Sewage Sludge Disposal in the North Sea

Abstract

The treatment of sewage leads to final products which cannot be reduced or eliminated by process changes at source. Throughout the ages, sewage has caused injury to health and aesthetic offence but in the modern world these problems are managed in three ways. Firstly by excluding sewage from the human environment (e.g. by development of sanitary engineering and sewerage), secondly by treatment to reduce its deleterious properties and thirdly by disposal of the raw or treated materials so as to avoid public health and aesthetic impact and, preferably to make use of natural processes to further “treat” the materials, which is largely effected by processes of decay. Disposal of sludge to land may also permit a benefit to be gained from the fertilising content of the material. The problems of sewage and sludge disposal have been exacerbated since the nineteenth century by diverting industrial aqueous wastes to the treatment facilities used for human sewage, which although permitting effective treatment of their degradable components, increases the contamination of sewage by persistent and/or toxic materials. This paper examines the options available for disposal of sludge from sewage treatment in North Sea bordering countries, the use made of marine disposal, and assessment of the factors involved in controlling the use of this option without unacceptable environment detriment.