Process Flow Diagram showing Major Equipment

dfdf Above is the process flow diagram that will be used in our production of PLA from whey.

Our whey will begin in a storage tank. While it is in the pipes being transferred to a fermenter, it will be heated to 110*C in order to kill all harmful bacteria. The solution will then sit in a fed-batch reactor fermenter for 14 hours a day, 365 days a year, using Lactobacillus helveticus as the lactic acid producing bacteria.

Once the fermentation process is complete, the lactic acid will be nano-filtered using a membrane to separate the lactic acid from the other byproducts in the solution. From the nanofilter, the lactic acid will be transfered to a storage tank until it is needed for bipolar electrodialysis.

From the electrodialysis, the whey will go through a two step evaporation system. Crude lactic acid is fed into the first evaporator which will remove water vapor. This water vapor will be collected and recycled to aid health in bacteria. The lactic acid of ~90% purity is collected and passed through a second evaporator to remove any pre-polymer formations. THis will concentrate the lactic acid to ~ 98%.

The collected purified lactic acid is then fed into a lactide reactor where there is an addition of Tin 2-ethylhexanoate, Sn(Oct)2 catalyst, and heat. This will be allowed to reactor for 2-5 hours. Two streams will then be output from this reactor: un-reacted impurities collected in the bottom stream and discarded, and vaporized lactides collected in top stream and sent through a partial condenser.

The distillation system has three streams: Stream one (tops): low boiling point distillate which is recycled to the lactide reactor, stream two (side stream): Lactide of 75-95% purity, and stream three (bottoms): high boiling point solids which will be discarded.

From the distillation, the lactides from stream 2 will flow to the polymer reactor. In this reaction there will be an addition of Tin 2-ethylhexanoate, Sn(Oct)2, catalyst, and heat (140-180*C). This reaction will take place for 2-5 hours to produce a projected amount of 50,000,000 lbs of polylactides.