Experimental investigation and chemometric analysis of gasification and co-gasification of olive pomace and Sida Hermaphrodita blends with sewage sludge to hydrogen-rich gas

In the paper the results of the systematic study on oxygen/steam co-gasification of sewage sludge blends with biomass waste such as olive pomace or energy crops such as Sida Hermaphrodita to hydrogen rich gas were presented. In the first part of the experimental campaign the oxygen/steam gasification of sewage sludge, Sida Hermaphrodita and olive pomace, respectively, at 700, 800 and 900 °C were gasified. Only small amount of the total gas was produced in the oxygen/steam gasification of analyzed sewage sludge in all studied temperatures. The carbon conversion rate varied between 64% at 700 °C to 66% at 900 °C. The hydrogen amount in the total gas produced in the sewage sludge gasification was 28%vol. at all studied temperatures. The main conclusion from this part of experiments was that gasification of sewage sludge is ineffective. Different conclusions were drawn on the basis of Sida Hermaphrodita and olive pomace gasification tests at all studied temperatures. Therefore in the second part of the experimental campaign the co-gasification experiments of Sida Hermaphrodita/olive pomace blends with 10%w/w and 20%w/w of sewage sludge. The co-gasification experimental campaign covered series of tests at temperatures of 700, 800 and 900 °C, respectively. The comprehensive analysis of the experimental results of co-gasification and the physical and chemical parameters important for the co-gasification process performance were also conducted with the application of chemometric methods, such as hierarchical clustering analysis and principal component analysis. Based on the experimental results the optimal fuel blends as well as the optimal conditions of co-gasification were determined. It was proven that steam co-gasification of sewage sludge with selected biomass is beneficial in terms of the total gas produced and its composition.