Ocean Disposal of Wastewater

The ocean has for all time been the ultimate sink for water-borne waste products coming from the land. Rivers and small creeks have always carried silt into the ocean and since the development of agriculture the products of the runoff from cultivated and pastoral land have gone via the rivers into the ocean. More recently the waste from urban and industrial communities has been disposed of in the ocean. This effluent, which is a very dilute mixture of human and other waste, is normally collected in a pipe system which carries it to a central location. After treatment, the effluent is discharged into the ocean. The disposal is carried out by constructing a pipeline on the bed of the ocean with a diffuser (Figure 1.1) or with a tunnel, risers and appropriate diffusers (Figure 1.2). The effluent, which has a density close to that of fresh water, rises to the surface and in doing so entrains the surrounding salt water and becomes very dilute …