Economic, Regulatory and Social Aspects Related to Wastewater Ocean Disposal through Submarine Outfalls

• Main Author: Menahem Libhaber
• Format: Article
• Language: English
• Published: Companhia de Saneamento Básico do Estado de São Paulo S.A (SABESP) 2016-10-01
• Series: Revista DAE
• Subjects: submarine outfalls; marine wastewater outfalls; wastewater treatment
• Online Access: http://revistadae.com.br/artigos/artigo_edicao_204_n_1648.pdf

The receiving body of wastewater and effluents of coastal cities is, in most cases, the ocean or the sea. For the most part, two wastewater management strategies are applied in coastal cities: (i) provision of secondary level wastewater treatment followed by effluent discharge to the sea via a short submarine outfall; and (ii) provision of preliminary level wastewater treatment followed by effluent discharge to the sea via an effective submarine outfall. A comparison between the two strategies is presented in the article, leading to a conclusion that Strategy (ii) of preliminary treatment followed by an effective outfall is economically, environmentally and socially superior. A preliminary treatment plant followed by an effective outfall is simple to operate and presents a low public health risk and a low level of negative environmental impacts. Many outfalls systems of this type are successfully functioning and have a proven track record in many coastal cities all over the world. For developing countries it is the essential solution since such countries cannot afford executing high investments in complex and unnecessary wastewater treatment plants. This strategy should be coupled with a sea water quality monitoring program beginning prior to and continuing after the construction of the outfall system, to verify the performance of the system and to determine if a higher than preliminary treatment level is necessary. This is a logical approach which prevents costly investments in unnecessary treatment installations.