A discussion of the treatment of wastewaters from petroleum refineries, coal gasification plants, and shale oil processes showed that a process should: remove pollutants at minimum cost; recover valuable by- or co-products; have low demand for capital investment and opportunity cost; and not create secondary wastes which can cause low usage environmental deterioration. The latter point has received the least consideration, e.g., the disposal of spent absorbents (carbon) and coagulents (lime). Biological treatment is attractive due to its low operation cost. The inability of a process to remove organics completely may be due to: the toxicity of highly polar constituents; the detergent-like character of some constituents; the inability of mild methods to decompose refractory substrates; and the fact that the metabolic products are large molecular clusters.