Conventionally lactic acid is produced from the starch and sugar sources which not only make the process expensive but also deplete the food reserves. On the other hand lactic acid can be produced at low cost using paper sludge as it is rich in cellulosic content and also does not require any pretreatment. The optimum temperature for the cellulase enzyme is around 50ºC and only thermophiles can sustain at that temperature. The use of thermophilic bacteria in Simultaneous Saccharification and Fermentation (SSF) along with the cellulase enzyme helps in increasing the yield of lactic acid.

Three thermophilic bacterial strains have been screened for their ability to produce lactic acid from the paper sludge by utilizing both cellulose and xylose. Two out of the three have given promising results. The conditions such as temperature and pH will be optimized in the further experiments so as to increase the lactic acid yield. Also the cellulase loading will be optimized. The complex media and the mineral media will be used for growing the cultures and also for fermentations and the results will be compared. Acetic acid and ethanol yields will also be monitored to see the selectivity of the strains in producing lactic acid. Finally batch and semi continuous methods will be compared for the lactic acid yield.