Optimization of a multibarrier treatment combining ozonation and biologically activated carbon for inorganic contaminant removal and effluent disinfection.

The development of microbial communities within granular-activated carbon (GAC) transforms it into a highly effective biofilter, integrating adsorption and biodegradation processes for contaminant removal. This study evaluated the performance of an O3-biological-activated carbon (BAC)-O3 system for removal of inorganic contaminants and secondary effluents disinfection. The BAC column was packed with 50 cm of commercial GAC, reaching biological stability after approximately 45 days of operation. System efficiency was assessed based on the removal of sodium (Na), calcium (Ca), magnesium (Mg), chloride (Cl-), and boron (B). A central composite design (CCD) was employed to the treatment process, generating mathematical models, statistically validated, to determine optimal treatment conditions, leading to the selection of an O3 dosage of 4 mg L-1 before and after the BAC stage. The system effectiveness was further tested through the removal of nine metals and microbial disinfection. Results confirmed that the O3-BAC process efficiently removed inorganic contaminants, while the additional post-BAC ozonation step was essential for achieving effluent disinfection. The final treated effluent achieved quality standards suitable for non-potable restricted reuse, and its successful application in hydroponic lettuce cultivation demonstrates a promising avenue for sustainable water reuse in controlled agricultural environments.