Analysis of the fouling build-up of a spiral wound reverse osmosis membrane in the treatment of two-phase olive mill wastewater

In the present work, modelization and plant dimension for batch reverse osmosis (RO) purification of olive mill wastewater from a two-phase olive oil mill (OMW2) is carried out through analysis of the fouling build-up the by means of the threshold flux theory, for fouling control and appropriate plant dimension. Inhibition and control of fouling is vital to definitely achieve the competitiveness of membrane technology at industrial scale. The fouling index was found to considerably increase when shifting the P-TM from 20 to 30 bar, that is, 31.3 %. However, there is no significant difference with regard to the fouling build-up within the range 10 - 20 bar. Therefore, it is recommended to work upon an operating pressure (P-TM) around 20 bar to maximize both the productivity (13.3 - 13.5 L h(-1)m(-2)) together with the rejection efficiency (R-COD, %) whereas on the other hand minimizing the flux decay during the operation time. Finally, a required membrane area (A(m)) equal to 95 m(2), that means an overdesign of 48%, is calculated on the basis of the obtained results at a P-TM of 20 bar. Finally, the compliance of the standards to reuse the purified effluent for irrigation purposes throughout the proposed treatment process was checked. At this operating pressure value, the organic matter rejection efficiency reaches 90.5 %, thus permitting reusing the final treated effluent in the proper olive oil production process to close the loop at industrial scale.