Removal characteristics of organics in bio-treated textile wastewater reclamation by a stepwise coagulation and intermediate GAC/O3 oxidation process

摘要

In this study, a novel hybrid process involving stepwise coagulation and intermediate ozonation in the presence of granular activated carbon (GAC/03) was employed to remove effluent organic matter (EfOM) from bio-treated textile wastewater. Removal behavior of EfOM in different processes, including biode-gradability, hydrophobic and hydrophilic property, and apparent molecular weight (AMW) distribution, were evaluated as well. When the polyaluminum chloride (PAC1) dose of 25 mg L~(-1) as Al was used in both pre-coagulation (pH 8.0) and post one (pH 5.5), and the ozone dose of 3.1 mg O3 mg~(-1) COD was applied in GAC/O3 (GAC 10 g L~(-1)) lasting 5 min, the superior removal efficiencies of water quality parameters like turbidity, color, COD, DOC and UV_(254) were 95.8%, 97.5%, 88.1%, 68.7% and 90.5%, respectively. Results also showed that GAC/O3 not only gave the efficient decolorization and DOC removal, but also enhanced the treatability of biodegradable and hydrophilic organics of AWM in 1-10 k Da by post coagulation, likely due to the effective removal of colored and hydrophobic organics in AMW > 1 k Da via pre-coagulation. Therefore, the hybrid process applying appropriate operational parameters was proved to be an attractive strategy in the wastewater reclamation.