Sewage: Towards Realistic Environmental Protection

The disposal of sewage into aquatic systems is attracting increasing regulation at the European Community level. Initially, pollution control strategies focussed on the protection of rivers and inland waters from excessive oxygen demand loading. This has led to an increasing use of marine waters for the disposal of sewage effluents and sludges. The bacteriological hazards associated with these practices are now well understood and have led in turn to restrictions on such disposal activities. This problem is illustrated with data from Venice Lagoon showing extreme bacterial contamination. A less commonly appreciated problem relates to the chemical contamination of sewage from both household and industrial chemicals. Results from analyses of a variety of sewage effluents are presented in this paper and the implications of the inventory of chemicals found are discussed.