Chrome tanned leather shavings (CTLS) are considered one of the more difficult wastes to manage in the tanning industry. At the same time, this waste is an important source of good quality collagen. The few methods described in the literature for the valorization of these wastes usually require pre-treatment or activation. In this study, an attempt was made to see if raw chrome tanned leather shavings (CTLS) could be modified to obtain secondary raw materials with new physical properties. Glutaraldehyde, glycerol, EDCs, pectin, and tannins were selected for modification of the CTLS. The effectiveness of the processes carried out was confirmed by FTIR analysis of the materials obtained. Changes in the intensity of the characteristic collagen peak (amide I, amide II, and amide III) and changes in the position of the bands in the 1200–1000 cm⁻¹ region were observed in the recorded spectra. The modifications introduced confirmed changes in the physical properties of samples M1–M5, including an increase in bulk density from 0.15 to 0.59 g cm⁻³, and improved tensile strength is some cases. The elemental content results of the samples tested showed the resulting modified CTLS were free of Cd, Hg, Pb, and Cr(VI). It was also confirmed tanning waste contained significant amounts of various valuable elements. The research also included preliminary tests to assess the environmental impact of the modified materials. In a phytotoxicity test conducted on modified CTLS, M1 with pectins showed the highest root stimulation (105%), while samples with glutaraldehyde and unmodified CTLS showed significant root inhibition (75%, 74%). Other samples showed moderate plant toxicity and seed germination was not significantly affected.

This review presents a recent study on improving energy crops (ECs) in the EU and discusses the potential use of biostimulants to enhance CO₂ sequestration processes in these plants. The novelty of this study lies in demonstrating alternative directions for improving productivity and increasing plant yield without relying on introducing new hybrids (GM) or using advanced agrotechnology. There is a great deal of discussion about using energy crops for direct combustion or biogas production. However, there is a paucity of information regarding the use of biostimulants and their role in increasing the yield of energy crops, particularly in terms of CO₂ compensation. In CO₂ sequestration, increasing the intensity of the photosynthetic process is considered crucial for the more efficient growth of energy crops. Traditionally, fertilization aimed at improving photosynthesis results in a large amount of alkaline elements, which can cause negative effects in boilers. This paper describes the use of amino acid biostimulants extracted from industrial waste, either chemically or biotechnologically, and their different forms of application. It addresses the current challenges and benefits of using biostimulants in energy crops to increase photosynthesis without the use of genetic engineering tools in plants.

The aim of this study was to examine the effects of foliar application of protein biostimulants in combination with extracts from field horsetail (E. arvense L.), common tansy (T. vulgare L.), or yarrow (A. millefolium L.) on winter wheat. Initially, the fungistatic activity and phytotoxicity of three extract concentrations (1%, 5%, 10%) were tested on reference plants. The average results indicated a decrease in root elongation stimulation with increasing concentrations of all extracts. Antimicrobial tests revealed that the 5% and 10% extracts exhibited the strongest activity, especially against S. griseus, whereas the 1% extracts showed no inhibitory effect. The 5% concentration was chosen as optimal due to its comparable efficacy to a reference fungicide. Subsequently, the impact of combining foliar application of extracts with protein biostimulants on wheat seedling and root length, chlorophyll fluorescence, photosynthetic pigments, and soil dehydrogenase activity was analyzed. Horsetail and yarrow extracts combined with biostimulants improved plant growth, depending on dose and combination. This was particularly evident for variants S5-B8, K5-B4, K5-B8, A-B8, for which seedling lengths were 23.6 cm (16.8%), 24.4 cm (20.8%), 23.9 cm (18.3%), and 23.6 cm (16.8%), respectively. The maximum increase in chlorophyll (a + b) content (38.30%, 35.81%, and 41.24%) occurred in plants treated with S5-B4, K5-B8, and A-B4, respectively, compared with non-treated plants. In contrast, tansy extracts reduced chlorophyll content (by up to 78%) and induced moderate stress. The research highlights the potential of natural fungicides to protect plants effectively while minimizing environmental and human health risks compared to conventional chemicals.

The aim of this study was to investigate the effects of treating maize (Zea mays L.) seeds with fish collagen hydrolysate (FC) and keratin (KE) derived from animal waste by-products of leather and meat production, as well as poly(hexamethylene biguanide) hydrochloride (P) and bentonite (B). This research is in line with the search for new, environmentally friendly methods to increase yields of industrial crops in a way that is compatible with sustainable development. The effect of the binders used was investigated by analysing the grown maize seedlings by determining changes in parameters of chlorophyll fluorescence, photosynthetic pigments, elemental composition and FTIR analysis on maize shoots. The results indicated a slightly higher fresh weight (FW) of shoots in plants treated with fish collagen, PHMB and bentonite (FC+P+B) and FW of roots in plants treated with keratin, PHMB and bentonite (KE+P+B). Unexpectedly, the FW and dry weight (DW) of both roots and shoots of all bentonite-treated plants were significantly higher than the corresponding non-bentonite-treated groups. In addition, changes in chlorophyll-a fluorescence were observed for the keratin, PHMB and bentonite variants. This study showed that the proposed materials could be promising seed pelleting agents to improve seed growth and yield.

Microplastics (MPs) are an increasingly significant environmental problem, and there is growing interest in their potential as an energy source. Current investigations in this area are scarce and heterogeneous, which hinders a comprehensive assessment of both technological feasibility and implementation prospects. The aim of this paper is to provide a comprehensive review of current research on energy recovery from MPs, with particular emphasis on technologies such as pyrolysis, gasification, electrochemical methods, and hybrid biomass-based technologies. The processes were analyzed in terms of energy balance, carbon conversion, composition and energy value of the products, energy losses and by-products, reaction time and process efficiency, as well as technological complexity and scalability. Within the reviewed methodologies, pyrolysis is the most scalable method, producing valuable oils and gases efficiently. Gasification can yield hydrogen-rich syngas but is still at pilot scale. Hybrid approaches improve efficiency but need feedstock optimization, while photodegradation and electrochemical methods remain at the research stage. Further progress requires method standardization, environmental and economic assessment, and integration with existing infrastructure.

This study evaluated protein hydrolysates from fish collagen (Col) and sheep keratin (Ker) as potential biostimulants in the hydro-priming of coriander (Coriandrum sativum L.) seeds. Seeds treated with low, non-nutritional doses of Col (0.5%) and Ker (1%) were compared with non-primed (C) and water-primed (H) controls under optimal conditions and after high-temperature stress (35 °C, 9 days). After stress removal, H-Col and H-Ker seeds achieved ~90% germination, whereas H and C reached 78% and 60%, respectively, confirming improved seed quality and post-stress recovery. Seedlings from Col- and Ker-treated seeds showed enhanced growth, higher biomass, and increased chlorophyll and precursor content. High-temperature stress also acted as a priming factor, modifying elemental profiles and stimulating carotenoid antioxidant synthesis. ATR–FTIR analyses indicated changes in cell wall composition and protein structure, particularly in the H-Ker variant. The results demonstrate that collagen and keratin hydrolysates, as industrial by-products, possess strong phytobiostimulatory potential and can be applied in sustainable strategies to improve seed quality and plant stress resilience.