Carbon abatement via treating the solid waste from the Australian olive industry in mobile pyrolysis units: LCA with uncertainty analysis

Biochar from date palm (Phoenix dactylifera L.) residues—a critical review

Biochar, a carbon rich organic amendment, derived from organic biomass by pyrolysis under high-temperature and zero oxygen condition, is a soil amendment to enrich soil with essential nutrients. Biochar is multidimensional in its benefits, including increase in soil carbon sequestration, reduction in green house emission, improved soil fertility, and prolonged soil moisture retention capability to overcome drought. Biochar can be produced from a wide array of biological residues, contributed by plants as well as animals. Date palm a common plant in Gulf region, leave enormous quantity of residues, which are disposed or burnt as waste in farms, that acts as a source of pollution in date-producing nations. The residual biomass from dates is utilized in cattle feed production in some countries. Disposing these residues without harming the environment is a challenge and the perfect solution is biochar. Based on the unique abatement potential of biochar and its functions to improve soil health and soil carbon sequestration, biochar can be considered as long-term agriculture adaptation strategy. This comprehensive review highlights the production of biochar from date palm biomass, the influence of different date palm parts in biochar production, and their potential benefits to the community. It is realized that the knowledge of biochar from date palm residues is still in its infancy which requires concerted efforts to educate the date palm farming community to utilize the valuable biomass from date palm for transformation to a nutritious and eco-friendly product, biochar.

Bibliometric Mapping of Research on Life Cycle Assessment of Olive Oil Supply Chain

The olive oil supply chain and even its individual stages have been extensively investigated through life cycle assessment (LCA) in recent decades. Most practices of the olive oil supply chain have been associated with negative environmental effects, such as soil degradation, carbon dioxide emissions, air and ground pollution, and depletion of groundwater. The current work aimed to perform a bibliometric analysis, through a science mapping approach, coupled with a review on the life cycle assessment (LCA) studies of the olive oil sector, with relevance to the environmental impacts of agricultural and industrial practices of this food sector. A total of 110 documents published in 2008–2021 were analyzed and discussed. More than 78% of documents were released from 2015. The main Scopus categories relating to the topic analyzed were environmental sciences (25%), energy (18%), and engineering (17%). The most productive countries were Italy, Spain, and Greece. The cluster analysis identified three main research topics related to the “agricultural phase”, “oil extraction”, and “waste management and by-product valorization”. Most of the recent publications focused on the application of LCA to evaluate the environmental impact of innovative agricultural practices, sustainable control of parasites and weeds, wastes, and by-products valorization within a circular economy.

Measuring Circularity in Food Supply Chain Using Life Cycle Assessment; Refining Oil from Olive Kernel

Valorization of food waste is a potential strategy toward a circular food supply chain. In this regard, measuring the circularity of food waste valorization systems is highly important to better understand multiple environmental impacts. Therefore, this study investigated the circularity of a food waste valorization system (refining oil from olive kernel) using a life cycle assessment methodology. An inventory of an industrial-based olive kernel oil production system is also provided in this study. The system boundary was the cradle to the factory gate of the production system. The results indicated that natural gas consumption was the highest contributor to most of the investigated impact categories. The global warming potential of one kg of oil produced from olive kernel was calculated to be 1.37 kg CO₂eq. Moreover, the calculated damages of 1 kg oil production from olive kernel to human health, ecosystem quality, and resource depletion were 5.29 × 10⁻⁷ DALY, 0.12 PDF∙m²∙yr., and 24.40 MJ, respectively.

Removal of phenolic compounds from aqueous solution using MgCl2-impregnated activated carbons derived from olive husk: the effect of chemical structures

Activated carbon (BC) prepared from olive oil solid waste (olive husk) by slow pyrolysis was chemically activated using MgCl₂ (BC-MgCl₂). The BC and BC-MgCl₂ were used as adsorbents for removal of three phenolic compounds, namely, phenol (P), p-methoxyphenol (PMP) and p-nitrophenol (PNP), from aqueous solution. The uptake of these three phenolic compounds by the BC and BC-MgCl₂ was better expressed by the Langmuir and Dubinin-Radushkevich (D-R) isotherm models than by the Freundlich isotherm, and the kinetics of the adsorption process followed the pseudo-second order kinetic model. The maximum monolayer adsorption capacity of P, PMP and PNP were increased from 24.938, 45.455 and 61.728 on BC to 43.860, 98.039 and 121.951 mg/g on BC-MgCl₂ by factors of 1.76, 2.16 and 1.98, respectively. Therefore, the chemical activation of BC by MgCl₂ is indeed of importance for improving its adsorption performances. For both adsorbents, the adsorption phenomenon for different substituted phenols is a strong function of solubility, polarity, molecule structure, and size. At the tested temperatures (25, 35 and 45 °C), the negative values of ΔG° and positive values of ΔH° and ΔS° for the adsorption of P, PMP and PNP on BC and BC-MgCl₂ demonstrated that the adsorption was a spontaneous, endothermic and entropy-increasing process.

Co-pyrolysis of lignocellulosic and macroalgae biomasses for the production of biochar - A review

Biochar properties are significantly influenced and controlled by biomass feedstock type and pyrolysis operating conditions, and the development of multiple biochar properties for various applications has necessitated the need for blending different feedstocks together. Co-pyrolysis as a potential technology has been proposed to improve the overall performance of biomass pyrolysis and has proved effective in improving biochar properties. Consequently, the combination of lignocellulosic and macroalgae biomasses has been targeted for biochar production and improvement of biochar properties through co-pyrolysis. This paper therefore presents a critical review of biochar production from co-pyrolysis of lignocellulosic and macroalgae biomass (CLMB). It discusses the biomass feedstock selection, characterization, pre-processing and suitability for thermal processing; and analyzes biochar production, characterization and reactor technologies for CLMB. Furthermore, the potential and economic viability of biochar production system from CLMB are highlighted; and finally, the current state and future directions of biochar production from CLMB are extensively discussed.

Environmental impacts in the life cycle of olive oil: a literature review

The production of olive oil is considered to be one of the largest agricultural business sectors in the Mediterranean area. Apart from its significant impact on the economies of countries in Southern Europe, Northern Africa and Middle East, olive oil production also involves considerable social and environmental considerations. However, despite such importance, the environmental effects of olive oil production have not been studied as much other agricultural productions and farming systems, which are more characteristic of central and northern Europe. We present a thorough and systematic literature review of scientific publications with respect to the use of environmental tools in the life cycle of olive oil. The analysis takes into consideration the farming of olive trees, the manufacture of olive oil, packaging, transportation and reverse logistics. To that end, journal publications up to 2015 in this specific field are recorded and, at the same time, the most important environmental impacts are revealed and a gap analysis is carried out. The analysis conducted reveals that farming of olive trees (with pesticide use and waste/by-product production being the 'hottest' topics) and the manufacturing of olive oil (concentrating mostly on waste/by-product production and management) are the phases with the highest environmental focus from the scientific community. Moreover, gaps in the literature are detected mostly with respect to fuel consumption and the use and promotion of renewable energy sources in olive oil production. © 2016 Society of Chemical Industry.

Characterization of biochar prepared from slow pyrolysis of Jordanian olive oil processing solid waste and adsorption efficiency of Hg2+ ions in aqueous solutions

Solid waste from Jordanian olive oil processing (OOSW) was used to prepare biochar samples by slow pyrolysis at terminal temperatures of 350, 450, 550 and 630 °C; henceforth known as BC-350, BC-450, BC-550 and BC-630, respectively. These samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction, ash content, moisture content and surface area. The ability of the biochar to remove Hg²⁺ ions from aqueous solutions was investigated in laboratory scale batch experiments. The kinetics, effect of pH and temperature were studied. The optimum pH value for Hg²⁺ adsorption was 5. Dubinin-Radushkevich (D-R) isotherm model was the best fit for the experimental results. Based on the D-R model, the maximum adsorption capacities at 25 °C were 84.93, 94.48, 96.11 and 104.59 mg.g^-1, for BC-350, BC-450, BC-550 and BC-630, respectively. The pseudo-second-order kinetic model was a good fit for the experimental data. The calculated change in free energy ΔG and enthalpy ΔH indicated that the adsorption process was spontaneous and exothermic in nature. The positive value of ΔS showed increased randomness of the solid/solution interface during the adsorption. The results indicated that biochar derived from OOSW can be a good adsorbent for treatment of water contaminated with Hg²⁺.

Biofuels from pyrolysis in perspective: trade-offs between energy yields and soil-carbon additions

Coproduction of biofuels with biochar (the carbon-rich solid formed during biomass pyrolysis) can provide carbon-negative bioenergy if the biochar is sequestered in soil, where it can improve fertility and thus simultaneously address issues of food security, soil degradation, energy production, and climate change. However, increasing biochar production entails a reduction in bioenergy obtainable per unit biomass feedstock. Quantification of this trade-off for specific biochar-biofuel pathways has been hampered by lack of an accurate-yet-simple model for predicting yields, product compositions, and energy balances from biomass slow pyrolysis. An empirical model of biomass slow pyrolysis was developed and applied to several pathways for biochar coproduction with gaseous and liquid biofuels. Here, we show that biochar production reduces liquid biofuel yield by at least 21 GJ Mg(-1) C (biofuel energy sacrificed per unit mass of biochar C), with methanol synthesis giving this lowest energy penalty. For gaseous-biofuel production, the minimum energy penalty for biochar production is 33 GJ Mg(-1) C. These substitution rates correspond to a wide range of Pareto-optimal system configurations, implying considerable latitude to choose pyrolysis conditions to optimize for desired biochar properties or to modulate energy versus biochar yields in response to fluctuating price differentials for the two commodities.