Wastewater treatment and disposal for the preservation of bathing and coastal water quality in touristic areas

Abstract

Copyright (c) 1997 Elsevier Science B.V. All rights reserved. The two main EU Directives related to wastewater treatment and disposal, namely EU Directive 91/271 concerning urban wastewater treatment and EU Directive 76/160 concerning the quality of bathing waters, are evaluated in the light of the experience gained in Greece, in a typical country of the Mediterranean area. Due to the high amenity value of the coastal waters, primary treatment is inadequate and seldom practiced. Biological treatment for carbon removal creates conditions for concurrent nitrification, due to the elevated temperatures, and thus serious operational problems due to uncontrolled denitrification in the final clarifiers. A nitrification-denitrification system which although not conforming to the strict effluent criteria for sensitive areas, is capable of removing a substantial part of the nutrient input, is more suitable as a typical system enabling effective control of eutrophication and smoother plant operation. The adoption of an advanced nutrient removal plant conforming to the requirements set for sensitive areas can be restricted to few cases of recipients with extremely poor hydrodynamic conditions. While eutrophication control calls for a more or less advanced treatment system, the favorable Mediterranean conditions with respect to solar radiation intensity, give the opportunity for effective control of microbial contamination of bathing waters through moderate in length and cost outfall without the need for effluent disinfection. © 1997 Elsevier Science B.V.