a sodium hypochlorite (NaClO) solution is evenly added to the raw water pipeline at a dosage of 3-5 mg / L via a metering pump, and then thoroughly mixed with the raw water in a static mixer. The mixed liquid enters the reaction tank, where the stirring device operates at a speed of 100-150 r / min to ensure that the NaClO and the Pseudospondylospora are fully in contact. During this process, the NaClO destroys the cell wall structure of the Pseudospondylospora through oxidation, thereby reducing the release of algal toxins. Experimental data show that when the NaClO dosage is controlled at 4 mg / L and the reaction time is 15 minutes, the Pseudospondylospora cell destruction rate reaches over 85%, while also avoiding the problem of byproduct formation caused by excessive addition.

[0073] Next, the raw water after pre-oxidation treatment enters the flocculation treatment step 2; according to the concentration of cylindrospermum spp. 8 cells / L, the polyaluminium chloride (PAC) dosage was set at 20mg / L. The PAC solution was added to the pipeline via a metering pump, initially dispersed in a static mixer, and then entered the flocculation reaction tank. The reaction tank was equipped with two agitators: the first agitator operated at 250r / min for 1 minute to quickly disperse the PAC; the second agitator operated at 70r / min for 15 minutes to promote floc formation. This design effectively trapped the Pseudospondylospora algae in the flocs while reducing reagent waste. Test results showed that after flocculation, the concentration of Pseudospondylospora algae in the water was reduced to approximately 60% of its original concentration.

[0074] Due to the high concentration of Cylindrospermum in the raw water, the order of flotation first and then flocculation was selected to improve the overall treatment efficiency. In the flotation treatment step 3, the raw water directly enters the flotation tank. The dissolved air system in the flotation tank dissolves air in the water through a high-pressure pump to form microbubbles with a particle size of 20-30μm. The surface load of the flotation tank is set to 8m 3 / (m 2 h), with an air flotation time of 8 minutes. During this process, most of the Cylindrosperma algae are separated and removed along with the scum, reducing the algae concentration in the remaining raw water to approximately 15% of the original concentration. A scraper at the top of the flotation tank regularly removes scum, while a mud discharge pipe at the bottom is used to remove sediment. This sequential adjustment significantly reduces the burden on subsequent flocculation treatment.

[0075] After flotation, the raw water enters coagulant treatment step 4. In this step, polyacrylamide (PAM) is added to the raw water as a coagulant at a dosage of 1.5 mg / L. The PAM solution is introduced into the pipeline via a metering pump, mixed with the raw water in a static mixer, and then enters the coagulant reaction tank. The low-speed agitator in the reaction tank runs at 50 r / min for 7 minutes to further promote the formation and growth of flocs. This step provides a good foundation for subsequent sedimentation and filtration.

[0076] After completing the aforementioned core steps, the raw water enters the inclined plate sedimentation tank for sedimentation treatment. The inclined plate sedimentation tank is designed to allow water to flow slowly along the inclined plates, accelerating the settling of particulate matter. The sedimentation time is set at 1.5 hours, and the supernatant then enters the quartz sand filter for filtration. The quartz sand filter is filled with coarse sand, fine sand, and a support layer, and the filtration rate is controlled at 9 m / h. After filtration, the effluent quality meets drinking water standards, with a removal rate of over 98% for Pseudomonas aeruginosa and a concentration of algal toxins reduced to below 0.5 μg / L.

[0077] Throughout the entire process, the various steps are closely connected and organized. For example, the pre-oxidation step 1 is connected to the flocculation step 2 via a pipeline, which is equipped with a flow meter and an online monitor for real-time monitoring of raw water flow and water quality changes. The flocculation step 2 is connected to the flotation step 3 via a lift pump, with a pressure gauge and valve installed at the lift pump outlet for regulating flow and pressure. The flotation step 3 is connected to the coagulation-assisted treatment step 4 via an overflow weir, the height of which can be adjusted according to actual needs to ensure a smooth transition of water flow. The coagulation-assisted treatment step 4 is connected to the sedimentation tank via gravity flow, and a sludge discharge valve is installed at the bottom of the sedimentation tank for regular sludge removal.

[0078] Furthermore, the intelligent control system plays a vital role in process operation. Sensors in the control system monitor key parameters such as raw water flow, reagent dosage, reaction time, and flotation tank surface load in real time. The PLC controller collects and analyzes this data and automatically adjusts the operating status of the metering pump, agitator, and scraper. For example, if the concentration of Pseudocylindrical spores in the raw water is detected to be increasing, the system will automatically increase the PAC dosage and extend the flocculation time to ensure the stability of the treatment effect.

[0079] In summary, the present invention achieves efficient and economical treatment of Pseudospondylospora in specific application scenarios by optimizing the parameter settings and sequence adjustment of each step; the pre-oxidation step effectively destroys the algal cell structure, the flotation step preferentially removes most of the algal bodies, and the flocculation and coagulant steps work synergistically to further enhance the removal effect, ultimately ensuring that the effluent quality meets the drinking water standard requirements.

[0080] The present invention is not limited to the above-described embodiments. Any structural changes made under the guidance of the present invention, which have the same or similar technical solutions as the present invention, should be understood to fall within the scope of protection of the present invention. The technologies, shapes, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A process for treating Cylindrospermum spp. in a waterworks, characterized in that: The following steps are involved: Step 1: Pre-oxidation treatment: Sodium hypochlorite is added to the raw water for pre-oxidation. The dosage of sodium hypochlorite is 3-6 mg / L and the reaction time is 10-15 min. Step 2, flocculation treatment: adding polyaluminium chloride as a flocculant, the dosage of polyaluminium chloride is 10-25 mg / L, stirring speed is 200-300 r / min for 1-2 min, and then stirring at 60-80 r / min for 15-20 min; Step 3, flotation treatment: adopt dissolved air flotation process, the flotation time is 5-15min, the dissolved air pressure is 0.35-0.4MPa, and the scum is separated and removed after flotation; Step 4, coagulant treatment: add polyacrylamide as a coagulant, the polyacrylamide dosage is 1-4 mg / L, the stirring speed is 40-60 r / min, and the reaction time is 5-10 min.

2. A process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: Step 3 can be performed before step 2, or after steps 1, 2, and 4 are combined.

3. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: In step 1, the dosage of sodium hypochlorite is 3-5 mg / L, and the reaction time is 15 min.

4. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: In step 2, the dosage of polyaluminium chloride is adjusted according to the concentration of Cylindrospermum: when the concentration of Cylindrospermum is 1.0×10 6 -4.0×10 6 cells / L, the dosage of polyaluminium chloride is 10-15mg / L; when the concentration of Cylindrospermum spp. is 3.0×10 8 -6.0×10 8 cells / L, the dosage of polyaluminium chloride is 20-25mg / L.

5. The process for treating Cylindrospermum spp. in a waterworks according to claim 2, characterized in that: When step 3 is performed prior to step 2, the flotation time is 5-10 minutes, and the concentration of Cylindrospermum spp. is reduced to 10%-20% of the original concentration after flotation.

6. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: In step 4, the polyacrylamide used is anionic polyacrylamide, the addition amount is 1-2 mg / L, the stirring speed is 50 r / min, and the reaction time is 7 min.

7. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: It also includes sedimentation and filtration steps: after flotation or flocculation, it is settled in an inclined plate sedimentation tank for 1-2 hours, and then filtered through a quartz sand filter at a filtration rate of 8-10m / h.

8. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: When steps 1, 2 and 4 are processed together, sodium hypochlorite is first added for pre-oxidation, then polyaluminium chloride is added for flocculation, and finally polyacrylamide is added as a coagulant aid. The addition interval of each step is less than 5 minutes.

9. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: The particle size of microbubbles produced by the dissolved air flotation process is 20-30μm, and the surface load of the flotation tank is 5-10m 3 / (m 2 ·h).

10. The process for treating Cylindrospermum spp. in a waterworks according to claim 1, characterized in that: When step 3 is performed prior to step 2, the dosage of polyaluminium chloride can be reduced by 30%-50%.

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