A procedure for the selection of the optimal adsorbent for phenolic compounds (PC) recovery from PC-rich wastes and wastewaters was innovatively proposed and applied to compare 4 neutral resins (Amberlite XAD16N, Optipore SD-2, Amberlite FPX66, Amberlite XAD761) and 1 ion-exchange resin (Amberlite IRA958 Cl) for PC recovery from a Tunisian olive mill wastewater (OMW). In the initial batch isotherm tests a neutral resin (XAD16N) performed best thanks to its high PC sorption capacity (81 mgPC/gdry resin) and PC content in the sorbed product (0.19 gPC/gvolatile solids). Also ionexchange resin IRA958, used in OH form in this work, resulted interesting thanks to its satisfactory performances and very low cost (8 €/L). These two pre-selected resins were further compared by means of continuous-flow adsorption/desorption tests conducted in a 1-m packed column. The results indicate that if a low (20%) breakpoint is selected, XAD16N leads to a PC-richer sorbed product (0.14 gPC/gvolatile solids) and a higher operating capacity (0.30) than IRA958. Conversely, if a very high (90%) breakpoint is selected, the two resins produce similar desorbed products in terms of both PC content (0.19-0.21 gPC/gvolatile solids) and antioxidant capacity (4.6-4.9 gascorbic acid equivalent/gPC). Resinspecific dynamic desorption procedures led to very high PC desorption yields (87-95%). The identification of the actual PCs present in the final desorbed product indicated for XAD16N a higher capacity to preserve the integrity of the PC mixture of the studied OMW. OMW microfiltration (0.2 μm pore-size) led to a 99.8% suspended solid removal -thus protecting the packed column from potential clogging -with a very low PC loss.

ab s t r ac tThis paper discusses the use of the non-oxidative biocide 2,2-dibromo-3-nitrilopropionamide (DB-NPA) to minimize and/or eliminate problems due to biofouling accumulation and to ensure longterm performance of a RO system. DBNPA is a suitable biocide due to its compatibility with reverse osmosis (RO) membranes. Our aim is to present a better understanding of DBNPA, its rejection by common RO membrane types and the environmental chemistry concepts for residual DBNPA and its by-products in the outlet concentrate stream. The application areas covered are industrial water and off-line drinking water systems. Examples of field studies conducted on full-scale RO systems that use DBNPA will be shown. Also discussed are the data obtained from the analysis that was carried out to determine the degradation of DBNPA in the RO feed and outlet stream. The benefits of using DBNPA for biofouling prevention include reducing the required feed pressure and the cleaning frequency of the RO system. Other benefits are reduced cleaning chemical costs, reduced downtime of the plant and reduced time of the operators. This results in increased output of the plant and reduced operating expenses of the RO operation.