title: Effect of free nitrous acid pre-treatment on primary sludge at low exposure times.
abstract: The present study was undertaken to investigate the effect of different free nitrous acid (FNA) concentrations at low pre-treatment times (PTs) (1, 2 and 5h) and without pH control with mild agitation on primary sludge (PS) biodegradability and methane production (MP). Increasing PTs resulted in an increase in the solubility of the organic matter (around 25%), but not on cell-mortality (>75% in all the cases with FNA) and neither on methane generation. FNA pre-treatment at low PTs improve MP (around 16% at PT of 1h and 650mg N-NO2-/L). However, a similar improvement was found with mild agitation of PS without FNA at 2 and 5h. Taking into account the potential costs associated with the FNA pre-treatment, a mild agitation without FNA would be preferred to enhance MP in PS.
authors.affiliation: Catalan Institute for Water Research (ICRA), Emili Grahit Street, 101, H(2)O Building, Scientific and Technological Park of the University of Girona, 17003 Girona, Spain. Electronic address: szahedi@icra.cat.
authors.forename: S
authors.initials: S
authors.lastname: Zahedi
authors.affiliation: Department of Innovation and Technology, FCC Aqualia, Balmes Street, 36, 6th Floor, 08007 Barcelona, Spain. Electronic address: PIcaranL@fcc.es.
authors.forename: P
authors.initials: P
authors.lastname: Icaran
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia 4072, Australia. Electronic address: Zhiguo@awmc.uq.edu.au.
authors.forename: Z
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Catalan Institute for Water Research (ICRA), Emili Grahit Street, 101, H(2)O Building, Scientific and Technological Park of the University of Girona, 17003 Girona, Spain. Electronic address: mpijuan@icra.cat.
authors.forename: M
authors.initials: M
authors.lastname: Pijuan
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D019149:Bioreactors; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000096:biosynthesis; D050296:Microbial Viability / Q000187:drug effects; D009573:Nitrites / Q000032:analysis; D009608:Nitrous Acid / Q000494:pharmacology*; D012722:Sewage / Q000737:chemistry*; D012995:Solubility; D013997:Time Factors
chemical_list: D009573:Nitrites; D012722:Sewage; D008697:Methane; D009608:Nitrous Acid
keywords: Anaerobic digestion; Free-nitrous acid pre-treatment; Methane production; Primary sludge; Sludge biodegradability