title: Effects of stabilization and sludge properties in a combined process of anaerobic digestion and thermophilic aerobic digestion.
abstract: A novel process of combining mesophilic (<35°C) anaerobic digestion with the thermophilic (55°C) aerobic digestion process (AN-TAD) was designed to stabilize sludge and economize aeration energy. Effects of stabilization and sludge properties for AN-TAD process were evaluated by batch experiments during a 25 d digestion period. The sludges digested by AN-TAD process achieved the requirements for Class-A sludge standard. The sludge at total solid (TS) 5.4% had the highest value of decay coefficient K(d(55)) at 0.1851 d(-1) among the three TS contents according to the first-order kinetics equation. Oxidation reduction potential at below 0 mV remained for sludges at TSs of 6.5%, 5.4%, and 4.6% for at least 15 d because of initial hydrolytic-acidification. Concentrations of nitrogen and phosphorus in sludges at TSs of 6.5%, 5.4%, and 4.6% gradually increased up to the highest values in the supernatant during the initial 13 d, causing low utilized value in land application as a fertilizer. Prolonging the retention time for more than 15 d was considered because soluble phosphorus precipitated in the solid phase. High content of soluble organic matters of the soluble chemical oxygen demand, protein, and polysaccharide in the supernatant caused deterioration in sludge dewaterability rates.
authors.affiliation: a School of Chemical and Environmental Engineering , Jiangsu University of Technology , Changzhou 213001 , People's Republic of China.
authors.forename: Jiehong
authors.initials: J
authors.lastname: Cheng
authors.affiliation: a School of Chemical and Environmental Engineering , Jiangsu University of Technology , Changzhou 213001 , People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Kong
authors.affiliation: b Department of Biological and Agricultural Engineering , University of Arkansas , Fayetteville , AR 72701 , USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.affiliation: c Southern Research and Outreach Center, College of Food, Agricultural and Natural Resource Sciences , University of Minnesota , Falcon Heights, Waseca , MN 56093 , USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wu
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D004867:Equipment Design; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage
keywords: mesophilic anaerobic digestion; sewage sludge; sludge property; stabilization; thermophilic aerobic digestion