This study shows that by-products obtained after cold-pressing oil production (flex oil cake, hemp oil cake, hull-less pumpkin oil cake) could be used as substrates for the sustainable and cost-effective production of lipase when cultivating Thermomyces lanuginosus under solid-state conditions (T = 45 °C, t = 9 days). Lipase showed optimum activity at T = 40 °C. The produced lipase extract was purified 17.03-folds with a recovery of 1% after gel chromatography. Three different batch experiments were performed in order to test the possibility of using the lipase in biodiesel production. Experiments were performed with a commercial, unpurified enzyme, and partially purified lipase with sunflower oil and methanol as substrates in a batch reactor at 40 °C. During the experiments, the operational stability of the enzyme was studied. The obtained results clearly showed that produced crude and purified lipase can be used for biodiesel production, but the process needs some additional optimization. As for operation stability, it was noticed that the commercial enzyme was deactivated after 30 h, while produced crude enzyme remained 8.25% of its activity after 368 h.

The development of innovative transformation techniques for various wastes generated by the agri-food industry is one of the goals of sustainable waste management oriented toward “zero-waste” approach. This includes the production of bulk and fine chemicals, bioactive compounds, enzymes and functional materials from various waste. The present research shows the possibility of the production of value-added products from eggshell waste using chemical transformation by acetic and o-phosphoric acid at a laboratory scale level. Eggshell-derived calcium acetate monohydrate and calcium hydrogen phosphate, both of high purity, as well as corresponding eggshell membranes as valuable by-products, were produced. Chemical transformation of 100 g of eggshell waste with 10% (w/v) acetic acid resulted in 111.41 ± 2.13 g of calcium acetate monohydrate and 2.90 ± 0.14 g of eggshell membranes, with a chemical yield in calcium acetate monohydrate of 79.16 ± 1.98%. On the other hand, the transformation of 100 g of eggshell waste in 15% (w/v) o-phosphoric acid yielded 77.06 ± 6.21 g of calcium hydrogen phosphate and 2.94 ± 0.08 g of eggshell membranes, with a chemical yield in calcium hydrogen phosphate of 71.36 ± 5.58%. Eggshell-derived calcium hydrogen phosphate met all prescribed criteria for food-grade additive, as determined by physicochemical analysis. On the other hand, calcium acetate monohydrate met the majority, except water insoluble and formic acid and oxidizable impurities content. Based on the obtained results, it can be concluded that the proposed eggshell waste transformation process by two different acids might be useful for the production of calcium acetate and calcium hydrogen phosphate as food-grade additives, as well as eggshell membranes as valuable by-products.

The present study investigated the possibility of complete utilization of eggshell waste (ESW) transforming it to adherent egg white protein solution, calcium chloride dihydrate, and eggshell membranes (ESM). Adherent egg white protein solution was obtained by washing ESW three times with distilled water at 25°C, followed by filtration, and analyzed for the protein content and lysozyme activity. ESM and calcium chloride were obtained simultaneously by the exposure of washed eggshells to 5% hydrochloric acid treatment at 25°C for 3 h, followed by separation by filtration. The separated ESM were washed, dried, and milled to powder and analyzed for protein and lipid content. The calcium chloride solution was exposed to the neutralization of excess hydrochloric acid by calcium hydroxide, followed by evaporation to one-tenth of volume. Calcium chloride crystals were precipitated from the concentrated solution with acetone, separated by filtration, dried at 110°C, and analyzed for chemical composition and purity. The obtained results revealed that 100 g of ESW can be transformed to 1.61 ± 0.34 g of adherent white proteins containing 485,821 U of lysozyme activity, 2.84 ± 0.16 g of ESM powder, and 108.74 ± 3.62 g of calcium chloride dihydrate of high purity.

This study presents a comprehensive economic and environmental evaluation of immobilized lipases produced on eggshell membrane-based carriers from eggshell waste, based on laboratory-scale experiments. By integrating economic analysis (EA) and life cycle analysis (LCA), the key factors affecting the economic viability and environmental impact of the process were identified, supporting sustainable and circular biorefinery concepts. The EA estimated the total process cost at EUR 25.63 for 15 g of product, while the effective net cost was negative (EUR −14.81) due to the valorization of anhydrous calcium chloride as a valuable by-product. The effective net cost reduction from by-product valorization of the immobilized lipase was estimated at 0.99 EUR/g as the minimum selling price (MSP). When expressed per unit of enzymatic activity, the immobilized lipase on the eggshell waste membrane-based carrier shows a substantially lower cost (EUR/U) compared with representative commercial immobilized lipases, demonstrating clear catalytic cost-efficiency advantages. The cradle-to-gate life cycle assessment, conducted using ReCiPe 2016 quantification methods, highlighted electricity consumption during drying as the primary environmental hotspot, accounting for up to 57% of the global warming potential. Sensitivity and uncertainty analyses showed that energy consumption strongly influences the impact in terms of climate change and fossil resource depletion, while the impact of chemical use was minimal. These results show that energy-efficient process optimization, especially in the drying phase, is crucial for further improving environmental and economic performance. These results indicate that optimizing energy efficiency, especially during the drying phase, is crucial for further improving the production process of immobilized lipases on eggshell membrane-based carriers, both environmentally and economically.

In line with the circular economy approach and the pursuit of sustainable solutions for spent coffee grounds, this study investigates the valorization of spent coffee grounds as a source of cellulose-based enzyme immobilization carriers. Considering that global coffee consumption generates approximately 6.9 million tonnes of spent coffee grounds annually, their disposal represents both an environmental challenge and an opportunity for value-added applications. A multistep extraction process, including Soxhlet extraction followed by sequential subcritical extraction with ethanol and water, and alkaline treatment, led to the production of cellulose-enriched carriers. The carriers obtained were characterized by their morphology, porosity and surface properties and subsequently used for the two lipases immobilization, Burkholderia cepacia (BCL) and Pseudomonas fluorescens (PFL), using three techniques: adsorption and covalent binding via direct and indirect methods. The immobilized lipases were analyzed for key biochemical and operational properties and compared with each other and with their free enzymes. Based on their stability, catalytic activity, and reusability, the lipases immobilized by adsorption were identified as the most efficient biocatalysts. These immobilized enzymes were then used in two selected reactions to demonstrate their practical utility: cocoa butter substitute synthesis using PFL and the enzymatic pretreatment of wastewater from the oil processing industry using BCL. Both immobilized lipases showed excellent catalytic performance and maintained their high activity over four consecutive reuse cycles.

The objective of this study was to valorise eggshell waste (ESW) by investigating its biosorption properties and evaluating its efficiency as a sustainable biosorbent for the removal of the synthetic dye Congo Red (CR) from model CR solutions and synthetic wastewater with the addition of CR. Batch biosorption experiments were conducted to investigate the influence of several factors on the biosorption process, including ESW concentration (1–15 g L⁻¹), contact time (1–360 min), temperature (15, 25, 35, 45 °C) and initial CR concentration (10–100 mg L⁻¹). Desorption experiments were performed using ultrapure water, 0.1 M NaCl, 50% ethanol, 0.1 M HCl, or 0.1 M NaOH as solvents. A higher ESW concentration improved CR removal, but the amount of CR adsorbed on ESW decreased. The dye uptake by ESW was increased with prolonged contact time and temperature increase. When the effect of CR initial concentration was investigated, the results indicated that the process is concentration-dependent and that overall, CR uptake by ESW was higher in synthetic wastewater than in the model dye solution. The biosorption process was better described by the Langmuir isotherm model than by the Freundlich model, indicating monolayer adsorption. Kinetic analysis showed that the pseudo-second-order model provided a better fit than the pseudo-first-order model. Desorption of CR from ESW under the applied experimental conditions was generally low (0.67–27.13%).