Sorption of phenols: influence of groundwater pH and of soil organic carbon content

Physical and chemical properties of soil, groundwater and pollutants deeply influenced the type and the strength of sorption phenomena involving hydrophobic organic contaminants: Soil fraction of organic carbon (foc) and cation exchange capacity, groundwater pH and pollutants hydrophobicity were with undoubtedly the predominant issues. Approach: In this study an experimental study of the sorption of phenol and 2-nitrophenol on three soils was performed considering three initial pH values, with the aim to evaluate the soil/pollutant interactions as a function of the relative abundance of the neutral contaminants and phenolate species and of the solid phase properties. Results: The considered soil samples (a silty clay, a silt and a sand coming from northern Italy) underwent to a physical and chemical characterization: Particle-size, mineralogical and chemical analyses were performed. The experimental data coming from some batch tests, carried employing aqueous phases containing different concentrations of phenol and 2-nitrophenol at initial pH values equal to 4, 7 and 10, were fitted by means of several isotherm models. Three Dual Mode Models (DMM), employing different isotherm models to represent the sorption of the neutral and the anionic species of the pollutants, were evaluated by the researchers to simulate the sorption of phenol and 2- nitrophenol in the examined conditions. Conclusion: The soil/contaminant interaction mechanisms determining the isotherm shapes were discussed: foc appeared to be the main issue, although the nitrogroup was able to promote sorption. In all considered soil samples and at all initial pH values, the highest foc (found in the silty soil) and the presence of the nitro-group determined the highest amounts of pollutant transferred on the solid phase. The two DMMs proposed by the researchers, implying nonlinearity, showed a higher reliability in simulating experimental data compared to a DMM based on linear sorption isotherms. Main sorption mechanisms were controlled by the partitioning of neutral pollutants in soil organic matter, but also the interactions between the pollutants, both in phenolate and in neutral forms and the soil mineral surface played a primary rol

Assessment of Microplastics Distribution in a Biological Wastewater Treatment

Full-scale wastewater treatment facilities are not able to prevent microplastics (MPs) from discharging into natural waters and they are also associated with the land application of the sludge. This study evaluates the distribution of microfibers (MFs) in a lab-scale sequencing batch reactor (SBR) fed by synthetic wastewater (SW) for 93 days. The MFs were analyzed through optical microscopy in the mixed liquor (ML) and the effluent, and sulfuric acid digestion was applied to discriminate between natural and synthetic MFs (i.e., MPs). The results of the optical microscopy analyses were further validated through FTIR spectroscopy. A model describing the evolution over time of the MF concentration in the ML was created, accounting for the MFs entering the system through the SW and atmospheric deposition. The ratio between the MF concentration in the ML and the effluent was 1409   781, demonstrating that MFs settle with the sludge. Consistently, in the ML, 64.9% of the recovered MFs were smaller than 1000 μm (average size 968 μm), while in the effluent, 76.1% of MFs were smaller than 1000 μm (average size 772 μm). Overall, 72% of MFs recovered from the ML were natural fibers and sulfuric acid digestion was successful in eliminating the natural MFs

Low-cost and environmentally friendly physic-mechanical pre-treatments to recycle lithium iron phosphate cathodes

Recycling Lithium Iron Phosphate (LFP) batteries is challenging, as their low economic value hinders the profitability of full-scale processes. Optimized pre-treatments are crucial for the overall efficiency and economic profitability of recycling processes. This study explored chemicals-free physic-mechanical pre-treatment processes aimed to detach waste LFP cathodes (production scraps and end-of-life, EoL) from aluminium current collectors. The technical performances of ultrasounds (35 kHz, in water at 25 °C for 5, 15, 30 min), ball milling (840–1080 rpm for 8, 16, 24 min), and thermal treatment (30 min at 200, 250, 300, 350,°C) coupled with ball milling (840 rpm for 5 min) have been compared. Environmental impacts and economic cost were calculated based on energy demand. The highest separation efficiency achieved were 95 ± 5% for Li, 99 ± 6% for Fe, and 80 ± 3% for P in scrap cathodes, treated at 200 °C for 30 min and ball milled at 840 rpm for 5 min; 93 ± 15% for Li, 97 ± 21% for Fe and 82 ± 20% for P in EoL cathodes, treated at 250 °C for 30 min and ball milled. The global warming impacts were: 3.33 ± 0.55 kg CO2 eq/kg of detached cathode for scraps and 3.08 ± 0.25 kg CO2 eq/kg for EoL cathodes; the costs were 1.45 ± 0.24 €/kg of detached cathode for production scraps samples and 1.34 ± 0.11 €/kg for EOL samples. In conclusion, chemicals-free mechanical detachment was effective both for production scraps and EoL cathodes, while thermal treatment was especially beneficial for EoL cathodes, and reducing milling time improved the environmental impacts and costs of the pre-treatment processes

Assessment tools for disposable and long durability products

The current market situation is characterized by planned obsolescence. It warns the need to design in a more efficiently way, by optimizing the recycle and disassembly operations and lowering the impact on the environment of all kind of products, from the easiest to the most complex ones. This paper focuses on short-lived and long durability products by analyzing them respectively according to the methodologies developed by the Observatory of EcoPack (OEP) and the Design by Components (DC) that share the same general framework and scenario. For disposable products, i.e. packaging, the analysis was carried out with a comparative analysis on components and communication, up to the definition of guidelines for a specific productive sector. Regarding the long durability goods, i.e. household appliances, the analysis is done according to the DC, in which the complex products are simplify to a function-essential structure. This is the starting point for a new design of complex goods focused on disassembly and maintenance. These two methodologies are able to provide useful tools for designing and innovating, through a scientific quali-quantitative analysis on products that are currently on the market

The Flavours of Coffee Grounds: the coffee waste as accelerator of new local businesses

Annual generation of Spent Coffee Grounds (SCG) is estimated around six million tonnes per year. They currently do not have a commercial value and are disposed of in landfills or as compost. Systemic Design approach developed by Politecnico di Torino (Department of Architecture and Design) wants to provide a holistic vision in which these productions are linked together through relationships, output and input, flows of energy and materials, in order to make the SCG recovery activity complex, with almost no waste. This research studies how to make real and profitable a system that values this waste considering the local condition

Material Flow Analysis of Lithium-Ion Battery Recycling in Europe: Environmental and Economic Implications

This study aimed at a quantitative analysis of the material flows associated with End of Life (EoL) lithium-ion batteries’ (LIBs) materials in Europe. The European electric vehicles fleet in 2020 was taken as a case study, assuming a 10-year lifetime for the batteries and that the related EoL LIBs would be processed by existing recycling plants via pyrometallurgy, hydrometallurgy, or their combination in sequence. The economic implications (recycling operative costs compared to the revenues from the sales of the recycled metals) and the environmental performances (CO2 eq. emitted, energy demand and circularity performances) were assessed. Based on the gathered results, the existing European recycling capacity will overlook over 78% of the forecasted EoL LIBs. The treatment efficiencies of the full-scale recycling processes allow for the recovery of over 90% of copper, cobalt, nickel, and manganese, 87% of aluminum, and only 42% of lithium and 35% of iron entering the recycling facilities. In overall, LIBs recycling in 2030 will involve the emission of 3.7 Mt of CO2 eq. and an energy demand of 33.6 GWh. Hydrometallurgy presents the best economic and environmental trade-off compared to other recycling strategies. In conclusion, this study demonstrated that current European LIBs’ recycling infrastructure will be inadequate in the near future and the direction (i.e., hydrometallurgy) that its strengthening should pursue

Recovery of Waste Polyurethane from E-Waste—Part I: Investigation of the Oil Sorption Potential

The shredding of end-of-life refrigerators produces every year in Italy 15,000 tons of waste polyurethane foam (PUF), usually destined for energy recovery. This work presents the results of the investigation of the oil sorption potential of waste PUF according to ASTM F726–17 standard. Three oils (diesel fuel and two commercial motor oils) having different densities (respectively, 0.83, 0.87, and 0.88 kg/dm3) and viscosities (respectively, 3, 95, and 140 mm2/s at 40 C) were considered. The waste PUF was sampled in an Italian e-waste treatment plant, and its characterization showed 16.5 wt% particles below 0.71 mm and 13 wt% impurities (paper, plastic, aluminum foil), mostly having dimensions (d) above 5 mm. Sieving at 0.071 mm was applied to the waste PUF to obtain a “coarse” (d > 0.71 mm) and a “fine” fraction (d < 0.71 mm). Second sieving at 5 mm allowed an “intermediate” fraction to be obtained, with dimensions between 0.71 and 5 mm. The oil sorption tests involved the three fractions of waste PUF, and their performances were compared with two commercial oil sorbents (sepiolite and OKO-PUR). The results of the tests showed that the “fine” PUF was able to retain 7.1–10.3 g oil/g, the “intermediate” PUF, 4.2–7.4 g oil/g, and the “coarse” PUF, 4.5–7.0 g oil/g, while sepiolite and OKO-PUR performed worse (respectively, 1.3–1.6 and 3.3–5.3 g oil/g). In conclusion, compared with the actual management of waste PUF (100 wt% sent to energy recovery), the amount destined directly to energy recovery could be limited to 13 wt% (i.e., the impurities). The remaining 87 wt% could be diverted to reuse for oil sorption, and afterward directed to energy recovery, considered as a secondary option

Evaluation of Hydrogen/Oxygen release compounds for the remediation of VOCs

Problem statement: In this work the potential of two reagents (HRC and ORC from Regenesis) for the remediation of Volatile Organic Compounds (VOCs) is evaluated considering the results of some laboratory tests. Approach: Five series of batch tests were performed with an artificial polluted aqueous phase and some soil coming from a polluted site in which natural attenuation of VOCs occurs. Hydrogen Release Compound (HRC) and Oxygen Release Compound (ORC) were tested about the degradation of benzene, toluene, ethylbenzene and xylene (BTEX) and some chlorinated aliphatic compounds (CAHs), and the net contribute of the soil in removing the pollutants from the aqueous phase by means of sorption processes was also evaluated. Results: The experimental data were modeled by means of different mathematical equations, considering zero and first order kinetics, and the results were discussed and compared. Conclusions: ORC exhibited a good efficiency in the degradation of BTEX and the zero order model was found as a reliable approximation of experimental data (with the exceptions of benzene and toluene, for which a first order kinetic model was trustworthy), while HRC showed a good efficiency in the degradation of CAHs and a first order model consistently estimated almost all experimental data

Recovery of Waste Polyurethane from E-Waste. Part II. Investigation of the Adsorption Potential for Wastewater Treatment

This study explored the performances of waste polyurethane foam (PUF) derived from the shredding of end-of-life refrigerators as an adsorbent for wastewater treatment. The waste PUF underwent a basic pre-treatment (e.g., sieving and washing) prior the adsorption tests. Three target pollutants were considered: methylene blue, phenol, and mercury. Adsorption batch tests were performed putting in contact waste PUF with aqueous solutions of the three pollutants at a solid/liquid ratio equal to 25 g/L. A commercial activated carbon (AC) was considered for comparison. The contact time necessary to reach the adsorption equilibrium was in the range of 60–140 min for waste PUF, while AC needed about 30 min. The results of the adsorption tests showed a better fit of the Freundlich isotherm model (R2 = 0.93 for all pollutants) compared to the Langmuir model. The adsorption capacity of waste PUF was limited for methylene blue and mercury (Kf = 0.02), and much lower for phenol (Kf = 0.001). The removal efficiency achieved by waste PUF was lower (phenol 12% and methylene blue and mercury 37–38%) compared to AC (64–99%). The preliminary results obtained in this study can support the application of additional pre-treatments aimed to overcome the adsorption limits of the waste PUF, and it could be applied for “rough-cut” wastewater treatment