Biological treatment of waste water

摘要

A method for biologically purifiying waste water which produces substantially no excess waste sludge is provided. In this method, a waste water containing biodegradable substances is treated in a biological fixed film type reactor and aqueous water sludge discharged from the reactor is aerobically digested after being separated from the biologically treated waste water. The digested aqueous sludge is returned to the reactor or the upstream thereof. This method can be advantageously combined with any installed activated sludge type water purification process, to thereby substantially eliminate the production of excess waste sludge from the water purification system.