Recycling treatment method of lignin production wastewater

Abstract

The invention relates to the utilization and circulation treatment of waste water after lignin is produced from black liquor in papermaking industry. The waste water after production, processing and extraction of lignin is heated-evaporated, and the evaporated waste liquid is cooled and circulated to crystallize and separate Glauber's salt and black liquor containing sulfuric acid. , the crystallization is separated to dissolve Glauber's salt and react with barium sulfide to produce barium sulfate and sodium sulfide that are insoluble in water, and a large amount of sodium sulfide is produced and concentrated into a 40%-50% solution by evaporation. Calcium chloride is added to the black liquor containing sulfuric acid, and the calcium chloride is converted into HCl. The black liquor treatment of potassium manganese tailings first generates CaSO4 2H2O insoluble in acid water; the remaining solution is added to the black liquor treatment of potassium manganese tailings. Press and filter to produce manganese dioxide, calcium chloride, and potassium chloride mother liquor with a content of 75% insoluble in the solution; calcium chloride and potassium chloride mother liquor are concentrated by stirring and evaporating, and potassium chloride is precipitated by cooling, and finally it is chloride Calcium liquor is reused in black liquor containing sulfuric acid to treat potassium manganese tailings.

Description

technical field [0001] The invention relates to a zero-discharge closed-circuit circulation treatment technology for the deep processing of waste water in papermaking industry, in particular to the utilization and circulation treatment of waste water after lignin is produced from black liquor in papermaking industry. Background technique [0002] For the treatment of lignin wastewater, the traditional use of lime milk to neutralize strong acidity will produce new pollution sources and discharge a large amount of acid residue. Because the chemical oxygen consumption is as high as 80000P·P·M-COD, it seriously pollutes aquatic aquatic plants and river water. Due to the high concentration of sodium sulfate in it, it will make the soil more compact. In addition, the content of organic carbohydrates is high, which will be heated and fermented by enzyme bacteria, and the consequences of pollution will be far-reaching. According to the process of conventional and traditional waste...

AI Technical Summary

Problems solved by technology

In addition, the content of organic carbohydrates is high, it will be heated and fermented by enzymes, and the consequences of pollution will be far-reaching.

According to the process of conventional and traditional wastewater engineering, although milk of lime can neutralize the sulfuric acid in the wastewater, it costs money to consume the lime in vain; the sulfuric acid in the wastewater is also wasted in vain, and a large amount of gypsum slag is generated, resulting in double resource utilization. waste

For salt, sodium sulfate can only flow away with the water, which not only pollutes the cement soil, but also wastes 400-500 kg of sodium sulfate and 300 kg of sulfuric acid per ton of lignin

[0003] Organic sugars, aldehydes, alcohols, etc. that increase the COD value are also treated by the cultivation of activated sludge bacteria, but it needs to form a pool, which occupies a large area, takes a long time, and costs high

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