A process for treating ammonia nitrogen wastewater using gaseous membrane

Abstract

The invention relates to a process for treating ammonia-nitrogen wastewater by using a gaseous membrane. The steps include: pre-treating high-concentration ammonia-nitrogen wastewater with a composite decolorizer and a heavy metal scavenger, sending it to a blow-off tower for ammonia-nitrogen removal, and the blown-off ammonia gas enters hydrochloric acid The absorption tower generates ammonium chloride; the waste water after stripping treatment is mixed with low-concentration ammonia nitrogen waste water to obtain waste liquid, and the pH of the waste liquid is adjusted to above 10.5, and then ultrafiltration is performed, and the waste liquid and absorption liquid after ultrafiltration enter In the gaseous membrane module, the flow rate and temperature are controlled to remove ammonia nitrogen, and ammonium salt solution and waste liquid with ammonia nitrogen content lower than 10mg / L are obtained; the ammonium salt solution is sent to the stripping tower after adjusting the pH value, and then passed through the hydrochloric acid absorption tower, Ammonium chloride is obtained. The ammonia nitrogen removal rate of this method exceeds 99%, and the waste liquid after treatment meets the discharge standard. During the process, the gaseous membrane has good stability, does not produce osmotic distillation of water, and the process of the gaseous membrane can be continuously carried out, which is beneficial to industrial implementation.

Description

technical field [0001] The invention belongs to the field of ammonia nitrogen wastewater treatment, and in particular relates to a process for treating ammonia nitrogen wastewater by using a gaseous membrane. Background technique [0002] In recent years, with the rapid development of petrochemical, coal chemical, fine chemical, fertilizer, pharmaceutical, metallurgy, electronics and other industries, the daily discharge of ammonia nitrogen wastewater has been increasing. Ammonia nitrogen in wastewater is an important substance for water eutrophication and environmental pollution, which affects water quality and human health, and also causes a huge waste of resources. Therefore, the country requires ammonia nitrogen-containing wastewater to be removed using ammonia nitrogen removal technology, and can only be discharged after reaching the "Comprehensive Wastewater Discharge Standard". [0003] At present, the most common ammonia nitrogen removal technologies include biologi...

AI Technical Summary

Problems solved by technology

[0005] However, in the gaseous membrane deamination process, not only ammonia molecules enter the absorption liquid through the membrane wall, but also water molecules enter the absorption liquid through the micropores on the membrane wall (associated osmotic distillation), resulting in rapid expansion of the absorption liquid volume, As a result, the absorption solution is diluted, and the higher the acid and salt concentration in the absorption solution, the more serious the osmotic distillation of water, so it is difficult to obtain the expected by-product, that is, a high-concentration ammonium salt solution

Chinese patent CN106186492A overcomes the accompanying osmotic distillation problem by keeping the temperature difference between the wastewater and the absorption liquid at 10-20°C, increasing the ammonia nitrogen concentration in the wastewater to 1000-10000mg / L, and adding electrolytes to the wastewater, but the temperature difference in this method Difficult to control, both sides quickly reach temperature balance, and high concentration of ammonia nitrogen affects the stability of gaseous membrane modules, resulting in easy pollution and shortened service life, which limits its popularization and application

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