酮连氮法制肼废水处理研究

Renovated treating method for the high-concentrated saline sewage from preparing hydrazine hydrate by means of ketazine process

针对酮连氮法制肼生产过程中产生的高盐废水,采用化学沉淀和次氯酸钠氧化两种方法联合处理。结果表明:调节废水pH=9.0,以MgCl2.6H2O和Na2HPO4.12H2O为沉淀剂,n(Mg2+)∶n(NH4+)∶n(PO34-)=1.2∶1.0∶0.9,NH4+-N去除率为96.8%;再向废水中投入次氯酸钠溶液,其加入量为废水量的1.3%～1.6%时,可使废水CODCr从1 650mg/L降至63.2mg/L,无机铵质量浓度为0,总铵质量浓度为1.8mg/L。经两步处理后的废水可用于一次盐水。

In this paper, we would like to introduce a renovated method for treating the high-concentrated saline sewage from preparing hydrazine hydrate by means of ketazine process, that is to say, a combined method that can integrate the chemical precipitation method and the sodium hypochlorite oxidation process into one to treat the sewage from preparing hydrazine hydrate in processing ketazine. The reason is that, on the part of sewage treatment, it can help to shift the treating process from the traditional removal to the recovery. As is known, the traditional biochemical method has been limited in use because the sewage to be treated is at low concentration of Chemical Oxygen Demand （CODcr）and high-salinity. Neither the chemical precipitation method can satisfy the need, for there come two chemicals containing Mg^2＋ and PO4^3- ions to be put into the sewage to gener- ate the magnesium ammonium phosphate （MAP）precipitation. Therefore, we prefer to choose MAP chemical precipitation technique for the MAP decomposition residues to be heated under the alkali condition can be reused in a recycling manner as magnesium and phosphate chemicals. Besides, the MAP chemical precipitation method enjoys a lot of advantages, such as simple in technology, fast in reaction speed, free from temperature limit, and high in the heavy-metal-ionsremoving efficiency. To improve the removing efficiency, we have installed a special device for producing chlorine gas and sodium hypoehlorite, which can be used as an oxidant in preparing azine. Since we have sufficient sodium hypoehlorite, which is safe and convenient in use, it would be possible for us to use sodium hypoehlorite to remove the sewage. Therefore, we have chosen the chemical pre- cipitation method and the sodium hypoehlorite oxidation process to treat the sewage under question in our research. The experimental results demonstrate that the ammonia removal efficiency could be achieved to 96.8% , when pH is regulated to 9.0, and the compo- nential elements would be MgCl2 · 6H2O and Na2HPO4 · 12H2O, n（Mg^2＋）：n（NH4^＋）：n（PO34-） = 1.2：1.0：0.9 in ratio. Then, adding the sodium hypochlorite with a dosage of 1.3 % - 1.6% of the sewage volume, the CODcr in it would be reduced from 1 650 mg/L to 63.2 mg/L, and, in turn, the inorganic ammonia would be reduced to 0 mg/L with the total ammonium decreased to 1.8 mg/L. In so doing, the sewage could be used as the primary brine through the above two-step treatment. Therefore, the treatment can not only change the waste metal ingredients into something reusable but also contribute greatly to the sustainable economic development, but also to the environmental protection.