Chlorine-free "salt-free" bleaching technology (Daishowa Paper Company, 1990s)

Chlorine-free "salt-free" bleaching technology (Daishowa Paper Company, 1990s)
In the 1990s, after Japan's response to pollution had been completed, water pollution caused by chemical substances and the sustainable use of forest resources became the focus of attention as new environmental issues. In particular, pulp bleaching, which uses chlorine-based chemicals, was internationally recognized as a problem due to the emission of AOX into rivers and the generation of dioxin, and a shift to chlorine-free bleaching was urgently needed.
The "chlorine-free bleaching technology" promoted by Daishowa Paper Company is an environmentally friendly process that whitens pulp using a combination of oxygen bleaching, ozone, and hydrogen peroxide, rather than the conventional chlorine gas and hypochlorous acid. This process has greatly reduced toxic byproducts and dramatically lowered the environmental impact of wastewater.
Salt-free bleaching is not a simple chemical substitution; it required a redesign of the entire process, including reaction conditions, pulp pretreatment, temperature and pressure control, and wastewater treatment. Daishowa Paper Company was an early adopter of this process on its industrial paper line, making it a model case for balancing local environmental protection and manufacturing. In the face of increasingly stringent international regulations, this technology was also a symbolic effort to transition the Japanese paper industry toward sustainability.