Abstract :
Waste-water treatment plants are the “frontier guards” of the technosphere [Part I], where unwanted chemicals contained in the waste water streams can and should be retained. Beyond these points, chemicals are released into the environment and out of control by man. Many lipophilic chemicals are enriched in the sewage sludge, which contains a high amount of organic carbon, and the persistent ones remain there. Sewage sludge, in one respect, is a valuable fertilizer and should be used as such. However, if it is contaminated with toxic and persistent chemicals [Part II], agricultural use would mean that the pollutants are dispersed again and enter into the environment via the surface of the soils and may eventually enter into the food chain. Polar persistent compounds, which are less strongly adsorbed in the soil, may reach the aquifer and thus pollute the ground water.
