Aspects related to the growing pollution of the natural environment and depletion of conventional fossil fuels have become the motive for searching for ecofriendly, renewable, and sustainable alternative energy sources. Particular attention is paid to industrial waste, especially waste of biomass materials, which can be converted into biofuels and energy that meets the growing needs of humanity. The use of biomass for energy purposes is less damaging to the environment, the materials are low-cost, locally available in large quantities, and create employment opportunities for workers in suburban and rural areas around the world. This article discusses issues related to the use of waste biomass materials as renewable energy sources. The current energy situation in the world is analyzed in terms of production, consumption, and investments in green energy. Types of biomass and individual physicochemical and energy properties of waste plant materials obtained for energy purposes are described. Currently available methods of converting biomass into energy, including mechanical, thermal, and biochemical techniques are discussed. The conducted analysis indicates the possibility of using it as a competitive source of electricity and heat. Understanding the properties of biomass materials allows us to understand the right way to use them for energy and reduce the consumption of fossil fuels in the future.

In these research studies, fly ash (SW-FA) resulting from the incineration of sunflower (20%) and wood (80%) waste employing the circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Pb(II) and Cu(II) ions in adsorption processes. Currently, great emphasis is placed on circular economy, zero waste or climate neutrality strategies. The use of low-cost SW-FA waste seems to fit well with pro-ecological, economic and energy-saving trends. Hence, this material was characterized by various techniques, such as granulation analysis, bulk density, SEM-EDX, XRD and XRF analysis, BET, BJH, thermogravimetry, zeta potential, SEM morphology and FT-IR spectrometry. As a result of the conducted research, the factors influencing the effectiveness of the adsorption process, such as adsorbent dosage, initial and equilibrium pH, initial metal concentration and contact time, were analyzed. The maximum removal efficiency were achieved at the level of 99.8% for Pb(II) and 99.6% for Cu(II), respectively. The kinetics analysis and isotherms showed that the pseudo-second-order equation and the Freundlich isotherm models better describe these processes. The experiments proved that SW-FA can act as an appropriate adsorbent for highly effective removal of lead and copper from wastewater and improvement of water quality.

Fly ash and slag were produced as a result of the incineration of municipal sewage sludge using the circulating fluidized bed combustion (CFBC) technology and were examined for the simultaneous recovery of lithium and uranium from seawater in batch adsorption experiments. These waste materials have been characterized in terms of their physicochemical properties using several research methods including particle size distribution, bulk density, SEM-EDS analysis, thermogravimetry, SEM and TEM morphology, BET, specific surface area, pore volume distribution by the BJH method, ATR FT-IR, and zeta potential. The fly ash and slag waste materials showed the following research results for Li-ion recovery: adsorption efficiency 12.1% and 6.8%, adsorption capacity 0.55 mg g⁻¹ and 0.15 mg g⁻¹, respectively. Better results were reported for U ion recovery: adsorption efficiency 98.4% and 99.9%, adsorption capacity 21.3 mg g⁻¹ and 56.7 mg g⁻¹ for fly ash and slag, respectively. In conclusion, the conducted research revealed that CFBC fly ash and slag are promising low-cost adsorbents for the effective recovery of Li and U ions from seawater.

The sustainable development of construction materials is an essential aspect of current worldwide trends. Reusing post-production waste in the building industry has numerous positive effects on the environment. Since concrete is one of the materials that people manufacture and use the most, it will continue to be an integral element of the surrounding reality. In this study, the relationship between the individual components and parameters of concrete and its compressive strength properties was assessed. In the experimental works, concrete mixes with different contents of sand, gravel, Portland cement CEM II/B-S 42.5 N, water, superplasticizer, air-entraining admixture, and fly ash from the thermal conversion of municipal sewage sludge (SSFA) were designed. According to legal requirements in the European Union, SSFA waste from the sewage sludge incineration process in a fluidized bed furnace should not be stored in landfills but processed in various ways. Unfortunately, its generated amounts are too large, so new management technologies should be sought. During the experimental work, the compressive strength of concrete samples of various classes, namely, C8/10, C12/15, C16/20, C20/25, C25/30, C30/37, and C35/45, were measured. The higher-class concrete samples that were used, the greater the compressive strength obtained, ranging from 13.7 to 55.2 MPa. A correlation analysis was carried out between the mechanical strength of waste-modified concretes and the composition of concrete mixes (the amount of sand and gravel, cement, and FA), as well as the water-to-cement ratio and the sand point. No negative effect of the addition of SSFA on the strength of concrete samples was demonstrated, which translates into economic and environmental benefits.