Pipe cleaning system, waste water treatment system, and pipe cleaning method

A waste water treatment system comprising:

• a fabrication plant (FAB) in which semiconductor manufacturing processes are performed;
• a buffer tank for temporarily storing copper waste water generated in the FAB;
• a first line connecting the FAB and the buffer tank to each other;
• a water collecting tank storing the copper waste water supplied from the buffer tank;
• a second line connecting the buffer tank and the water collecting tank to each other;
• a treatment tank for treating the copper waste water supplied from the water collecting tank;
• a third line connecting the water collecting tank and the treatment tank to each other;
• a sedimentation tank in which a process of sedimentation of the copper waste water supplied from the treatment tank is performed;
• a fourth line connecting the treatment tank to the sedimentation tank;
• an alkali waste water supply line connected to a storage for storing alkali waste water, and providing a passage through which the alkali waste water moves;
• and
• a connecting line connecting the alkali waste water supply line to at least one of the first to fourth lines,
• wherein the first to fourth lines are copper waste water supply lines for supplying copper waste water.

A pipe cleaning method comprising:

• checking a blockage issue in a pipe due to copper sludge in a copper waste water supply line;
• blocking supply of the copper waste water to the pipe;
• supplying alkali waste water to the pipe;
• and
• re-supplying copper waste water to the pipe,
• wherein the supplying of the alkali waste water to the pipe comprises:
• supplying the alkali waste water to the pipe via a connecting line connecting, to the copper waste water supply line, an alkali waste water supply line for supplying the alkali waste water.