| 摘要 |
<p>PROBLEM TO BE SOLVED: To control additional facilities for purifying river water by a method in which after nutrients being removed by algae on the surface of pebbles, and river water is collected in a catchment part formed in the lower part of a screen and discharged downstream through a siphon part which allow the catchment part to communicate with the downstream place of a weir. SOLUTION: When multistage facilities for purifying a river are arranged at intervals in the upstream and downstream directions, in respective places, river water W is retained by a weir 1. By microorganisms such as algae adherent to a pebble layer 3, organic substances and nutritious salts of phosphorus, nitrogen, and others contained in the river water W are removed, and the purified river water W descends, after algae and others being filtered by the pebble layer 3, and collected in a catchment part 4 through a screen 2. The water stored in the catchment part 4 overflows from a downstream side opening 5a through a siphon part 5 to flow downstream.</p> |
