SEPTIC TANK

摘要

PROBLEM TO BE SOLVED: To miniaturize a septic tank and to inexpensively and stably supply and stop air if needed with simple constitution. SOLUTION: In the septic tank where air is branched and supplied to a plurality of tanks 1 and 2, an air supply pipe 1a is arranged in the tank 1 where the depth of water changes. A relief pipe R changing the supply of air to the air supply pipe 1a to the other tank 2 when the depth of water becomes not less than maximum one is arranged.