title: Enhancing post aerobic digestion of full-scale anaerobically digested sludge using free nitrous acid pretreatment.
abstract: Post aerobic digestion of anaerobically digested sludge (ADS) has been extensively applied to the wastewater treatment plants to enhance sludge reduction. However, the degradation of ADS in the post aerobic digester itself is still limited. In this work, an innovative free nitrous acid (HNO2 or FNA)-based pretreatment approach is proposed to improve full-scale ADS degradation in post aerobic digester. The post aerobic digestion was conducted by using an activated sludge to aerobically digest ADS for 4 days. Degradations of the FNA-treated (treated at 1.0 and 2.0 mg N/L for 24 h) and untreated ADSs were then determined and compared. The ADS was degraded by 26% and 32%, respectively, in the 4-day post aerobic digestion period while being pretreated at 1.0 and 2.0 mg HNO2-N/L. In comparison, only 20% of the untreated ADS was degraded. Economic analysis demonstrated that the implementation of FNA pretreatment can be economically favourable or not depending on the sludge transport and disposal cost.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Lai
authors.initials: L
authors.lastname: Peng
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Dongbo
authors.initials: D
authors.lastname: Wang
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Xie
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia. Electronic address: zhiguo@awmc.uq.edu.au.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001315:Australia; D019149:Bioreactors / Q000382:microbiology; D003365:Costs and Cost Analysis; D008962:Models, Theoretical; D009608:Nitrous Acid / Q000737:chemistry*; D012722:Sewage / Q000032:analysis* / Q000737:chemistry / Q000382:microbiology; D062065:Wastewater / Q000032:analysis / Q000737:chemistry* / Q000382:microbiology; D018508:Water Purification / Q000191:economics / Q000295:instrumentation / Q000379:methods*
chemical_list: D009608:Nitrous Acid; D012722:Sewage; D062065:Wastewater
keywords: Anaerobically digested sludge; Free nitrous acid; Post aerobic digestion; Sludge degradation