Fine bubble plate diffuser for sewage treatment is structured in the unique manner that makes the aeration system maintain constant oxygenation transfer efficiency within the wide range of working air.The diffuser`s support board is made of aluminum alloy with a layor of membrane horizontally laid on the board.The membrane,once formed,will not suffer debonding .The diffuser can be applied to either intermittent or continuous operation system.Therefore, Holly series plate-type diffuser is the preferred choice for large-scaled and medium-scaled sewage treatment plants.