Conversion of kitchen waste effluent to H2-rich syngas via supercritical water gasification: Parameters, process optimization and Ni/Cu catalyst

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 degrees C to 480 degrees 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/Al2O3 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/gamma Al2O3 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/Al2O3 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.

Automated summary

In this study, supercritical water gasification was used to convert kitchen waste effluent into energy, increasing the gasification efficiencies. By investigating different operating parameters and catalysts, it was found that increasing temperature significantly increased hydrogen yield, hydrothermal pretreatment accelerated the supercritical water gasification reaction, and Ni/Cu bimetallic catalyst enhanced the reaction rate. These findings provide a promising option for the treatment of kitchen waste effluent.