Abstract

A new process to remove non-ionic surfactants from tannery wastewater, using a bed of adsorbent synthetic resin, has been investigated at laboratory and pilot scale. A small pilot column (V=2 litres) has been tested at a tannery in Northern Italy. The wastewater was filtered on a sand-bed and then fed to the adsorbent resin. The column operated at very short nominal residence time, lower than 7 minutes. Non-ionic surfactants were monitored in the column influent and effluent. Two regeneration procedures were tested: hot water with soda and solvent extraction by acetone. Only the latter was quite successful and allowed a complete recovery of the absorbate. More basic experiments were carried out at laboratory scale using synthetic solutions made of tap water and a non-ionic surfactant industrial product to evaluate equilibrium isotherms and adsorption kinetics. A first approximation economical evaluation of the process was also carried out. The experimental results indicate that the removal of non-ionic surfactants from industrial wastewater (tannery effluent) by adsorbent resin is feasible and economically competitive.