TREATMENT OF WASTE WATER

PURPOSE:To discharge permeated water in a sewerage and to reduce raw water by cleaning off the solder flux residue of a mounted printed circuit board with a specified detergent, washing the board and then concentrating the waste washing water with a water permselective oil-water separation semipermeable membrane. CONSTITUTION:The solder flux residue of a mounted printed circuit board is cleaned off with a petroleum hydrocarbonic detergent, that is a substitute for fluorocarbon, and then the board passes successively through the first, second and third washing tanks 1, 2 and 3 and cleaned. Pure water 10 is supplied to the third washing tank 3, the overflow washing water flows toward the first washing tank 1, and the first washing tank has the highest concn. of detergent. The waste cleaning water passes through a prefilter 5 and an oil-water separation semipermeable membrane 6 to be concentrated. The concentrated water is discharged outside the system from a line 8, and the permeated water is discharged into sewerage from a line 7. The TCC concn. of the treated water is reduced by a half at the line 7 and concentrated about 25 times at the line 8.