Disposal of effluents into the ocean

OCEAN DISPOSAL OF WASTEWATER

• The ocean has been the ultimate sink for water-borne waste products coming from the land.
• Waste from urban and industrial communities has been disposed off in the ocean.
• The effluent which is a very dilute mixture of human and other waste is collected in a pipe system and carried 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.
• The effluent that has a density close to that of fresh water, rises to the surface and entrains the surrounding salt water in the process. Hence surrounding salt water and becomes very dilute
• Of the total pollution of marine water, disposal by land or land based discharge amounts to 44%.
• Using oceans to dispose effluents is an example of dilute-and-disperse philosophy of waste disposal
• Ocean dumping is a small but potentially growing part of the overall ocean pollution picture
• Oceans will ultimately provide the most environmentally acceptable repository for limited types of man generated waste at specific sites and under specific conditions
• A marine outfall is a pipeline that discharges industrial or municipal wastewater, stormwater, combined sewer overflows, cooling water or brine effluents from water desalination plants into the ocean. Usually this is under the water surface (submarine outfall).
• In order to successfully dispose effluents into the ocean, the water quality should meet the objectives and requirements set by regulatory authorities
• The environmental (physical, chemical and biological) data of the proposed site should be collected for atleast one year. This describes the undisturbed pre-discharge condition and defines the environment in which plume mixing and dispersion occur.
• Plume behaviour is strongly affected by density stratification and currents
• Structural engineering design requires a detailed bathymetric map, information on the wave environment and geotechnical investigation of foundation conditions.
• Effluent quality is determined by degree of treatment. Buoyancy of the effluent relative to sea water is important to dynamics of the plume.
• Disposal of effluents will have some effects which depend on system design.
• The effects of ocean disposal of effluents will be muich less than the effects of other possible engineering solutions of effluent disposal to land or inland water bodies.