Evaluating Wood Fines as a Physical Conditioner for Dewatering Biosludge

Wood fines are sometimes used to improve biosludge dewatering and to supplement primary sludge, but how they improve biosludge dewaterability is not well understood. Wood fines (0-78% moisture content, dosages of 50-300%), and primary sludge fibres are added to biosludge, dewatered with a Crown Press, and evaluated with a mass balance. The wood fines used absorb on average 2.8ml of water per gram dry weight, which is more water than they help release. Thus, the increase in the dry solid content of the filter cake is primarily due the dry mass of the wood fines themselves, not an increase in water removal. Primary sludge fibres outperformed wood fines when evaluated on the Crown Press without a polymer, but the two conditioners performed similarly when a polymer was used. In a field study, wood fines are found to be an unsuitable physical conditioner when tested in a laboratory scale screw press.M.A.S