###### Abstract  
In this study, three locally available biomasses, namely miscanthus, hops, sewage sludge, and additionally, their mixtures, were subjected to the torrefaction process to improve their fuel properties. The torrefaction process was conducted at 250-350 \({}^{\circ}\)C and 10-60 min in a nitrogen (N\({}_{2}\)) environment. The torrefaction temperature and time were studied to evaluate the selected biomass materials; furthermore, heating values, mass and energy yields, enhancement factors, torrefaction severity indexes (TSI), and energy-mass co-benefit indexes (EMCI) were calculated. In addition, thermogravimetric (TGA) and Fourier transform infrared analyses (FTIR) were performed to characterize raw and torrefied biomass under the most stringent conditions (350 \({}^{\circ}\)C and 60 min). The results showed that with increasing torrefaction temperature and duration, mass and energy yields decreased, and heating values (HHVs) increased for all studied biomasses. The results of the TSI and EMCI indexes showed that the optimum torrefaction conditions were as follows: 260 \({}^{\circ}\)C and 10 min for pure miscanthus and hops, whilst this could not be confirmed for the sewage sludge. Furthermore, the combination of sewage sludge and the above-mentioned types of lignocellulosic biomass exhibited better fuel properties than sewage sludge alone. lignocellulosic biomass; sewage sludge; torrefaction; thermogravimetry; TSI 2022 20220220220220220220220222022202  
country that can help to reduce the impact of social and economic outbursts [7; 8] and also produce biofuels [9; 10]. Due to high moisture content and low bulk density, as well as low calorific value, raw biomass is characterized by low-quality final products [11; 12]. Pretreatment processes of raw biomass may also be required, which is connected with economic factors [13; 14]. Numerous pretreatment processes have been investigated to date; most of them are related to thermochemical conversion processes such as pyrolysis [15], combustion [16], gasification [17], or liquefaction [18]. Raw lignocellulosic and non-lignocellulosic biomass materials, such as coffee grounds [19], miscanthus [20], rice husk [21], municipal solid waste [22], or sewage sludge [23] have already been successfully applied to the aforementioned thermochemical processes. In particular, the main components of lignocellulosic biomass are cellulose, hemicellulose, and lignin, followed by various proportions of minerals, moisture, and proteins [24]. It can be mostly used for green fuel production [25], as it is more or less derived from natural jungles, farms, and agricultural wastes [26; 27]. Furthermore, it is characterized as the most abundant biomass on the planet, with an annual production of over 100 billion tonnes [28]. In Slovenia, this proportion is 8,419,970 m\({}^{3}\) per year or 7.10 m\({}^{3}\) per hectare [29], as Slovenia is fourth among the woodiest countries in the EU [29]. Even though forests cover approximately 58% of the country's area, municipal solid waste, industrial waste, or sewage sludge could replace lignocellulosic biomass in thermochemical processes [30; 31] due to environmental friendliness and cost-effectiveness [32; 33]. Sewage sludge (SS) co-combustion has been studied recently for energy utilization while improving organic compounds share [34; 35]. Sewage sludge is an incidental product generated in biological wastewater treatment plants [36]. The content of dry matter is in the range of 60-70% during aerobic treatment [37; 38]. Generally, it consists of various complex components due to its diverse sources, from garbage, work activity, and industrial processes [39]. Nowadays, the sludge is landfilled [40], gasified, or pyrolyzed [41]. Every year, up to 10 million tonnes of dry sewage sludge are produced worldwide [42], and the number is still increasing due to the growing urban population and urbanization [43].