超重力强化折点氯化法处理低浓度氨氮废水

Treatment of low concentration ammonia nitrogen wastewater by high gravity enhanced breakpoint chlorination

折点氯化法具有反应速度快、氨氮脱除率高等优点,广泛应用于氯碱等行业中,但反应过程中产生二氯胺致使废水中余氯浓度过高,无法满足离子膜法烧碱生产安全技术规定(HAB004—2002)。为解决这一问题,本文提出了超重力技术强化折点氯化法处理氨氮废水的新工艺,利用超重力技术强化传质的特点,实现次氯酸钠和氨氮的快速反应以及二氯胺的有效去除,研究了超重力因子(β)、氯氮比(Cl/N)、pH和液体流量QL等操作参数对氨氮脱除率和余氯的影响规律。研究结果表明,当Cl/N=11、β=30、pH=6~8和液体流量QL=80L/h时,氨氮去除率>95%,余氯浓度<1.5mg/L。与传统反应器相比,二氯胺去除效果明显,处理后的水中氨氮满足烧碱安全生产技术规定,此方法对于氯碱行业中低浓度氨氮的去除具有广阔的应用前景。

The breakpoint chlorination method has the merits of high removal efficiency of ammonia nitrogen,rapid response,which was used to the fields of the chlor-alkali industry.However,dichloramine will be produced in the process of the reaction and make the residual chlorine concentration in the treated wastewater too high,and the ammonia nitrogen removal efficiency in the traditional reactor is low,which cannot meet the safety technical regulations for ion-exchange membrane caustic soda production(HAB004-2002).In order to solve this problem,a new process for the treatment of ammonia nitrogen wastewater by using high gravity technology to enhance the breakpoint chlorination method was proposed.Effects of high gravity factor,ratio of Cl/N,pH and liquid flow rate on the removal efficiency of ammonia nitrogen and residual chlorine concentration were investigated.The experimental result showed that the removal rate of ammonia nitrogen was more than 95%,the concentration of ammonia nitrogen in wastewater was reduced to 1 mg/L,the residual chlorine concentration was less than 1.5mg/L when Cl/N=11,β=30,pH=6-8 and QL=80L/h.The removal efficiency of ammonia nitrogen in RPB is better than other reactors,the concentration of ammonia nitrogen and residual chlorine in the treated water meets the technical regulations.The present method has a broad application prospect for the treatment of low concentration ammonia nitrogen wastewater in the chlor-alkali industry.