Method of recovering phosphorus

A technology of hydrated calcium silicate and crystals, applied in chemical instruments and methods, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc., can solve problems such as increased operating costs, increased operating costs, and blockages , to achieve the effect of avoiding the increase of sludge volume, avoiding waste and reducing by-products

Active Publication Date: 2014-08-06
CHONGQING UNIV OF ARTS & SCI
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Problems solved by technology

The current crystallization phosphorus recovery technology mainly recovers phosphate in wastewater in the form of struvite (MAP) or hydroxyapatite (HAP), which has the following shortcomings: (1) Phosphorus is recovered in the form of MAP, It is necessary to provide sufficient magnesium sources, which cannot be realized in inland areas where magnesium sources are relatively scarce, and will undoubtedly increase actual operating costs; (2) Recover phosphorus in the form of HAP. In the HAP system, supersaturation phenomenon is common, although maintaining A high pH value (>10.5) is a necessary condition for the formation of HAP, but it is worth noting that the high pH value environment not only makes it difficult to coordinate the chemical phosphorus removal (recycling) system and the sewage biological treatment system, but also increases the cost of chemical treatment. Reduce the composition of effective phosphorus in phosphorus recovery products; (3) When recovering phosphorus in the form of HAP, when the surface of the crystal is covered with HAP, due to the coating effect of the dense pore structure of HAP on the crystal particles, the crystal no longer has the ability to dissolve calcium and release alkali capacity, which limits the phosphorus recovery performance of crystal particles; (4) Due to the presence of carbonates in wastewater, the current HAP phosphorus recovery reactor often suffers from fouling due to the large amount of by-product calcium carbonate generated during the phosphorus recovery process Phenomenon, causing blockage of the reactor tube wall; in order to avoid the impact of the existence of carbonate on the phosphorus recovery efficiency, the existing technology often blows off CO by adding chemicals to reduce the pH value and aeration. 2 , and then add lye to maintain the pH in an alkaline environment to realize the phosphorus recovery process, which will inevitably increase the operating cost in actual operation; (5) the existing phosphorus recovery reactor, due to no effective solid-liquid separation measures, Phosphorus recovery crystal particles are often lost with the effluent flow, resulting in waste of crystals and affecting the phosphorus recovery effect

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Examples

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Embodiment 1

[0036] Example 1 The recovery of phosphorus in phosphorus-containing wastewater

[0037] 10L of phosphorus-containing wastewater was collected; the phosphorus-containing wastewater came from the effluent of the secondary sedimentation tank of a certain urban sewage treatment plant in Chongqing, and the phosphorus content in the wastewater was measured to be 5mg / L.

[0038] Take phosphorus-containing wastewater (calculated by the mass of phosphorus) and the excess interplanar spacing is 1.3nm, which has an X-ray diffraction absorption peak at 2θ=30.55°, and the infrared characteristic peak is: δ(Si-O-Si) 455cm -1 , V δ (Si-O-Si) 652 cm -1 , V(Si-O)Q 1 816cm -1 , V(Si-O)Q 2 970cm -1 After mixing the excess calcium silicate hydrate crystals with a calcium-silicon molar ratio of 10g, they are mixed with excess carbonate (carbonates include sodium carbonate, sodium bicarbonate or calcium bicarbonate.) Mix, collect 100 ~ 140μm 1.04g of precipitate; 8.97g of precipitate wit...

Embodiment 2

[0043] Example 2 Recovery of Phosphorus in Phosphorous Wastewater

[0044] 10L of phosphorus-containing wastewater was collected; the phosphorus-containing wastewater came from the effluent of an anaerobic phosphorus release tank of a certain urban sewage treatment plant in Chongqing, and the phosphorus content in the wastewater was measured to be 10mg / L.

[0045] Take phosphorus-containing wastewater (calculated by the mass of phosphorus) and the excess interplanar spacing is 1.3nm, which has an X-ray diffraction absorption peak at 2θ=30.55°, and the infrared characteristic peak is: δ(Si-O-Si) 455cm -1 , V δ (Si-O-Si) 652 cm -1 , V(Si-O)Q 1 816cm -1 , V(Si-O)Q 2 970cm -1 After mixing the excess calcium silicate hydrate crystals with a calcium-silicon molar ratio of 10g, they are mixed with excess carbonate (carbonates include sodium carbonate, sodium bicarbonate or calcium bicarbonate.) Mix, collect 100 ~ 140μm 1.08g of precipitate; 3.94g of precipitate with a parti...

Embodiment 3

[0049] Example 3 Recovery of Phosphorus in Phosphorous Wastewater

[0050] 10L of phosphorus-containing wastewater was collected; the phosphorus-containing wastewater came from the effluent of an anaerobic phosphorus release tank of a certain urban sewage treatment plant in Chongqing, and the phosphorus content in the wastewater was measured to be 20mg / L.

[0051] Take phosphorus-containing wastewater (calculated by the mass of phosphorus) and the excess interplanar spacing is 1.3nm, which has an X-ray diffraction absorption peak at 2θ=30.55°, and the infrared characteristic peak is: δ(Si-O-Si) 455cm -1 , V δ (Si-O-Si) 652 cm -1 , V(Si-O)Q 1 816cm -1 , V(Si-O)Q 2 970cm -1 After mixing the excess calcium silicate hydrate crystals with a calcium-silicon molar ratio of 10g, they are mixed with excess carbonate (carbonates include sodium carbonate, sodium bicarbonate or calcium bicarbonate.) Mix, collect 100 ~ 140μm 1.18g of precipitate; 8.95g of precipitate with a parti...

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Abstract

The invention relates to the technical field of water treatment in environmental engineering and particularly relates to use of calcium silicate hydrate crystals for recovering phosphorus from phosphorus containing wastewater and a method of recovering phosphorus. The method comprises the following steps: carrying out full contact and reaction on calcium silicate hydrate and phosphate to quickly form HAP (Hydroxyapatite) on the surface of calcium silicate hydrate; and then mixing with CO3<2->, wherein CO3<2-> replaces OH- in HAP, and converting HAP on the surface of calcium silicate hydrate into CHAP with more developed pore structures. According to the method provided by the invention, CO3<2-> in water is not blown by aeration and the pH value is not adjusted by an added calciferous chemical reagent. The phosphorus recovery process can be stably carried out in a weakly alkaline environment and the calcium silicate hydrate crystals further can take part in the phosphorus recovery reaction circularly so as to improve the effective utilization ratio of the calcium silicate hydrate crystals and the phosphorus recovery efficiency.

Description

technical field [0001] The invention relates to the technical field of environmental engineering water treatment, in particular to the use of calcium silicate hydrate crystals for recovering phosphorus from phosphorus-containing wastewater and a method for recovering phosphorus. Background technique [0002] Phosphate rock is an important non-metallic resource of strategic significance, mainly used in the production of phosphate fertilizer, phosphoric acid and phosphorus chemical products. In 2007, the Ministry of Land and Resources listed phosphate rock as one of the important minerals that cannot meet the needs of national economic development after 2010. According to statistics, it is predicted that the amount of phosphorus discharged from point sources in the Yangtze River Basin in 2020 will be 12.3×10 4 t or so, an increase of nearly double that of 2003. Assuming that the annual growth rate of sewage discharge is controlled at about 3%, the sewage discharge in the Yan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04
Inventor 关伟谢志刚吉芳英
Owner CHONGQING UNIV OF ARTS & SCI
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