Simultaneous mass transfer with biochemical and chemical reactions is a complex subject, particular with the need to develop a clear-cut method in engineering design where these processes occur. This book provides such an approach to develop an applicable design. All known design approaches are carefully examined and compared, with emphasis on the advantages and disadvantages in the selection of design methods. This involves carefully stating, comparing and assessing the theoretical basis of each design model. Carefully developed Existence and Uniqueness Theorems for the general design model are developed and established; step-by-step design guidelines provided.