title: [Enhanced hydrolysis of excess sludge by external enzymes].
abstract: The effects of external enzymes to enhance excess sludge hydrolysis were investigated. Protease and alpha-amylase were added singly and in combination, and it was found that external enzymes can enhance sludge hydrolysis. When treated with single enzyme, alpha-amylase had higher efficiency than protease, SCOD/TCOD rose from 16.3% to 22.3% and VSS reduction improved from 39.8% to 54.24% at the optimal dosage of 60 mg/g (calculated by addition of enzyme in TS). Furthermore, mixture enzymes showed better hydrolysis efficiency than single enzyme. The highest VSS reduction was observed at an enzyme mixture ratio of 1:3 with protease and amylase when the hydrolysis temperature was 50 degrees C, and the VSS reduction achieved 68.43%. Correspondingly, the concentration of reducing sugar and NH4+ -N rose from 37.29, 47.60 mg/L to 177.8, 143.43 mg/L, respectively. According to the kinetic and enzymatic analysis of hydrolysis process, sludge hydrolysis within prior 4 h was consistent with first-order reaction dynamic. During the hydrolysis, both protease and amylase activity rose gradually, the highest activity observed were 2.57 U/mL and 4.64 U/mL at 4h after hydrolysis. Thereafter, the enzyme activity decreased.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, China. luokungood2006@163.com
authors.forename: Kun
authors.initials: K
authors.lastname: Luo
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Xiao-ming
authors.initials: XM
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.forename: Zhu-qiang
authors.initials: ZQ
authors.lastname: Luo
authors.forename: Jing-jin
authors.initials: JJ
authors.lastname: Liu
mesh_terms: D019149:Bioreactors; D006868:Hydrolysis; D008567:Membranes, Artificial; D010316:Particle Size; D010447:Peptide Hydrolases / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D008567:Membranes, Artificial; D012722:Sewage; D000516:alpha-Amylases; D010447:Peptide Hydrolases