Device and method for recovering phosphorus from acid oil wastewater and preparing carbon source for water treatment

Abstract

The invention relates to a device and method for recovering phosphorus from acid oil wastewater and preparing a water treatment carbon source, the device comprises a wastewater concentration unit and a phosphorus recovery reaction unit, the wastewater concentration unit comprises a heating stirring tank and a cooling crystallization tank, and the phosphorus recovery reaction unit comprises two phosphorus recovery reaction tanks. The wastewater is concentrated by adopting the characteristics that the solubility change of sodium sulfate at 0-45 DEG C is large and free water in the wastewater can be converted into crystal water to form mirabilite during crystallization precipitation, and compared with an MVR (mechanical vapor recompression) method and an electrodialysis reverse osmosis method, the structure is simple, the equipment investment is low, and the operation cost is saved; the acid oil wastewater is subjected to resource utilization. By utilizing the characteristics of high phosphorus content, high COD (Chemical Oxygen Demand) equivalent and good biodegradability of the acidified oil wastewater, a large amount of phosphorus resources can be recovered from the acidified oil wastewater and finally prepared into a water treatment carbon source.

Description

Technical Field

[0001] The invention relates to the field of industrial wastewater treatment. Background Art

[0002] Fatty acid products have a wide range of applications in the global oil and fat chemical industry and are very critical industrial raw materials. The production of these products usually uses saponins, which are by-products of vegetable oil processing plants, to obtain crude fatty acids through sulfuric acid treatment. Subsequently, these crude fatty acids will undergo medium-pressure continuous hydrolysis and high-vacuum continuous distillation processes to ultimately produce high-quality refined fatty acids, stearic acid and vegetable asphalt. In the above production process, a large amount of acidified oil wastewater will be generated, which is characterized by a COD content of about 3.50×10 4 mg / L, phosphate content 3000-5000mg / L, animal and vegetable oil about 100mg / L, pH value about 3.0, salt content of 5-10% (salt is mainly sodium sulfate), in addition, it also contains phospholipids, soaps, organic acids and other pollutants.

[0003] At present, the mainstream process for treating acidified oil wastewater is the MVR (mechanical vapor recompression technology) treatment method. After the wastewater is treated, MVR evaporated liquid and concentrated liquid are obtained. The MVR evaporated liquid is further treated by biochemical treatment process until it meets the discharge standards. There is currently no ideal treatment method for the concentrated liquid produced. If it is not properly treated, it will cause serious pollution to the environment. Another treatment method is to use electrodialysis and reverse osmosis to concentrate and desalinate the wastewater, but this method will have the following two problems when treating high-concentration organic wastewater. On the one hand, this method has a high one-time investment, and the maintenance and replacement of the osmotic membrane are expensive. Secondly, the higher the degree of wastewater pollution, the cost of electrodialysis and reverse osmosis will rise sharply, and serious membrane pollution will occur, so it is difficult to promote.

[0004] Acidified oil wastewater contains a large amount of organic pollutants such as organic acids and glycerol, which contribute a large amount of COD. However, the phenomenon of low carbon-nitrogen ratio in urban domestic sewage is common at present, and the discharge standards have increasingly higher requirements for total nitrogen removal, resulting in insufficient carbon sources required for denitrification, and external carbon sources are often required to ensure the denitrification effect. Acidified oil wastewater contains rich organic matter, which can be used by microorganisms as electron donors to promote the denitrification process. Acidified oil wastewater comes from vegetable oil processing and fatty acid production. It has good biodegradability and extremely low toxic substance content. However, its use as a carbon source is affected by its high total phosphorus content. Phosphorus is an important indicator of sewage treatment discharge. At the same time, phosphorus is also an important element for metabolism and maintenance of physiological functions in animals, and is an important resource material. The raw material source of phosphorus mainly depends on phosphate rock, and phosphate rock resources are non-renewable and will be exhausted with over-exploitation. If the phosphorus in the acidified oil wastewater is extracted, not only can phosphorus resources be obtained, but it can also be further made into a carbon source for water treatment, and at the same time, the treatment cost of acidified oil wastewater is reduced, which can be said to kill two birds with one stone. Summary of the invention

[0005] In order to solve the above problems existing in the treatment of acidified oil wastewater, the present invention provides a device and method for recovering phosphorus from acidified oil wastewater and preparing a carbon source for water treatment.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a device for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source, comprising a wastewater concentration unit and a phosphorus recovery reaction unit. The wastewater concentration unit comprises a heating stirring tank and a cooling crystallization tank; the phosphorus recovery reaction unit comprises two phosphorus recovery reaction tanks. The water inlet of the heating stirring tank is connected to the wastewater pipeline, the heating stirring tank is provided with a feeding port, and the water outlet of the heating stirring tank is connected to the water inlet of the cooling crystallization tank through a pipeline; the cooling crystallization tank is provided with a feeding port and a crystallization discharge port, and the water outlet of the cooling crystallization tank is connected to the water inlet of the No. 1 phosphorus recovery reaction tank through a pipeline; the water outlet of the No. 1 phosphorus recovery reaction tank is connected to the water inlet of the No. 2 phosphorus recovery reactor through a pipeline, and the No. 1 phosphorus recovery reaction tank and the No. 2 phosphorus recovery reaction tank are provided with a feeding port and a solid discharge port.

[0007] The phosphorus recovery reactor is provided with a stirring device and a pH probe inside, and the reaction tank feeding device can control the feeding and stopping of the feeding through the numerical value fed back by the pH probe.

[0008] A method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source comprises the following steps:

[0009] S1: The acidified oil wastewater is fed into the heating stirring tank of the wastewater concentration unit, and anhydrous sodium sulfate solid is added into the heating stirring tank through the feeding port to stir and dissolve;

[0010] S2: After sodium sulfate is completely dissolved in the wastewater, the wastewater enters the cooling crystallization tank, and sodium sulfate is continuously precipitated in the form of sodium sulfate decahydrate crystals. Solid-liquid separation is performed in the cooling crystallization tank to obtain mirabilite crystals and concentrated liquid;

[0011] S3: the concentrated liquid enters the No. 1 phosphorus recovery reaction tank of the phosphorus recovery unit, a phosphorus recovery agent is added to the concentrated liquid from the feed port of the No. 1 phosphorus recovery reaction tank and stirred continuously, PAM is added for precipitation and solid-liquid separation is performed to obtain the first step phosphorus-containing solid, and the remaining concentrated liquid enters the No. 2 phosphorus recovery reaction tank;

[0012] S4: adding a phosphorus recovery agent to the phosphorus recovery reaction tank No. 2 from the feed port of the phosphorus recovery reaction tank No. 2 and continuously stirring, and allowing the reaction to stand for solid-liquid separation to obtain a solid and a water treatment carbon source after phosphorus recovery.

[0013] In the step S1, the amount of sodium sulfate added is controlled to be saturated in the wastewater at 45°C, and the heating and stirring tank is equipped with a built-in heating and stirring device to heat the wastewater temperature to 45°C and continuously stir and dissolve.

[0014] In step S2, the wastewater temperature is cooled to minus 1°C.

[0015] In step S3, the dosage of the phosphorus recovery agent is controlled so that the pH value is not greater than 4.0 and no precipitation is generated.

[0016] In step S3, the recovered phosphorus agent is calcium carbonate or calcium hydroxide.

[0017] In step S4, the pH of the concentrated solution after the complete reaction is 7.0-8.0.

[0018] In step S4, the phosphorus recovery agent is preferably calcium hydroxide and calcium oxide, and can also be sodium hydroxide, sodium oxide, magnesium hydroxide, magnesium oxide, potassium hydroxide and potassium oxide. The latter can also achieve the effect of phosphorus recovery, but it will cause calcium deficiency and introduce other metal cations.

[0019] The device and method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source have the following advantages:

[0020] (1) Compared with the MVR method, electrodialysis and reverse osmosis method, the treatment method of the present invention has significant advantages. First, its structure is simpler and does not require the investment of large-scale equipment, so the investment cost is lower. Secondly, due to the simplification of equipment and processes, operating costs are also more economical. In addition, this method also avoids the common problems of clogging, scaling and high power consumption of other treatment methods, thereby improving the treatment efficiency and the service life of the equipment. The treatment method provided by the present invention is expected to significantly reduce the cost of acidified oil treatment by 40-60%.

[0021] (2) The treatment method of the present invention utilizes the characteristics of sodium sulfate having a large solubility change at 0-45°C, and the characteristic of converting free water in the wastewater into crystal water to form sodium sulfate during crystallization, so as to effectively concentrate the wastewater. When treating acidified oil wastewater, anhydrous sodium sulfate and recovered phosphorus agent are mainly used. Anhydrous sodium sulfate can be recycled, reducing material costs. And recovered phosphorus agents: calcium carbonate, calcium hydroxide, calcium oxide, sodium hydroxide, etc., are all low-priced products with stable market supply.

[0022] (3) Utilize the acidified oil wastewater as a resource. Taking advantage of the high phosphorus content, high COD equivalent and good biodegradability of acidified oil wastewater, a large amount of phosphorus resources can be recovered from it and finally made into a carbon source for water treatment. The recovered phosphorus-containing substances are mainly calcium hydrogen phosphate, which is the main raw material for producing feed and phosphate fertilizers and has a high use value. In addition, the recovery of phosphorus resources can alleviate the problem of phosphate mine depletion; the liquid after phosphorus recovery contains a large amount of biological organic matter. When used as a carbon source for water treatment, it has a fast denitrification reaction rate, high efficiency, and a good denitrification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the principle of recovering phosphorus from acidified oil wastewater and preparing it into a water treatment carbon source according to the present invention. DETAILED DESCRIPTION

[0024] The device for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to the present invention is as follows: Figure 1 As shown, it includes two processing units, namely, the acidified oil wastewater concentration unit and the phosphorus recovery reaction unit. The wastewater concentration unit is provided with a heating stirring tank and a cooling crystallization tank, and the phosphorus recovery reaction unit is provided with two phosphorus recovery reaction tanks. The tank body and related parts of the heating stirring tank need to be salt-resistant and rust-resistant. The tank body is provided with a water inlet, a feeding port, an observation port and a water outlet, and a heating device and a stirring device are provided inside. The heating device can be turned on and off according to the internal temperature change to achieve a constant temperature effect. The tank body and related parts of the cooling crystallization tank need to be salt-resistant and rust-resistant. The tank body is provided with a water inlet, a feeding port, an observation port and a water outlet. The material is uniformly cooled inside, can be quickly crystallized and the particles are uniform, avoiding dead corners at the discharge port, generating crystallization, and convenient discharge. The tank body and related parts of the phosphorus recovery reaction tank need to be salt-resistant and rust-resistant. The tank body is provided with a water inlet, a feeding port, an observation port and a water outlet. A stirring device and a pH probe are provided inside. The stirring intensity should make the internal reaction fully and thoroughly, and a mud bucket is provided at the bottom for solid-liquid separation.

[0025] The water inlet of the heating and stirring tank is connected to the wastewater pipeline, the heating and stirring tank is provided with a feeding port, the water outlet of the heating and stirring tank is connected to the water inlet of the cooling crystallization tank through a pipeline, the cooling crystallization tank is provided with a feeding port and a crystallization discharge port, the water outlet of the cooling crystallization tank is connected to the water inlet of the No. 1 phosphorus recovery reaction tank through a pipeline, the water outlet of the No. 1 phosphorus recovery reaction tank is connected to the water inlet of the No. 2 phosphorus recovery reactor through a pipeline, and the No. 1 phosphorus recovery reaction tank and the No. 2 phosphorus recovery reactor are provided with a feeding port and a solid discharge port.

[0026] The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source comprises the following steps:

[0027] S1: Add the acidified oil wastewater to the heating and stirring tank of the concentration unit. The top of the stirring tank is provided with a feed port, and anhydrous sodium sulfate solid is added inside. The amount of sodium sulfate added is controlled to be saturated in the wastewater at 45°C. The heating and stirring device built into the heating and stirring tank heats the wastewater temperature to 45°C and continuously stirs and dissolves.

[0028] The added anhydrous sodium sulfate solid can be obtained by treating the sodium sulfate crystals obtained in step 2, and the treatment method can be hot air drying, evaporation crystallization, or heat melting. It can also be purchased industrial sodium sulfate, which must meet the feed additive standards to avoid affecting the quality of the produced calcium hydrogen phosphate and carbon source.

[0029] Usually, acidified oil wastewater contains a certain amount of sodium sulfate, about 10-20g / L. On the one hand, it can reduce the amount of added sodium sulfate, and on the other hand, it does not introduce exogenous pollutants.

[0030] The wastewater can be heated directly, or it can be heated by contact heating using hot cooling water pipes, or by using other industrial waste heat or solar energy.

[0031] S2: Sodium sulfate is completely dissolved in the wastewater and then enters the cooling crystallization tank to cool the wastewater to -1°C. As the wastewater temperature drops, sodium sulfate is continuously precipitated in the form of sodium sulfate decahydrate crystals (glauber's salt). After the crystals are completely precipitated, solid-liquid separation is performed in the cooling crystallization tank to obtain Glauber's salt crystals and a primary concentrated solution. Whether to conduct secondary or multiple concentrations depends on the indicators of the primary concentrated solution.

[0032] Wastewater will not freeze after being cooled to -1°C because the presence of sodium sulfate lowers the freezing point of wastewater. At this temperature, sodium sulfate in wastewater can be precipitated to the maximum extent, but the temperature cannot be lower than -1°C. As the temperature continues to decrease, the solubility of sodium sulfate will increase, which is not conducive to crystallization and will also increase energy consumption. As the temperature decreases, the water in the wastewater changes from free state to crystal water during the crystallization process, so that the liquid is concentrated. This process replaces the traditional evaporation concentration process.

[0033] S3: The obtained concentrated solution enters the phosphorus recovery reaction tank 1 of the phosphorus recovery unit, and the phosphorus recovery agent calcium carbonate is added to the concentrated solution from the top feeding port and continuously stirred. The pH rises during the reaction, and the dosage is controlled to be no more than pH 4.0 and no precipitation is generated. PAM is added to precipitate it and solid-liquid separation is performed to obtain the first step phosphorus-containing solid, and the remaining concentrated solution enters the phosphorus recovery reaction tank 2.

[0034] The phosphorus recovery agent is added in the form of slurry, and the mass concentration is controlled at 100g / L. The purpose of adding the phosphorus recovery agent is to introduce calcium ions and increase the pH of the concentrate, and react with the sulfate and phosphate ions in the concentrate to form a precipitate for separation.

[0035] The phosphorus recovery agent is preferably calcium carbonate. The reaction rate of adding calcium carbonate in a first-stage reaction is much slower than that of calcium hydroxide, and the CO2 gas generated during the reaction can further disperse the solid particles, making the local saturation reduction reaction more controllable and the product crystal form better. When the phosphorus recovery reaction tank 1 is fully stirred, the reaction time is 30 minutes, and the reaction temperature needs to be controlled at 30-40°C. The amount of phosphorus recovery agent added should not be too much, and the pH should be controlled to be no more than 4.0. During the solid-liquid separation process after precipitation, the solid-liquid separation can be achieved by stopping stirring and allowing the precipitation to stand, thereby obtaining an upper liquid and a lower precipitate. The lower precipitate should be filtered after mechanical concentration, and the main component of the solid obtained after filtering is calcium sulfate. The upper liquid and the obtained filtrate enter step 4 for treatment.

[0036] S4: Continue to add phosphorus recovery agent calcium hydroxide and calcium oxide to the phosphorus recovery reaction tank 2, and continue stirring to control the pH of the concentrated solution after complete reaction to be 7.0-8.0, at which time a large amount of solids are produced, mainly calcium hydrogen phosphate. After the reaction, the solution is allowed to stand for solid-liquid separation to obtain calcium hydrogen phosphate solid and concentrated solution after phosphorus recovery.

[0037] The purpose of adding a phosphorus recovery agent is to increase the pH value of the wastewater and introduce excess calcium ions to form calcium phosphate / calcium hydrogen phosphate precipitation in the wastewater to extract phosphorus from the wastewater. The added phosphorus recovery agent can be sodium hydroxide, sodium oxide, calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, potassium hydroxide, potassium oxide, etc. However, due to cost constraints and the lack of introduction of other metal substances, calcium hydroxide and calcium oxide should be used. If the alkalinity is insufficient, sodium hydroxide can be added in appropriate amounts to supplement it. Calcium salts are commonly used phosphorus recovery agents and flocculants in the water treatment industry. The subsequent water treatment carbon source contains some calcium hydroxide, which can also play a role in phosphorus recovery and flocculation, but it should not be too much, and its pH should not be greater than 8.0.

[0038] The amount of recovered phosphorus agent added should not be too much, and the amount added should be controlled so that the pH of the solution after the reaction is between 7.0 and 8.0. Excessive addition will cause waste of the recovered phosphorus agent, and will also make the pH of the obtained liquid carbon source too high, which cannot meet the requirements of the carbon source. If the recovered phosphorus agent is added excessively to make the pH greater than 8.0, the produced calcium hydrogen phosphate will be converted into calcium phosphate and hydroxy calcium phosphate, resulting in impure calcium hydrogen phosphate. In addition, the excessive alkalinity will also cause the organic matter in the obtained concentrated solution to react and produce precipitation, which will reduce the COD of the obtained carbon source, thereby reducing the equivalent of the obtained carbon source and reducing the quality of the carbon source. Experiments have shown that excessive addition of recovered phosphorus agent to a pH of about 10.0 will reduce the COD of the obtained concentrated solution by about 40%. For reference, for a concentrated solution with a TP concentration of about 10,000 mg / L, the amount of recovered phosphorus agent calcium hydroxide added is about 55 kg / m 3 .

[0039] The reaction time during the stirring process is at least greater than 1 hour, preferably 1-1.5 hours. Sufficient stirring must be ensured. If stirring is insufficient, stratification will occur. After the addition of the phosphorus recovery agent is stopped, the pH value will gradually rise by about 1 value because the reaction speed is slower than the addition speed of the phosphorus recovery agent.

[0040] During the solid-liquid separation process after precipitation, the solid-liquid separation can be achieved by stopping the stirring and allowing the sediment to settle to obtain an upper layer of liquid and a lower layer of sediment. The lower layer of sediment is preferably filtered after mechanical concentration, and the solid obtained after the filtration is air-dried to obtain high-quality calcium hydrogen phosphate solid. The filtrate is precipitated again, and the clear liquid is filtered through a ceramic membrane or a sand filter, and can be used together with the upper layer of liquid as a carbon source for water treatment.

[0041] The COD of 100L of acidified oil wastewater was 3.25×10 4 mg / L, TP is 2578 mg / L (in terms of P), pH is 3.47, and after two concentrations, COD is 1.05×10 5 mg / L, TP was 8741 mg / L, pH was 3.14, and the volume of the concentrated solution was 30.2 L. After two-stage neutralization reaction and solid-liquid separation, 23.8 L of liquid carbon source was obtained, and the COD of the liquid carbon source was measured to be 8.97×10 4 mg / L, TP is 274mg / L, pH is 7.82. After filtration, the solid obtained is about 2320g after air drying. The solid phosphorus content is 17.4%, the citrate-soluble phosphorus content is 14.8%, and the calcium content is 23.1%. It meets the requirements of Type I products in GB22549-2017 "Feed Additive Calcium Hydrogen Phosphate".

[0042] The liquid carbon source obtained after filtration was used for the experiment. Three groups of SBR reactors were used to treat domestic sewage, without adding carbon source, adding sodium acetate carbon source and adding the prepared liquid carbon source. The aeration method was intermittent aeration, and the hydraulic retention time was 1d. The ammonia nitrogen of the domestic sewage was 15-30mg / L, the total nitrogen was 25-45mg / L, and the COD was 60-100mg / L. The three groups of reactors adopted the same reaction conditions as mentioned above, and the amount of carbon source added to the carbon source group was to increase the overall COD by 50mg / L. After 30 days of testing, the average total nitrogen removal rate of the group without adding carbon source was 48%, and the average total nitrogen removal rates of the group with sodium acetate carbon source and the prepared carbon source group were 78% and 73%. It shows that the prepared carbon source can significantly improve the denitrification efficiency of low carbon-nitrogen ratio domestic sewage.

[0043] The present invention is described by way of embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the protection scope of the present invention.

Claims

1. A device for recovering phosphorus from acidified oil wastewater and preparing it into a carbon source for water treatment, characterized in that: The invention comprises a wastewater concentration unit and a phosphorus recovery reaction unit. The wastewater concentration unit comprises a heating stirring tank and a cooling crystallization tank. The phosphorus recovery reaction unit comprises two phosphorus recovery reaction tanks. The water inlet of the heating stirring tank is connected to a wastewater pipeline. The heating stirring tank is provided with a feeding port. The water outlet of the heating stirring tank is connected to the water inlet of the cooling crystallization tank through a pipeline. The cooling crystallization tank is provided with a feeding port and a crystallization discharge port. The water outlet of the cooling crystallization tank is connected to the water inlet of a No. 1 phosphorus recovery reaction tank through a pipeline. The water outlet of the No. 1 phosphorus recovery reaction tank is connected to the water inlet of a No. 2 phosphorus recovery reactor through a pipeline. The No. 1 phosphorus recovery reaction tank and the No. 2 phosphorus recovery reaction tank are provided with a feeding port and a solid discharge port.

2. The device for recovering phosphorus from acidified oil wastewater and preparing a carbon source for water treatment according to claim 1, characterized in that: A stirring device and a pH probe are arranged inside the phosphorus recovery reaction tank.

3. A method for recovering phosphorus from acidified oil wastewater and preparing it into a carbon source for water treatment, characterized in that: The following steps are involved: S1: The acidified oil wastewater is fed into the heating stirring tank of the wastewater concentration unit, and anhydrous sodium sulfate solid is added into the heating stirring tank through the feeding port to stir and dissolve; S2: After sodium sulfate is completely dissolved in the wastewater, the wastewater enters the cooling crystallization tank, and sodium sulfate is continuously precipitated in the form of sodium sulfate decahydrate crystals. Solid-liquid separation is performed in the cooling crystallization tank to obtain mirabilite crystals and concentrated liquid; S3: the concentrated liquid enters the No. 1 phosphorus recovery reaction tank of the phosphorus recovery reaction unit, a phosphorus recovery agent is added to the concentrated liquid from the feed port of the No. 1 phosphorus recovery reaction tank and stirred continuously, PAM is added for precipitation and solid-liquid separation is performed to obtain the first step phosphorus-containing solid, and the remaining concentrated liquid enters the phosphorus recovery reaction tank 2; S4: adding a phosphorus recovery agent to the phosphorus recovery reaction tank No. 2 from the feed port of the phosphorus recovery reaction tank No. 2 and continuously stirring, and allowing the reaction to stand for solid-liquid separation to obtain a solid and a water treatment carbon source after phosphorus recovery.

4. The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to claim 3, characterized in that: In the step S1, the amount of sodium sulfate added is controlled to be saturated in the wastewater at 45°C, and the heating and stirring tank is equipped with a built-in heating and stirring device to heat the wastewater temperature to 45°C and continuously stir and dissolve.

5. The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to claim 3, characterized in that: In step S2, the wastewater temperature is cooled to minus 1°C.

6. The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to claim 3, characterized in that: In step S3, the dosage of the phosphorus recovery agent is controlled so that the pH value is not greater than 4.0 and no precipitation is generated.

7. The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to claim 3, characterized in that: In step S3, the recovered phosphorus agent is calcium carbonate or calcium hydroxide.

8. The method for recovering phosphorus from acidified oil wastewater and preparing a carbon source for water treatment according to claim 3, characterized in that: In step S4, the pH of the concentrated solution after the complete reaction is 7.0-8.

0.

9. The method for recovering phosphorus from acidified oil wastewater and preparing a water treatment carbon source according to claim 3, characterized in that: In step S4, the recovery agent is sodium hydroxide, sodium oxide, calcium hydroxide, calcium oxide, magnesium hydroxide, magnesium oxide, potassium hydroxide or potassium oxide.

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