Hybrid remediation strategies for industrial effluents

Thesis

Many industrial effluents are toxic, difficult to treat and contain potentially valuable resources. Current treatment methods are expensive and unsustainable. Bioprocess- ing is a promising alternative, but poses multiple challenges due to the chemically complex nature and high variability of different industrial effluents. As a result, it benefits from being combined with advanced oxidation processes. In this study, the potential benefit of coupling bioprocessing with nanoscale zero-valent iron and electron beam treatment was examined. Both processes have shown great promise individually in environmental applications but have not previously been applied in a hybrid system. This triple combination proved to be an effective approach when tested against two recalcitrant metalworking fluids, a textile dyeing effluent and a dis- tillery wastewater. Strategies to remediate the different industrial effluents included a selection of key performance indicators and their amalgamation into a novel remedia- tion index to assess treatment effectiveness. The different treatments were optimised both individually and in combination. Hybrid sequential e-beam, bioprocessing and nanoscale zero-valent iron treatment followed by bioprocessing synergistically detox- ified both metalworking fluids and reduced their chemical oxygen demand (COD) by 92.8 ± 1.4 % and 68.4 ± 1.6 % respectively. E-beam pre-treatment of the met- alworking fluids enabled high-COD bioprocessing at the expense of residence time. Hybrid treatment also remediated the textile dyeing wastewater achieving a 99.4 ± 0.4 % reduction in colour, a 54.6 ± 6.1 % reduction in COD, a 89.0 ± 3.5 % reduc- tion in sulphate and a 67.7 ± 4.2 % reduction in total nitrogen. E-beam treatment also enabled the recovery of copper from a distillery wastewater, whilst proving to have significant potential for the disinfection of industrial effluents post-bioprocessing. Overall process economics, footprint and sustainability were evaluated on a lab-scale and estimated for an industrial-scale implementation. The scope for improvements in the hybrid treatment system is discussed and suggests that future implementations of novel hybrid processes could provide tailor-made solutions for sustainable in situ treatment of a wide range of industrial effluents.

Authors: Thill, P

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford