Feasibility study of the treatment of aniline hypersaline wastewater with a combined adsorption/bio-regeneration system

Treatment of aniline hypersaline wastewater with a combined physical–biological method was investigated in this study. This method consisted of the physical adsorption of aniline from hypersaline effluents by resins and the biodegradation of the adsorbate and the regeneration of the adsorbent in the subsequent stage. The XDA-1 resin, selected from five commercial products, could separate aniline from salt effectively. The adsorption rate increased with the increase of salinity. Biodegradation of the aniline desorbed from the exhausted resin could be realized easily without salt interference. During the repetitive six combined operations, the percentage regeneration (PR) and NaCl separation efficiency (SE) of XDA-1 were 92.3% and 98.3%, respectively. No obvious difference could be found in pore size distribution between virgin XDA-1 and samples repeated six regeneration cycles. The PR of specific surface area and total pore volume of the bio-regenerated XDA-1 resin were 94.5% and 97.2%, respectively. It was indicated that XDA-1 could be bio-regenerated successfully and the regenerated resin could be re-utilized.

A combined process of adsorption/bioregeneration was investigated for treatment of aniline hypersaline wastewater. The XDA-1 resin was selected from five commercial products for aniline adsorption. The isotherm data of aniline adsorption fitted well with Freundlich equation. The adsorption of aniline onto XDA-1 was proved to be a physisorpt process. It was shown that adsorption capacity of XDA-1 was enhanced with the increase of salinity, and the adsorption rate equation could be expressed [Eq. (9)]. In the bio-regeneration process, the desorbed aniline concentration was controlled below 1100 mg/l for efficient biological work and the optimal regeneration time was 120 h under conditions mentioned above. The adsorption and bioregeneration process repeated for up to six cycles, the PR and NaCl SE of XDA-1 remained 92.3% and 98.3%, respectively. The bio-regeneration process did not destroy the pore structure and the surface properties of XDA-1 resin. The static studies showed that the combined adsorption/bioregeneration process could treat aniline hypersaline wastewaters efficiently.