In all developed countries, large quantities of agricultural, industrial and municipal wastes are generated. Land application of wastes as a means of disposal, also nutrient recycling and water conservation are becoming increasingly popular. A major attraction of landfill disposal has been its low cost. The 1972 London Dumping Convention specifies the ban of sea dumping of certain hazardous wastes unless it is proven that the hazardous substance is in trace amounts and would be harmless in the sea. In the EU, discharge of untreated sewage to sea will be phased out in the next few years, except in special circumstances. The management of waste application on land is a challenging task and requires rigorous scientific input. Sludges and effluents contain significant concentrations of metals, also plant nutrients, particularly nitrogen, phosphorus and organic matter. Land application of wastes is becoming more widespread as regulatory authorities move to protect water quality by restricting waste disposal into rivers, lakes and the marine environment.