ORCID Profile
0000-0001-5178-355X
Current Organisation
The University of Auckland
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Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.BIORTECH.2014.07.037
Abstract: A hybrid technique incorporating a wet oxidation stage and secondary fermentation step was used to process Pinus radiata pulp mill effluent sludge. The effect of hydrothermal oxidation at high temperature and pressure on the hydrolysis of constituents of the waste stream was studied. Biochemical acidogenic potential assays were conducted to assess acid production resulting from anaerobic hydrolysis of the wet oxidised hydrolysate under acidogenic conditions. Significant degradation of the lignin, hemicellulose, suspended solids, carbohydrates and extractives were observed with wet oxidation. In contrast, cellulose showed resistance to degradation under the experimental conditions. Extensive degradation of biologically inhibitory compounds by wet oxidation did not show a beneficial impact on the acidogenic or methanogenic potential compared to untreated s les.
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.BIORTECH.2013.07.098
Abstract: In order to remove wood extractive compounds from pulp mill sludge and thereby enhancing anaerobic digestibility, s les were subjected to either oxidative hydrothermal treatment (wet oxidation) or non-oxidative hydrothermal treatment (thermal hydrolysis). Treatments were carried out at 220 °C with initial pressure of 20 bar. More than 90% destruction of extractive compounds was observed after 20 min of wet oxidation. Wet oxidation eliminated 95.7% of phenolics, 98.6% fatty acids, 99.8% resin acids and 100% of phytosterols in 120 min. Acetic acid concentration increased by approximately 2 g/l after 120 min of wet oxidation. This has potential for rendering sludge more amenable to anaerobic digestion. In contrast thermal hydrolysis was found to be ineffective in degrading extractive compounds. Wet oxidation is considered to be an effective process for removal of recalcitrant and inhibitive compounds through hydrothermal pre-treatment of pulp mill sludge.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.BIORTECH.2013.04.114
Abstract: The main objective of this study was to investigate the rheology of mixed primary and secondary sludge and its dependency on solid content and temperature. Results of this study showed that the temperature and solid concentration are critical parameters affecting the mixed sludge rheology. It was found that the yield stress increases with an increase in the sludge solid content and decreases with increasing temperature. The rheological behaviour of sludges was modelled using the Herschel-Bulkley model. The results of the model showed a good agreement with experimental data. Depending on the total solid content, the average error varied between 3.25% and 6.22%.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.BIORTECH.2013.12.066
Abstract: With rapid world population growth and strict environmental regulations, increasingly large volumes of sludge are being produced in today's wastewater treatment plants (WWTP) with limited disposal routes. Sludge treatment has become an essential process in WWTP, representing 50% of operational costs. Sludge destruction and resource recovery technologies are therefore of great ongoing interest. Hydrothermal processing uses unique characteristics of water at elevated temperatures and pressures to deconstruct organic and inorganic components of sludge. It can be broadly categorized into wet oxidation (oxidative) and thermal hydrolysis (non-oxidative). While wet air oxidation (WAO) can be used for the final sludge destruction and also potentially producing industrially useful by-products such as acetic acid, thermal hydrolysis (TH) is mainly used as a pre-treatment method to improve the efficiency of anaerobic digestion. This paper reviews current hydrothermal technologies, roles of wet air oxidation and thermal hydrolysis in sludge treatment, and challenges faced by these technologies.
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.BIORTECH.2016.01.039
Abstract: The current study investigated the formation of organic acids and alcohols as major intermediate products of wet oxidation of municipal sludge. Municipal sludge was subjected to 60-min wet oxidation at temperatures ranging from 220 to 240°C, with 20bar oxygen partial pressure. Acetic acid was the main intermediate compound produced in this study, followed by propionic, n-butyric, iso-butyric and pentanoic acids and methanol. It was found that the process severity has a significant influence on the formation and degradation of these intermediate products.
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.BIORTECH.2013.08.160
Abstract: In idual and interactive effects of process variables on the degradation of fermented municipal sludge were examined during wet oxidation. The process was carried out at 220-240°C using 1:1-2:1 oxygen to biomass ratio and 300-500 rpm stirring speed. Response surface methodology coupled with a faced-centred central composite design was used to evaluate the effect of these variables on total suspended solids, volatile suspended solids and total chemical oxygen demand. Multivariate analysis was conducted for the initial and near completion stages of reaction: 5 and 60 min treatments, respectively. Temperature had the most significant effect on degradation rate throughout. During the initial stage the effect of mixing intensity was less significant than that of oxygen ratio. Mixing intensity did not influence degradation rate at the later stage in the process. During the near completion stage, the interaction of temperature and oxygen ratio had significant effect on sludge degradation.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 03-2013
No related grants have been discovered for Saeid Baroutian.