摘要
Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wa stewater treatment since the high salinity significantly impedes organic pollutant degradation by oxidation or incineration.In the study,acidification combined electrodialysis(ED)was attempted to effectively separate Cl-ions from organics in concentrate pulping wastewater.Membrane’s rejection rate to total organic carbon(TOC)was 85%at wastewater intrinsic pH=9.8 and enhanced to 93%by acidifying it to pH=2 in ED process.Negative-charged alkaline organic compounds(mainly lignin)could be liberated from their sodium salt forms and coagulated in acidification pretreatment.Neutralization of the organic substances also made their electro-migration less effective under electric driving force and in particular improved separation efficiency of chloride and organics.After acid-ED coupled treatment(pH=2 and J=40 mA·cm-2)[TOC]remarkably reduced from 1.315 g·L-1 to 0.048 g·L-1 and[Cl-]accumulated to 130 g·L-1 in concentrate solution.Recovery rate of NaCl was 89%and the power consumption was 0.38 kW·h·kg-1 NaCl.Irreversible fouling was not caused as electric resistance of membrane pile maintained stably.In conclusion,acidic-ED is a practical option to treat salinity organic wastewater when current techniques including thermal evaporation and pressure-driven membrane se paration present limitations.
Inefficient separation of inorganic salts and organic matters in crystallization mother liquor is still a problem to industrial wa stewater treatment since the high salinity significantly impedes organic pollutant degradation by oxidation or incineration.In the study,acidification combined electrodialysis（ED） was attempted to effectively separate Cl-ions from organics in concentrate pulping wastewater.Membrane’s rejection rate to total organic carbon（TOC） was 85% at wastewater intrinsic pH=9.8 and enhanced to 93% by acidifying it to pH=2 in ED process.Negative-charged alkaline organic compounds（mainly lignin） could be liberated from their sodium salt forms and coagulated in acidification pretreatment.Neutralization of the organic substances also made their electro-migration less effective under electric driving force and in particular improved separation efficiency of chloride and organics.After acid-ED coupled treatment(pH=2 and J=40 mA·cm-2) [TOC] remarkably reduced from 1.315 g·L-1 to 0.048 g·L-1 and [Cl-] accumulated to 130 g·L-1 in concentrate solution.Recovery rate of NaCl was 89% and the power consumption was 0.38 kW·h·kg-1 NaCl.Irreversible fouling was not caused as electric resistance of membrane pile maintained stably.In conclusion,acidic-ED is a practical option to treat salinity organic wastewater when current techniques including thermal evaporation and pressure-driven membrane se paration present limitations.
基金
Supported by the Prosepective Joint Research Project of Jiangsu Province(BY2014005-06).
作者简介
Corresponding authors:Ming Zhou,NO.30 Puzhu Road(S),211816 Nanjing,China.E-mail addresses:mingzhou@njtech.edu.cn;Corresponding authors:Weihong Xing,NO.30 Puzhu Road(S),211816 Nanjing,China.E-mail addresses:xingwh@njtech.edu.cn
