盐酸作吸收剂用于气态膜法从废水中脱除/回收氨氮

Supported-gas-membrane process for removal of ammonia from aqueous solution by using dilute hydrochloric acid as absorbent

考察了盐酸作吸收剂时用气态膜技术从水溶液中脱氨的可行性,鉴于盐酸的挥发性,着重考察了不同料液氨水浓度下气态膜过程可以稳定操作时所对应的吸收液中盐酸的临界浓度。在此基础上,研究了料液氨氮浓度、料液流速、吸收液流速、吸收液盐酸浓度和操作温度等操作参数对膜传质性能的影响,并考察了该工艺的长期操作稳定性。实验结果证明,气态膜脱氨过程可采用一定浓度的稀盐酸溶液作为吸收剂,并可通过向吸收液中不断添加浓盐酸的方式得到浓度为>15%的氯化铵溶液。在料液浓度为2000 mg/L、吸收液盐酸浓度为2%、操作温度为25℃的操作条件下,中空纤维膜组件持续稳定运行了650 h以上,总传质系数保持在4.25×10 6m/s左右。用盐酸作吸收剂时废水中氨氮可脱至15 mg/L以下,符合国家环保标准。这表明采用盐酸作吸收液用气态膜法从废水中脱除回收富集氨氮是可行的。

Supported-gas-membrane process for removal/recovery of ammonia from a wastewater stream was studied by using volatile hydrochloric acid as the absorbent. The experimental feasibility was identified and the critical concentration of hydrochloric acid for various feed-in ammonia concentrations were found in order to assure operation stability. The effects of feed-in ammonia concentration,feed-in flow rate,flow rate of the stripping solution,HCl concentration in the stripping solution , as well as operation temperature , on the overall mass transfer coefficient were also investigated. The experimental results showed that hydrochloric acid as absorbent was feasible,and that it was possible to obtain a highly concentrated by-product of〉15% NH4Cl solution. The operational stability had been tested for 〉650 h under the following experimental conditions：feed-in ammonia concentration of 2000 mg/L,hydrochloric acid concentration of 2%,and temperature of 25 ℃,and the overall mass transfer coefficient was around 4.25×10？6 m/s during the whole testing period,which demonstrated a high operational stability and feasibility.