Production of Bio-ethylene From Wastes of Microalgae to Biodiesel Biorefinery

This work shows the valorization of marine microalgae protein wastes (MMPW), generated from biodiesel production, by obtaining a substrate that can be metabolized for ethylene production. MMPW were hydrolyzed with H 2 SO 4 diluted to get both sugars and amino acids. This hydrolyzate was adapted for the growth of Pseudomonas savastanoi pv. glycinea . Reducing sugars, soluble protein, elemental analysis and gross analysis allowed determining the critical carbon-to-nitrogen ratio, which are associated to maximum specific growth rate, µ max . A chemically defined medium (CDM) was designed and optimized by using the collected information from fifty-two fermentations with different glucose, glutamate, NaCl, ferrous sulphate, minerals and stirring rotational speed. It was obtained a function that relates the carbon to nitrogen ratio with µ max for ethylene production. For C/N = 1.25, ethylene production and µ max were 15 µmol ethylene per Dry Cell Weight (DCW), and 0.151 h −1 , respectively. However, when the C/N ratio increased to 28, these values were 140 µmol ethylene g DCW −1 and 0.421 h −1 . The methodology proposed in this work will permit to design and evaluate others substrates of raw waste biomass for the production of ethylene.