Wastewater valorisation through adsorption processes and anaerobic digestion

When contaminants possess an intrinsic economic value, their removal from the waste and their recovery as a marketable product, does not only reduce the environmental footprint of the waste disposal, but also provides a revenue-generating opportunity. This is the case of the two wastewater (WW) investigated in the current study: olive-mill wastewater (OMWW) containing high content of phenolic compounds (PC) and municipal wastewater (MWW) which is today considered the most potential new source of phosphorus (P). In terms of WW valorisation adsorption-based technologies result an extremely attractive solution since the pollutant values can be recovered along with their removal from the effluents. In the first part of the current work a procedure for the selection of the optimal adsorbent for PC-recovery from actual OMWW was proposed and applied to compare 4 neutral resins (Amberlite XAD16N, Optipore SD-2, Amberlite FPX66, Amberlite XAD761) and one ion-exchange resin (Amberlite IRA958Cl), by means of batch and continuous-flow tests. Moreover, anaerobic digestion tests were conducted on both raw and dephenolized OMWW to drive the development of a cost-effective and integrated biorefinery process aimed at producing a directly reusable irrigation-quality water. The second part of the thesis focused on P-recovery from MWW. This study represents one of the really first attempt to place an adsorption-based process within an existing sewage works to remove and recover P from secondary effluent MWW. The process was investigated through a pilot-scale plant, treating 10m3d-1 of WW and characterized by 35L of the commercially available hybrid ion exchange resin HAIX LayneRT. The investigated system went successfully through 66 adsorption/desorption cycles proving the potential of the novel conduction method proposed, based on the multiple usage of the regenerant solution through consecutive adsorption/desorption cycles. Moreover lab-scale trials were performed to investigate the resin performances after the long operating time in the actual field-experience.