Wet oxidation of aqueous phase from hydrothermal liquefaction of sewage sludge

TY - JOUR

T1 - Wet oxidation of aqueous phase from hydrothermal liquefaction of sewage sludge

AU - Thomsen, Lars Bjørn Silva

AU - Anastasakis, Konstantinos

AU - Biller, Patrick

PY - 2022/2/1

Y1 - 2022/2/1

N2 - Hydrothermal liquefaction (HTL) is a thermochemical process for the conversion of biomass into bio-crude oil. However, treatment of post-HTL aqueous by-products is an emerging issue towards the commercialisation of HTL technology. This study investigates the use of non-catalytic wet oxidation (WO) for the reduction of organic compounds and heat production at different temperatures (200–350 °C), residence times (RT) (2–180 min) and excess oxygen. The aqueous phase from HTL of sewage sludge is investigated, and 97.6% of the chemical oxygen demand (COD) and 96.1% of the total organic carbon (TOC) were removed at the highest temperature and retention time. The minimum energy requirement achieved was 9.6 kWh/kg COD removed at 200 °C for 180 min, and the exothermic reactions of the process can generate 28.3% of the required heat. GC-FID and -MS analysis revealed that the degradation of different groups of organic compounds generates acetic acid as an intermediate by-product of WO, being further oxidised at temperatures higher than 300 °C. NH4+and NH3 are generated from the decomposition of nitrogenated organic compounds showing the highest concentration of 704.5 mg NH4+ /L at 350 °C after 180 min.

AB - Hydrothermal liquefaction (HTL) is a thermochemical process for the conversion of biomass into bio-crude oil. However, treatment of post-HTL aqueous by-products is an emerging issue towards the commercialisation of HTL technology. This study investigates the use of non-catalytic wet oxidation (WO) for the reduction of organic compounds and heat production at different temperatures (200–350 °C), residence times (RT) (2–180 min) and excess oxygen. The aqueous phase from HTL of sewage sludge is investigated, and 97.6% of the chemical oxygen demand (COD) and 96.1% of the total organic carbon (TOC) were removed at the highest temperature and retention time. The minimum energy requirement achieved was 9.6 kWh/kg COD removed at 200 °C for 180 min, and the exothermic reactions of the process can generate 28.3% of the required heat. GC-FID and -MS analysis revealed that the degradation of different groups of organic compounds generates acetic acid as an intermediate by-product of WO, being further oxidised at temperatures higher than 300 °C. NH4+and NH3 are generated from the decomposition of nitrogenated organic compounds showing the highest concentration of 704.5 mg NH4+ /L at 350 °C after 180 min.

KW - Aqueous phase

KW - Hydrothermal liquefaction

KW - Sewage sludge

KW - Wet oxidation

U2 - 10.1016/j.watres.2021.117863

DO - 10.1016/j.watres.2021.117863

M3 - Journal article

C2 - 34844067

SN - 0043-1354

VL - 209

JO - Water Research

JF - Water Research

M1 - 117863

ER -