Biofouling mitigation by functional membranes used in wastewater treatment from olive oil source

Membrane fouling is an undesired event, which can seriously affect the performance of a membrane separation process in terms of flux decline and rejection abatement. So, frequent and expensive cleaning procedures are required, often compromising the integrity of the membranes and without achieving full restoration of the membrane process. Sometimes the correction of operating conditions is not enough and the replacement of the membrane modules is the only solution with heavy consequences from economics point of view. In this respect, our goal is to mitigate biofouling events onto membrane surfaces when microfiltration operations are worked for recovering nutraceutics components, i.e. biophenols, from oil processing by-products. During wastewater treatment, membranes suffer severe biofouling conditions owing to the build up of colloidal particles, agglomeration of pectin and biophenols along with by-products of microorganism growth. With the intent on prolonged service life of the membranes and maintenance of high standards for the separation process, we modified membrane surfaces by using nanoparticles/pH-responsive polymer complexes in order to mitigate adhesion events and promote self-cleaning function. Based on nano-assembly concepts, the supra-molecular chemistry of the membrane surface was, hence, addressed for three kinds of modified fluoropolymers to manipulate attractive/repulsive interfacial forces, causing the foulants to reduce their adsorption onto the surface. The behaviour of the membranes before and after functionalization was investigated in static and dynamic modes under different pH conditions. The role of morphological factors and chemical functions on the control of adhesion events was studied by combining wetting experiments with infrared analysis in ATR mode and atomic and electronic microscopy. Permeation experiments were carried out with pure water and, then, with wastewater from oil source in order to evaluate the ability of the functional membranes to induce self-cleaning with full recovery of both the flux and rejection. The results obtained with these types of membranes under various operating conditions will be presented.