Integration of advanced oxidation processes and activated sludge for the treatment of high refractory industrial wastewater

BACKGROUNDThe aim of this research was centered on the development of a suitable strategy for the treatment of a wastewater from the production of automotive coating pipes. RESULTSCoagulation and Fenton treatments were ineffective and did not achieve the desired objectives, however, ozone based processes were shown to be an interesting technology. Several parameters affecting ozonation, such as pH, the addition of hydrogen peroxide as co-oxidant and the contact time, were optimized. It was concluded that the best efficiency was attained with ozone (2 g h(-1)) using a multi-stage pH procedure. After 1200 min reaction, this system achieved 98% chemical oxygen demand (COD) removal and the final effluent presented a BOD5/COD improvement from 0.11 to 0.30. CONCLUSIONThis study proposes an effective method to treat this specific wastewater. Fenton oxidation enabled an increase in effluent biodegradability, however, not sufficient to enable a posterior biological treatment. Using ozonation, the operating conditions can be adapted to provide an effluent able to be discharged into the hydro resources (COD < 150 mgO(2) L-1), or to be sent to the municipal sewage plant (COD < 1000 mgO(2) L-1) where it will be further refined in a biological system. (c) 2015 Society of Chemical Industry