An innovative bioreactor for sustainable treatment of high salinity wastewater aimed to process water reuse

Relevance of saline wastewater in different industrial sectors is well known: high NaCl content is found in water originated from chemical industry (mainly the chloralkali sector), and agro-food industries. Consistent salt levels also characterize the petroleum, textile and leather industries wastewater as well as the effluents of hard water softening process. The consequence is a wide and heterogeneous production of saline streams characterized by the presence of biorefractory/toxic organics. This feature requires a double optimization of the wastewater treatment to achieve both high removal efficiency of organic components and efficient removal/recovery of salts. Furthermore, the toxic organic content of saline wastewater and the high salt level exert inhibitory/toxic effects on biocatalysts, thus making challenging the application of a conventional biological unit process. Two-Phase Partitioning Bioreactors (TPPBs) were proven effective for xenobiotic removal: main feature of TPPBs is to partition high xenobiotic concentrations from a cell-containing aqueous phase by an immiscible phase (organic solvents or granular polymers) and to deliver these compounds back to the cells because of metabolic demand. An innovative configuration of a continuous TPPB (C-TPBB) was recently proposed for treatment of highly saline wastewater: a hybrid bioreactor operated with a polymeric tubing able to achieve simultaneously the gradual delivery of organic substrates and the separation of the "hostile" wastewater from the microbial culture. Objective of this study is to demonstrate the feasibility of the C-TPPB for the biological treatment of a highly saline wastewater in a range of organic influent loads of 20-56 mg/h with the additional benefit of producing a saline stream free from other organic compounds suitable for reuse in the process cycle.