Sustainable process ing ha s attracted recently an increasing interest in the process systems engineering literature. From a practical perspective , addressing sustainability inevitably require s a Multi - Objective analysis and optimization to evaluate the environmental impact in additi on to the economic performance. Bio - based process es are typically used in order to promote sustainability, although the quality of the bio - mass us ually is variable and present an uncertainty behavior . However, the approaches presented so far to address mul ti objective problems under uncertainty have focused on simplifying the optimiz ation model reducing the set of feasible choices and neglecting the potential effects of quality variations streams on the overall system performance . We present here an altern ative approach based on the State Task Network formulation capable to address M ulti - O bjective Optimization problems under uncertain conditions, which includes the material quality effect, all together. The resulting set of solutions are then assessed using ELECTRE IV method, which identif ies the ones showing better overall performance within the uncertain parameters space