Industrial water treatment and industrial marine outfalls both function together to reduce the pollutant concentrations in the effluent and mitigate the potential impact on the environment. The former uses environmental treatment technology with energy and material cost considerations, while the latter utilizes the natural assimilation potential of the coastal water environment achievable at the outfall location. Because of their synergistic nature, marine outfalls are now commonly used for the disposal of partially treated domestic and industrial effluents in many coastal cities around the world, with many successful examples of low and acceptable risks to the environment. The objective of this paper is to review their balance from both environmental and economic considerations. We also discuss the end-of-the-pipe and mixing zone approaches for industrial effluents, and give some recommendations particularly for developing countries. Finally, we emphasize that a compulsory and vigorous monitoring program is essential regardless of how the balance is achieved.
