Fenton and biological-Fenton coupled processes for textile wastewater treatment and reuse

Abstract

Both Fenton oxidation and the combination of aerobic Sequencing Batch Reactor (SBR) + Fenton oxidation were investigated in a bench-scale study to degrade and reuse a real textile wastewater with a TOC = 465 mg L − 1 C, COD = 2100 mg L − 1 O 2 and Escherichia coli = 80,000 CFU mL − 1 , according to RD 1620/2007 (Spanish Normative for wastewater reclamation and reuse). The independent variables considered for the optimization of the oxidative process were temperature, H 2O 2 and Fe (II) concentrations. Under the best stand-alone Fenton operating conditions: T = 25 °C, pH = 3; [H 2O 2] = 1650 mg L − 1 and [Fe (II)] = 216 mg L − 1 , we achieved 64% TOC reduction and > 99% E. coli removal. However, the best results were obtained when applying Fenton process with [H 2O 2] = 1518 mg L − 1 and [Fe (II)] = 66.5 mg L − 1 , as a biological polishing step. The aerobic biological treatment was conducted using a SBR with 1 day HRT. In this case 92% TOC and > 99% E. coli removal were accomplished. The obtained results showed the feasibility of both processes to achieve suitable water qualities for internal reuse, according to RD 1620/2007.