ABSTRACT

This chapter deals with the nature of wastewater treatment. As the function of wastewater treatment processes is to prevent or minimise the adverse effects of sewage effluent on natural waters. The chapter addresses how natural waters are impaired when untreated sewage is discharged into them. It explains the nature of sewage treatment works and summarizes their environmental effects. The chapter discusses the current state of sewage treatment in both countries and also deals with the water quality in the United Kingdom and Germany. The chemical and biological composition of wastewaters depend upon the emitters in the catchment area and vary dramatically from site to site. The chapter focuses mainly upon municipal sewage works that, in most cases, treat sewage which is about 99.9 per cent water and 0.1 per cent impurities. Natural waters have a limited capacity to cope with sewage pollution and to purify themselves.