Search

Recently,biorefinerieshave emerged globally as an attractive alternative to conventional fuel production, but costs still need to be competitive. Latest policy actions such as the Green Deal or the Circular Economy Action Plan encourage maximising the biomass-to-products value chain through the use of all valuable compounds available in side-streams to the full extent. Side-streams from corn and rapeseed-based biofuels industries represent excellent sources of bioactive compounds and proteins, mainly under-utilised as animal feed without uncovering their full potential at industrial sectors such as food supplement, speciality chemicals, cosmetics, and household products. The main objective of the research conducted is to pave the way for side-streams valorisation technologies upgrading and market penetration by assessing current availability and future production rates of corn oil, thin stillage,rapeseed mealand other biodiesel andbioethanol productionside-streams. Through a bibliographic analysis of peer-reviewed articles and grey literature, key information and valuable data are presented. It is possible to conclude that trends in biofuel markets (supported by regional regulations) lead to increased biofuel production, as well as increased availability of the specified side-streams. Corn oil is produced at a rate of 60 million L/year on average in Europe, a total of 1.6 billion L of thin stillage is produced each year, and rapeseed meal is generated at a global rate of 68 million tons per year. Future research to trigger further developments and investments could dive into the types and regional availability of relevant active compounds found in the selected side-streams.

Acid mining drainage has a serious impact on the environment. Forward osmosis allows the concentration of acid mine waters to favor the formation of enrichment sludges and subsequent selective metal precipitation. In this work, a methodology was proposed to treat mining effluents from the Iberian Pyrite Belt. Forward osmosis experiments were performed using different osmotic pressures from 0.5M to 2.5M NaCl to evaluate water fluxes and recovery. The water recovery obtained was in the range of 50-80%, and the flux remained above 5 (L•m−2•h−1). Four combined processes were modelled to determine the feasibility of eliminating water and precipitating metals. Furthermore, a new hybrid membrane process was proposed to recover at least 75% of water with recovery yields of Al, Fe, Cu, Zn and Mn of greater than 70%. A water production cost of 2.01 $/m3 and a specific energy consumption of 8.03 kWhe/m3 were estimated for the hybrid process.

In this work, the recovery of valuable metals from Bayer red mud using hydrometallurgical techniques and the subsequent use of the solid remaining after leaching as the principal component of the fired bricks were analyzed. Water, sulfuric acid, and sodium hydroxide were used as leaching agents. Different L/S ratios and contact times were also tested. According to technical, economic, and environmental considerations, the optimal conditions to recover valuable elements from red mud were 2 M H2SO4, in contact for 24 h, with an L/S ratio = 5. Under these conditions, high leaching yields of valuable elements such as La (47.6%) or V (11%) were achieved. After the leaching process, the remaining solid was mixed with clay and water to produce bricks. Two doses of red mud (50 and 80% w) and two different sintering temperatures (900 and 1100 °C) were tested. When the proportion of treated RM in the mix was increased, the compressive strength of the bricks was reduced, but it was increased as the sintering temperature was increased. The environmental safety of the bricks manufactured (leaching of heavy metals and radionuclides) was also studied, and it was found that it was more favorable when red mud was treated instead of fresh red mud being used.

Acid mine drainage induced by the mining industry causes environmental and economic issues. Acid mine drainage contains mainly metals such as Fe, Al, Cu, Ca, Mg, Mn and Zn. Preventing the formation of acid mine drainage has not been found feasible. As a consequence, remediation treatments have been developed during the last years to remove metals and obtain high-quality water, which may be reused. We review here several treatment options such as selective metal precipitation, adsorption, electrochemical processes and membrane processes. Adsorption is the most employed commercially since it can recover 99% of the metals. Membrane processes are promising according to lab-scale results, notably because high-quality water is obtained. Further research is necessary to implement combination of technologies, e.g., adsorption membrane, at larger scales, as well as to obtain more valuable products that can balance the overall economy for the mining industry.

In this work, a comprehensive discussion of forward osmosis membrane technology is presented. Forward osmosis is an interesting and promising system to concentrate multiple kind of solutions in different industrial areas as an alternative solution to classical water evaporation. Therefore, the number of publications and works related to this topic has considerably increased in the last years. Several aspects of forward osmosis have been discussed such as membrane fouling, concentration polarization phenomena, the different available draw solutions and the industrial applications in which forward osmosis has been applied. Cellulose triacetate membranes and thin-film composite membranes are the most employed nowadays. Chemical industry, desalination of drinking water, food industry and pharmaceutical industry are analyzed in deep since these are the most studied areas for forward osmosis application. Herein, the potential of forward osmosis for a sustainable industrial growth is widely proved in every sense.

For sustainable growth, an economic model must tend toward a circular system, especially in the field of waste management. This work focuses on the valorization of spent fluid catalytic cracking catalyst from oil refineries, which generate 400,000 metric tons of spent catalyst per year worldwide, most of which is sent to landfills. A new alternative to landfilling is proposed for this waste, based on the combination of acid leaching for the recovery of lanthanum, a valuable rare earth, and the reuse of the leached solid residue as a cement substitute. A comparative life cycle assessment was made, including four environmental impact categories, i.e. global warming, fossil resource scarcity, mineral resource scarcity and water consumption, in order to quantify the potential environmental benefits of secondary lanthanum recovery from industrial waste with respect to primary lanthanum extraction from mineral resources. A maximum of 85.6% La recovery was achieved and 15 wt% of cement can be substituted with leached solid residue without changing the original cement classification. The waste management process presented in this paper promotes the sustainable management of the spent fluid catalytic cracking catalyst and contributes to the development of a new resource for a critical material such as lanthanum. The implementation of this novel waste management process could reduce global warming and mineral resource scarcity but would increase fossil resource scarcity and water consumption in comparison with primary La extraction.

This paper focused on the germanium recovery from an Integrated Gasification with Combined Cycle fly ash (IGCC FA). The global process comprised the leaching of the IGCC fly ash with an aqueous solution containing tartaric acid, retention of the germanium-tartaric chelate onto a conventional anionic resin (IRA-900) and elution of germanium. The last step consisted of the germanium precipitation which was accomplished with tannic acid. The leaching experiments were performed with tartaric aqueous solutions and with the raffinate from the subsequent ion-exchange (IX) step. Raffinate from the IX step can be reintroduced in the process as leaching solution. When the contact between FA and leaching solution was maintained for 3 h at pH = 1, the Ge leaching efficiency achieved 86%. The effect of pH, resin dosage and tartaric acid dosage on the Ge retention onto the IRA-900 resin was investigated employing a centered composite rotatable design (CCRD) for experimental design and analysis of results. The retention of Ge-tartaric acid complex onto IRA-900 was optimized using design-expert software and the optimum predicted efficiency and loading capacity were 90–98% and 3.0–3.5 mg·g−1. The experimental affinities that IRA-900 showed for the elements extracted (leached) were: Ge >> Sb > V > Ni > As > Sn > B > Zn. Different eluting solutions were tested, and more than 90% of Ge elution was achieved with 2 M HCl. Final solutions contained Ge, Sb and V. Precipitation tests focused on the optimum pH for Ge precipitation adding tannic acid to the elution solutions. A 99.3% of Ge was precipitated from eluting solution, adding 33.3 g of tannic acid per g of Ge. V also precipitated in some extent along with Ge but the rest of elements practically remained in solution.

Within the framework of a sustainable economy, industrial effluent management currently faces minimal liquid discharge or zero liquid discharge processes. To reduce energy consumption, forward osmosis has been introduced into zero liquid discharge system. The main disadvantage of forward osmosis is the high-energy consumption of the draw solution regeneration. Herein the regeneration stage is subjected to a techno-economic analysis using a novel membrane technology known as cascading osmotically mediated reverse osmosis. The objective of this work was the techno-economic study of water recovery from real effluents from the metallurgical industry, using a novel combined novel system. The liquid effluents employed in this work were real currents provided by Atlantic Cooper (Huelva, Spain). The experimental results showed that up to 75% of water can be recovered (for 20 L/m2·h at 20% of sodium chloride). The specific energy consumption and economic cost of the novel hybrid process were estimated as 7.4 kWhe/m3 and 6.05 $/m3 of recovered water, respectively. Thus, this novel proposal seems a promising alternative for zero liquid discharge systems in the metallurgical industry.

Gasification is a process which occurs when coal, char or mixtures of coal and other organic by-products, such as biomass or petcoke, react with an oxidizer to produce a gaseous fuel-rich product. Integrated Gasification Combined Cycle (IGCC) is a clean technology for power generation. IGCC by-products are related to the residues of syngas production. The most abundant residues are slag and sulfur, and to a lesser extent ash and ammonia. The quantities and composition of each by-product vary considerably depending on the gasification system and the feedstock characterization. In many cases, gasification plants are able to make the residue reusable as a raw material in other industries. The above-mentioned residues can be considered as a by-product depending on the plants’ ability to market and sell it. When utilization of residues is not possible, they have to be disposed of.

The paper is concerned with the recovery of germanium from dilute aqueous solutions. The method is based on the sorption of the selective complex formed by catechol with germanium onto low-cost anionic resins. Experimental investigations were undertaken using conventional quaternary ammonium macroporous resins: Amberlite IRA-900 and IRA-958. The influence of pH, metal concentration, and amounts of resin and catechol on the sorption capacity were investigated. For a proper set of experiments, a statistical technique such as a response surface methodology (RSM) has been used. For the investigation of the exchange equilibrium, the experimental data were analyzed using the Langmuir, Freundlich and Dubinin−Radushkevich equations, the Freundlich isotherm in general constituting a better fit. The uptake of the germanium complex by the ion-exchange resins was reversed by acid and neutral solutions. The results obtained showed better performance for IRA-900 than IRA-958, measured in terms of global recovery yields...