阅读说明：本技术 一种污泥中磷的释放和回收方法 (Method for releasing and recovering phosphorus in sludge ) 是由 刘雪瑜 魏健 王方舟 肖书虎 杜丛 邓齐玉 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种污泥中磷的释放和回收方法,主要包括以下步骤：向污泥中加入絮凝剂并进行搅拌,再进行超声波预处理,最后进行机械脱水；对脱水污泥进行烘干处理,经研磨机研磨后制成干污泥备用；将制备的干污泥焚烧得到污泥焚烧灰,将焚烧灰置于容器中,加入浸提剂,在一定的液固比条件下,离心处理,得到富含大量磷的污泥上清液；对得到的富含大量磷的上清液加入至反应器中进行精纯处理；取精纯处理后的上清液作为储备液,置于容器中,调节pH后,加入MgCl<Sub>2</Sub>·6H<Sub>2</Sub>O,得到磷化沉淀物,本方法从源头处提高了污泥中磷的回收利用率,适合广泛推广。(The invention discloses a method for releasing and recovering phosphorus in sludge, which mainly comprises the following steps: adding a flocculating agent into the sludge, stirring, performing ultrasonic pretreatment, and finally performing mechanical dehydration; drying the dewatered sludge, grinding the dewatered sludge by a grinder to prepare dry sludge for later use; incinerating the prepared dry sludge to obtain sludge incineration ash, putting the incineration ash into a container, adding an extracting agent, and performing centrifugal treatment under a certain liquid-solid ratio condition to obtain sludge supernatant rich in a large amount of phosphorus; adding the obtained supernatant rich in a large amount of phosphorus into a reactor for fine purification treatment; taking refined and pure treatmentThe supernatant is used as stock solution and put in a container, after the pH is adjusted, MgCl is added 2 ·6H 2 And O to obtain the phosphorization precipitate, and the method improves the recovery and utilization rate of phosphorus in the sludge from the source and is suitable for wide popularization.)

1. A method for releasing and recovering phosphorus in sludge is characterized by mainly comprising the following steps:

s1, selecting a part of sludge of a sludge treatment plant, adding a flocculating agent into the selected sludge, stirring the sludge added with the flocculating agent to accelerate the flocculation speed, setting the stirring speed to be 200r/min, stirring for 10-25min, performing ultrasonic pretreatment on the stirred sludge, mechanically dehydrating the sludge after the ultrasonic pretreatment, and removing interstitial water and capillary water in the sludge;

s2, drying the dewatered sludge subjected to mechanical dewatering treatment for 12 hours at 105 ℃, removing adsorbed water and water inside the sludge, and grinding the sludge into powder of 100 meshes by a grinder to prepare dry sludge for later use;

s3, placing the prepared dry sludge in a crucible, placing the crucible in a muffle furnace, setting the temperature to 600-^-1The lixiviant is reacted for 2 hours at normal temperature under the condition of 15-150mL/g liquid-solid ratio and then is centrifugally treated to obtain sludge supernatant rich in a large amount of phosphorus;

s4, adding the obtained sludge supernatant rich in a large amount of phosphorus into a reactor for fine purification: setting pulse voltage of 20Kv and pulse frequency of 200-300Hz, placing the upper and lower electrode plates in the supernatant, and setting the distance between the upper and lower electrode plates to be 8 mm;

s5, taking the supernatant after S4 fine purification as stock solution, putting the stock solution into a container, adjusting the pH value of the stock solution to 8-11, adding MgCl with the ratio of n (Mg) to n (P) of 0.8-2₂·6H₂O, at 200r/min^-1Reacting for 24 hours under stirring, and then reacting at 4000 r.min^-1Centrifuging for 10min, and removing supernatant to obtain the final product.

2. The method for releasing and recovering phosphorus from sludge as claimed in claim 1, wherein in S3, the residue left after centrifugation is washed with secondary deionized water for several times, returned to the crucible, dried, incinerated and centrifuged.

3. The method for releasing and recovering phosphorus from sludge as claimed in claim 2, wherein the temperature of the residue left after centrifugation in S3 is raised to 1200 ℃ during the second incineration, and after cooling, lixiviant is added, and after 0.5-1h of reaction at normal temperature, the residue is centrifuged to obtain supernatant.

4. The process for the release and recovery of phosphorus from sludge as claimed in claim 1, wherein the leaching agent in S3 is selected from H₂SO₄HCL and HNO₃One of them.

5. The method for releasing and recovering phosphorus from sludge as claimed in claim 1, wherein the supernatant is removed in S5 by discharging the supernatant as a supernatant, and the effluent is covered with a 0.45um filter membrane.

6. The method for releasing and recovering phosphorus from sludge as claimed in claim 1, wherein in S1, the ultrasonic frequency is set to 20-100Hz and the ultrasonic treatment time is set to 10 min.

Technical Field

The invention relates to the technical field of sludge recycling, in particular to a method for releasing and recycling phosphorus in sludge.

Background

Phosphorus is an important non-metallic mineral resource which is difficult to regenerate, and is one of the most important elements for life activities. At present, the reserves of 27 hundred million standard phosphate ores in China are only enough to maintain the reuse of China for about 70 years, and the reserves also contain over 90 percent of non-phosphorus-rich ores. If the method is only calculated by the phosphorus reserves of rich phosphate rocks, the method can only be used for 10 to 15 years in China.

After the sludge is incinerated at high temperature, about 170 million of incineration ash is generated in the world every year, and after the phosphorus-rich sludge is dehydrated and incinerated, the phosphorus content in the incineration ash can reach 8% -10%, and the incineration ash can replace natural phosphate ore. However, most of the generated incineration ash is buried, the part capable of being recycled is used as raw materials for sintering bricks, producing clay substitutes and cement, and the like, wherein valuable phosphate is not reasonably utilized, and the phosphorus recovered from the sludge incineration ash can be used as a source for producing fertilizers and other phosphate products, so that the problem of shortage of phosphorus resources at present can be relieved.

The key point of recovering phosphorus from sludge incineration ash is to leach the phosphorus from the sludge incineration ash, the incineration ash is generally treated by a wet chemical method, common leaching agents comprise inorganic acid, alkali, organic acid, chelating agent and the like, the wet chemical method has a relatively simple leaching process and less loss, and the leaching efficiency of the phosphorus depends on the type, concentration, liquid-solid ratio, sludge incineration temperature and the like of the leaching agent. The inorganic acid can leach 84.3-100.0% of phosphorus, so that the method is widely applied.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for releasing and recovering phosphorus in sludge.

The technical points of the invention are as follows:

a method for releasing and recovering phosphorus in sludge mainly comprises the following steps:

s1, selecting a part of sludge of a sludge treatment plant, adding a flocculating agent into the selected sludge, stirring the sludge added with the flocculating agent to accelerate the flocculation speed, setting the stirring speed to be 200r/min, stirring for 10-25min, performing ultrasonic pretreatment on the stirred sludge, mechanically dehydrating the sludge after ultrasonic treatment to remove interstitial water and capillary water in the sludge, and breaking cell walls of biological cells in the sludge after ultrasonic pretreatment of the sludge, so that the improvement of the biodegradability of the sludge is beneficial to subsequent dehydration;

s2, drying the dewatered sludge after mechanical dewatering at 105 ℃ for 12h, removing the adsorbed water and the water inside the sludge, grinding the sludge into powder of 100 meshes by a grinder to prepare dry sludge for later use, wherein the dry sludge is convenient for subsequent incineration, and when the dry sludge is ground into powder and then incinerated, organic phosphorus in the sludge can be completely decomposed, and the total phosphorus almost consists of inorganic phosphorus and is easier to be leached by acid;

s3, placing the prepared dry sludge in a crucible, placing the crucible in a muffle furnace, setting the temperature to 600-^-1The lixiviant reacts for 2 hours at normal temperature under the condition of 15-150mL/g liquid-solid ratio, and then is subjected to centrifugal treatment to obtain sludge supernatant rich in a large amount of phosphorus, the large amount of phosphorus is released into the supernatant, the subsequent recovery of the phosphorus in the supernatant is convenient, the cost is saved for the conventional method for directly recovering the phosphorus in sewage, and the recovery rate of the phosphorus recovered in the supernatant is better;

s4, adding the obtained sludge supernatant rich in a large amount of phosphorus into a reactor for fine purification treatment, setting pulse voltage of 20Kv and pulse frequency of 200-300Hz, placing the upper electrode plate and the lower electrode plate in the supernatant, setting the distance between the upper electrode plate and the lower electrode plate to be 8mm, wherein the supernatant after pulse treatment is more fine and pure, and the phosphorus content in the supernatant is higher;

s5, taking the supernatant after S4 fine purification as stock solution, putting the stock solution into a container, adjusting the pH value of the stock solution to 8-11, adding MgCl with the ratio of n (Mg) to n (P) of 0.8-2₂·6H₂O, at 200r/min^-1Reacting for 24 hours under stirring, and then reacting at 4000 r.min^-1Centrifuging for 10min, and removing supernatant to obtain the final product.

Furthermore, in the step S3, the residue left after centrifugation is continuously washed for multiple times by secondary deionized water, and then returned to the crucible, and then dried, burned and centrifuged, so that the resource waste is reduced.

Furthermore, when the residual residue after centrifugation in S3 is subjected to secondary incineration, the temperature is raised to 1200 ℃, after the residual residue is cooled, an extracting agent is added, the mixture reacts for 0.5 to 1 hour at normal temperature and then is subjected to centrifugal treatment to obtain a supernatant, and phosphide crystals can also be obtained from the supernatant after secondary separation.

Further, the leaching agent in S3 is selected from H₂SO₄HCL and HNO₃One of them.

Furthermore, when the supernatant is removed in S5, the supernatant is discharged in a mode of upper water outlet, and the water outlet is sealed by a 0.45um filter membrane, so that the loss of phosphide precipitate is prevented, and the phosphide precipitate is separated more quickly.

Further, in S1, the ultrasonic frequency is set to be 20-100Hz, the ultrasonic treatment time is set to be 10min, and low-frequency sound waves can improve the biodegradability of the sludge and ensure that beneficial components in the sludge are not damaged.

Compared with the prior art, the invention has the beneficial effects that:

first, the invention selects H₂SO₄HCL and HNO₃The phosphorus in the incineration ash is leached, the phosphorus leaching rate is improved to the maximum extent by controlling the incineration temperature of the sludge, the concentration of the leaching agent and the liquid-solid ratio, the release rate of the phosphorus reaches over 80 percent under specific reaction conditions, and a foundation is laid for the maximum recovery of the phosphorus.

Secondly, the sludge is subjected to ultrasonic pretreatment, the dehydration performance and the biodegradability of the sludge are improved, the sludge is dried and incinerated, and most of phosphorus in the sludge is converted into inorganic phosphorus after high-temperature incineration, so that the inorganic phosphorus is more easily leached by acid. When the temperature is 900 ℃, the TP release rate of the sludge incineration ash is also the highest and reaches 85.28%, and the content of phosphate radicals in the supernatant is more than 80%, so that the recovery of phosphorus is easy.

Thirdly, in the prior art, most of the generated incineration ash is buried, so that huge resource waste is generated, and the utilization value of the sludge ash cannot be exerted.

Detailed Description