Environmental impacts of an HMEZS biorefinery

Abstract

The life cycle analysis (LCA) of a six-stage biorefinery (BRF) called HMEZS-NN (hydrogen, methane, acids, solvents, enzymes, saccharified and nanobioparticles), which processes the organic fraction of municipal solid waste to obtain bioenergy and value-added products (concentrated organic acids and solvents, cellulolytic and xylanolytic enzymes, and nanobioparticles) for the water remediation industry, was carried out. The 18 intermediate point impact categories were analyzed with the 2016 hierarchical ReCiPe method. It was found that the BRF is self-sufficient in total energy, in an amount close to 600 MJ that consists entirely of high and low voltage electrical energy,but it has a 37 % deficit in the heat category. With an ad hoc sensitivity analy-sis, it was found that by raising the value of the fraction of fermented solids generated by the bioreactor H destined for the methanogenic bioreactor M from 40 to 54.12 %, it could be self-sufficient in heat and generate a very significant surplus of electrical energy. The stages that contributed significantly to several midpoint impact categories were the Z and NN stages and various processes nested within them. Less frequently, and acting on specific categories, stages M (in global warming, for example), H, and E (extraction of organic acids, essential in stratospheric ozone deterioration) were placed. In the various categories of ecotoxicity, a marked trend was noted for Z and NN predominant contribution. Almost all processes related to the purification of residues from the production of phosphoric acid and various processes for treating mining waste, coal, ash, and tailings are non-explicit.