Catalytic Gasification of Sewage Sludge in Supercritical Water: Influence of K₂CO₃ and H₂O₂ on Hydrogen Production and Phosphorus Yield

Abstract

In this work, the catalytic gasification of sewage sludge in supercritical water was investigated in a batch reactor (460 °C, 27 MPa, 6 min), and the separate and combined effects of the catalyst on the H2 production and phosphorus yield were investigated. The experimental results indicated that K2CO3 alone improved the H2 yield, gasification efficiency (GE), and carbon gasification efficiency (CE). The largest H2 yield of 54.28 mol/kg was achieved, which was approximately three times that without a catalyst. Furthermore, the inorganic phosphorus (IP) yield increased with the addition of K2CO3. However, when H2O2 was added, the H2 yield quickly decreased with increasing H2O2 coefficient, and more than 97.8% of organic phosphorus (OP) was converted into IP. The H2 yield increased with the addition of various K2CO3/H2O2 ratios, whereas the IP yield decreased.

Evolution and Prospects in Managing Sewage Sludge Resulting from Municipal Wastewater Purification

“…Consequently, SCWG coupled with HTC could represent an interesting alternative to incineration when phosphorous recovery must be achieved. The catalytic gasification of sewage sludge in supercritical water enhanced phosphorous recovery and hydrogen production [232,233]. The final and complete destruction of the organic pollutants in the gaseous mixture has also been considered as an alternative, using supercritical water oxidation (SCWO) technology.…”

Quantification of Total Organic Carbon in Ashes from Smoldering Combustion of Sewage Sludge via a Thermal Treatment—TGA Method

“…Sewage sludge of high moisture content (>80 wt %) is a major byproduct from wastewater treatment plants, the high annual production of which poses great challenges for its proper disposal or use. − Sewage sludge is mainly applied to land for agricultural purposes, disposed via landfilling, and/or incinerated for energy recovery, , which are expensive because of high energy inputs and long transportation distance, necessitating the development of novel alternative technologies. One of the promising technologies is smoldering combustion that has been extensively investigated from a fire safety perspective. , It is a flameless and heterogeneous oxidation reaction limited by the diffusion rate of oxygen into the surface of fuels .…”

Hydrothermal liquefaction of sewage sludge. Investigation of the effects of process parameters, recycling of aqueous phase, and co-liquefaction on bio-crude properties: Hydrothermal liquefaction of sewage sludge

“…Reutilizing waste sources is a promising option for the formation of valuable products, which supports the concept of a green environment, and biofuel production technologies simultaneously. In the past researchers tried to valorize the sewage sludge through various methods including thermochemical and biological processes, like pyrolysis [28], gasification [29][30][31], and anaerobic digestion [32,33] for the formation of a variety of products (bio-crude, hydrogen, methane gas, etc.). Gasification and anaerobic digestion processes are particularly recognized for gas production, whereas pyrolysis works on dried feedstocks and leaves a substantial amount of oxygen in the bio-crude.…”