Wet oxidation of activated sludge: Transformations and mechanisms

Urrea, José Luis; Collado, Sergio; Laca, Amanda; Dı́az, Mario

doi:10.1016/j.jenvman.2014.07.043

Cited by 35 publications

(6 citation statements)

References 31 publications

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“…A further increase in deconstruction temperature to 350 °C for gloves, face shields and surgical masks, resulted in an increased solid reduction of 92.2%, 94.2% and 91.9%, respectively. These results align with recent results on hydrothermal deconstruction by Anthraper et al, 2018 , Javid et al, 2021a , Urrea et al, 2014 , Yousefifar et al, 2017 who reported a solid reduction (%) of up to 99.3% for municipal solid waste, 93% for pharmaceutical waste and activated sludge and 100% for cellulose, respectively at deconstruction temperatures varying between 160 °C and 350 °C. This increase in solid reduction with elevation in reaction temperature is due to the improved solubility, reaction kinetics and rate of gas–liquid mass transfer at severe reaction conditions ( Anthraper et al, 2018 , Javid et al, 2021a ).…”

Section: Resultssupporting

confidence: 92%

Hydrothermal deconstruction of single-use personal protective equipment during the COVID-19 pandemic

Javid

Xin²,

Derraik³

et al. 2022

Waste Management

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Section: Resultssupporting

confidence: 92%

Hydrothermal deconstruction of single-use personal protective equipment during the COVID-19 pandemic

Javid

Xin²,

Derraik³

et al. 2022

Waste Management

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“…As has already been established, the increase in solubilized material during this phase of the reaction is mainly due to the complete destruction of cellular components caused by reactions of either thermal hydrolysis or oxidation. In previous studies, we have identified that the presence of an oxidizing atmosphere during the hydrothermal treatment of the sludge improves its degree of solubilization. , This has also been reported by Baroutian et al The theory that the initial attack of radicals in organic compounds takes place on the α carbon, starting with the abstraction of a hydrogen atom, is commonly accepted. However, other mechanisms based on the rupture of a C–C bond (β or γ carbon position) have also been considered possible, and this would lead to the reduction in the size of the polymers until their solubilization.…”

Section: Resultssupporting

confidence: 70%

“…The WO experiments were carried out in a PARR series 4520 reactor. A detailed description of the characteristics of the equipment has already been given in Urrea et al 23 A typical experiment was as follows: 500 mL of sample (EPS fraction, naked cells or raw sludge) were loaded into the reactor and then the operating conditions (190 °C and 65 atm) were adjusted. These conditions were selected because they are within the typical ranges of temperatures (150−365 °C) and pressures (30−250 bar) reported in the literature for the WO of sewage sludge.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Formation and Degradation of Soluble Biopolymers during Wet Oxidation of Sludge

Urrea

Collado

Oulego

et al. 2017

ACS Sustainable Chem. Eng.

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In this paper, wet oxidation was applied to an activated sludge as a potential technique for the recovery of products of industrial value. With this end, the effect of the treatment on the polymeric composition of the sludge was analyzed. To establish differences due to the origin of the biopolymers (extracellular or intracellular), the sludge was separated into fractions: soluble microbial products (SMP), loosely bound extracellular polymeric substances (LB-EPS), tightly bound extracellular polymeric substances (TB-EPS) and naked cells and each was treated at 190 °C and 65 atm. A model that describes the evolution of soluble biopolymers during the wet oxidation of sludge was proposed and successfully fitted to the experimental data. Results showed a rapid solubilization of polymers during the first minutes of reaction, achieving values of 23.1%, 14.7%, 8.3%, 0.9% and 0.5% for proteins, humic acids, carbohydrates, uronic acids and DNA, respectively, with regard to the initial volatile suspended solids concentration. Afterward, the oxidation reactions led to a considerable reduction in these substances, which underwent a degree of decomposition higher than 70%. Finally, it was demonstrated that the mineralization of soluble biopolymers depended on their location within the floc structure, mineralization being higher when the polymer was more internal.

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“…At the end of treatments (187 minutes), the CN obtained with TH was a bit higher (8% more) than that with WO, despite the SCOD concentrations were very similar between the final effluents of both treatments. The ability of WO to reduce the colour on different wastewater or sewage sludge has been widely proved (Fu and Kyzas, 2014;Urrea et al, 2014) as well as the generation of high coloured intermediates…”

Section: Effects On Colour and Phmentioning

confidence: 99%

Sludge hydrothermal treatments. Oxidising atmosphere effects on biopolymers and physical properties

Urrea

García

Collado

et al. 2018

Journal of Environmental Management

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In this work, the role of an oxidising atmosphere during the hydrothermal treatment of an activated sludge at 160 °C and 40 bar, was determined. The composition and molecular weight sizes of the soluble biopolymers generated during the sludge treatment in presence (wet oxidation "WO") or absence (thermal hydrolysis "TH") of oxygen were compared. Likewise, the characteristics of organic material, settleability, colour and pH of the treated sludge during both treatments were analysed. The thermal treatment in presence of oxygen provided better results in terms of solubilisation, settleability and mineralisation. WO initially favoured a more intense cellular lysis, causing a higher degree of solubilisation than that achieved by TH. Either in presence or absence of oxygen, thermal treatments caused a marked worsening of the settleability of the sludge. However, the degradation of biopolymers during WO led subsequently to an improvement of the settleability properties for longer reaction times. Both treatments caused a fast solubilisation of biopolymers at the beginning by effect of the release of extracellular and intracellular material from sludge. Subsequently, the presence of oxygen produced a significant decrease in the concentration of those biopolymers. In contrast, the proteins were the only one biopolymer that was degraded during TH.

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Wet oxidation of activated sludge: Transformations and mechanisms

Cited by 35 publications

References 31 publications

Hydrothermal deconstruction of single-use personal protective equipment during the COVID-19 pandemic

Hydrothermal deconstruction of single-use personal protective equipment during the COVID-19 pandemic

Formation and Degradation of Soluble Biopolymers during Wet Oxidation of Sludge

Sludge hydrothermal treatments. Oxidising atmosphere effects on biopolymers and physical properties

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