Mechanical pretreatment of waste activated sludge for anaerobic digestion process

This research investigated the effect of mechanical pretreatment of waste activated sludge (WAS) to a pilot scale (2000 l) anaerobic digestion process. Mechanical pretreatment of WAS by jetting and colliding to a collision-plate at 30 bar made the sludge solubilized, as examining some parameters before and after mechanical pretreatment of waste-activated sludge; for example, Suspended Solid (SS), Soluble Chemical Oxygen Demand (SCOD), Soluble Total Organic Carbon (STOC), particle size, protein, ammonia–nitrogen (NH3–N), total phosphorus (T–P), and alkalinity. This research showed that solubilization of WAS is effective to the digester performance through measuring the unit gas production, volatile fatty acids (VFA), pH, and volatile mass reduction efficiency. WAS pretreatment allowed a decrease in the digester SRT from 13 to 6 days, without major effects on process efficiency and on effluent quality. It enhanced volatile mass reduction and unit gas production.