Solvent impregnated resin (SIRs) for the trace removal of aromatic nitrogen containing compounds from wastewater streams

The removal of aromatic nitrogen containing compounds from wastewater streams is a difficult process. The most cost-effective technology used in industry is biological treatment, but is difficult to apply when pyridine and its derivatives are present. In this paper a new process using solvent impregnated resins (SIRs) is developed for the removal of model compound 4- cyanopyridine (4CP) from an aqueous stream that also contains organic acids prior to biological treatment. A solvent screening was performed and it was found that phenol based extractants have the highest potential. Distribution co-efficients from 50 to 1000 and selectivities of 150 to 700 for 4CP over model acid acetic acid have been obtained. The commercially available extractant nonylphenol was used for a preliminary process evaluation with laboratory scale column experiments. It has been determined that 14 bed volumes of 0.5 g/L 4CP can be treated using the SIR. Full regeneration using a pH 1 solution of hydrochloric acid can be obtained within 6 bed volumes and 86% regeneration within 2 bed volumes. A total amount of 10 loading and regeneration cycles have been performed without loss of capacity, demonstrating the stability of the SIR and confirming the potential of this technology. It is expected that in future work, even higher capacities and selectivity’s will be observed when applying improved extractants.