Production of Lactic Acid from Wastepaper as a Cellulosic Feedstock

Lactic acid promises to be an important commodity chemical in the future as a monomer for the production of biodegradable polylactic acid (PLA). As the demand for lactic acid increases, the need to explore alternative feedstock sources and process options that are inexpensive and efficient is bound to gain importance. This document reports the results of a study of the production of lactic acidfrom wastepaper as a representative cellulosic feedstock, using a batch, bench-scale simultaneous saccharification and fermentation (SSF) process. The effect on process performance of operating parameters such as pH, temperature, enzyme loading, solids concentration, and enzyme preparation has been examined. A lactic acid product yield of 84% of theoretical was achieved at a solids loading of5%, using 25 filter paper units (FPU) of cellulase per gram of cellulose, at 45 .deg.C and pH 5.0. The pH and temperature of operation have been selected to achieve good performance of both the cellulase and the microorganism in the SSF process. Our studies show that a feedstock such as wastepaper offers considerable promise and opportunity in the future for development of a biomass-basedprocess for lactic acid production.