Conversion of kitchen waste effluent to H2-rich syngas via supercritical water gasification: Parameters, process optimization and Ni/Cu steam reforming reaction. Moreover

• Supercritical water gasification for kitchen waste effluent disposal was proposed. • Reaction temperature, residence time, hydrothermal pretreatment and Ni/Cu catalyst addition were investigated. • H 2 -rich syngas production and TOC, COD removal efficiencies were studied. • Higher efficiencies, and energy input optimization on SCWG were achieved. Large amount of kitchen waste effluent (KWE) was produced during the kitchen waste (KW) treatment. The conventional biological method had the limitation of low hydrolysis rate and long operation time, and the sensitive nature of the microorganisms. In this work, supercritical water gasification was adopted to realize the energy conversion from KWE. The different operation parameters including temperature and residence time were investigated. Furthermore, hydrothermal pretreatment (pre-HT) and Ni/Cu bimetallic catalyst were studied to reduce the energy cost and increase the gasification efficiencies. With the increase of temperature from 360 °C to 480 °C, the H 2 yield exhibited a significant increase from 150.32 mmol/L to 563.43 mmol/L. Pre-HT significantly accelerated the subsequent SCWG process, and shortened the SCWG reaction time. In addition, Ni/Al 2 O 3 enhanced the reaction rate during SCWG, and the reactions were further accelerated with different Cu loading content. The highest H 2 yield of 727.44 mmol/L was obtained at 10Ni-2.5Cu/γAl 2 O 3 in addition due to the improved catalytic performance of Ni by loading Cu and the high activity in water–gas shift reaction during SCWG process. Pre-HT was provided to shorten the SCWG reaction time for energy saving, moreover, appropriate amount of Ni-Cu/Al 2 O 3 catalyst was presented for the reaction acceleration. Findings from this work can pave a promising treatment option for KWE, with energy input saving and gasification efficiencies increasing, making it possible for industrial application of SCWG of KWE.