ABSTRACT
It is clear from the material presented in the preceding chapters that our ability to design bioreactors for oxidation of biogenic organic matter, nitrification, and denitrification is well established. Furthermore, our understanding of biological phosphorus removal is advancing rapidly, leading to better models which will result in improved design procedures. Less well established, however, is our ability to design biological treatment systems for the biodegradation of xenobiotic organic chemicals (XOCs). The term xenobiotic means "foreign to the biosphere" and xenobiotic chemicals are those that have been produced by humankind through our chemical industry. While there is no question that the modern chemical industry has had a large beneficial effect on society, there have also been negative effects associated with the release of XOCs to the environment. One job of the environmental engineer is to minimize those negative effects and keep them at acceptable levels through effective destruction of chemical residues. Biological treatment systems are important tools in that effort. Consequently, in this chapter we will explore some of the factors that must be considered when applying biological treatment systems for the destruction of water-borne XOCs.
