The synergy of catalysis and biotechnology as a tool to modulate the composition of biopolymers (polyhydroxyalkanoates) with lignocellulosic wastes

Abstract

An integrated method coupling of heterogeneous and biological catalysis has proven effective for producing biopolymers using lignocellulosic urban solid waste as feedstock. Catalysts based on cheap and earth-abundant metals, such as Fe, Mg, Ca, or Zr with basic or acid properties, were used in the pre-treatment step, and phototrophic mixed cultures were chosen for the biological step. By changing catalysts composition, reaction temperature, and catalysts loading, high performance of the catalysts was achieved under the more optimal pre-treatment of lignocellulose waste, with a solid conversion up to 86%, enriching the solid phase in the lignin polymer. The biological conversion of the liquid effluent in a photobioreactor yielded high production of PHA (up to 36 wt% on a dry basis). The characteristics of the polymer were strongly dependent on liquid feed, the composition of which depended on the type of catalysts used in the previous step. A poof of the concept of a new biorefinery design has been presented in this work, showing that it is possible to enhance the advantages of two different disciplines, heterogeneous catalysis, and photoheterotrophic biotechnology.