Multi-stage hydrothermal liquefaction modeling of sludge and microalgae biomass to increase bio-oil yield

This study aims to elucidate the effect of Multi-Stage HTL with a constant resident time of 30 min for three different feedstocks including kitchen wastewater sludge (KwWs), freshwater microalgae Chlorella sorokiniana (UUIND6), Co-HTL (KwWs + UUIND6) to obtain the maximum bio-oil yield. According to the results obtained, KwWs appears to be the most suitable for conversion into energy-dense bio-oil under a sustainable biorefinery approach for increased bio-oil yields i.e., 72.75 +/- 0.37 wt%, with HHV of 40.52 MJ/kg and energy recovery of 53.64 wt%. Further, the bio-oils and bio-chars derived from different types of biomasses obtained at different temperature conditions were analyzed by GC-MS, NMR, FTIR, and Raman spectroscopy to identify variations in the bio-crude compounds.

Automated summary

This study investigates the effect of Multi-Stage HTL on different feedstocks and finds that kitchen wastewater sludge is the most suitable for producing high-energy bio-oil. The study also analyzes the compound variations in bio-oils and bio-chars derived from different biomasses using various testing methods.