【摘要】 采用空气增湿去湿工艺处理纳滤（NF）浓缩液,着重考察此技术用来处理浓缩液的可行性和pH值对COD、TOC、UV254和NH₃-N去除效果的影响。此工艺使NF浓缩液与空气在填料表面直接逆流接触进行传热传质。用NaOH或H₂SO₄溶液调节浓缩液pH值至酸性（pH值约3和5）和碱性（pH值约9）,研究酸性和碱性条件下对COD、TOC、UV254和NH₃-N的处理效果。结果表明,当浓缩液流量240 L/h、空气流量200 m³/h时,体积传热速率和产水率分别达到236k W/m³和8.11 kg/h。冷凝水出水水质满足GB 16889—2008《生活垃圾填埋场污染控制标准》的排放要求。此外,COD去除率在碱性条件下更高,而NH₃-N去除率随pH值增加而降低,UV254去除率受pH值的影响不大,酸性条件有助于TOC的去除。与蒸发法比较,空气增湿去湿法具有更高的经济可行性。更多还原

【Abstract】 The paper intends to introduce a treating method for the landfill leachate from a nanofiltrating（ NF） unit through the air humidification-dehumidification（ HD） process,and study the effects of different pH values on the removing efficiencies of COD,TOC,UV254,and NH₃-N. In the said air HD process,it is expected for the heat and mass transfer to take place between the nanofiltration（ short for NF） condensate and the air on the package surface,while the water steam can be transferred from the NF condensate to the air and then subsequently condensed.The results of our test show that the volumetric heat transfer velocity and the water-producing rate can be made to increase up to236 k W/m³ and 8. 11 kg/h on the condition that the NF condensate and the air flowing rates are to be as high as 240 L/h and 200 m³/h,respectively. Then,pH values of NF condensate can be regulated to those of 3. 11,5. 23,and 9. 14 by adding NaOH or H2SO₄ to the solution. As a result,it can be found that,COD removal rate may tend to get higher under the alkaline condition than under the acidic one,whereas the removal rate for NH₃-N tends to decrease with the increase of pH value. More specifically speaking,the removal rate of UV254 can be made as high as about 98. 0 % at various pH values with the removal rate of TOC reaching its maximum one hour later at pH value of 3. 11. More exactly speaking,the maximum removal rates for COD,NH₃-N,TOC,and UV254 should respectively be increased as high as98. 15%,97. 9%,99. 0%,and 99. 0%,whereas the mass concentrations of NH₃-N,COD,TOC,and the absorbance of UV254 in the condensate may have dropped to 1. 95 mg/L,32. 00 mg/L,7. 00 mg/L,and 0. 037 cm^-1,in respective accordance.Therefore,the condensating water quality should be able to attain the acceptable discharge limits. Therefore,as compared to the evaporation method,the air HD technology here introduced can be expected to exhibit highly promising economic feasibility,whereas the HD process can be regarded as an effective way to treat the NF condensate.更多还原