Thursday, April 22, 2010 - 3:30 PM
12-05

Membrane based down stream processing of lactic acid fermentation broth

Joachim Venus, Bioengineering, Leibniz-Institute for Agricultural Engineering Potsdam-Bornim, Max-Eyth-Allee 100, Potsdam, D-14469, Germany

Lactic acid, its salts and esters have a wide range of potential uses and are extensively used in diverse fields. Originally, lactic acid was produced from pure starch or from glucose. Increasingly, however, renewable resources such as grains and green biomass are also being used as raw materials for the production of microbial lactic acid. A high-productivity lactic acid bacterium strain was selected, process parameters were optimized for the fermentation on a laboratory scale, and its lactate productivity at cultivation on several substrates was examined up to the pilot scale [1]. The strain is able to accumulate more than 100 g of lactic acid per litre in the medium and the yield of lactic acid can be higher than 90%. The objective was to test the suitability of alternative feedstocks for use as raw materials in lactic acid fermentation. According to the intention to substitute expensive nutrient supplements by cheeper materials from renewable resources there were tested several materials for the cultivation of lactic acid bacteria.

Exploitation of high quality lactic acid for the production of biodegradable polymers is one of the recent applications. Conventional processes for down-streaming are based on precipitation steps that generate large amounts of chemical effluents. Consequently the environmental impact and the operating costs of traditional processes can be reduced by using alternative technologies, such as electrodialysis with monopolar and bipolar membranes. Desalination, purification and concentration of sodium lactate after fermentation are possible by conventional electrodialysis and the concentrated sodium lactate can be converted into lactic acid and cleaned further by means of water-splitting electrodialysis with bipolar membranes.

[1]        Venus, J.; Richter, K. (2007) Development of a Pilot Plant Facility for the Conversion of Renewables in Biotechnological Processes. Eng. Life Sci. 7(4) 395-402


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