Effects of pretreatments on the solubilization and theoretical methane production of waste activated sludge from a Brazilian eucalyptus kraft pulp mill

Waste activated sludge (WAS) originating from kraft pulp mill effluent treatment plants represents an important environmental challenge for this industry. Anaerobic digestion is a promising option WAS treatment, with the added benefit of biogas production. This paper presents application thermal, thermal-alkaline, and mechanical pretreatment methods in order to promote solubilization organic matter enhance anaerobic Brazilian Eucalyptus bleached mill. A total 16 operating conditions were compared. Chemical analyses showed improvement solubilization, increase greater than 7-fold soluble chemical oxygen demand 4-fold biochemical demand. Nutrient 10-fold Kjeldahl nitrogen 3-fold phosphorus. Theoretical methane potential was improved 211 mLCH4/gVS raw 333-343 after pretreatment, 314-360 thermal 373-378 thermal-alkaline pretreatment. In general, best results all evaluated parameters, advantage requiring lower temperature retention time when compared conditions.