Electrochemical Treatment of ROC
During membrane treatment of secondary effluent from wastewater treatment plants, a reverse osmosis concentrate (ROC) is produced. ROC treatment for removal of ammonium and nitrate is partially incorporated into some Advanced Water Treatment Plants (AWTPs). However, environmental regulation has some concerns regarding nitrogen and organics (including some micro-pollutant) concentrations. Previous research at the Advanced Water Management Centre at the University of Queensland investigated treatment options including coagulation (alum), advanced oxidation (ultra-violet or hydrogen peroxide) and activated carbon. However, all have high cost implications of $1.5-3.0/kL. Preliminary tests using electro-chemical oxidation with specialised electrodes suggests highly efficient removal of colour at a fraction of these costs. Effective and economic treatment methods for full ROC streams are required.
This project leveraged Alliance funding to contribute to a multi-stakeholder project which secured Australian Research Council linkage funding. Other contributing parties include Veolia Water Australia, Seqwater and Magneto Special Anodes (Netherlands), an international electrode manufacturer.
TThis project investigated electrochemical oxidation and reduction of ROC, with a particular focus on the removal of trace organic contaminants. It aimed to evaluate a series of different electrode materials, process configurations and operating conditions, and determine removal efficiency and factors of influence. It also sought to understand the degradation pathways of organic contaminants, potentially resulting in hazardous by-products in the presence of chloride ions, and possible post-treatment requirements.
Key Publications and Outputs
This project developed a number of important intellectual property developments. These include a methodology for multi-residue analysis of trace organics, elucidation of electrochemical oxidation pathways of model compounds, and efficiency estimates for different electrode materials and currents/potentials applied.
- Technical Report 82 addresses "Electrochemical treatment of problematic water recycle waste streams"
- Conference papers listed on the Alliance website
- Proceedings of the Alliance Science Forums
Further information is published in journal papers listed below, and in "Electrochemical oxidation for the removal of organic micro-pollutants", Micropol and Ecohazard conference in Sydney, 11-13 July 2011, or is available from the Project Leader.
Radjenović, J., Farré, M.J., Mu, Y., Gernjak, W. and Keller, J. (2012) Reductive electrochemical remediation of emerging and regulated disinfection byproducts. Water Research 46 (6) 1705-1714.
Bagastyo, A., Radjenovic, J., Mu, Y., Rozendal, R.A., Batstone, D.J. and Rabaey, K. (2011). Electrochemical oxidation of reverse osmosis concentrate on mixed metal oxide (MMO) titanium coated electrodes, Water Research, 45 (4), 4951-4959.
Radjenovic, J., Escher, B.I. and Rabaey, K. (2011). Electrochemical degradation of the beta-blocker metoprolol by Ti/RuIrO2 and Ti/SnO2-Sb electrodes, Water Research, 45 (4), 3205-3214.
Due to the generation of chlorinated by-products when electro-oxidizing ROC, electrodialysis prior to electrochemical oxidation seems to be the most adequate option for efficiently degrading the trace organic contaminants without an increase in the effluent toxicity. Furthermore, there is large potential for the outcomes of this work to be adopted in different steps of wastewater treatment. For example this could include wastewater disinfection or removing disinfection by-products in drinking water treatment.
Dr Jelena Radjenovic, The University of Queensland
Ph: +61-7-3346 3234