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A method for recovering phosphorus in the secondary effluent of a sewage plant

A technology of secondary water effluent and recovery method, which is applied in the direction of water/sewage multi-stage treatment, water/sewage treatment, chemical instruments and methods, etc., and can solve problems such as large equipment or structures, and difficulty in improving the quality of phosphorus removal processes. , to achieve the effect of simple and easy process transformation, high recycling value and stable phosphorus removal effect

Active Publication Date: 2021-11-19
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method uses a fluidized bed and a fixed bed in series, and the respective hydraulic retention times are as long as 5.46h and 4.58h. 3 / d sewage plant as an example, the total volume of equipment or structures required by this method is 40,000 m 3 , which is obviously difficult to achieve in the upgrading of the secondary effluent deep phosphorus removal process in the sewage plant
[0007] In a word, so far, there has been no report on the suitability modification method of phosphorus recovery and utilization in the deep phosphorus removal process of sewage plant, so that after modification, it can meet the requirements of the first-level A standard on the phosphorus concentration limit, and at the same time, it can recycle phosphorus

Method used

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  • A method for recovering phosphorus in the secondary effluent of a sewage plant
  • A method for recovering phosphorus in the secondary effluent of a sewage plant

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] The concentration of phosphorus in the secondary effluent of the sewage plant is 1.05mg / L, and the treatment capacity is 2m 3 / h, the hydraulic retention time of the primary sedimentation tank and the secondary sedimentation tank are the same as the coagulation tank and sedimentation tank of the sewage plant, which are 20min and 2h respectively, and the corresponding device volumes are 670L and 4000L. The filtration rate of the filter tank is the same as that of the sewage plant filter tank, which is 20m / h. The hydraulic retention time of the forced agglomeration crystallizer is 5min, and the corresponding volume is 180L. The hydraulic retention time of the hydrocyclone concentrator 6 is 20s, the corresponding volume is 12L, and the initial seed crystal dosage is 50g / L.

[0048] After the reaction is stable, the flow rate of the return sludge pump is 0.5m 3 / h, lift 40m. The pH in the forced agglomeration crystallizer 1 is controlled at 8.5, Ca 2+ The dosage is cont...

Embodiment 2

[0051] The difference from Example 1 is that the phosphorus concentration in the secondary effluent is 2.62 mg / L (winter effluent from the sewage plant). The pH in the forced agglomeration crystallizer 1 is controlled at 8.5, Ca 2+ The dosage is controlled at 10mg / L, and the stirring speed is controlled at 50rpm. After the reaction is stable, the average particle size of seed crystal HAP is maintained at about 100 μm, and the number of seed crystals is stable at about 25 g / L.

[0052] The operation results show that after the reaction is stable, the phosphorus concentration in the effluent of the system is stable below 0.25mg / L, and the pH is stable at about 8.2, which meets the first-class A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002), and can also be It meets the Class IV standard of "Surface Water Environmental Quality Standard" (GB 3838-2002). The recycling rate of phosphorus in the system is above 90%.

Embodiment 3

[0054] The difference from Example 1 is that the phosphorus concentration in the secondary effluent is 0.8 mg / L (summer effluent from the sewage plant). The flow rate in the forced agglomeration crystallizer 1 is controlled at 12m / h, the pH is controlled at 8.8, and the Ca 2+ The dosage is controlled at 40mg / L, and the stirring speed is controlled at 100rpm. After the reaction was stable, the average particle size of seed crystal HAP was maintained at about 75 μm, and the number of seed crystals was stable at about 50 g / L.

[0055] The operation results show that after the reaction is stable, the phosphorus concentration in the effluent of the system is stable below 0.2mg / L, and the pH is stable at about 8.4, which meets the first-class A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002), and can also be It meets the Class IV standard of "Surface Water Environmental Quality Standard" (GB 3838-2002). The recycling rate of phospho...

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Abstract

The invention discloses a method for recovering phosphorus in the secondary effluent of a sewage plant. The secondary effluent is pumped into a forced agglomeration crystallizer, and calcium salt, lye and a large number of fine particles of HAP seeds are put into the forced agglomeration crystallizer. ; PO in the secondary effluent water of the forced agglomeration crystallizer 4 3‑ with OH from lye ‑ and Ca from the calcium salt 2+ First, cluster reaction occurs to form nano HAP molecular clusters; the HAP molecular clusters in the forced agglomeration crystallizer and the HAP seed crystals with high particle number density, under the combined action of rising water flow and forced stirring, undergo rapid agglomeration and crystallization, forming The crystallization product HAP; the crystallization product HAP enters the sedimentation tank with the rising water flow, and the supernatant after the crystallization product HAP is removed by the sedimentation tank enters the filter tank to meet the standard discharge. The present invention is a retrofitting method for phosphorus recovery in the existing deep dephosphorization process of the sewage plant which is simple and applicable to be fully promoted in the sewage plant. The remarkable characteristics of high recycling rate and high recycling value.

Description

technical field [0001] The invention belongs to the technical field of phosphorus recovery from sewage, and in particular relates to a method for recovery of phosphorus in the secondary effluent of a sewage plant. Background technique [0002] In order to comprehensively curb water environmental pollution and control eutrophication of water bodies, since 2006, my country has begun to comprehensively carry out the upgrading and transformation of sewage plants, and the effluent standards have been changed from the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB 18918-2002) to the first level. B is upgraded to level A, where phosphorus is the core control indicator. The limits of phosphorus in Class I B and Class A standards are 1.0 mg / L and 0.5 mg / L, respectively. [0003] At present, many urban sewage plants in my country have built deep phosphorus removal units. Among them, the physical and chemical deep phosphorus removal technology of adding "coagulat...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/04C02F101/10
CPCC02F1/001C02F1/58C02F9/00C02F2001/007C02F2001/5218C02F2101/105C02F2209/06C02F2209/18C02F2209/44C02F2301/08
Inventor 聂小保易晋侯方东蒋昌波隆院男金筱英胡明睿周梨
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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