Feasibility study of treatment of amoxillin wastewater with a combination of extraction, Fenton oxidation and reverse osmosis

Wastewater from the synthesizing of amoxillin is characterized by its very high TOC and low biodegradability and the presence of organic solvents and dissolved salts. These hamper direct biological or membrane-based treatments. A combined process of extraction (EX), Fenton oxidation (FO) and a two-stage reverse osmosis (RO) was proposed to treat such wastewater. EX and FO were performed in a serial approach to function as the pretreatments to remove the solvents and other organics before RO treatment. It was noted the appropriate phase ratio (A/O) was 1:1 and the contact time was 3 h. Appropriate dosages of FeSO4 and H2O2 were 10 g/l and 2 g/l, respectively. Under the appropriate conditions, TOC can be reduced by 50.6% and 37.8% in the EX and FO units, respectively. TOC can be further reduced 10.1% and 1.2% in the first and second RO processes, respectively. There was consequently an overall TOC removal efficiency of 99.7% after the whole process of EX–FO–RO–RO. Dissolved salts were also greatly removed during the two-stage RO process. The observations by using SEM showed that the RO membrane can be protected well by the pretreatments of EX and FO.