Biologically clarified waste water - applied directly to an agriculturally used surface rather than into pre-flooding tanks

摘要

Biologically clarified water which contains fertiliser salts such as phosphates and nitrates is directed onto surfaces used in agriculture rather than into a pre-flooding tank. It acts both as irrigation and as fertiliser and this avoids aquatic plant growth in the water which reduces its oxygen content. In this way sewage fields, previously used for filtering mechanically clarified water can be brought back into use.