In my previous post ( http://wp.me/p7I0V6-1j ), I covered the first on three main types of contamination. I will continue with number 2 in this post.
2. Dead spots in the process loop. This is a very common problem with fermentors and other vessels of similar design. It can also affect other process equipment as well, like ultrafiltration skids, etc. In all cases, areas of slow or no movement can be areas where contamination will build up. An example is a 100 liter sterilized in place fermentor I was working on. The agitation was from the bottom and had a live steam seal (steam is needed to keep the seal in place). Well, there were some small grooves in this seal and the seal (made if high temperature rubber) acted as insulation. This allowed some material to build up and and cause partial contamination of some broths I was working on. Eventually, I talked to the equipment manufacturer who came up with a new seal design and installed it.
It is important if there is contamination, even a small amount, to evaluate all equipment to discern where it comes from.
In part 3, I will talk about cleaning procedures.
David Slomczynski, Ph.D; Geometrick Enterprises