title: Alkaline post-treatment for improved sludge anaerobic digestion.
abstract: Alkaline post-treatment was tested in order to improve sludge anaerobic digestion. Between the 8th and the 12th hour of a 24-h digestion cycle, 5% of sludge was extracted from a semi-continuous digester with a sludge retention time of 20 days. The sludge was then disintegrated with 0.1 mol/L NaOH and returned to the digester after neutralization. The results showed that alkaline post-treatment increased the level of soluble organic substances in the extracted sludge, particularly of volatile fatty acids and polysaccharides. This process resulted in a 33% enhancement of biogas production in comparison with the control. When the ratio of the recycled sludge was further increased to 10% or 15%, the increment of biogas yield was reduced, due to excessive inactivation of anaerobic bacteria in the digester. Alkaline post-treatment had a minimal impact on the dewaterability of digested sludge.
authors.affiliation: Shenzhen Environmental Microbial Application and Risk Control Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China. lihuansz@qq.com
authors.forename: Huan
authors.initials: H
authors.lastname: Li
authors.forename: Shuxin
authors.initials: S
authors.lastname: Zou
authors.forename: Chenchen
authors.initials: C
authors.lastname: Li
authors.forename: Yiying
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000468:Alkalies / Q000494:pharmacology*; D000693:Anaerobiosis / Q000187:drug effects; D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D059027:Recycling; D012722:Sewage / Q000382:microbiology*; D012972:Sodium Hydroxide / Q000494:pharmacology; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000468:Alkalies; D056804:Biofuels; D012722:Sewage; D012972:Sodium Hydroxide