Plastic pollution is one of the biggest environmental problems of our time, which is why there is a growing need for the production of biodegradable polymers, including polylactic acid. The purpose of the thesis is to review the various options for obtaining lactic acid from 2nd generation biomass (industrial and agricultural waste) and its polymerization into polylactic acid through all four steps (raw material pretreatment, fermentation, lactic acid purification, polymerization). Substrate pretreatment is of key importance for facilitating easier saccharification, especially in the case of lignocellulosic waste. Fermentation is carried out with bacteria or fungi, with process parameters (pH, temperature, aeration, inhibitors) varying depending on the organism and substrate. Various techniques are used in the purification of lactic acid, such as crystallization-acidolysis and reactive extraction. The purification process is carried out in several steps, which results in lower extraction yields. The polymerization of lactic acid is carried out by direct polymerization, azeotropic dehydration or the lactide ring-opening method, the latter of which yields the highest quality polymer but is the most energy-intensive. Future developments in polylactic acid production aim to improve the efficiency of the lactic acid purification process and the use of organisms (natural or genetically modified) that would have a lower nutrient requirement, the possibility of homofermentatively utilizing both hexoses and pentoses, and greater resistance to harsh industrial conditions (high temperature, low pH, inhibitors). This would make polylactic acid production more economically competitive and sustainable.
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