Effect of water quality on the yield and quality of the products from hydrothermal liquefaction and carbonization of rice straw

The need for fresh water limits the application and scale-up of hydrothermal technologies to convert waste biomass to energy and chemicals. In an effort to demonstrate the use of wastewater for sustainable process development, this work is focused on hydrothermal liquefaction (HTL) (350 degrees C, 18 MPa, 30 min) and carbonization (HTC) (200 degrees C, 7 MPa, 4 h) of rice straw with water from various sources (milli-Q water, tap water, seawater, recycled wastewater and industrial wastewater). The bio-crude yield from HTL was maximum (36.4 wt %) with industrial wastewater, while the yield of hydrochar from HTC was maximum (74.5 wt%) with seawater. The ions like K+, PO43- and NH4+ accumulated in the aqueous phase from rice straw. The hydrochars from HTL experiments contained significantly higher amount of ash compared to that from HTC experiments. Cyclopentenones and phenols were the major constituents of the bio-crude, whose HHV was 26.3 MJ/kg using seawater.

Automated summary

This study focuses on the hydrothermal liquefaction (HTL) and carbonization (HTC) of rice straw using water from various sources. The results show that industrial wastewater yields the highest bio-crude production, while seawater yields the highest hydrochar production.