Laccase (EC 1.10.3.2), a biogenic catalyst of many oxidative reactions, has been previously identified to mitigate the risks to human health linked to the presence of phenolic contaminants at sub-nanomolar concentrations in water resources. Operational performance and cost-effectiveness of biocatalytic processes are key aspects for successful applications, although they have been overlooked in environmental biocatalysis. The thesis objectives were i) to delineate important features for the scalability of environmental biocatalytic processes, ii) to define a methodology for laccase insolubilization, iii) to decipher immobilized laccase activity and stability toward pollutant removal and iv) to assess the process economic viability. Multivariate analysis and modeling were effective in identifying Pareto-optimal formulation of laccase immobilized on mesoporous silica. High catalytic rates of immobilized laccase at low pollutant concentrations were obtained in a continuous flow packed-bed reactor given the observed reaction order. The reactor conversion rate increased in pollutant mixtures due to radical-mediated oxidations. Internal mass transfer limitations were found to control the conversion rate of weak acids but also to change inactivation kinetics in denaturing as well as operational conditions, conferring apparent stability to the biocatalysts. Although stable in wastewater, immobilized laccase was prone to a turnover- and substrate-dependent inactivation mechanism. Given the process performance, a laccase-based water treatment could be economically competitive in the industrial water market if fungal laccase price falls thanks to recent advances in heterologous laccase production. (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2014