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Torefikacija je blaga piroliza, ki se uporablja z namenom izboljšanja lastnosti biomase. Proizvodnja trdnih biogoriv s torefikacijo iz različnih virov biomase se je zaradi ekonomskih in tehnoloških zmožnosti izkazala kot zelo učinkovita alternativa premogu v industrijskih aplikacijah. Magistrsko delo prikazuje študijo torefikacijskega procesa, kjer smo odpadno biomaso pretvorili v trdno biogorivo z višjo kurilno vrednostjo in hidrofobnostjo. Material je med procesom izpostavljen inertni atmosferi oziroma atmosferi z zelo nizko koncentracijo kisika. Študija je bila narejena na treh različnih vrstah biomase, mešanem odpadnem lesu, hrastovem lesu in dehidriranem, granuliranem komunalnem mulju iz čistilne naprave. Vzorci so bili termično obdelani v temperaturnem območju od 220 °C do 400 °C, proces je potekal od 30 min do 120 min. Proizvedenim trdnim biogorivom smo izmerili vsebnost vlage, pepela, analitske vlage, hlapnih snovi in delež ogljika, vodika, dušika in žvepla. Določili smo izgubo mase, energijski izkoristek, masni izkoristek, faktor povečanja kurilne vrednosti, indeks stopnje torefikacije v smislu izgube mase, dosežene z zaostrovanjem pogojev torefikacije in delež dekarbonizacije ter dehidrogeniranja. Ugotovili smo, da je vpliv temperature večji od vpliva obratovalnega časa, s podaljšanjem trajanja in povišanjem temperature procesa kurilne vrednosti naraščajo, izguba mase se veča. Optimalna temperatura znaša 260 °C, pri tej temperaturi je najboljše razmerje med izboljšanjem kurilne vrednosti in dovedeno energijo. Nadalje smo pri optimalni temperaturi spreminjali čas procesa. Rezultati kažejo, da optimalni čas procesa znaša 1,2 h, do tega obratovalnega časa imamo pozitivno energetsko bilanco. Torefikacija odpadnega mešanega in hrastovega lesa se je izkazala za energetsko učinkovit proces. Solid fuel production from different biomass sources become a very challenging area. The paper presents the torrefaction process, mild pyrolysis, where biomass material is converted into solid biofuel with higher heating value. The material is processed in inert atmosphere or in the atmosphere with very low oxygen concertation. The study was done for three varied materials, oak wood, mixed wood and dehydrated, granulated sewage sludge. Biomass wastes have been torrefied at a temperature range of 220-400°C for 30-120 min to produce biochars. The properties of torrefied biomass such as the mass drop, energy yield, mass yield, enhancement factor of higher heating value, torrefaction severity index, decarbonization and dehydrogenation have been investigated. The influence of the temperature was analysed and the optimal temperature of 260°C for exact samples were determined. Furthermore, the optimal operation time for each material was evaluated. The experiments were done without flue gases integration. The results show that from energy point of view the optimal operation time for oak and mixed wood is around 1.2 h at 260°C. The torrefaction of sewage sludge is energetically unjustified.

Diplomsko delo prikazuje potek priprave komunalnega mulja za sežig v energetskih objektih. Opisani so postopki priprave komunalnega mulja, ki jih uporabljamo pred samim sežigom oziroma so-sežigom. Prav tako smo analizirali kapaciteto in karakteristike komunalnega mulja v zadnjih letih v Sloveniji. Preučili smo, katere črpalke se uporabljajo za transport mulja in kakšne so njihove lastnosti. Pri transportu mulja prihaja do linijskih izgub, med katerimi so najpomembnejše predvsem izgube, ki nastanejo zaradi trenja. V diplomskem delu so navedeni postopki za določitev koeficienta trenja, s pomočjo katerega lahko izračunamo tlačne izgube. Prav tako so navedene metode za določitev energijskih izgub in aplikacije reologije za določitev le-teh. Opisane so karakteristike cevovodov, ki jih uporabljamo za črpanje komunalnega mulja. Preučili smo vpliv aditivov na zmanjšanje trenja v ceveh. Ugotovili smo, da lahko za zmanjšanje trenja uporabljamo tako različne polimere, kot tudi nekatere površinsko aktivne snovi. The Bachelor thesis presents the preparation of sewage sludge for combustion purposes. The methods of sewage sludge pre-treatment, before it enters combustion unit are described in this thesis. Furthermore, the sludge production rate and characteristics in Slovenia are also considered and briefly described. Nonetheless, the commercially available pumps for sludge transportation are evaluated together with their operational characteristics. During the sewage sludge transport linear loses regularly occur, especially ones influenced by frictional forces. The thesis also include the methods for determination of frictional coefficients, which are further used for calculation of pressure losses. At the second part of the thesis, the methods for energy losses evaluation together with rheology aspects are taken into consideration. The characteristics of regular pipelines, used for transportation of sewage sludge, are considered and briefly explained. The influence of additives on frictional loses is also evaluated. It can be concluded that surface active additives can be used for frictional losses decreases, and also different types of polymers are used.

In this study, the life cycle analyses of two cement blends with wood biomass ash are compared with those of commercially available cement. In addition, technical and logistical challenges of using new materials in cement sector have been identified.

Despite the many advantages of biomass energy, especially wood biomass, its combustion generates large amounts of waste - wood biomass ash (WBA). Due to excellent chemical, physical and mineralogical properties of WBA, the sustainability of the precast concrete industry can be improved by using alternative supplementary-cementitious materials (SCM), using WBA as a partial replacement for cement and fine aggregates in low-carbon building materials and products. But, the complex characteristics of each WBA, which depend on the type of wood biomass and combustion technologies used in biomass power plants, as well as the lack of technical and legal regulations, present challenges in converting WBA into a secondary raw material. Therefore, the promotion of recycling, i.e. the transformation of waste from one industry - the energy sector - into raw materials from another industry - the concrete industry - contributes to the realization of the principles of the circular economy.

Sewage sludge incineration is extensively practiced in European countries such as the Netherlands, Austria, and Germany, where legislative developments prohibit the direct spreading of sewage sludge on agricultural land. These and other countries opt for mandatory P recovery from the sewage sludge ash (SSA) from incineration since this type of ash has a very high phosphorous concentration (about 10% per weight). Since P is on the EU list for critical raw materials, this element should be recovered from the ash, but no technology is yet implemented for such recovery. This work focuses on the development of an electrodialytic method for the recovery of P from SSA.

Municipal solid waste incineration (MSWI) plays an important part in waste management strategies, as it significantly reduces the volume of municipal solid waste and the embodied energy can be recovered. Apart from energy, by-products in form of particulate materials such as bottom and fly ash are also produced. Bottom ash is already valorized in several countries, mainly in road construction or embankments, after metals are separated for recycling.