ABSTRACT
Annoying odors in the vicinity of sewage-treatment plants has long been a recognized problem. Land adjoining these sites may become subdivided and subsequently developed for industrial and residential purposes. This is especially true in metropolitan areas where land is markedly scarce. Odors from domestic wastewater usually result from some sort of biological activity in the sewer collection system and wastewater-treatment plants. Gases that generally arise from domestic sewage are inorganic. Sewage containing industrial wastes may have odor problems compounded by organic gases from any waste chemicals added to the sewer system. Fresh domestic sewage containing dissolved oxygen has a slight odor, which is usually described as musty. Natural aerobic breakdown of the sewage, whether it occurs in a sewer system or wastewater-treatment plant, depletes the DO. Of course, in a wastewater-treatment plant the DO is being replaced by mechanical means.
