Lactic acid and xanthan gum synthesis in moving bed biofilm reactors

What is it about?

In the present study, synthesis of lactic acid and Xanthan gum from cheese whey permeate in moving bed biofilm reactors has been analyzed. Cheese whey is the mother liquor left behind after the separation of fats (casein) from milk and is often discharged as a waste effluent. Lactic acid synthesis is a two phase process, while Xanthan gum synthesis involves a three phase (gas – liquid – solid) system. Lactic acid is the starting material (monomer) for the synthesis of the popular bioplastic, PLLA(Poly laevo lactic acid). Xanthan gum is widely used as an emulsifying and stabilizing agent in many food and dairy industries.

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Why is it important?

The performance characteristics of moving-bed biofilm reactors (MBBRs) have been analyzed both mathematically and experimentally. Both two phase operation (lactic acid synthesis from cheese-whey permeate) and three phase operation (Xanthan gum production) in both batch and continuous flow reactors have been studied. Mathematical simulation has been performed considering the heterogeneous nature of the system with appropriately defined effectiveness factor being incorporated to account for resistance to substrate transfer into biofilm.The flow reactors are modeled based on the tanks-in-series approach. The mathematical models (software packages) developed have been adequately verified by comparing with experimental data. The interesting performance features of these reactors have been highlighted and the dependence of reactor performance on key system / operating parameters such as batch time / space time, catalyst loading and catalyst size has been well – illustrated. The limitation that these bioreactors are best suited mainly for small capacity installations has also been indicated.

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