Controlling the settling of activated sludge in pulp and paper wastewater treatment plants

Filamentous bulking and floc formation often adversely affect the treatment of forest industry wastewaters. The effects of addition of a fine, talc-based powder, Aquatal, to the aeration tanks of wastewater treatment plants of pulp and paper mills were evaluated in 2 case studies. Two strategies were examined a long-term (18 month) strategy; and a short-term, trouble-shooting strategy. Talc addition resulted in an increase in floc aggregation and the production of heavier and well-structured flocs. The sludge settling velocity increased and efficient liquid solid separation was achieved. Excess sludge had good thickening properties and dewatering was improved.