MICROALGAE-MEDIATED REMOVAL OF WATERBORNE PATHOGENS FOR WASTEWATER DISINFECTION

Abstract

Contaminated water presents an alarming global concern, with a high prevalence of pathogens in the treated or disinfected water. Amidst the global challenges of water pollution and waterborne diseases, microalgal technology has emerged as a viable alternative for wastewater treatment. The ability of microalgae to remove pathogens from wastewater has been recently brought to the limelight. However, the microalgae-mediated pathogen removal (MAPR) process is still underexplored. The present thesis entails an exhaustive analysis of MAPR, including optimization of key process parameters and bioprospecting microalgal strains for MAPR efficiency. Subsequently, an in-depth analysis has been conducted for each plausible pathogen removal mechanism in MAPR followed by reactor-scale validation studies. Finally, life cycle assessment (LCA) and quantitative microbial risk assessment (QMRA) have been employed to conduct a combined enviro-microbial assessment of MAPR. The Chlorella pyrenoidosa-mediated Escherichia coli removal from municipal wastewater was considered as the model MAPR system. A multivariate optimization technique was employed to obtain optimal MAPR conditions for maximum pathogen removal efficiency. A significantly high removal efficiency of 99.98% was obtained for C. pyrenoidosa-mediated E. coli removal under high illumination (18000 lux) and 37℃. Thereafter, a comparative MAPR demonstrated that C. pyrenoidosa was the most robust microalgal strain with efficient E. coli removal rates and beneficial biochemical characteristics. The C. pyrenoidosa-based MAPR was validated with real sewage samples whereby the microalgal process demonstrated 98% total bacteria removal, 98% Enterobacteriaceae removal, and complete removal of Salmonella sp. Along with efficient pathogen removal, the sewage-cultivated MAPR biomass demonstrated a high abundance of beneficial biomolecules, thus providing opportunities for resource recovery.