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Method for preparing and purifying struvite from residual sludge

A technology of excess sludge and struvite, applied in the field of resources and environment, to achieve rapid results

Inactive Publication Date: 2012-05-23
TIANJIN URBAN CONSTR COLLEGE
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Problems solved by technology

[0007] At present, the research on the method of recovering nitrogen and phosphorus in sludge by struvite precipitation method is mostly focused on the discussion of the formation conditions, but there are few reports on the method of obtaining higher purity struvite from excess sludge

Method used

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  • Method for preparing and purifying struvite from residual sludge
  • Method for preparing and purifying struvite from residual sludge

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Embodiment Construction

[0020] Take a sewage treatment plant (using A 2 / O process) return the remaining sludge in the sludge pumping station, put it in the nitrogen and phosphorus release device in the remaining sludge, and control the stirring speed in the range of 70-90r / min (at this time, the remaining sludge can be stirred evenly but not too much vortex), use 2mol / L HCl and NaOH solution to adjust the pH to be within the range of 3±0.2, and react at room temperature. After the reaction is carried out for 4 hours, the concentration of ammonia nitrogen, orthophosphate, and calcium and magnesium ions are respectively 239.2 mg / L, 128mg / L, 399.7mg / L and 196.2mg / L sludge supernatant. While releasing nitrogen and phosphorus in excess sludge, use 3% MgCl 2 The solution changes the purchased 001×7 strongly acidic cation exchange resin from the sodium type to the magnesium type. Then, take 40ml of modified magnesium-type strong acid cation exchange resin, put it into the exchange column, and use a peris...

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Abstract

The invention relates to a method for preparing and purifying struvite from residual sludge in an urban sewage treatment factory and is characterized in that the method contains the following steps of: controlling pH within the range of 3-5 for releasing nitrogen and phosphor from the residual sludge; modifying a sodium storng-acid cation exchange resin by using an MgCl2 solution; carrying out ion exchange on a supernatant of the sludge containing rich nitrogen and phosphor by using the modified resin so as to reduce the impact of calcium ion on the formation of the struvite substance; controlling pH within the range of 8.5-9.5, stirring a solution obtained after ion exchange until a lot of off-white precipitates, standing for settling, and recovering the off-white precipitates. By adoption of the acid-base adjustment and ion exchange methods for the preparation and purification of the struvite substance from the residual sludge, the high-purity struvite substance can be obtained, and the impact load of supernatant reflux generated during the sludge treatment process on nitrogen and phosphor during the sewage treatment flow can be mitigated, so as to improve operation of the sewage treatment factory.

Description

technical field [0001] The invention relates to a method for preparing and purifying struvite from excess sludge in urban sewage treatment plants, belonging to the technical field of resources and environment. Background technique [0002] With the continuous improvement of urban sewage treatment capacity, the amount of sludge, especially the excess sludge, produced by sewage treatment plants is increasing, and the harm is becoming more and more serious. At the same time, sludge is also an available resource, containing nutrients such as nitrogen, phosphorus, and potassium needed for plant growth, various trace elements to maintain normal growth and development of plants, and organic matter and humus that can improve soil structure. Therefore, how to realize the reduction, stabilization, recycling and harmlessness of sludge has become a major issue to be solved urgently in the sewage treatment industry. In the research on the resource utilization of excess sludge, the recyc...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 苑宏英吴丽杰牛四芳陈轶
Owner TIANJIN URBAN CONSTR COLLEGE
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