Clean technology in the crystal glass industry

Acid polishing of crystal glass generates hazardous wastes containing lead and fluoride to which very strict discharge limits are applied in Korea. However, with conventional end-of-pipe technology it is very difficult to meet the enforced effluent standards. The object of this study was to develop a zero-discharge system in the crystal glass industry in which treated wastewater is directly recycled to the manufacturing process. To establish the zero-discharge system, nanofiltration coupled with lime-precipitation was developed to remove scale-forming ions, such as calcium, sulphates and silicates, from wastewater and to obtain recycled water of high quality. This clean technology has been applied to one crystal glass industry and it made four improvements possible: water conservation, wastewater treatment, recycling of treated wastewater and reduction of wastewater treatment facilities.