*3.1. Feedstock Characterization Results*

The basic characteristics of sewage sludge, *Typha latifolia* grass and cattle rumen fluid, such as total dry solids content (TS), water content, total nitrogen (TN) content, total phosphorus (TP) content and total carbon (TC) content are gathered in Table 2. Sewage sludge contained 18.6% of dry solids, grass 7.4% and rumen fluid 2.3%. The content of heavy metals and the content of TN were higher in sewage sludge samples than in the grass samples. As expected, grass contained high amounts of potassium (K), but did not contain much phosphorus (TP). Among heavy metals, the concentration of Zn ions stands out from the results for sewage sludge. Other values were in the range typical of sewage sludge [26] and grass samples [27].
