Waste valorization by biotechnological conversion into added value products

Abstract

Fossil fuel reserves depletion, global warming, unrelenting population growth, and costly and problematic waste recycling call for renewable resources of energy and consumer products. As an alternative to the 100 % oil economy, production processes based on biomass can be developed. Huge amounts of lignocellulosic wastes are yearly produced all around the world. They include agricultural residues, food farming wastes, "green-grocer's wastes," tree pruning residues, and organic and paper fraction of urban solid wastes. The common ways currently adopted for disposal of these wastes present environmental and economic disadvantages. As an alternative, processes for adding value to wastes producing high added products should be developed, that is the upgrading concept: adding value to wastes by production of a product with desired reproducible properties, having economic and ecological advantages. A wide range of high added value products, such as enzymes, biofuels, organic acids, biopolymers, bioelectricity, and molecules for food and pharmaceutical industries, can be obtained by upgrading solid wastes. The most recent advancements of their production by biotechnological processes are overviewed in this manuscript.

Treatment technologies for urban solid biowaste to create value products: a review with focus on low- and middle-income settings

“…Enzymatic hydrolysis is the most common pre-treatment method in ethanol production from food waste (Pham et al 2015). Recently, even source-separated urban solid biowaste including kitchen waste, food waste, garden waste and fruit waste are being considered as suitable substrates for ethanol production (Gupta and Verma 2015;Liguori et al 2013). …”

“…On the way to cost-effective and competitive bioethanol production from lignocellulosic feedstock several challenges remain, such as developing more efficient pre-treatment technologies and integrating the optimal components into ethanol production systems (Chen and Fu 2016;Liguori et al 2013). These challenges can be attributed to four aspects, which are (1) feedstock: obstacles are cost, supply and handling, (2) conversion technology: hindrances are biomass processing, proper and cost effective pretreatment technology, (3) hydrolysis process: challenge is to achieve an efficient process for depolymerization of cellulose and hemicellulose to produce fermentable monomers with high concentration, and (4) fermentation configuration: challenges involved are xylose and glucose co-fermentation, and the use of recombinant microbial strains (Mussatto et al 2010;Sarkar et al 2012).…”

Second Generation Ethanol Production from Brewers’ Spent Grain

“…A global interest in using the lignocellulosic residues and waste as source of added value bioproducts is rising due to their renewability, low cost, abundance, and non-competitiveness with food [3], boosting the development of the biorefinery concept and advancing sustainable waste management [4].…”

Concepts for further sustainable production of foods

“…More recently, by-products are considered to be useful for the production of bioenergy, either through a fermentation process (biofuels), or through direct incineration. In too many cases though, the by-products are discarded as landfill (Liguori et al, 2013). Boye and Arcand (2013) made an interesting overview of how the various by-products/waste streams could be used in a better way.…”