Treatment of Fenton Sludge with Iron Reducing Bacteria

Abstract The Fenton reaction is an advanced oxidation process (AOP) for treating industrial wastewater. It offers significant advantages in breaking down toxic compounds compared to conventional activated sludge treatment. However, the homogeneous Fenton process has certain drawbacks, particularly the use of non-recyclable soluble iron salts, which generate large quantities of ferric hydroxide sludge that is difficult to manage and dispose. To tackle this issue, a cost-effective biological method for managing Fenton sludge is needed. By utilizing iron-reducing bacteria (IRB), iron (III) in the sludge can be reduced back to iron (II), creating an opportunity to recycle the sludge as a source of iron for the Fenton reaction. This study investigates the reduction of iron (III) to iron (II) using Shewanella oneidensis. Laboratory experiments were conducted under both aerobic and anaerobic conditions, with Shewanella oneidensis introduced into iron (III) solutions for 7 to 21 days, using nutrients from fruit fermentation broth. The efficiency of iron conversion was measured via spectrophotometry, analysing the remaining iron (III) and iron (II) in the solution. Encouragingly, the study successfully demonstrated conversion and yield of 53.7 % and 21.5%, respectively under aerobic conditions. Meanwhile, under anaerobic conditions, the conversion and yield were 51.95 % and 36.95 %, respectively. These findings highlight the potential of Shewanella Oneidensis to enhance the sustainability and efficiency of the Fenton process by enabling the recycling of iron, thus mitigating the environmental impact of Fenton sludge disposal.