System for preparing potassium sulfate from high-salt-content industrial wastewater and technology of system

Abstract

The invention relates to a system for preparing potassium sulfate from high-salt-content industrial wastewater and belongs to the field of water treatment. The high-salt-content industrial wastewater is pretreated through a regulating pool, a pipeline mixer, a high-density precipitate pool, a V-type filter pool, ion exchange resin and an ultrafiltration membrane system and then concentrated through a first section reverse osmosis membrane system and a second section reverse osmosis membrane system and then enters a nanofiltration membrane system for salt separation, nanofiltration produced water and thick water enter a plate-pipe type high-pressure flat sheet membrane system II and a plate-pipe type high-pressure flat sheet membrane system I respectively to be concentrated again, the concentrated thick water enters a freezing crystallization system for crystallization, crystals enter a potassium sulfate preparing system to be converted, freezing mother liquor and the concentrated nanofiltration produced water enter an advanced oxidizing system for oxidation and then enter an evaporative crystallization system for crystallization, and produced sodium sulfate crystal salt enters a potassium sulfate preparing system for conversion. The system has the advantages that the scale of the nanofiltration system is reduced, and investment cost is reduced; salt separation is thorough, and operation cost is low; the purity of the crystallization salt is high; mirabilite and sodium sulfateare converted into potassium sulfate, and the economic value is improved.

Description

technical field

[0001] The invention belongs to the field of water treatment, and relates to a system and a process for preparing potassium sulfate from high-salt industrial waste water. Background technique

[0002] The industrial wastewater with high salt content described in the present invention mainly comes from the coal chemical industry. The high-salt wastewater in the coal chemical industry mainly comes from the coal gas washing wastewater in the production process, the drainage of the circulating water system, and the drainage of the chemical water station. It is characterized by high salt content, high hardness, complex composition, refractory organic matter, and large fluctuations in water quality. In recent years, environmental protection departments in many areas are not only concerned about the discharge of waste water up to the standard, but also require coal chemical companies to maximize the reuse of high-salt water, especially in environmentally sensitive ...

Examples

Embodiment

[0044] Highly salty wastewater discharged from a chemical industry park, the wastewater COD≤90mg / L, TDS≤12000mg / L, NaCI≤3000mg / L, Na 2 SO 4 ≤6000mg / L, total hardness ≤1000mg / L.

[0045] (1) chemical softening

[0046] Chemical softening uses sodium carbonate and sodium hydroxide to remove calcium and magnesium ions in wastewater. After the influent is precipitated by 25% NaOH and 20% sodium carbonate, add 8% to 12% polyferric sulfate (coagulant) and 0.8% PAM (coagulant aid) to coagulate in the sedimentation tank 3 Most of the hardness and calcium and magnesium ions in the concentrated water of precipitation, solid-liquid separation, and a stage of reverse osmosis are removed.

[0047] Table 1

[0048] water quality Chemical softening of incoming water chemical softening water Removal rate (%) Total hardness mg / L 980 39 96

[0049] (2) Resin softening

[0050] The water produced by the sand filter is further softened by ion exchange resin 5 to r...

technical field

[0001] The invention belongs to the field of water treatment, and relates to a system and a process for preparing potassium sulfate from high-salt industrial waste water. Background technique

[0002] The industrial wastewater with high salt content described in the present invention mainly comes from the coal chemical industry. The high-salt wastewater in the coal chemical industry mainly comes from the coal gas washing wastewater in the production process, the drainage of the circulating water system, and the drainage of the chemical water station. It is characterized by high salt content, high hardness, complex composition, refractory organic matter, and large fluctuations in water quality. In recent years, environmental protection departments in many areas are not only concerned about the discharge of waste water up to the standard, but also require coal chemical companies to maximize the reuse of high-salt water, especially in environmentally sensitive ...

Examples

Embodiment

[0044] Highly salty wastewater discharged from a chemical industry park, the wastewater COD≤90mg / L, TDS≤12000mg / L, NaCI≤3000mg / L, Na 2 SO 4 ≤6000mg / L, total hardness ≤1000mg / L.

[0045] (1) chemical softening

[0046] Chemical softening uses sodium carbonate and sodium hydroxide to remove calcium and magnesium ions in wastewater. After the influent is precipitated by 25% NaOH and 20% sodium carbonate, add 8% to 12% polyferric sulfate (coagulant) and 0.8% PAM (coagulant aid) to coagulate in the sedimentation tank 3 Most of the hardness and calcium and magnesium ions in the concentrated water of precipitation, solid-liquid separation, and a stage of reverse osmosis are removed.

[0047] Table 1

[0048] water quality Chemical softening of incoming water chemical softening water Removal rate (%) Total hardness mg / L 980 39 96

[0049] (2) Resin softening

[0050] The water produced by the sand filter is further softened by ion exchange resin 5 to r...

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