title: Advanced thermal hydrolysis: optimization of a novel thermochemical process to aid sewage sludge treatment.
abstract: The aim of this work was to study in depth the behavior and optimization of a novel process, called advanced thermal hydrolysis (ATH), to determine its utility as a pretreatment (sludge solubilization) or postreatment (organic matter removal) for anaerobic digestion (AD) in the sludge line of wastewater treatment plants (WWTPs). ATH is based on a thermal hydrolysis (TH) process plus hydrogen peroxide (H(2)O(2)) addition and takes advantage of a peroxidation/direct steam injection synergistic effect. On the basis of the response surface methodology (RSM) and a modified Doehlert design, an empirical second-order polynomial model was developed for the total yield of: (a) disintegration degree [DD (%)] (solubilization), (b) filtration constant [F(c) (cm(2)/min)] (dewaterability), and (c) organic matter removal (%). The variables considered were operation time (t), temperature reached after initial heating (T), and oxidant coefficient (n = oxygen(supplied)/oxygen(stoichiometric)). As the model predicts, in the case of the ATH process with high levels of oxidant, it is possible to achieve an organic matter removal of up to 92%, but the conditions required are prohibitive on an industrial scale. ATH operated at optimal conditions (oxygen amount 30% of stoichiometric, 115 °C and 24 min) gave promising results as a pretreatment, with similar solubilization and markedly better dewaterability levels in comparison to those obtained with TH at 170 °C. The empirical validation of the model was satisfactory.
authors.affiliation: Department of Chemical Engineering and Food Technologies, Faculty of Sciences, University of Cádiz, 11510 Puerto Real (Cádiz), Spain. jose.abelleira@uca.es
authors.forename: Jose
authors.initials: J
authors.lastname: Abelleira
authors.forename: Sara I
authors.initials: SI
authors.lastname: Pérez-Elvira
authors.forename: Juan R
authors.initials: JR
authors.lastname: Portela
authors.forename: Jezabel
authors.initials: J
authors.lastname: Sánchez-Oneto
authors.forename: Enrique
authors.initials: E
authors.lastname: Nebot
mesh_terms: D057919:Biological Oxygen Demand Analysis; D002244:Carbon / Q000032:analysis; D005374:Filtration; D006868:Hydrolysis; D009930:Organic Chemicals / Q000302:isolation & purification; D012722:Sewage / Q000032:analysis*; D012995:Solubility; D013030:Spain; D013696:Temperature; D014867:Water / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D009930:Organic Chemicals; D012722:Sewage; D014867:Water; D002244:Carbon