Lactic acid for poly-lactate is requested to guarantee not only quite high optical purity but also its quite high purity as lactic acid. In lactic acid fermentation, any higher class purification technology to yield pure lactic acid is required because the fermentation broth contains a variety of compositions. Usually distillation technology is adopted for this purpose: In the purification of lactic acid from fermented kitchen garbage, butyl-lactate is separated by distillation after esterification of lactic acid with butanol. Moreover, ammonia can be recovered in the estirification reaction, which can be again used for pH adjustment in the fermentation. However, in this process more energy would be required to remove water to encourage the esterification reaction. When the energy would be supplied from fossil resources, it is neither ecologically nor economically suitable. Utilization of unused heat energy form incinerators should be an acceptable solution.

Further information

Morichi, T. Physiology and metabolism of lactic acid bacteria: Biseibutsu 6(1), 27-34 (1990) (in Japanese) Sakai, K.; Murata, Y.; Yamazumi, H.; Tau, Y.; Mori, M.; Moriguchi M.; Shirai, Y. Selective proliferation of lactic acid bacteria and accumulation of lactic acid during open fermentation of kitchen refuse with intermittent pH adjustment: Food Science and Technology Research, 6, 140-145 (2000)

Hassan, M. A.; Nawata, O.; Shirai, Y.; Nor’Aini A. R.; Phang L. Y.; Ariff, B. A.; Abdul Karim, M. I. A Proposal for Zero Emission from Palm Oil Industry Incorporating the Production of Polyhydroxyalkanoates from Palm Oil Mill Effluent: Journal of Chemical Engineering of Japan, 35 (1) 9-14 (2002)

Sakai, K.; Taniguchi, M.; Miura, S.; Ohara, H.; Matsumoto, T.; Shirai, Y. Novel process of poly-L-lactate production from municipal food waste: Journal of Industrial Ecology, 7(3, 4), 63-74 (2004)

Mori, T.; Kosugi, A.; Murata, Y.; Tanaka, R.; Magara, K. Ethanol and Lactic Acid Production from Oil Palm Trunk: Proceedings of Annual meeting of the Japan Institute of Energy, 16, 196-197 (2007) (in Japanese)