Air pollution control and flue gas desulfurization residues from Polish copper smelting facility as adsorbents of Pb(II) and Cu(II) from aqueous solutions

Mitigation of PBDE net discharge in hazardous waste thermal treatment system through reintroducion of sludge and fly ash into GASMILD operations

The presence of polybrominated diphenyl ethers (PBDEs) in consumer products, waste treatment processes, and treated ashes poses a significant environmental threat. Due to the lack of research on the removal of PBDEs during waste incineration, this study investigated the effectiveness of a Hazardous Waste Thermal Treatment System (HAWTTS) utilizing reburning of sludge and fly ash (SFA) with gasification-moderate or intense low-oxygen dilution (GASMILD) combustion for PBDE removal. The closed-loop treatment of sludge and ash within the HAWTTS provides a potential pathway for near-zero PBDE emissions. The GASMILD combustion addresses potential combustion issues associated with fly ash recirculation. The system achieved an impressive overall removal efficiency of 98.4% for PBDEs, with minimal stack emissions (2.45 ng/Nm³) and a negative net discharge rate (-1.02 μg/h). GASMILD combustion played a crucial role (92.7%-97.6% destruction) in addressing challenges associated with high-moisture feedstocks and SFA residues. Debromination of highly brominated PBDEs occurred within the incinerator, resulting in an increased proportion of lower brominated PBDEs in the bottom slag compared to the feedstock. Air Pollution Control Devices (APCDs) achieved a total PBDE removal efficiency of 74.4%. However, the hydrophobic nature of PBDEs limited removal efficiency in scrubbers (36.0%) and cyclonic demisters (37.86%). This study demonstrates that reintroducing SFA into the GASMILD combustion process offers an effective and environmentally sustainable strategy for reducing net PBDE levels in hazardous waste. This approach also provides additional benefits such as energy conservation, reduced carbon emissions, and lower operating costs associated with secondary treatment of thermally treated byproducts.

Enhanced Cu(II) adsorption using sodium trimetaphosphate-modified cellulose beads: equilibrium, kinetics, adsorption mechanisms, and reusability

The current study is focused on the simple synthesis of two novel biosorbent beads: BASB/STMP and CNFB/STMP, derived respectively from bleached almond shell (BAS) and cellulose nanofiber from almond shell (CNF) by means of chemical crosslinking with sodium trimetaphosphate (STMP). These biosorbents were thoroughly characterized in terms of structure (FTIR), texture (N₂ adsorption-desorption), thermal behavior (TGA/DTG), morphology (SEM), and surface properties (XPS). The adsorption kinetics of Cu(II) ions onto BASB/STMP and CNFB/STMP materials proved the chemisorption interaction between Cu(II) ions and the STMP functionalized beads. The BASB/STMP equilibrium data were successfully described by the Redlich-Peterson model and the CNFB/STMP data by the Sips model which disclosed maximum adsorption capacities of 141.44 mg g^-1 and 147.90 mg g^-1, respectively. Furthermore, the BASB/STMP bioadsorbent offers easy regeneration and better reusability with high efficiency (> 83%). This study sheds light on the preparation of low-cost adsorbents for wastewater treatment in order to improve the competitiveness and eco-friendliness of agrowaste-based processes.