CN116143219A - Water treatment method based on coagulation coupling self-emission type air floatation process - Google Patents

Abstract

A water treatment method based on a coagulation coupling self-emission type air floatation process comprises the following steps: adding a cross-linking agent into a water body to be treated, wherein the dissolved oxygen content of the water body to be treated is more than 4mg/L, stirring for 30-120 seconds at the speed of 100-200 rpm, uniformly mixing, adding a coagulant, stirring for 15-60 seconds at the speed of 400-600 rpm, uniformly mixing, and finally standing for 10-20 minutes to finish flotation. The invention is based on the water treatment technology of coagulation coupling self-hairing air floatation, effectively utilizes dissolved gas in water, and obtains cloud-like gel flocs by controlling the adding proportion of a cross-linking agent and a coagulant, the adding method and hydraulic conditions, and the flocs can effectively wrap dissolved gas oxygen, thereby realizing self-stabilizing high-efficiency floatation. Compared with the traditional process, the water treatment method based on the coagulation coupling self-emission type air floatation process shortens the operation time, does not need an additional air dissolving device and pressure equipment, effectively reduces the capital construction and operation cost of a wastewater treatment plant, and simultaneously reduces the carbon emission.

Description

Water treatment method based on coagulation coupling self-emission type air floatation process

Technical Field

The invention relates to the technical field of water treatment, in particular to a water treatment method based on a coagulation coupling self-hairing type air floatation process.

Background

Coagulation is an indispensable operation technology of a front unit in a plurality of sewage treatment process flows, and the treatment efficiency of the front unit determines the operation condition, the treatment cost and the final effluent quality of the subsequent flows to a great extent; and the air floatation is used as an efficient solid-liquid separation technology and coagulation technology coupling to effectively remove pollutants in the water body. Because of simple operation, the coagulation-pressurization dissolved air floatation process is widely applied to the fields of algae removal, mineral separation, drug degradation, brewing wastewater treatment, sea water desalination and the like. The process mainly depends on a large number of tiny bubbles generated by pressure equipment, and the tiny bubbles are adhered to the surface layer of the flocculate generated by coagulation in the floating process, and then float together to a liquid level area to form a large number of bubbles or scum, so that the aim of effectively removing pollutants is fulfilled. However, this process requires the cooperation of pressure and dissolved air equipment, which greatly increases the construction, operation and maintenance costs of sewage treatment plants. In addition, with the conventional coagulation-pressurized dissolved air flotation technology, bubbles are adsorbed on the surface of flocs generated by coagulation, and collision of the flocs with each other during the rising process usually causes partial gas desorption, thereby causing a decrease or fluctuation in flotation efficiency.

With the increasing serious water resource shortage and water pollution in recent years, how to improve the efficiency of the existing coagulation-pressurization dissolved air floatation process and reduce the running cost becomes a research hot spot in the field of water treatment. Although subsequent improvements, including mixed ozone coagulation, colloidal gas adsorption, etc., can improve gas flotation efficiency to some extent, more expensive gas sources and complex operating procedures greatly increase the cost and power consumption of industrialization. Jin Pengkang et al report a microbubble ozone-coagulation-air floatation process (CN 201310654568), and by switching two branch pipes on the return pipe, the change of the ozone adding sequence, that is, the mutual conversion of ozone adding before and after coagulation, is realized, and good pollutant removal efficiency is achieved. However, the molecular weight of the contaminants is significantly reduced by the action of ozone, and the oxidation of this unsaturated organic species accelerates the ozone depletion. In addition, the stability and oxidizing ability of ozone are significantly affected by factors such as temperature and pH, requiring further tuning and monitoring.

Therefore, in order to reduce the cost of expensive gas sources and equipment operation and maintenance, there is a need for improvements in the conventional process of water treatment by coagulation-pressurized dissolved air flotation.

Disclosure of Invention

Based on the method, the invention provides a water treatment method based on a coagulation coupling self-emission type air floatation process, so as to solve the technical problems that the traditional coagulation-pressurization dissolved air floatation process ignores original dissolved gas in wastewater, and an additional air source and aeration equipment improve energy consumption, construction and operation cost, thereby increasing carbon emission of a sewage treatment plant.

In order to achieve the above purpose, the invention provides a water treatment method based on a coagulation coupling self-emission type air floatation process, which comprises the following steps:

adding a cross-linking agent into a water body to be treated, wherein the dissolved oxygen content of the water body to be treated is more than 4mg/L, stirring for 30-120 seconds at the speed of 100-200 rpm, uniformly mixing, adding a coagulant, stirring for 15-60 seconds at the speed of 400-600 rpm, uniformly mixing, and finally standing for 10-20 minutes to finish flotation; wherein the cross-linking agent is at least one of sodium alginate, laminarin and enteromorpha polysaccharide, and the coagulant is at least one of aluminum sulfate, polyaluminum chloride, ferric chloride and polyferric sulfate. The dosage ratio of the cross-linking agent to the coagulant is 3:2-3:1, preferably 2:1, based on mass concentration.

As a further preferable technical scheme of the invention, the dissolved oxygen content of the water body to be treated is required to be higher than 8mg/L, and the floatation temperature is required to be higher than 5 ℃.

As a further preferable technical scheme of the invention, the water body to be treated is natural surface water, algae-containing surface water, printing and dyeing wastewater, papermaking wastewater, mining wastewater, brewing wastewater, antibiotic medicine wastewater or micro-plastic polluted water.

The abundant dissolved gas (such as dissolved oxygen) exists in various polluted water bodies, such as surface water, domestic sewage, industrial wastewater and the like of algae burst, and the dissolved oxygen is used as a flotation carrier, so that the effective utilization of the dissolved gas in a coagulation-coupling self-emission type air flotation process (called a coagulation-air flotation process for short) can be realized. Inspired by clouds, it is envisaged to form lighter gelatinous flocs to effectively encapsulate dissolved gases contained in the sewage itself during coagulation, eventually completing spontaneous flotation under the action of buoyancy. Therefore, the coagulation-air floatation process provided by the invention can produce the effect of spontaneous flotating the floccules without introducing an additional air source when the dissolved oxygen content is higher than the range of 4mg/L, thereby greatly reducing the operation cost of the coagulation floatation process.

In addition, in the traditional coagulation-pressurization dissolved air floatation technology, coagulation and floatation are two sections of independent process units, and in contrast, the integration of a coagulation and floatation device can be realized by means of spontaneous adsorption of flocs and encapsulation of bubbles, so that the infrastructure investment of a sewage treatment plant can be effectively reduced. The technology core of the process is how to generate gel flocs with low density through the selection of coagulant and cross-linking agent, the control of dosage and the optimization of hydraulic conditions, thereby effectively encapsulating dissolved gas to realize a spontaneous flotation process, and further achieving stable process efficiency and lower water treatment cost.

The crosslinking agent of the present invention is used for providing a large amount of-COOH and-OH, and the coagulant is used for providing Al ³⁺ Or Fe (Fe) ³⁺ The cross-linking agent and the coagulant can produce-AlO ₆ or-FeO ₆ . The characteristics of the water purifying agent system of the invention are as follows: firstly-COOH chelates (crosslinks) with metal ions and secondly-OH generates a radical pair O ₂ The strongest adsorption binding energy, again-AlO ₆ (-FeO ₆ ) Structural sites (steric hindrance of adsorption process is greater); al (Al) ³⁺ Having a specific Fe ³⁺ Lighter atomic mass and higher charge density (same charge carrying capacity and smaller ion radius); fe (Fe) ³⁺ Can produce a specific Al ³⁺ Stronger floc properties (greater structural size and crush strength). Therefore, different water purifying agent combinations can be used for different pollutant water systems, and water resource recovery strategies according to local conditions can be designed.

Preferably, the combination of sodium alginate (or enteromorpha polysaccharide) and polyaluminum chloride (or aluminum sulfate) can produce stronger crosslinking effect (-AlO) ₆ ) The three-dimensional network cross-linked structure with lower parting dimension can be formed, and the method is suitable for cross-linked flotation of sewage with low organic matters and high-density suspended particles; the laminarin and polyaluminum chloride (or aluminum sulfate) can generate stronger gas adsorption capacity (-OH more) and are suitable for purifying and floating sewage with high turbidity or high pollutant concentration; the combination of sodium alginate (or enteromorpha polysaccharide) and polyferric chloride (or ferric chloride) can generate stronger floc crushing strength (-FeO) ₆ ) The method is suitable for capturing and floating the high-turbidity sewage with high organic matter content.

The water treatment method based on the coagulation coupling self-emission type air floatation process can achieve the following beneficial effects by adopting the technical scheme:

1) The dosage of the cross-linking agent is higher than that of the coagulant, and the cross-linking agent is added before the coagulant so as to ensure that the cross-linking agent can be packaged in the floccule together with the subsequent pollutant adsorption and pollutant net capturing, and the high dosage of the cross-linking agent can ensure that the Al content is lower than the national water purification standard (0.2 mg/L) ³⁺ Residue (0.0485-0.0837 mg/L);

2) The total hydraulic stirring time (within 2 min) and the total coagulation purification time (within 20 min) required by adding the coagulant are shorter, so that the service cycle of a flocculation tank in industrial purified water is effectively shortened, and bubbles are mainly distributed in flocculation in the flotation process and can exist stably for 8h for a long time, thereby meeting the requirements of desorption and stability of gas from water and enabling the floatation process to be more efficient and stable;

3) The flocculation size normalization trend formed by the coagulation coupling self-induced air floatation is obvious, the macroscopic structure of the flocculation size normalization trend is more like a cloud, the larger flocculation size can effectively increase the collision probability among pollutants, coagulant and bubbles, and the purification disadvantage of low collision adhesion efficiency caused by small flocculation size in the traditional external aeration flotation method is improved.

4) Compared with the traditional coagulation-pressurization dissolved air floatation technology, the method has two obvious advantages: (1) The invention eliminates the need for external air sources and pressure equipment, and the coagulation tank and the air flotation tank can be integrated, which significantly reduces the construction and operation costs of the water treatment plant; (2) The dissolved gas of the present invention can be effectively encapsulated within the gel wadding rather than adsorbed on the surface, resulting in a faster flotation process and more stable flotation efficiency.

Drawings

The invention will be described in further detail with reference to the drawings and the detailed description.

FIG. 1 is a schematic diagram of desorption of microbubbles in a gel floc of the present invention.

FIG. 2 is a graph showing the treatment performance of the coagulation-coupled self-propelled air-floatation process of example 1 on algae-laden surface water.

FIG. 3-1 is a graph showing the organic matter removal rate in the treatment efficiency of the coagulation-coupling self-propelled air-floatation process for heavy metal wastewater in example 2;

FIG. 3-2 is a graph showing the heavy metal removal rate in the treatment efficiency of the coagulation-coupling self-propelled air-floatation process for heavy metal wastewater in example 2;

FIG. 3-3 is a graph showing turbidity removal rate in treating heavy metal wastewater by the coagulation coupling self-propelled air floatation process in example 2;

FIG. 4 is a graph showing the time relationship of the floating of gel flocs in a water sample in example 2;

FIG. 5 shows the treatment performance of the coagulation-coupled self-priming air-floatation process of example 3 on dye wastewater, and the abscissa corresponds to the stirring time of adding the crosslinking agent and the coagulant under different hydraulic conditions, for example: 5-15 is the stirring time of adding the cross-linking agent for 5s and the stirring time of adding the coagulant for 15s.

Fig. 6 is a photograph of water samples before, during and after the acid red dye was subjected to flotation in example 3.

Fig. 7 is a graphical representation of water samples corresponding to the effect of various process conditions deviating from the preferred range on flotation.

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concepts pertain. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.

The natural polysaccharide (sodium alginate, laminarin, enteromorpha polysaccharide) can rapidly form gel under wide water quality conditions, and has a large amount of-COO in its molecular structure ^- and-OH exhibits polyanionic behaviour, -OH is capable of adsorbing and collecting microbubbles having electronegative dissolved gases or interfacial electronegativity in water. Al generated by dissociation of aluminum sulfate and polyaluminum chloride ³⁺ Can be effectively combined with three-COO ^- Crosslinking to partially free Al ³⁺ Complexing electronegative organics by means of electric neutralization. At the same time, the adsorption bridging and net capturing rollThe residual cross-linking agent in the water is captured in a sweeping mode, and the cross-linking agent is directionally captured and encapsulated in the floccule. At this time, due to the occurrence of the flock in the crosslinking process, the system is divided into two areas, namely a liquid phase area (I) and a flock area (II), and as shown in fig. 1, a high-concentration organic polymer solution appears in the area II due to the packaging effect of the flock and the characteristic that polymer gel can absorb and contain a large amount of water, which definitely affects the saturated solubility of the dissolved gas in the water sample in the flock, so that the saturated solution or nearly saturated solution (initial water sample) of the dissolved gas originally becomes a supersaturated solution. The water environment of metastable state in the floc is formed by adhesion of micro bubbles, aluminum and-COO in initial stage ^- Conjugated structure (-AlO) produced by crosslinking ₆ ) And hydroxyl groups in the molecular structure of the cross-linking agent act as sites to precipitate supersaturated gas, thereby creating macroscopic bubbles. The small floccules dispersed in the II area can collide, adhere and gather gradually in the hydrolysis process of the coagulant to form large floccules with higher aggregation degree, and the buoyancy of the whole floccules is slowly increased along with the progress of the gas precipitation process until the floccules float on the liquid surface, so that the coagulation-spontaneous air floatation phenomenon is generated. On the other hand, most of the cross-linking agent in zone I is encapsulated in zone II with contaminants, and the bulk concentration of the agent is significantly reduced, ensuring a lower residual concentration of organics in zone I. The action mechanism of ferric chloride, polymeric ferric sulfate and cross-linking agent in the water purifying agent system is the same as that of aluminum sulfate and polymeric aluminum chloride, and will not be described here. Thus, the combination of natural polysaccharides and aluminium/iron salt coagulants presents great potential in achieving gel floc formation and spontaneous flotation processes.

In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention will be further described in detail by means of specific examples and comparative experiments.

Example 1:

natural surface water-quinine river water in the explosion period of algae in Xuzhou city of Jiangsu province is taken as a water sample to be treated, the water sample to be treated is uniformly mixed, then a cross-linking agent-laminarin is added into the water sample to be treated, the water sample to be treated is rapidly stirred for 40 seconds at a speed of 150 revolutions per minute, then a coagulant-aluminum sulfate (the dosage ratio of laminarin to aluminum sulfate is 2:1) is added, the water sample to be treated is stirred for 20 seconds at a speed of 400 revolutions per minute, and then the water sample to be treated is left for air floatation for 20 minutes. After the air flotation was completed, the supernatant was removed and the algae removal efficiency was measured, and the results are shown in fig. 2.

Through the test analysis of the water quality of the water sample to be treated, the related information of the original water sample is as follows: dissolved oxygen (13-20 mg/L), extracellular polysaccharide (15-20 mg/L), pH (7.20-8.20) and temperature (25-30 ℃). As can be seen from FIG. 2, the surface water of Xuzhou city in the algae burst period mainly contains several common dominant algae species such as Oscillatoria, nostoc, chlorella, tetracyhalos, etc., and the water body thereof can be called algal bloom wastewater.

The laminarin-aluminum sulfate composite agent is selected and applied to a coagulation coupling self-induced air floatation process, rich dissolved oxygen can immediately respond to a floatation process (completed within 3-8 min), along with the continuous increase of the adding amount of aluminum sulfate (calculated by aluminum), the dosage ratio of laminarin to aluminum sulfate is kept to be 2:1, the algae removal rate is also continuously increased, more than 95% of algae can be removed under the adding amount of 14mg/L, the algae removal efficiency is excellent, and the method has strong application potential in the actual algae wastewater treatment.

Example 2:

the method for preparing the water sample to be treated by using the humic acid-nano titanium dioxide simulated heavy metal polluted wastewater comprises the following steps: accurately weighing 1.0g of humic acid and 0.4g of sodium hydroxide, dissolving the humic acid and the sodium hydroxide in 800mL of deionized water, fully dissolving, fixing the volume to 1L to prepare humic acid stock solution, and storing the humic acid stock solution in a brown reagent bottle; 14mg of nano titanium dioxide particles are accurately weighed and added into 28mL of humic acid stock solution, and the humic acid-nano titanium dioxide simulated water sample is prepared by dispersing and fixing volume in 14L of tap water after ultrasonic mixing, wherein the contents of nano titanium dioxide and HA are respectively 1mg/L and 2mg/L.

The prepared simulated water sample is uniformly mixed, then a cross-linking agent sodium alginate is added into water to be treated, the water is rapidly stirred for 30 seconds at the speed of 200 revolutions per minute, then a coagulant-polyaluminum chloride (or aluminum sulfate) is added, the water is stirred for 15 seconds at the speed of 500 revolutions per minute, and then the water is left to stand for air floatation for 12 minutes. After the air flotation is finished, the supernatant is taken out to measure the removal efficiency of organic matters, nano titanium dioxide and turbidity, and the obtained results are shown in figures 3-1 to 3-3. The simulated water quality has the dissolved oxygen content of 8.0-8.8 mg/L, the temperature of 20-25 ℃, and after flotation for about 10 minutes, the gel flocs can spontaneously and rapidly float to the liquid level in a whole form, and the relationship of the gel flocs floating up with time is shown in figure 4.

As can be seen from fig. 3-1 to 3-3, the coagulation coupling self-induced air floatation process has good treatment efficiency on heavy metal wastewater: the low coagulant addition concentration (4-6 mg/L) can still maintain the removal rate of the organic matters and the metal oxide nano particles to be more than 60%, and the removal rate of the turbidity to be more than 90%. At higher coagulant addition concentration (8-10 mg/L), the removal rate of organic matters, metal oxide nano particles and turbidity can reach about 75%, 90% and 95% respectively. In addition, the results in fig. 3 show that the dosage ratio of the cross-linking agent to the coagulant is an important factor affecting the performance of the coagulation coupling self-induced air flotation process, and for the humic acid-nano titanium dioxide simulated water sample, the optimal dosage ratio is 2:1, so that the lower dosage is satisfied, i.e. the higher removal rate is achieved.

Example 3:

the acid red simulated printing and dyeing wastewater is used as a water sample to be treated, and the preparation method comprises the following steps: accurately weighing 0.1g of acid red dye, dissolving the acid red dye in 800mL of deionized water, and after full dissolution, fixing the volume to 1000mL, wherein the content of dissolved oxygen in the simulated water is 9.5-10.8 mg/L.

Mixing the prepared simulated water sample of the printing and dyeing wastewater uniformly, adding an organic flocculant-enteromorpha polysaccharide into water to be treated according to the dosage ratio (mass concentration) of a cross-linking agent to a coagulant of 2:1, rapidly stirring for 5-150 seconds at the speed of 200 rpm, adding an inorganic coagulant-ferric chloride (or polymeric ferric sulfate), stirring for 15-60 seconds at the speed of 500 rpm, and standing for air floatation for 20 minutes. After the flotation was completed, the removal efficiency of the dye was measured by taking the supernatant, and the results are shown in fig. 5. The water samples before, during and after flotation are shown in fig. 6, and the red substances in the cups are acid red dyes.

As can be seen from FIG. 5, the coagulation coupling self-emission type air floatation process has good treatment efficiency on printing and dyeing wastewater, and the removal rate after air floatation for twenty minutes can reach more than 80%. Meanwhile, the results of fig. 5 show that the hydraulic conditions have a great influence on the efficiency of the coagulation coupling self-priming air floatation process, and for simulating a printing and dyeing wastewater sample, an organic flocculant, namely enteromorpha polysaccharide, is added into the water sample to be treated, the water sample is rapidly stirred for 60 seconds at the speed of 200 rpm, then an inorganic coagulant, namely ferric chloride (or polymeric ferric sulfate) is added, the water sample is stirred for 30 seconds at the speed of 500 rpm, and finally the water sample is left to stand and air float for 20 minutes, so that the dye removal rate of 85% can be achieved. Furthermore, as can be seen from FIG. 5, when the hydraulic conditions are outside the range of "stirring at a speed of 100 to 200 rpm for 30 to 120 seconds" or "stirring at a speed of 400 to 600 rpm for 15 to 60 seconds", substantially no spontaneous flotation phenomenon occurs, and the removal rate of the resulting dye is very low.

Example 4:

the same experimental subjects as in example 1, and the water treatment method of the same process parameters, were selected, and only the coagulant was replaced with polymeric ferric sulfate (or ferric chloride, or polyaluminum chloride). The dosage ratio of the cross-linking agent to the coagulant is 2:1, and the algae removal rate can reach 80-95% at the dosage of about 14 mg/L.

Example 5:

selecting the same experimental object and the water treatment method with the same technological parameters as those of the embodiment 2, and replacing only the flocculant with enteromorpha polysaccharide and the coagulant with polymeric ferric sulfate (or ferric chloride). The test results are: the best effect is achieved with the dose ratio of the mass concentration of 2:1 under different dose ratios of the cross-linking agent and the coagulant, and the higher removal rate can be achieved with a smaller dosage. When the coagulant concentration is (6-8 mg/L), the removal rate of the organic matters, the metal oxide nano particles and the turbidity can reach about 78%, 92% and 95%, respectively, which is equivalent to the technical effect of the embodiment 2.

Example 6:

the same experimental subjects as in example 3, and the water treatment method of the same process parameters were selected, and only the flocculant was replaced with laminarin and the coagulant was replaced with polyaluminum chloride (or aluminum sulfate). In experimental tests, laminarin is added into a water sample to be treated, and is rapidly stirred for 60 seconds at a speed of 200 rpm, then polyaluminium chloride (or aluminum sulfate) is added, and is stirred for 30 seconds at a speed of 500 rpm, and finally, the mixture is left to stand and air float for 20 minutes, so that the dye removal rate of 76% can be achieved. Moreover, when the hydraulic conditions are in the range of "100-200 rpm for 30-120 seconds" or "400-600 rpm for 15-60 seconds", i.e. the stirring time period for adding the flocculant is too long or too short, or the stirring time period for adding the coagulant is too long or too short, no spontaneous flotation phenomenon is generated basically, and the removal rate of the obtained dye is very low and less than 8%.

In order to further study the influence of each process parameter in the coagulation coupling self-emission type air floatation process on water treatment, the following comparative tests are respectively carried out:

(1) As a comparative experiment of example 2, under the condition that other process parameters and conditions are not changed, only the dosage of coagulant is insufficient, and after flotation is finished, macroscopic results of a water sample are shown as a in fig. 7, and it is seen that the pollutant removal efficiency is limited and the aggregation degree of floccules is not high; also, the same comparative experiment was conducted for example 1, which was the same as the comparative experiment result for example 2.

(2) As a comparative experiment in example 1, under the condition that other process parameters and conditions are not changed, only the dosage of the cross-linking agent is insufficient, and the macroscopic result of the water sample after flotation is finished is shown as b in fig. 7, it can be seen that the floccules are layered to generate a sandwich structure, and an ideal flotation effect cannot be generated; also, the same comparative experiment was conducted for example 2, which was the same as the comparative experiment result for example 1.

(3) As a comparative experiment in example 2, under the condition that other process parameters and conditions are not changed, only the content of dissolved oxygen in the water sample to be treated is insufficient (less than 4 ml/L), and the macroscopic result of the water sample after flotation is finished is shown as c in fig. 7 because of the lack of dissolved oxygen as a flotation carrier, and thus, the flocs are deposited on the lower layer of the water bottom, and the flotation phenomenon cannot be completed. In addition, when the content of dissolved oxygen is lower than 4ml/L, the optimal dosage ratio of the cross-linking agent and the coagulant is adopted, and under the condition of the maximum dosage, the removal rate of the organic matters and the metal oxide nano particles is lower than more than 10 percent, so that the requirements of industrial sewage treatment cannot be met.

(4) As a comparative experiment of example 2, when the addition order of the coagulant and the crosslinking agent is merely reversed under the condition that other process parameters and conditions are not changed, a typical crosslinking structure cannot be generated, a large amount of organic crosslinking agent remains in the liquid phase, the coagulant cannot effectively fix the crosslinking agent, and only a small amount of micro bubbles are generated outside the flocs, and the macroscopic result of the water sample after the flotation is shown in fig. 7 d.

(5) As a comparative experiment in example 1, under the condition that other process parameters and conditions are not changed, when the hydraulic conditions deviate from the preferred ranges, the stirring time of adding the crosslinking agent is more than 120s or/and the stirring time of adding the coagulant is more than 60s, and the failure of the floccule packaging micro-bubbles is caused by the overlong action time (as shown in e in fig. 7), the reduction of the crosslinking efficiency and the delay of the flotation time are caused by the insufficient shearing force.

While particular embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely illustrative, and that many variations or modifications may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined only by the appended claims.

Claims (4)

1. The water treatment method based on the coagulation coupling self-hairing type air floatation process is characterized by comprising the following steps of:

adding a cross-linking agent into a water body to be treated, wherein the dissolved oxygen content of the water body to be treated is more than 4mg/L, stirring for 30-120 seconds at the speed of 100-200 rpm, uniformly mixing, adding a coagulant, stirring for 15-60 seconds at the speed of 400-600 rpm, uniformly mixing, and finally standing for 10-20 minutes to finish spontaneous flotation; wherein the cross-linking agent is at least one of sodium alginate, laminarin and enteromorpha polysaccharide, and the coagulant is at least one of aluminum sulfate, polyaluminum chloride, ferric chloride and polyferric sulfate;

the dosage ratio of the cross-linking agent to the coagulant is 3:2-3:1 according to mass concentration.

2. The water treatment method based on the coagulation coupling self-induced air floatation process according to claim 1, wherein the dosage ratio of the cross-linking agent to the coagulant is 2:1 based on mass concentration.

3. The water treatment method based on the coagulation coupling self-propelled air floatation process according to claim 1, wherein the dissolved oxygen content of the water body to be treated is higher than 8mg/L.

4. A water treatment method based on a coagulation coupling self-induced air flotation process according to any one of claims 1 to 3, wherein the water body to be treated is natural surface water, algae-containing surface water, printing and dyeing wastewater, papermaking wastewater, mining wastewater, brewing wastewater, antibiotic drug wastewater or microplastic contaminated water.

Images