Mariana Reis
Universidade Nova de Lisboa, Portugal
Title: Acidogenic valorisation of food industry wastes for polyhydroxyalkanoate (PHA) biosynthesis
Biography
Biography: Mariana Reis
Abstract
A high variety of wastes/wastewater/surplus products from food industry are a promising source of organic matter (e.g. sugars) that can be valorised through biotechnological processes. Anaerobic acidogenesis converts these feedstocks into fermentation products (FP) with multiple applications, among which the production of polyhydroxyalcanoates (PHA) by mixed microbial cultures. The aim of this study was to examine acidogenic fermentation of twelve industrial wastes (including wastes or by-products of fruit, wine, beer and oil industries) for their potential as substrates for PHA production to be used in food packaging. It is known that the profile of FP highly affect the properties of subsequently produced PHA, namely the proportion of HB (acetate, butyrate and ethanol):HV (propionate, valerate, lactate) precursors. The physico-chemical characteristics of the feedstocks (organic matter, sugars, nutrients and solids) were analysed, and batch tests were carried out to assess their acidogenesis potential. Based on these results and on estimated availability, seasonability and cost of each waste, the most promising feedstock (fruit processing waste) was further investigated. The latter studies were carried out in a continuous stirred tank reactor inoculated with sludge from a full scale anaerobic digester, to determine the operating conditions that maximise productivity and enable the manipulation of the FP profile. The FP stream was fed to a reactor containing a PHA accumulating mixed culture. The polymer produced was offline and online analyzed in terms of monomeric composition and physical/thermal properties determined. This study demonstrated that fruit pulp waste is a valuable feedstock for acidogenic fermentation, and that controlling the acidogenic reactor operational conditions (pH, OLR, HRT) it is possible to manipulate the acidogenic fermentation products in order to produce an appropriate proportion of HB/HV precursors for food packing applications.