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The intensive development of the polyurethanes industry and limited resources (also due to the current geopolitical situation) of the raw materials used so far force the search for new solutions to maintain high economic development. Implementing the principles of a circular economy is an approach aimed at reducing the consumption of natural resources in PU production. This is understood as a method of recovery, including recycling, in which waste is processed into PU, and then re-used and placed on the market in the form of finished sustainable products. The effective use of waste is one of the attributes of the modern economy. Around the world, new ways to process or use recycled materials for polyurethane production are investigated. That is why innovative research is so important, in which development may change the existing thinking about the form of waste recovery. The paper presents the possibilities of recycling waste (such as biochar, bagasse, waste lignin, residual algal cellulose, residual pineapple cellulose, walnut shells, silanized walnut shells, basalt waste, eggshells, chicken feathers, turkey feathers, fiber, fly ash, wood flour, buffing dust, thermoplastic elastomers, thermoplastic polyurethane, ground corncake, Tetra Pak®, coffee grounds, pine seed shells, yerba mate, the bark of Western Red Cedar, coconut husk ash, cuttlebone, glass fibers and mussel shell) as additives or fillers in the formulation of polyurethanes, which can partially or completely replace petrochemical raw materials. Numerous examples of waste applications of one-component polyurethanes have been given. A new unexplored niche for the research on waste recycling for the production of two components has been identified. [ABSTRACT FROM AUTHOR]

In the wake of economic and population growth, increased wastewater production poses a challenge related to sewage sludge treatment, which is problematic given its high moisture content, amount, and hazardous characteristics. This study focuses on the hydrothermal carbonization of sewage sludge to produce carbonous material–hydrochar, which may be an alternative to fossil fuels. The effect of process parameters, namely, temperature (180, 240, 300 °C) and duration time (30, 90, 180 min), on hydrochar properties (proximate and ultimate analysis, heating values) and process performance were studied. Obtained results indicate and confirm that hydrothermal carbonization, especially temperature increase, improves the fuel properties of carbonized sewage sludge. The highest low heating value was obtained for hydrochar derived at 300 °C in 180 min (~23 MJ × kg−1). The highest energy gain was noted for hydrochar derived at 240 °C in 180 min (~23%). As well as relatively high mass and energy yield in comparison to other hydrochars, these parameters are considered the most favorable for sewage sludge hydrothermal carbonization. However, high energy consumption (over 1300 kJ × g−1) suggests that more research on the process's economical efficacy is required. [ABSTRACT FROM AUTHOR]

The influence of sewage sludge torrefaction temperature on fuel properties was investigated. Non-lignocellulosic waste thermal treatment experiment was conducted within 1 h residence time, under the following temperatures: 200, 220, 240, 260, 280 and 300°C. Sawdust was used as lignocellulosic reference material. The following parameters of biochar have been measured: moisture, higher heating value, ash content, volatile compounds and sulfur content. Sawdust biochar has been confirmed to be a good quality solid fuel. High ash and sulfur content may be an obstacle for biochar energy reuse. The best temperature profile for sawdust torrefaction and fuel production for 1 h residence time was 220°C. At this temperature the product contained 84% of initial energy while decreased the mass by 25%. The best temperature profile for sewage sludge was 240°C. The energy residue was 91% and the mass residue was 85%. Higher temperatures in both cases caused excessive mass and energy losses.

Pozostałości z biogazowni rolniczych stanowią bogaty w substancje nawozowe surowiec, w przypadku którego, jego rolnicze wykorzystanie, może zmniejszyć stosowanie nawozów mineralnych i poprawić właściwości gleby. Jednakże poferment powinien być wcześniej odwodniony i przetworzony termicznie. Ograniczona stosowalność w środowisku przyrodniczym pofermentu może szczególnie wystąpić w okresie zimowym oraz na terenach zagrożonych eutrofi zacją. Wykorzystanie pofermentu podlega także ograniczeniom prawnym w zależności od tego czy jest traktowany jako nawóz, osad lub odpad. Celem artykułu jest przedstawienie efektów zastosowania termicznego przetwarzania odwodnionego pofermentu w procesach pirolizy i zgazowania. Proces pirolizy pofermentu prowadzono w temperaturze 500°C. Monitorowano skład i kaloryczność gazu pirolitycznego. Wykonano porównawcze analizy kaloryczności odwodnionego pofermentu i uzyskanego w wyniku pirolizy karbonizatu. Gazyfi kację prowadzono w temperaturze 850°C w atmosferze CO2. Wykazano, iż uzyskany w procesie gazyfi kacji gaz syntezowy posiadał wyższą kaloryczność, jednak dodatkowy produkt procesu pirolizy karbonizat posiadał dobre właściwości do wykorzystania jako paliwo stałe.