18. Contamination and Clean Surface of Materials

In this chapter, contamination on material surfaces is discussed from the viewpoint of the relationship between bacterial activity and contaminants. Contamination can be divided into three main groups: water soluble, oil-based, and solid contamination. However, in any of these cases, contaminants are completely inanimate substances. The bonding of the contaminants with material surfaces is not usually strong so the contaminants can be easily removed. When bacteria are attached to material surfaces, they grow, and then biofilm tends to form on these surfaces. Exopolymeric substances (EPS) in the biofilm are very sticky and make the contaminants stick to material surfaces. Some practical problems following the adhesion are predicted, introduced, and explained in this chapter. Also included is a concrete example that one of the authors investigated in a national project for Japan.