Agro-industrial Wastes: Environmental Toxicology, Risks, and Biological Treatment Approaches

The great challenge for agro-industries, the “green chemistry” market, and related areas in recent years is to find viable alternatives to reduce dependence on the use of fossil fuels and traditional chemical solvents in energy production. These can have negative effects on human and environment health, combined with insecurity due to their high potential for flammability, volatility, and toxicity. As a solution, natural origin sources have become a scientific and industrial trend in biofuel generation. Lignocellulosic biomass, which includes solid organic waste consisting mainly of cellulose, hemicellulose, and lignin (LiP) and liquid waste composed of organic matter and suspended solids, is an economically viable alternative, since it comes from natural and renewable sources. Besides that, when used as raw material, it promotes a significant reduction in the production process final cost; and it conforms to sustainable development. However, cellulosic content pretreatment is necessary, mainly to break the lignin chemical structure and to remove other recalcitrant components. Biological treatment, specifically with white rot fungi (WRF), emerges as an excellent technology in organic product degradation, mainly to those which resist conventional treatment. They have a nonspecific and oxidative ligninolytic enzyme system, composed of the enzymes laccase (Lac) and manganese peroxidase (MnP), which are able to convert bioavailable polysaccharides in the vegetal wall structure (cellulose and hemicellulose) into sugars of easy assimilation and promote degradation of various agroindustrial wastes and effluents. In addition, toxicity is importantly addressed by new scientific, industrial, and political strategies which assist in the evaluation of these wastes’ toxic interactions and their consequences that affect the ecosystem water bodies. In this context, this chapter focuses mainly on several aspects of biological treatment with white rot fungi and their ligninolytic enzyme production as a sustainable technology to degrade agro-industrial residues and components of lignocellulosic biomass into products with high added value. As well, it aims to study the eco-toxicity to estimate maximum permissible levels of toxic compounds. In general, this new approach is an alternative method for obtaining technological products and processes that enable the improvement of industrial sustainability through the use of ecologically renewable inputs, as well as reducing costs and increasing process efficiency.