Application of an integrated pyrolysis and chemical leaching process for pulper waste conversion into coal, hydrogen and chemical flocculating agent.

This work aims to investigate the potentials of integrating slow pyrolysis and chemical leaching to recycle pulper waste (PW), the waste generated by paper mills, and consists of plastics, metallic films, and biobased polymers. The concentration of chlorine and metals is a barrier against PW valorisation by combustion or high temperature thermochemical processes. In this study, PW was tested by slow pyrolysis at 400 °C and 500 °C. Chemical leaching tests were performed by processing both chars in a 1.4 M HCl solution, at 80 °C for 2 h, to remove inorganic compounds and upgrade the char to a coal-like material. Then, precipitation by NaOH was conducted on the leachate. Slow pyrolysis led to a char mass yield around 30 %. Due to the high inorganic matter concentration (almost 36 %, mainly including chlorine, calcium, and aluminium), the char retained only 25 % of the feedstock's chemical energy, while the remaining 75 % was recovered in the pyrogas. Leaching of the 500 °C pyrolysis char led to extract 93 % of aluminium, and almost 100 % of calcium and chlorine, resulting in an upgraded char containing 15.5 % ash, comparable to a fossil coal. By char leaching, the oxidation reaction of aluminium could produce 8 kg hydrogen per dry ton PW. The effectiveness of the precipitated compounds as flocculating agents was demonstrated, enabling a closed-loop recycling in the same paper mill. In conclusion, the proposed process demonstrated to be an effective solution to convert PW into high quality products.

Study on the effects of carbon dioxide atmosphere on the production of biochar derived from slow pyrolysis of organic agro-urban waste.

Slow pyrolysis, a widely recognized thermochemical technique, is employed to produce biochar usually under inert atmospheres. Recently, there is a growing interest in utilizing CO2 as a carrier gas during pyrolysis as an alternative to inert atmospheres, aiming to modify the resulting pyrolytic products and make them suitable for different applications. This study investigated and compared the impact of CO2 atmosphere with N2 on pyrolysis of food waste, rice husk, and grape tree branches waste via slow pyrolysis at temperatures of 400, 500, and 600 °C at 5 and 15 °C/min for 1 h, to evaluate biochar production and its properties. The results demonstrate that CO2 atmosphere increased the biochar yield for all feedstocks and significantly influenced the physicochemical properties of biochar. Compared to N2, CO2-derived biochar exhibited less volatile matter, higher carbon content, lower O/H and O/C molar ratios and enhanced textural properties. This study highlighted the potential of utilizing CO2 for biochar production and tailoring biochar properties for specific applications and the findings contribute to the establishment of sustainable and efficient waste management systems and the production of value-added biochar products.

Assessment of the Use of Common Juniper (Juniperus communis L.) Foliage following the Cascade Principle.

Juniperus communis L. is a species commonly grown in regions of the Northern Hemisphere, and is a good candidate to be cultivated in marginal lands. Plants coming from a pruning performed in a natural population located in Spain were used to assess the yield and quality of different products obtained following the cascade principle. A total of 1050 kg of foliage biomass were crushed, steam-distilled, and separated into fractions to produce biochar and absorbents for the pet industry using pilot plants. The obtained products were analysed. The essential oil, with a yield of 0.45% dry basis and a qualitative chemical composition similar to that described for the berries in international standards or monographs, showed antioxidant activity with promising CAA results (inhibition of 89% of the cell's oxidation). However, regarding antibacterial and antifungal activities, it only inhibited the growth of microorganisms at the maximum concentration tested, 2.5%. Concerning the hydrolate, it did not show bioactivity. Regarding the biochar, whose yield was 28.79% dry basis, interesting results were obtained for its characterisation as a possible soil improver for agronomic purposes (PFC 3(A)). Finally, promising results were obtained regarding the use of common juniper as absorbent, taking into account the physical characterisation and odour control capacity.

Recovery of Terephthalic Acid from Densified Post-consumer Plastic Mix by HTL Process.

In this study, we investigate the hydrothermal liquefaction (HTL) of PET separated from a densified postconsumer plastic mix, with the aim of recovering its monomer. This second raw material is made up of 90% polyolefin, while the remaining 10% is made up of PET, traces of metals, paper, and glass. After preliminary separation by density in water, two batch experiments were performed on the sunken fraction (composed mainly of PET) in a stainless steel autoclave at 345 °C for 30 and 20 min. Both trials resulted in similar yields of the three phases. In particular, the solid yield is around 76% by weight. After a purification step, this phase was analyzed by UV-Vis, 1H-NMR, and FTIR spectroscopy and resulted to be constituted by terephthalic acid (TPA), a product of considerable industrial interest. The study proved that the hydrothermal liquefaction process coupled with density separation in water is effective for obtaining TPA from a densified postconsumer plastic mix, which can be used for new PET synthesis.

Bioeconomy and green recovery in a post-COVID-19 era.

The spread of the COVID-19 pandemic has generated a health crisis and repetitive lockdowns that disrupted different economic and societal segments. As the world has placed hope on the vaccination progress to bring back the socio-economic "normal," this article explores how the bioeconomy can enhance the resilience and sustainability of bio-based, food, and energy systems in the post-COVID-19 era. The proposed recovery approach integrates technological innovations, environment, ecosystem services, "biocities," food, rural economies, and tourism. The importance of integrating culture, arts, and the fashion industry as part of the recovery is underlined towards building a better bioeconomy that, together with environmental safeguards, promotes socio-cultural and economic innovations. This integration could be achieved supporting communities and stakeholders to diversify their activities by combining sustainable production with decarbonization, stimulating private investments in this direction and monitoring the resulting impact of mitigation measures. Food systems should become more resilient in order to allow adapting rapidly to severe crises and future shocks, while it is important to increase circularity towards the valorization of waste, the integration of different processes within the biorefinery concept and the production of bio-based products and biofuels.

Towards a better understanding of the HTL process of lignin-rich feedstock.

The hydrothermal liquefaction reactions (HTL) in subcritical conditions of a lignin residue has been studied on a lab scale. The starting material was a lignin rich residue co-produced by an industrial plant situated in Northern Italy producing lignocellulosic bioethanol. The reactions were carried out in batch mode using stainless steel autoclaves. The experiments were under the following operating conditions: two different temperatures (300-350 °C), the presence of basis catalysts (NaOH, and NH4OH) in different concentrations and the presence/absence of capping agent 2,6-bis-(1,1-dimethylethyl)-4-methylphenol (BHT). Lignin residue and reaction products were characterized by analytical and spectroscopic techniques such as CHN-S, TGA, GC-MS, EPR, and 1H-NMR with (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (T.E.M.P.O.). The addition of BHT did not significantly affect the yield of char which is formed by radical way. Spectroscopic analysis indicated that the level of radicals during the reaction was negligible. Therefore, the results obtained experimentally suggest that the reaction takes place via an ionic route while radical species would play a minor role.

Security of supply, strategic storage and Covid19: Which lessons learnt for renewable and recycled carbon fuels, and their future role in decarbonizing transport?

The present work analyses the lessons learnt from the Covid19 (Coronavirus) pandemic that could possibly apply to the energy sector, with a special focus to decarbonizing transport. Distinguishing between short/medium- and medium/long-term options, the scope is to discuss how issues such energy security, energy storage and energy system resilience should deserve more attention. Today, fuel demand has fallen to unprecedented levels, with jet fuel demand being the most affected one. Oil price is at the lowest values recorded for many years while on 20 April it even reached a negative price in the US for the first time in history. While in the short-term low oil prices would be attractive, the long-term negative consequences could be very relevant, with significant associated costs for the EU economy and Member states (MS) related to the collapse of demand and to the socio-economic impacts. New measures should thus be considered in the post Covid19 strategy. In particular, while in a short- to medium-term view the oil sector will require specific support measures to overcome the economic and physical shock brought in by the pandemic, in a medium to long-term perspective domestic sources such as Renewable and Recycled Carbon Fuels (RRCF) should be regarded as a way to secure energy supply, leading to significant technical and economic advantages. Thus, EU should allocate adequate resources in the post-Covid recovery plans to definitely allow the transition to renewable energy sources and particularly to bio-based economy and stainable transport fuels. Decarbonisation of transport through RRCF and economic recovery do not compete, but rather represent a win-win solution in a well-designed and sustainable implementation strategy, especially when low or zero interest-rate investments are foreseen. The EU should take the opportunity to match the UN SDG (Sustainable Development Goals) and EU Green Deal goals with the need to inject economic and financial resources into the real economy improving the socio-economic conditions of EU populations. Both agroforestry and RRCF industry are ready to produce (biomass) or source (waste) the feedstocks as well as the technologies, systems and components needed by the industry along the whole value chain. The roadmap to cleaner transport fuels thus represent an evident opportunity to meet climate, economic and societal post-Covid19 goals, in a win-win-win approach.

Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations.

Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal's energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

Oil production by the marine microalgae Nannochloropsis sp. F&M-M24 and Tetraselmis suecica F&M-M33.

Nannochloropsis sp. F&M-M24 and Tetraselmis suecica F&M-M33 were cultivated outdoors in Green Wall Panels under nutrient deficiency to stimulate oil synthesis. Under nitrogen deprivation, Nannochloropsis attained average biomass and lipid productivities of 9.9 and 6.5 g m(-2) day(-1), respectively. Starved Tetraselmis cultures achieved a biomass productivity of about 7.6 g m(-2) day(-1) and a lipid productivity of 1.7 g m(-2) day(-1). Lipids represented 39.1% and 68.5% of non-starved and starved Nannochloropsis biomass, respectively. Starvation did not increase lipid content in Tetraselmis biomass. Important differences in lipid classes and in fatty acid composition were observed under the different cultivation conditions for both microalgae.