阅读说明：本技术 一种生产磷酸法活性炭的含磷废水回收利用方法 (Method for recycling phosphorus-containing wastewater generated in production of phosphoric acid method activated carbon ) 是由 程祥武 陈卫群 方世国 曹阳 于 2021-09-28 设计创作，主要内容包括：本发明提供一种生产磷酸法活性炭的含磷废水回收利用方法,属于含磷废水资源回收技术领域；其方法是将含磷废水收集后经多级净化、浓缩,得到高浓度含磷水和净化后的工业用水,高浓度含磷水与硫酸钙滤饼经沉淀反应生产磷酸氢钙沉淀,再经浓硫酸置换反应、过滤,滤液即为得到高纯度磷酸,硫酸钙滤饼经洗涤循环回用,梯度洗涤水再次配磷酸氢钙浆料进行循环回用。本发明具有高效回收含磷废水中磷资源和工业用水,工业化操作简单有效,生产成本低,容易工业化推广。(The invention provides a method for recycling phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon, belonging to the technical field of phosphorus-containing wastewater resource recovery; the method comprises the steps of collecting phosphorus-containing wastewater, performing multi-stage purification and concentration to obtain high-concentration phosphorus-containing water and purified industrial water, performing precipitation reaction on the high-concentration phosphorus-containing water and a calcium sulfate filter cake to produce calcium hydrophosphate precipitate, performing replacement reaction by concentrated sulfuric acid, and filtering to obtain filtrate, namely high-purity phosphoric acid, washing and recycling the calcium sulfate filter cake, and preparing calcium hydrophosphate slurry into gradient washing water for recycling. The method has the advantages of high-efficiency recovery of phosphorus resources and industrial water in the phosphorus-containing wastewater, simple and effective industrial operation, low production cost and easy industrial popularization.)

1. A method for recycling phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon is characterized by comprising the following steps:

1) purifying and concentrating phosphorus-containing wastewater: the method comprises the following steps of collecting, adjusting pH, primary filtering, heat exchanging, sand filtering, softening, precise filtering and concentrating discharged phosphorus-containing water produced by phosphoric acid method activated carbon production to obtain purified high-concentration concentrated solution and purified dialysate;

2) preparing high-purity calcium hydrophosphate: placing the high-concentration concentrated solution and the calcium sulfate filter cake in the step 1) into a precipitation reaction kettle for precipitation reaction, continuously stirring, adjusting the pH value by using liquid alkali during the reaction to ensure that phosphate radical is completely converted into calcium hydrophosphate, and then filtering and washing the filter cake to obtain the purified high-purity calcium hydrophosphate filter cake.

3) Preparing and recovering phosphoric acid: and (3) performing a replacement reaction on the calcium hydrogen phosphate filter cake obtained in the step 2) and concentrated sulfuric acid in a reaction kettle containing bottom water according to a preset mass ratio, standing, cooling and filtering to obtain filtrate, namely phosphoric acid with the purity of over 90%, performing gradient washing on the calcium sulfate filter cake, and recycling, wherein the washing water is used as the bottom water of the calcium hydrogen phosphate filter cake for recycling.

2. The method for recycling phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon according to claim 1, wherein the phosphorus-containing water in the step 1) is obtained from washing drainage of phosphoric acid method activated carbon and does not contain tar and oil macromolecular organic matters.

3. The method for recycling phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon according to claim 2, wherein the primary filtration in step 1) is used for intercepting phosphoric acid method activated carbon powder in water; the phosphorus-containing water is subjected to heat exchange by clear water to obtain water with the temperature within 45 ℃, and the clear water is reused for producing washing water.

4. The method for recycling the phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon according to claim 2, wherein the pH value is automatically adjusted to 3-7 by using an industrial sodium hydroxide solution in the step 1); softening by adopting sodium ion conversion ion exchange resin, and adding an inorganic phosphorus scale inhibitor into the softened phosphorus-containing water; the precise filtration adopts an ultrafiltration filter with the filtration precision within 2 um.

5. The method for recycling the phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon according to claim 4, wherein the inorganic phosphorus scale inhibitor is one or more of sodium polyphosphate, sodium hexametaphosphate and sodium tripolyphosphate; the dosage of the inorganic phosphorus scale inhibitor accounts for 10-100 ppm of the total phosphorus-containing water.

6. The method for recycling the phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon according to claim 2, wherein a reverse osmosis membrane is used for concentration in the step 1), the content of phosphate radicals in the concentrated solution is 2-10%, and the dialyzate is reused as industrial water for gradient washing of phosphoric acid method activated carbon.

7. The method for recycling the phosphorus-containing wastewater generated in the production of the phosphoric acid method activated carbon according to claim 1, wherein the precipitation reaction in the step 2) adopts liquid alkali to adjust the pH value to 9-11 within 30-60 min, the reaction is carried out for 2-4 h after the pH value is adjusted, and the filter cake is washed at 50-80 ℃ until the conductivity of the filtered water is within 2000 us/cm.

8. The method for recycling phosphorus-containing wastewater generated in the production of activated carbon by a phosphoric acid method according to claim 7, wherein calcium sulfate is supplemented in each precipitation reaction, and the added amount of calcium sulfate accounts for CaSO in a calcium sulfate filter cake₄2-5% of the total amount.

9. The method for recycling phosphorus-containing wastewater generated in the production of activated carbon by a phosphoric acid method according to claim 1, wherein the calcium hydrogen phosphate filter cake and concentrated sulfuric acid in the step 3) are mixed according to phosphate radicals and H contained in the materials₂SO₄The molar mass ratio of (1: 1) - (1.1) is added, the reaction time is 2-4 h, the standing time is 1-6 h, and the temperature is reduced to be within 50 ℃ through heat exchange.

10. The method for recycling phosphorus-containing wastewater from the production of phosphoric acid method activated carbon according to claim 1, wherein the amount of the bottom water of the gradient washing water is controlled in step 3); the mass concentration of the obtained phosphoric acid solution is 10-20%, and the purity of phosphoric acid is more than 90%.

Technical Field

The invention belongs to the technical field of phosphorus-containing wastewater resource recovery, and particularly relates to a method for recycling phosphorus-containing wastewater for producing phosphoric acid method activated carbon.

Background

The phosphorus resource has wide application in the fields of agriculture, chemical industry, medicine, food and the like. The phosphorus resource is mainly from phosphorite which is mined and utilized by human beings, the phosphorite is a non-renewable important mineral resource, and the most important purpose is to produce phosphate fertilizer. The sustainable development and utilization of phosphorus resources are related to global food safety and the sustainable development of human society. At present, the treatment of phosphorus-containing wastewater at home and abroad has the following two technologies. (1) The chemical phosphorus removal method mainly comprises a chemical coagulating sedimentation method, an adsorption method and a crystallization method, and is mainly suitable for treating inorganic phosphorus-containing wastewater, wherein the sedimentation method and the crystallization method can be used for treating high-concentration phosphorus-containing water, but the sludge yield is high, and the treatment cost is high. (2) The biological phosphorus removal method utilizes the action of microorganisms of phosphorus accumulating bacteria to absorb phosphorus into sludge biological cells through cell synthesis, and is mainly suitable for treating low-concentration organic phosphorus-containing wastewater. The two technologies can generate a large amount of sludge, which belongs to solid waste, and phosphorus resources in the sludge are difficult to recycle.

The prior phosphorus-containing wastewater treatment technology has the following defects that (1) the dosage of a medicament for treating the phosphorus-containing wastewater is large, a large amount of solid waste sludge is generated, and phosphorus resources are difficult to recycle; (2) the treatment of phosphorus-containing wastewater does not achieve "zero discharge" or reduced discharge of the wastewater.

Disclosure of Invention

The invention aims to provide a method for recycling phosphorus-containing wastewater from the production of phosphoric acid method activated carbon, so as to solve the problems.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for recycling phosphorus-containing wastewater generated in the production of phosphoric acid method activated carbon comprises the following steps:

1) purifying and concentrating phosphorus-containing wastewater: the method comprises the following steps of collecting, adjusting pH, primary filtering, heat exchanging, sand filtering, softening, precise filtering and concentrating discharged phosphorus-containing water produced by phosphoric acid method activated carbon production to obtain purified high-concentration concentrated solution and purified dialysate;

2) preparing high-purity calcium hydrophosphate: placing the high-concentration concentrated solution and the calcium sulfate filter cake in the step 1) into a precipitation reaction kettle for precipitation reaction, continuously stirring, adjusting the pH value by using liquid alkali during the reaction to ensure that phosphate radical is completely converted into calcium hydrophosphate, and then filtering and washing the filter cake to obtain the purified high-purity calcium hydrophosphate filter cake.

3) Preparing and recovering phosphoric acid: and (3) performing a replacement reaction on the calcium hydrogen phosphate filter cake obtained in the step 2) and industrial concentrated sulfuric acid in a reaction kettle containing bottom water according to a preset mass ratio, standing, cooling and filtering to obtain phosphoric acid with the purity of more than 90%, performing gradient washing on the calcium sulfate filter cake, and recycling, wherein the washing water is used as the bottom water of the calcium hydrogen phosphate filter cake for recycling.

Furthermore, the phosphorus-containing water in the step 1) comes from washing drainage of phosphoric acid method activated carbon and does not contain tar and oil macromolecular organic matters.

Further, the primary filtration in the step 1) is mainly used for intercepting phosphoric acid method activated carbon powder in water; the phosphorus-containing water is subjected to heat exchange by clear water to obtain water with the temperature within 45 ℃, and the clear water is reused for producing washing water.

Further, in the step 1), an industrial sodium hydroxide solution is adopted to automatically adjust the pH value to 3-7; softening by adopting sodium ion conversion ion exchange resin, and adding an inorganic phosphorus scale inhibitor into the softened phosphorus-containing water; the precise filtration adopts an ultrafiltration filter with the filtration precision within 2 um.

Further, the inorganic phosphorus scale inhibitor is one or more of sodium polyphosphate, sodium hexametaphosphate and sodium tripolyphosphate; the dosage of the inorganic phosphorus scale inhibitor accounts for 10-100 ppm of the total phosphorus-containing water.

Further, a reverse osmosis membrane is adopted in the concentration in the step 1), the reverse osmosis membrane has the function of intercepting phosphate radicals, the content of the phosphate radicals in the concentrated solution is 2% -10%, and the dialyzate is used as industrial water for gradient washing of phosphoric acid method activated carbon.

Further, the precipitation reaction in the step 2) adopts liquid alkali to adjust the pH value to 9-11 within 30-60 min, the reaction is carried out for 2-4 h after the pH value is adjusted, and the filter cake is washed at 50-80 ℃ until the electric conductivity of the filtered water is within 2000 us/cm.

Further, calcium sulfate is supplemented in each precipitation reaction, and the supplement amount accounts for CaSO in the calcium sulfate filter cake₄2-5% of the total amount.

Further, the calcium hydrogen phosphate filter cake and the industrial concentrated sulfuric acid in the step 3) are mixed according to phosphate radicals and H contained in the materials₂SO₄The molar mass ratio of (1: 1) - (1.1) is added, the reaction time is 2-4 h, the standing time is 1-6 h, and the temperature is reduced to be within 50 ℃ through heat exchange.

Further, controlling the amount of the bottom water of the gradient washing water in the step 3); the mass concentration of the obtained phosphoric acid solution is 10-20%, and the purity of phosphoric acid is more than 90%.

The recovery rate of the phosphate radical in the phosphorus-containing wastewater is more than 90 percent by adopting the method.

The invention has the following advantages:

1. the method for recycling the phosphorus-containing wastewater can effectively solve the problem of treatment of the phosphorus-containing wastewater generated in the production of the phosphoric acid method activated carbon, no solid waste is generated in the treatment process, and zero emission of the phosphorus-containing wastewater is basically realized.

2. The phosphorus resource in the wastewater can be efficiently recycled, the phosphoric acid with high added value is obtained, and the phosphoric acid is recycled for production, so that the low-carbon environmental protection value of the cyclic utilization of the phosphorus resource and the water resource is realized.

3. The invention has simple process, low production cost and easy industrial popularization.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a process flow diagram of an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to the attached figure 1, the embodiment provides a method for recycling phosphorus-containing wastewater from the production of phosphoric acid method activated carbon, which comprises the following steps:

1) purifying and concentrating phosphorus-containing wastewater: collecting phosphorus-containing water discharged in the production of activated carbon by a phosphoric acid method, adjusting the pH to 3-7 by using an industrial sodium hydroxide solution, filtering by using a primary plate frame, cooling to below 45 ℃ by heat exchange, performing sand filtration, softening by using ion exchange resin to obtain phosphorus-containing softened water, adding 10-100 mg/L of inorganic phosphorus scale inhibitor into the phosphorus-containing softened water, uniformly mixing, filtering by using a precision filter, and finally conveying to a reverse osmosis membrane for concentration to obtain purified high-concentration concentrated solution containing 2-10% of phosphate radicals and purified dialysate, wherein the dialysate can be used as industrial water for washing in the production of activated carbon.

2) Preparing high-purity calcium hydrophosphate: placing the high-concentration concentrated solution and the calcium sulfate filter cake in the step 1) into a precipitation reaction kettle, simultaneously adding industrial calcium sulfate with the total calcium sulfate amount of 2-5% (because the calcium sulfate has certain solubility in water and phosphoric acid, the calcium sulfate can be dissolved into wastewater and phosphoric acid in the production process, the loss amount needs to be supplemented to keep the balance of the calcium sulfate in the whole system), continuously stirring for precipitation reaction, automatically adjusting the pH to 9-11 by adopting liquid alkali within 30-60 min, carrying out precipitation reaction for 2-4 h to completely convert phosphate radical into calcium hydrophosphate, filtering, washing the filter cake with hot water at 50-80 ℃ until the conductivity of the filter liquor is within 2000us/cm, obtaining a purified high-purity calcium hydrophosphate filter cake, and discharging the filter liquor which is up to the standard wastewater.

3) Preparing and recovering phosphoric acid: mixing the calcium hydrogen phosphate filter cake obtained in the step 2) with industrial concentrated sulfuric acid according to phosphate radicals and H contained in the materials₂SO₄Adding the calcium hydrogen phosphate filter cake into a reaction kettle according to the molar mass ratio of 1: 1-1.1, uniformly mixing, reacting for 2-4 h, standing for 1-6 h, performing heat exchange, cooling to a temperature within 50 ℃, performing plate-and-frame filtration to obtain clear filtrate, namely phosphoric acid with the purity of over 90%, performing gradient washing on calcium sulfate filter cakes, and recycling, wherein washing water is used as bottom water of the calcium hydrogen phosphate filter cake.

Example 1

1) Purifying and concentrating phosphorus-containing wastewater: collecting phosphorus-containing water discharged in the production of activated carbon by a phosphoric acid method, adjusting the pH to 3.5 by using an industrial sodium hydroxide solution, filtering by using a primary plate frame, cooling to 40 ℃ by heat exchange, performing sand filtration, softening by using ion exchange resin to obtain phosphorus-containing softened water, adding 20mg/L of inorganic phosphorus scale inhibitor into the phosphorus-containing softened water, uniformly mixing, filtering by using a precision filter, conveying to a reverse osmosis membrane for concentration to obtain purified high-concentration concentrated solution containing 2.5% of phosphate radicals, and recycling the purified dialyzate as industrial water for washing in the production of activated carbon.

2) Preparing high-purity calcium hydrophosphate: placing the concentrated solution obtained in the step 1) and the calcium sulfate filter cake in a precipitation reaction kettle, continuously stirring for precipitation reaction, simultaneously adding industrial calcium sulfate accounting for 2% of the total amount of the calcium sulfate, automatically adjusting the pH to 9.5 by using liquid caustic soda within 50min, carrying out precipitation reaction for 2h to completely convert phosphate radicals into calcium hydrophosphate, filtering, washing the filter cake with hot water at 65 ℃ until the conductivity of the filtrate is 1980us/cm, obtaining a purified high-purity calcium hydrophosphate filter cake, and discharging the filtrate which is up-to-standard wastewater.

3) Preparing and recovering phosphoric acid: mixing the calcium hydrophosphate filter cake obtained in the step 2) with industrial concentrated sulfuric acid according to phosphate radicals and H contained in the materials₂SO₄Adding the mixed solution into a reaction kettle according to the molar mass ratio of 1:1.05, uniformly mixing and reacting for 2 hours, standing for 2 hours, carrying out heat exchange and cooling to 48 ℃, and carrying out plate-and-frame filtration to obtain clear filtrate, wherein the purity of phosphoric acid is 94.8%, and the mass concentration of the phosphoric acid solution is 16%; the calcium sulfate filter cake is recycled after gradient washing, and the washing water is recycled as the bottom water of the calcium hydrophosphate filter cake. The recovery rate of phosphate radicals in the phosphorus-containing wastewater is 97.5 percent.

Example 2

1) Purifying and concentrating phosphorus-containing wastewater: collecting phosphorus-containing water discharged in the production of activated carbon by a phosphoric acid method, adjusting the pH to 6 by using an industrial sodium hydroxide solution, filtering by using a primary plate frame, cooling to 42 ℃ by heat exchange, performing sand filtration, softening by using ion exchange resin to obtain phosphorus-containing softened water, adding 50mg/L of inorganic phosphorus scale inhibitor into the phosphorus-containing softened water, uniformly mixing, filtering by using a precision filter, conveying to a reverse osmosis membrane for concentration to obtain purified 8% high-concentration concentrated solution containing phosphate radicals, and recycling the purified dialyzate as industrial water for washing in the production of activated carbon.

2) Preparing high-purity calcium hydrophosphate: placing the concentrated solution obtained in the step 1) and the calcium sulfate filter cake in a precipitation reaction kettle, continuously stirring for precipitation reaction, simultaneously adding industrial calcium sulfate accounting for 5% of the total amount of the calcium sulfate, adjusting the pH to 10.5 by using liquid caustic soda within 60min, carrying out precipitation reaction for 3h to completely convert phosphate radicals into calcium hydrophosphate, filtering, washing the filter cake with hot water at 60 ℃ until the conductivity of the filtrate is 1990us/cm, obtaining a purified high-purity calcium hydrophosphate filter cake, and discharging the filtrate which is up to the standard wastewater.

3) Preparing and recovering phosphoric acid: mixing the calcium hydrophosphate filter cake obtained in the step 2) with industrial concentrated sulfuric acid according to phosphate radicals and H contained in the materials₂SO₄Adding the mixed solution into a reaction kettle according to the molar mass ratio of 1:1.08, uniformly mixing and reacting for 3 hours, standing for 3 hours, carrying out heat exchange and cooling to 45 ℃, and filtering by using a plate frame to obtain clear filtrate, wherein the purity of phosphoric acid in the clear filtrate is 95.2%, and the mass concentration of the phosphoric acid solution is 19%; the calcium sulfate filter cake is recycled after gradient washing, and the washing water is recycled as the bottom water of the calcium hydrophosphate filter cake. The recovery rate of phosphate radicals in the phosphorus-containing wastewater is 96.8 percent.

Example 3

1) Purifying and concentrating phosphorus-containing wastewater: collecting phosphorus-containing water discharged in the production of activated carbon by a phosphoric acid method, adjusting the pH to 7 by using an industrial sodium hydroxide solution, filtering by using a primary plate frame, cooling to 40 ℃ by heat exchange, performing sand filtration, softening by using ion exchange resin to obtain phosphorus-containing softened water, adding 100mg/L of inorganic phosphorus scale inhibitor into the phosphorus-containing softened water, uniformly mixing, filtering by using a precision filter, conveying to a reverse osmosis membrane for concentration to obtain purified 8% high-concentration concentrated solution containing phosphate radicals, and recycling the purified dialyzate as industrial water for washing in the production of activated carbon.

2) Preparing high-purity calcium hydrophosphate: placing the concentrated solution obtained in the step 1) and the calcium sulfate filter cake in a precipitation reaction kettle, continuously stirring for precipitation reaction, simultaneously adding industrial calcium sulfate accounting for 10% of the total amount of the calcium sulfate, adjusting the pH to 11 within 30min, carrying out precipitation reaction for 4h to completely convert phosphate radicals into calcium hydrophosphate, filtering, washing the filter cake with hot water at 80 ℃ until the conductivity of the filtrate is 1980us/cm, obtaining a purified high-purity calcium hydrophosphate filter cake, and discharging the filtrate which is up to the standard wastewater.

3) Preparing and recovering phosphoric acid: mixing the calcium hydrophosphate filter cake obtained in the step 2) with industrial concentrated sulfuric acid according to phosphate radicals and H contained in the materials₂SO₄In a molar mass ratio of 1:1.1, addingPutting the mixture into a reaction kettle, uniformly mixing the mixture, reacting for 4 hours, standing for 6 hours, carrying out heat exchange, cooling to 45 ℃, and filtering by using a plate frame to obtain clear filtrate, wherein the purity of phosphoric acid in the clear filtrate is 95.8%, and the mass concentration of the phosphoric acid solution is 11%; the filter cake calcium sulfate is recycled after gradient washing, and the washing water is recycled as the bottom water of the calcium hydrophosphate filter cake. The recovery rate of phosphate radicals in the phosphorus-containing wastewater is 97.2 percent.

The above-mentioned embodiments, which further illustrate the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.