Transverse-mounted membrane filtration apparatus

A transverse-mounted membrane filtration apparatus comprising:

• a membrane module;
• an inlet pipe through which a raw water flows to the membrane module, the raw water flowing in a flow path of a membrane element of the membrane module in an approximately horizontal direction;
• and
• an air diffuser device including a shelf-shaped member and a gas-feeding unit, the shelf-shaped member including a plurality of shelf boards being arranged in a flow path segment immediately adjacent to an upstream end surface of the membrane module, such that the shelf-shaped member is disposed with a gap of a predetermined distance from an end surface of the membrane element and covering an entire flow path of the membrane element along a vertical direction, the gas-feeding unit feeding a gas to the raw water for washing the membrane element through a gas-feeding port provided at a bottom portion of a flow path of the shelf-shaped member, wherein
• a shelf board at a lowermost position of the shelf-shaped member is inclined toward a side of the end surface of the membrane element in a vertically upper direction so that the shelf board at the lowermost position of the shelf-shaped member along a vertical direction disperses the gas blown out from the gas-feeding port into a predetermined ratio of a first gas and a second gas, the first gas is forced into a flow path of a lower region of the end surface of the membrane element through the gap between the shelf-shaped member and the end surface of the membrane element and the second gas is detoured from an upstream side of the shelf-shaped member and forced into a flow path of an upper region of the end surface of the membrane element,
• the gas-feeding port is provided at a position below the shelf board at the lowermost position in the vertical direction, such that the position of the gas-feeding port is overlapped with the shelf board at the lowermost position in the vertical direction, and
• the gas-feeding unit is configured to blow out the gas towards a vertically lower surface of the shelf board at the lowermost position from the gas-feeding port.