Method for delaying calcium sulfate scaling in pretreatment and hardness removal processes of desulfurization wastewater

A desulfurization wastewater and pretreatment technology, which is applied in gaseous discharge wastewater treatment, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc., can solve the problems of high cost and difficulty, and achieve high utilization rate, The effect of less dosage and improved calcium sulfate scaling

Pending Publication Date: 2022-07-22
ZHAOQING FEINAN METAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In industrial applications, in addition to considering the efficiency and effect of descaling, factors such as scaled pipelines and equipment structures, scale removal costs, and waste liquid and residue treatment are also considered, which is difficult and costly

Method used

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  • Method for delaying calcium sulfate scaling in pretreatment and hardness removal processes of desulfurization wastewater
  • Method for delaying calcium sulfate scaling in pretreatment and hardness removal processes of desulfurization wastewater
  • Method for delaying calcium sulfate scaling in pretreatment and hardness removal processes of desulfurization wastewater

Examples

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Effect test

Embodiment 1

[0067] The present embodiment provides a method for delaying the scaling of calcium sulfate in desulfurization wastewater during pretreatment and dehardening, which includes the following steps:

[0068] S1. Oil removal and impurity removal treatment: The high COD and high salt flue gas scrubbing and desulfurization wastewater is passed into a grease trap to remove oil slicks. Enter the second-stage oil separator, add liquid caustic soda (NaOH) to the oil removal waste liquid to adjust the pH of the oil removal waste liquid to 7.5, and then enter the nano air flotation tank to continue to scrape the floating oil, and the waste liquid after the secondary oil separation enters the Neutralize the reaction tank.

[0069] S2. Neutralization, precipitation and magnesium removal treatment: Add lime milk as a neutralizing agent to the neutralization reaction tank for neutralization, precipitation and magnesium removal for 2 hours to obtain a neutralization solution with a pH value of ...

Embodiment 2

[0076] The present embodiment provides a method for delaying the scaling of calcium sulfate in desulfurization wastewater during pretreatment and dehardening, which includes the following steps:

[0077] S1. Oil removal and impurity removal treatment: The high COD and high salt flue gas scrubbing and desulfurization wastewater is passed into a grease trap to remove oil slicks. Enter the second-stage oil separator, add liquid caustic soda (NaOH) to the oil removal waste liquid to adjust the pH of the oil removal waste liquid to 8, and then enter the nano air flotation tank to continue scraping the floating oil, and the waste liquid after the secondary oil separation enters the Neutralize the reaction tank.

[0078] S2. Neutralization precipitation and magnesium removal treatment: Add lime milk as a neutralizing agent to the neutralization reaction tank for neutralization, precipitation and magnesium removal treatment for 1 h to obtain a neutralization solution with a pH value o...

Embodiment 3

[0085] The present embodiment provides a method for delaying the scaling of calcium sulfate in desulfurization wastewater during pretreatment and dehardening, which includes the following steps:

[0086] S1. Oil removal and impurity removal treatment: The high COD and high salt flue gas scrubbing and desulfurization wastewater is passed into a grease trap to remove oil slicks. Enter the second-stage oil separation tank, add liquid alkali (NaOH) to the oil removal waste liquid to adjust the pH of the oil removal waste liquid to 7, and then enter the nano air flotation tank to continue to scrape the floating oil, and the waste liquid after the secondary oil separation enters the Neutralize the reaction tank.

[0087] S2. Neutralization, precipitation and magnesium removal treatment: Add lime milk as a neutralizing agent to the neutralization reaction tank for neutralization, precipitation and magnesium removal for 1.5 hours to obtain a neutralization solution with a pH value of ...

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Abstract

The embodiment of the invention provides a method for delaying calcium sulfate scaling in pretreatment and hardness removal processes of desulfurization wastewater, and relates to the field of wastewater treatment. The method comprises the steps that the high-COD and high-salt flue gas washing desulfurization wastewater is subjected to neutralization magnesium removal treatment to obtain a neutralization solution, the pH value of the neutralization solution is larger than or equal to 11, and lime milk is contained in the neutralization solution; adding quantitative sodium carbonate into the neutralization solution for pre-softening treatment until 1g / L to 2g / L of calcium ions are precipitated, so as to obtain a pre-softened treatment solution; carrying out primary solid-liquid separation on the pre-softening treatment liquid to obtain a separation liquid; sodium carbonate is added into the separation liquid for softening treatment, and softening treatment liquid is obtained; and carrying out flocculation treatment and secondary solid-liquid separation on the softening treatment liquid. After the method provided by the invention is used, the calcium sulfate scaling condition of a plate-and-frame filter press or filter cloth for carrying out first-time solid-liquid separation is well improved, and the calcium sulfate scaling condition is effectively delayed.

Description

technical field [0001] The invention relates to the field of wastewater treatment, in particular to a method for delaying calcium sulfate scaling in desulfurization wastewater during pretreatment and dehardening. Background technique [0002] The heavy metal sludge smelting flue gas is easy to be treated and discharged after washing, but the generated washing wastewater contains a large amount of copper, nickel, manganese, zinc, magnesium, calcium, ammonium, chlorine, sulfate, fluorine and other ions and organic substances, which are heavy metals. High-salt and difficult to treat high-COD and high-salt flue gas scrubbing desulfurization wastewater; it is of great significance to achieve zero discharge of such high-salt wastewater. [0003] In the pretreatment and dehardening stage of the wastewater zero-discharge treatment system, the calcium sulfate solution becomes supersaturated, and then slowly precipitates and precipitates calcium sulfate crystals, which are deposited o...

Claims

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Application Information

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IPC IPC(8): C02F9/04C02F103/18
CPCC02F1/66C02F1/5245C02F2103/18
Inventor 周兆安刘小文张陆峰李加兴毛谙章陆新密韦相仪田广广李俊
Owner ZHAOQING FEINAN METAL
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