Selenium (Se) pollution has led to several cases of severe aquatic ecosystem deterioration due to Se poisoning caused by bioaccumulation over time. However, the removal of selenate (SeO42-) from wastewater streams with co-contaminants has been largely considered as a black box in anaerobic biological systems using mixed consortia. This research aimed at addressing the effect of wastewater characteristics, i.e. co-contaminants such as nitrate (NO3-) and sulfate (SO42-), heavy metals and pH, on the biological reduction of SeO42- and evaluating process integration for Se-laden wastewater treatment with co-contaminants. This study demonstrated that the presence of co-contaminants can actually be beneficial for Se removal provided that the concentrations are carefully monitored and appropriate operating conditions and process configurations are used. The Se removal (total Se and SeO42-) efficiency increased by ~30% in the presence of NO3- and/or SO42- compared to systems with SeO42- alone. Additionally, an integrated process of an ion exchange (IX) column and bioreactors showed improved overall removal capacity for SO42- and total Se. The knowledge and information gained from this research can help in the advancement and application of biological processes, i.e. predicting of reactor performance, solving specific design or practical problems and implementing novel treatment techniques for Se-laden mine wastewater.
Lea Chua Tan was born in 1987 in Manila, Philippines. She obtained her bachelor in science (BSc) in Chemical Engineering from De La Salle University - Manila, and earned her Chemical Engineering License in 2009. Lea worked in the industry until 2012 as a Wastewater Engineer Supervisor at Ibiden Philippines Inc., as a Field Service Coordinator at Emerson Electric Asia Ltd. Rosemount Analytical Division and as a Research Assistant at the Center for Sustainable Development (CeSDR) in De La Salle University - Manila. She earned her master in science (MSc) degree in Environmental Engineering from Hokkaido University in 2014, where she worked on the biological-based response evaluation of different reclamation systems using a combination of conventional bioassay and transcriptome-based analysis as test battery. Lea started a PhD Fellow at UNESCO-IHE, Delft, the Netherlands in 2014, focussing on understanding the biological anaerobic treatment process for mine wastewater for the removal of selenate and its co-contaminants. She successfully earned her PhD on the 18th December 2017, and is currently working as a post-doctoral researcher at National University of Ireland, Galway focusing on anaerobic digestion.