Iron and Steel Pickling Wastewater Recycling and Zero Discharge Process

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a steel pickling waste water resourcization and zero discharge process. The steel pickling waste water resourcization and zero discharge process comprises the following process steps of: (a) introducing steel pickling waste water; (b) carrying out Fenton reaction on the steel pickling waste water to reduce the COD (Chemical Oxygen Demand) of the steel pickling waste water to be less than or equal to 60 mg / L, convert Fe<2+> into Fe<3+> and reduce TDS (Total Dissolved Solids) to be less than or equal to 2000 mg / L; (c) carrying out FeC microelectrolysis reduction reaction on the steel pickling waste water; (d) carrying out neutralization flocculation; (e) desalting a membrane assembly to reduce the TDS of the steel pickling waste water to be less than or equal to 200 mg / L; (f) recycling effluent water. The steel pickling waste water resourcization and zero discharge process disclosed by the invention realizes the cleaning production, realizes the resourcization utilization of waste water, waste acid and iron mud, generates the benefit and realizes the zero discharge.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to resource utilization and zero discharge process of steel pickling wastewater. Background technique [0002] Iron and steel pickling wastewater includes waste acid and wastewater. Wherein the waste acid accounts for 2-3% of the total water, and the pollution index of the waste water is shown in the following table: [0003] [0004] . If steel pickling wastewater is improperly treated and discharged into the water body, it will cause the following pollution: 1. Lower the pH value of the water body, resulting in the death of aquatic plants, algae, and fish. 2. Fe 2+ Form colloidal Fe(OH) in water 2 , Fe(OH) 3 , but under the hydraulic conditions of the river channel, floc precipitation cannot be formed, but it forms a yellow-gray and black colloidal pollution belt with organic sulfur and humic acid in the river channel water, which has a very poor sensor...

AI Technical Summary

Problems solved by technology

If steel pickling wastewater is improperly treated and discharged into the water body, it will cause the following pollution: 1. Lower the pH value of the water body, causing aquatic plants, algae, and fish to die

2. Fe 2+ Form colloidal Fe(OH) in water 2 , Fe(OH) 3 , but under the hydraulic conditions of the river channel, floc precipitation cannot be formed, but it forms yellow-gray and black colloidal pollution belts with organic sulfur and humic acid in the river channel water, which is extremely poor in appearance

3. The organic chemicals that constitute COD are surfactants, phosphates, and lubricating oils, and the eutrophication of water bodies is irreversible.

[0008] ① High cost: In theory, to neutralize wastewater with a pH value of 2 to a pH value of 7, the alkali consumption per ton of water is 1.5kg NaOH, and some lime is used to replace NaOH, plus power consumption and manual depreciation, the treatment cost is 4.5 yuan / tons of water

[0010] ③COD is not up to standard

This shows that COD in this type of wastewater is soluble and cannot be separated and removed by neutralization and precipitation; it also shows that Fe(OH) 2 Colloidal flocs have extremely poor adsorption to such COD substances (surfactants, organic phosphates, lubricants, etc.)

[0011] ④The amount of residue is extremely large and extremely difficult to handle

[0012] ⑤ Drainage cannot be reused directly

Even if 50% of the water is reused, the TDS in the system will reach 10000mg / L and the COD will reach 1000mg / L in a few days, and the reclaimed water reuse system will not work normally

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