Method for treating wastewater with trivalent arsenic

Abstract

The invention discloses a method for treating wastewater with trivalent arsenic. The method includes simultaneously feeding the to-be-treated wastewater with the trivalent arsenic, iron salt solution and sulfate solution and simultaneously sufficiently colliding the to-be-treated wastewater, the iron salt solution and the sulfate solution with one another to obtain first mixtures; regulating the pH (potential of hydrogen) of the first mixtures until the pH of the first mixtures reaches 1.8-3.0; uniformly mixing the first mixtures with one another at the normal temperature; carrying out reaction; separating precipitates. The method has the advantages that feeding reaction is carried out under the conditions of the temperatures of 25+ / -1 DEG C, the speeds of 600+ / -20 r / min and the pH of 2.4 for 18 min when the arsenic solution with the As <3+> content of 20.5 g / L, the iron salt solution with the Fe <3+> content of 23.0 g / L and the sulfate solution with the SO<4><2-> content of 6.56 g / L are added into 30 mL of deionized water at the speeds of 1.8 mL / min, water hydroxyl sarmientite minerals are good in crystallization, and the As <3+> removal rate is 87.6%; the method for treating the wastewater with the trivalent arsenic is high in arsenic removal efficiency, good effects can be realized, raw materials are low in cost and are easily available, conditions are mild, procedures can be controlled, the precipitates are high in arsenic content, are stable and are easy to separate, secondary pollution can be prevented, and accordingly the method has a broad practical application prospect.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and more specifically relates to a method for treating wastewater containing trivalent arsenic. Background technique [0002] With the continuous development of my country's non-ferrous metal smelting industry, wastewater containing trivalent arsenic has the characteristics of high acidity, high content of trivalent arsenic, and complex components, which seriously threatens environmental safety and residents' health, and has gradually attracted widespread attention. Nowadays, The recovery and treatment of arsenic-containing pollutants, especially trivalent arsenic-containing pollutants, has become the most difficult problem that my country's non-ferrous metal smelting industry must face. [0003] In the prior art, the wastewater containing trivalent arsenic is mainly treated by iron salt precipitation method, which is limited by the solubility product and needs to consume a large amou...

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Problems solved by technology

[0003] In the prior art, the wastewater containing trivalent arsenic is mainly treated by iron salt precipitation method, which is limited by the solubility product and needs to consume a large amount of alkali and iron salt to make the removal rate of trivalent arsenic reach the standard, and at the same time lead to a large amount of waste residue The production, and its long-term stability can not meet the needs of practical applications, there are problems such as high cost, secondary pollution and difficult operation

[0004] In recent years, methods such as ion exchange, reverse osmosis, and biological arsenic removal, which have developed rapidly in recent years, have been used to remove arsenic in wastewater, and have achieved good results. However, the cost of ion exchange and reverse osmosis is relatively high, and they are limited to small The treatment of low-concentration arsenic-containing wastewater with a single scale and single component; and the biological arsenic removal method has the potential to directly treat trivalent arsenic-containing wastewater without oxidation, and has good safety, and has gradually been favored by many researchers. However, the actual On the one hand, the biological arsenic removal method needs to cultivate microorganisms, which takes a long time, and the arsenic removal effect of different microorganisms varies greatly, and the actual arsenic removal operation is not easy to control. On the other hand, the biological oxidation used in this method forms minerals to achieve The reaction process of removing arsenic takes a long time and must be carried out under harsher reaction conditions

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