Case Studies On Synthesis Of PLLA Bioplastic Starting From Food And Agricultural Wastes

C. M. Narayanan

Abstract


Polylaevo Lactic Acid (PLLA) is an excellent biopolymer that is biodegradable and has characteristics exactly similar to polystyrene. However, at present, the market price of this biopolymer is significantly higher than polystyrene and other synthetic plastics. The major hindrances to the large scale manufacture of this polymer are the lack of availability of a cheap raw material and the overall economy of synthesis of lactic acid from the same. In this paper, the solutions to the above two bottlenecks are discussed based on the successful industrial projects handled by the author. The two recommended raw materials for the synthesis of PLLA are (1) cheese whey and (2) molasses. Both are discharged as waste effluents by industries, the former by dairy farms and milk processing units and the latter by sugar manufacturing units. In the case of cheese whey, it has to be first freed from proteins by ultrafiltration. A novel design of tubular ultrafiltration module developed by the author, that employs variable area tubes, provides much higher permeation rate and enhanced solute rejection. The protein concentrate obtained is of food grade and thus forms a valuable byproduct of the process. The cheese whey permeate/molasses is fermented to produce lactic acid in a continuous fluidized bed biofilm reactor, the former using a culture of Lactobacillus helveticus and the latter Enterococcus faecalis. The performance of the bioreactor has been simulated mathematically and a multi-parameter CAD (software) package has been developed. The package has been tested and verified using elaborate experimental data (collected both on laboratory scale as well as on pilot plant scale). Direct industrial adaptation of the developed CAD software can be thus recommended with confidence. Based on the above innovations, lactic acid can be economically synthesized on commercial scale starting from low cost natural materials and this would make industrial production of a biodegradable plastic such as PLLA substantially cost effective.

Keywords: Bioplastics, PLLA, cheese whey, molasses, ultrafiltration, diverging-converging tubes, fluidized bed biofilm reactor, lactic acid synthesis, CAD software

Full Text:

PDF

References


REFERENCES

Stevans E.S. Green Plastics: An Introduction to the New Science of Biodegradable Plastics. New York, Princeton University Press; 2001.

Narayanan C.M. Performance Analysis of Constricted Tube Ultrafiltration Unit for the Production of Food – grade Protein Concentrates from Food Wastes. Journal of Chemical Engineering and Material Science. 2011; 2(9), 149–55p.

Anjana D.N. and Kumar S. Kinetic modeling of lactic acid production from molasses using Enterococcus faecalis RKY1. Biochemical Engineering Journal. 2008; 3(38): 277 –84p. doi:10.1016/j.bej.2007.07.014

Schepers A.W., Thibault J., Lacroix, C. Lactobacillus helveticus growth and lactic acid production during pH-controlled batch cultures in whey permeate/yeast extract medium. Part I. multiple factor kinetic analysis. Enzyme and Microbial Technology. 2002; 30(2): 176–86p. doi:10.1016/S0141-0229(01)00465-3

Gottifredi J.C. and Gonzo E.E. Approximate expression for the effectiveness factor estimation and a simple numerical method for concentration profile calculation in porous catalyst. Chemical Engineering Journal. 2005; 109 (1-3): 83–7p. doi:10.1016/j.cej.2005.03.012

Wen C.Y. and Yu Y.H. A generalized method for predicting the minimum fluidization velocity. AIChE Journal. 1996; 12(3): 610–2p. doi:10.1002/aic.690120343

Narayanan C.M. and Bhattacharya B.C. Mechanical Operations for Chemical Engineers. III Edn. New Delhi: Khanna Publishers; 1998.

Al – Dibouni M.R. and Garside J. Particle mixing and classification in liquid fluidized beds. Transactions of Institution of Chemical Engineers. 1979; 57: 94p.

Narayanan C. M. Cost–effective Synthesis of PLLA Bioplastic, Keynote Lecture. International Conference on Natural Products and Biomaterials. Kottayam, India. 2012 Oct 26–28.

Narayanan C. M., Basak A., Saha A. et al. Studies on Performance Characteristics of Diverging – Converging Fluidized Bed Biofilm Reactor with Special Reference to Lactic Acid Synthesis from Molasses and Cheese Whey. International Reviews of Chemical Engineering. 2014; 6(4): 142–52p.


Refbacks

  • There are currently no refbacks.