Abstract
Since the discontinuance of production of specific fluorocarbons, 1, 1, 1-trichloroethane and so forth in 1995, many water soluble detergents such as ethylene glycol are used as substitutes. For recycling of a waste cleaning water containing ethylene glycol or some surface-active agents, waste water is ozonized together with ultraviolet (UV) radiation and hydrogen peroxide oxidation. Oxidized solution is passed through an activated carbon column, a cation exchange column and then an anion exchange column. The advantage of this oxidation process is no production of salts which should be removed when the cleaning water is reuse. By the ozonization combined with UV radiation and hydrogen peroxide oxidation, organic substances were oxidized with high efficiency.
Treated water by activated carbon can be reused as water to dissolve cleaning chemicals. The electric conductivity of the effluent from the anion exchange column was smaller than 20μS/cm. This effluent can be used as rinsing water at the final rinsing process.
On the basis of the present experimental results, we derived a practical recycling system of cleaning water. This recycling technique has enabled the reuse of waste water as detergents dissolving water or final rinsing water without water discharge.
