The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.
<div>The research project focuses on the effect of hydro-thermal pre-treatment of the thickened waste activated sludge (TWAS). Reducing the amount of waste generated by the process called anaerobic digestion (AD) includes the benefits of low cost and supplies source of renewable energy. Fermentation is the first part of AD where volatile fatty acids (VFAs) are produced. In this study hydro-thermal pre-treatment was conducted before the fermentation process to enhance the production of VFAs from TWAS. The study is a comparison between the pre treated sludge and raw sludge using Semi-continuous fermentation for 40 days with hydraulic retention time of 3 days. TWAS was pre-treated at 170○C for 30 min at the pressure 3 bar before the semi-continuous fermentation process, and compared with the raw sample performance. It was found that the amount of VFAs produced from the pre-treated sludge were 26 % higher than that one from the raw sludge. Also, the chemical oxygen demand (COD) solubilisation for the hydrothermally pre-treated sample was higher than that of raw sludge.</div><div><br></div>
<div>The research project focuses on the effect of hydro-thermal pre-treatment of the thickened waste activated sludge (TWAS). Reducing the amount of waste generated by the process called anaerobic digestion (AD) includes the benefits of low cost and supplies source of renewable energy. Fermentation is the first part of AD where volatile fatty acids (VFAs) are produced. In this study hydro-thermal pre-treatment was conducted before the fermentation process to enhance the production of VFAs from TWAS. The study is a comparison between the pre treated sludge and raw sludge using Semi-continuous fermentation for 40 days with hydraulic retention time of 3 days. TWAS was pre-treated at 170○C for 30 min at the pressure 3 bar before the semi-continuous fermentation process, and compared with the raw sample performance. It was found that the amount of VFAs produced from the pre-treated sludge were 26 % higher than that one from the raw sludge. Also, the chemical oxygen demand (COD) solubilisation for the hydrothermally pre-treated sample was higher than that of raw sludge.</div><div><br></div>
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