Method of recovering phosphorous from municipal sludge by hydrothermal carbonization

A technology of hydrothermal carbonization and municipal sludge, applied in the field of environmental engineering, can solve the problems of low recovery rate, high cost, complicated sludge phosphorus recovery technology, etc., and achieve the effect of high economic value

Inactive Publication Date: 2019-04-09
CHONGQING UNIV
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Problems solved by technology

[0005] In view of this, the purpose of the present invention is to provide a method for recovering phosphorus by hydrothermal carbonization of municipal sludge, which solves the shortcomings of c

Method used

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Embodiment 1

[0026] Step (1): Take 60g (dry weight) of municipal sludge from a sewage treatment plant, with a phosphorus content of 2.25g, and add 540g of water to prepare a raw material with a moisture content of 90%. Hydrothermal carbonization was carried out under the reaction conditions of 200° C., 20 atmospheres, and 3 hours.

[0027] Step (2): The carbonized product in step (1) was filtered for solid-liquid separation to obtain 37.81 g of biochar and 2.08 g of phosphorus, that is, 92% of the phosphorus in the sludge was converted into biochar.

[0028] Step (3): adding 0.8 mol / L sulfuric acid to the biochar filtered in step (2), adjusting the pH value to 2.0, and obtaining the extracted biochar and filtrate by filtering, washing and drying.

[0029] Step (4): With the filtrate in step (3), add MgCl 2 solution and NH 4 Cl solution, make Mg:P molar ratio in the solution be 1.3:1, N:P molar ratio is 2:1, adjust pH value to be 9.0, form struvite crystal and give recovery, phosphorus co...

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Abstract

The invention discloses a method of recovering phosphorous from municipal sludge by hydrothermal carbonization. The method comprises the following steps: (1) carrying out hydrothermal carbonization onmunicipal sludge to obtain a carbonized product; (2) carrying out solid liquid separation on the carbonized product obtained in the step (1) to obtain charcoal and a liquid phase product, separately;(3) extracting phosphorous from charcoal obtained in the step (2) by an acid leaching method and filtering the mixture to obtain a filtrate; and (4) adding magnesium salt and ammonium salt into the filtrate obtained in the step (3), adjusting the pH to form struvite crystals and recovering the same. By converting organic phosphorous in sludge through the hydrothermal carbonization reaction into inorganic phosphorus and concentrating the inorganic phosphorus into charcoal and carrying out acid extraction on the phosphorous enriched charcoal and crystallizing struvite, simple and efficient municipal sludge treatment and phosphorous recovery with a low cost are achieved.

Description

technical field [0001] The invention belongs to the technical field of environmental engineering, and in particular relates to a method for recovering phosphorus by hydrothermal carbonization of municipal sludge. Background technique [0002] As of the end of September 2015, a total of 3,830 sewage treatment plants have been built in cities and towns across the country, and the sewage treatment capacity has reached 162 million m 3 / d, the associated sludge has exceeded 30 million t / year (based on a moisture content of 80%). The "Thirteenth Five-Year Plan" National Urban Sewage Treatment and Recycling Facilities Construction Plan (December 2016) specifies that by the end of 2020, the rate of harmless disposal of sludge in prefecture-level and above cities will reach 90%, and that in other cities will reach 75%; Strive to reach 60%; key towns increase by 5 percentage points, and initially realize overall planning and centralized treatment and disposal of sludge in established...

Claims

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Application Information

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IPC IPC(8): C01B25/45C05B7/00C01B32/05
CPCC01B25/451C01B32/05C05B7/00
Inventor 方俊华许劲吕秋颖唐琦范准李杨
Owner CHONGQING UNIV
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