FERRATE (VI) AS A NEW TREATMENT CHEMICAL FOR WATER RECLAMATION

Ferrate(VI) is an emerging environmentally friendly chemical oxidant due to its high redox capacity and non-toxic final product. It can function as an oxidant, coagulant and sorbent, which allows ferrate (VI) to be a new and potential treatment chemical to achieve water reclamation in a single step. In this study, we evaluated the technical feasibility of ferrate, as a new agent for water reuse, for simultaneous removal of traditional contaminants from secondary effluent. Six various dimensionless ferrate doses were applied (0.1, 0.25, 0.5, 1, 2, and 3), which is defined as the equivalent ratio of K₂FeO₄ to initial chemical oxygen demand (COD). Six traditional chemical contaminants in influent and effluent were analyzed, including COD, total organic carbon (TOC), UV₂₅₄, total phosphate (TP), nitrate nitrogen, and ammonia nitrogen. Total coliform and E.coli were also quantified to evaluate the disinfection efficiency. Results showed that ferrate was able to appreciably remove all the six chemical contaminants. Without pH adjustment, COD, UV₂₅₄, TP, nitrate nitrogen and ammonia nitrogen were removed by up to 41%, 48%, 95%, 67%, and 57%respectively. More than 99% total coliform and E. Coli. could be inactivated within 5 minutes. At an acidic environment, the ferrate treatment could somehow promote the contaminant removal. For example, at pH 5.5, up to 59% COD, 89% TOC, 57% UV₂₅₄, 99% TP and 74% nitrate nitrogen were removed, respectively. These encouraging results demonstrate that ferrate-based treatment can be a promising alternate option for water reuse.