PROBLEM TO BE SOLVED: To contribute to a steam reduction in the papermaking process by recovering waste heat of activated sludge treatment tank inflow hot wastewater treating organic pollutants in pulp bleaching wastewater and hot concentrated waste black liquor generated from a pulp manufacturing plant. SOLUTION: Hot fresh water obtained by heat exchange between the activated sludge treatment tank inflow hot wastewater and fresh water is mixed with papermaking process water, and the temperature of the process water after the mixing is measured to control the opening of an automatic control valve installed on the hot fresh water side so as to adjust the temperature within a preset temperature range. The temperature of the hot wastewater after the heat exchange is measured to control the opening of an automatic control valve installed on the fresh water side so as to adjust the temperature within a preset temperature range. COPYRIGHT: (C)2009,JPO&INPIT
