Treatment Of High Salinity And Aniline Concentration Wastewater By GAC Adsorption-Biological Regeneration

The discharge of high salinity and high organic concentration wastewater causes serious environmental pollution. As it contains not only high concentration of salinity, but also a great quantity of solvable organic compounds, which are toxic and hard for degradation, the performances of conventional processes were always uncompetitive and unstable. Thus, a new treatment process which integrated granular activated carbon (GAC) adsorption separation and biological regeneration was established and the characteristics were investigated carefully.The characteristics of aniline-degrading bacterial community which acclimated from the activated sludge were investigated. It was found that the cultures were effectively and the adaption periord was short. The optimal growth conditions are: 25℃, pH 7 and 0.5% (w/w) NaCl. The aniline can be totally degraded when the initial aniline concentrations were between 50 and 1000 mg/L, while the time needed increased with the initial aniline concentration. Under the same initial aniline concentration, both the adaption periord and the time needed for degradation decreased with the increase of inoculation amounts.The characteristics of adsorption were also studied. The results show that aniline and NaCl can be effectively separated by GAC adsorption. The adsorption isotherms were well fitted with the Freundlich modle, and the equilibrium time was about 4 h. NaCl and acidic conditions can enhance the adsorption capacity of aniline on GAC. While NaCl percentage increased from 0 to 15%, the adsorption capacity increased from 320 mg/gGAC to 380 mg/gGAC. And the adsorption capacity increased from 320 mg/gGAC to 453 mg/gGAC while pH changed from 7 to 3. The main influcing factors of dynamic desorption process are: influent aniline concentration, NaCl percentage and influent flow.On the other hand, the feasibility of biological regeneration and the influencing factors of percentage regeneration were studied. It was found that this process is effective and stable. The percentage efficiency can reach to 70-80% without second pollution. After 4 rounds of adsorption - regeneration cycles, both separation efficiency and percentage regeneration demonstrated no obvious decrease. The method has no harm for the surface properties and pore size distribution of GAC. 78% of BET surface area and total pore volume were recovered.