Membrane bioreactor system

A membrane bioreactor system comprising:

• an aerobic tank configured to receive a wastewater from at least one of a flow control tank, an anoxic tank and an anaerobic tank;
• a fine bubble generator disposed in the aerobic tank to increase a dissolved oxygen of the wastewater introduced into the aerobic tank;
• and
• a filtration apparatus submerged in the wastewater introduced into the aerobic tank, the filtration apparatus disposed directly above the fine bubble generator,
• wherein the filtration apparatus comprises:
• a filtration membrane module;
• and
• a bubble-converting device disposed below the filtration membrane module and configured to convert a portion of fine bubbles provided by the fine bubble generator into coarse bubbles suitable for filtration membrane cleaning,
• wherein the bubble-converting device comprises:
• a case having a lower opening and a collecting space configured to confine the portion of the fine bubbles introduced therein via the lower opening;
• a main pipe extending downwardly from a circumference of a first hole formed in an upper plate of the case;
• and
• a branch pipe extending from a circumference of a second hole formed in a side of the main pipe, and
• wherein the main pipe is in fluid communication with the collecting space via the branch pipe.