Every year, important quantities of winemaking waste create problems for wine producers. These problems arise from the difficulty of disposing of grape marc, which can pollute the environment and affect nearby agricultural crops. The present research proposes a new direction for the valorization of this agri-food waste in residual water depollution. Four biomaterials obtained from winemaking waste were tested for Pb removal: raw Merlot grape marc (MR), raw Sauvignon Blanc grape marc (SbR), Merlot grape marc biorefined (ME) and Sauvignon Blanc grape marc biorefined (SbE). The effects of biosorbent mass and initial Pb concentration, adsorption kinetic, equilibrium isotherms and the matrix influence from a mine effluent were assessed. Very good perspectives for the practical application in lead uptake from wastewaters arise, with better results for biorefined grape marc compared to raw material. The lead removal percentage from an initial solution containing 20 mg Pb/L, at optimum pH (5.5 ± 0.5) was 71%—MR, 78%—SbR, 80%—ME, and 97%—SbE. A Langmuir model revealed a very good removal capacity for ME (40 mg/g) and SbE (64 mg/g). Thus, the grape marc, a polluting waste, can turn into a low-cost and easy-to-prepare sorbent for the bioremediation of contaminated water.

The conversion of lignocellulosic waste ascends as a promising path to generate new materials with wide industrial and environmental uses. Pyrolytic biochar (PBc), hydrochar (Hc), and activated hydrochar (AcHc) produced from the waste of Picea Abies bark were considered bio-based sorbents for lead uptake from aqueous effluents. PBc was obtained through slow pyrolysis (550 °C), while Hc resulted under hydrothermal conversion (280 °C). In order to enhance the specific surface, Hc was subjected to a physical activation, resulting AcHc. All three carbonaceous materials were prepared through relatively simple processes from a readily locally available resource. The carbonaceous materials were characterized using infrared spectroscopy and scanning electron microscopy. The Pb (II) removal has been tested in batch mode on a synthetic monocomponent wastewater matrix, as well as on a real mine drainage effluent. A significant effect of pH was observed, while the equilibrium was achieved in a short time, about 60 min for PBc and Hc and 120 min for AcHc. Langmuir model predicted a maximum adsorption capacity of 15.94 mg/g for PBc, 9.99 mg/g for Hc, and 37.46 mg/g for AcHc. All materials studied had good uptake capacities for lead with no drastic effect of typical coexisting species.

This study investigates the capacity of green and brown algae to sustainably remove oxyanions from contaminated waters, highlighting their cost-effectiveness. Often considered biomass waste and contributors to organic contamination, these algae can be used as effective biosorbents, aligning with circular economy principles and sustainable waste management. Various pre-treatments were tested to enhance adsorption capacity, with mixed results regarding their effectiveness. The focus then shifted to the use of Cladophora sericea algae for the uptake and removal of selenium species, specifically selenite (Se(IV)) and selenate (Se(VI)). The effects of different operational parameters on oxyanion uptake by algae were studied in batch mode. The assessments were conducted on a single-component and a multi-component synthetic matrix. The results indicate that pH significantly impacts biosorption, with equilibrium achieved in 90 min. Both pseudo-first-order and pseudo-second-order models provided a good fit to the experimental data. The algae’s retention capacity for selenium remained largely unaffected by the presence of other anions, a key advantage for application in complex real effluent matrices. Kinetic studies performed under different values of initial pollutant concentration and biosorbent mass indicate a biosorbed amount at an equilibrium of 570 µg g⁻¹.

The large quantities of agri-food waste produced worldwide by the tomato processing industry require recovery. This study evaluated the efficiency of the by-product resulting from tomato juice preparation as an innovative biomaterial for removing lead from water. The pomace was dried and tested in two forms: raw (RT) and after extraction of soluble compounds (ET). The extracts obtained from the preparation of ET, could be reintroduced into the food industry (as colorants, etc.) according to the “zero waste” principle, but further studies are needed. No other chemical pre-treatment was applied to improve the lead-adsorption capacity. The pH influence, biosorbent dosage, kinetics and equilibrium were evaluated. Analytical methods, such as atomic absorption spectrometry, elemental chemical analysis, FTIR, scanning electron microscopy, and predictive models, were applied. The outcomes demonstrated a lead-adsorption efficiency of 99.22% for ET and 89.83% for RT, an optimum pH of 4.0 ± 0.5, and an initial solution containing 20 mg Pb²⁺/L. The Langmuir model predicted high removal capacities: 142.18 mg/g for ET and 90.91 mg/g for RT. Both forms of tomato pomace were efficient for sustainable and cost-effective water remediation, but an improvement was noticed after the extraction of soluble components that could be valorized in other products within the circular economy.

Soils contaminated with heavy metals including cadmium, lead, zinc, copper, and chromium continue to represent a significant environmental issue, particularly in areas affected by industrial activities. In this context, the present study aimed to assess the feasibility and efficiency of an integrated bioremediation technique that combines, in a synergistic approach, phytoremediation with the use of natural amendments in order to reduce soil pollution with heavy metals. In addition, the potential for heavy metal recovery was investigated. The experiments were conducted under field conditions in the vicinity of the CET II Holboca power plant, using two plant species, Trifolium repens and Brassica napus, as bioaccumulators, while biochar was applied as a natural amendment. The analyses focused on metal concentrations, translocation factors, the degree of heavy metal recovery, and morpho-structural characteristics. The results indicated a high accumulation of metals in plant roots, particularly in soils treated with higher doses of biochar (4905.93 mg/kg iron for B. napus), and a significant growth stimulation (root elongation increases of up to 78% in T. repens and up to 29% in B. napus). B. napus exhibited greater translocation of metals to the aerial parts (with values up to 0.83 for zinc), whereas T. repens predominantly retained metals within the root system. The highest recovery efficiency values were observed in the case of lead, reaching 224.7% in T. repens and 86.7% in B. napus in soil amended with increased amounts of biochar. Overall, biochar application stimulated plant growth and enhanced metal uptake efficiency, suggesting a viable and practically applicable method for the ecological reconversion of contaminated land.