Chemical Energy Recovery Research Articles

Towards a high-rate operation of contact stabilization process: A microscopic view of carbon capture properties

Carbon capture performance is a key factor determining the chemical energy recovery potential of the high-rate contact stabilization (HiCS) process. However, the mechanisms of organic carbon capture are complex, involving surface adsorption, extracellular adsorption, and intracellular storage. A unique characteristic of the HiCS process is its low sludge residence time (SRT). Unfortunately, the influence of SRT on carbon capture has not been thoroughly studied, especially in terms of the underlying mechanisms. In this study, the microscopic changes in carbon capture performance during the transition from a conventional contact stabilized (CS) system to a high-rate mode of operation were demonstrated using intracellular carbon sources, extracellular polymeric substances (EPS), signaling molecules, and microbial community assays. The results showed that the extracellular carbon adsorption and intracellular carbon storage performance increased, and the microbial community structure changed significantly with converting the CS system to the high-rate operation mode. The enhancement of extracellular carbon adsorption performance mainly relied on the growth of EPS, which was accomplished by the strong growth of the relative abundance of the dominant bacterial group Cloacibacterium within the HiCS system, offsetting the negative effect produced by the decline of acyl-homoserine lactones. 98 mgCOD/gSS, 343 mgCOD/gSS, and 500 mgCOD/gSS of polyhydroxyalkanoates (PHAs) per sludge unit were obtained at SRT-24d, 8d, and 2d, respectively, suggesting that the HiCS system is more advantageous for rapid PHAs production.

Combining pre-fermentation and microbial electrolysis for efficient hydrogen production from food wastewater

Energy-rich food wastewater (FWW) offers a sustainable feedstock for bioelectrochemical hydrogen production. However, its complex characteristics and high suspended solids content hinder its direct utilization in dual-chamber microbial electrolysis cells (MECs) for producing high-purity hydrogen. This study explored pre-fermentation under uncontrolled pH conditions as a method to improve the exoelectrogenic utilization of FWW in dual-chamber MECs. Across 2–5 d hydraulic retention times (HRTs), pre-fermentation was effective in conditioning FWW to a more favorable composition for exoelectrogenic utilization. Short-chain organic acids and ethanol constituted 48–72% of the total chemical oxygen demand (COD) in pre-fermentation effluents, a substantial increase from 27% in raw FWW. In subsequent MEC experiments, the MECs fed with pre-fermentation effluents exhibited significantly higher current-generating and hydrogen-producing performance compared to those fed with raw FWW. The MECs fed with the 2-d HRT pre-fermentation effluent showed the highest hydrogen yield of 911 mL/g COD fed, which represents a 34.4% increase compared to the MECs fed with raw FWW, resulting in a 1.28-fold higher recovery of chemical energy from organic matter in raw FWW as hydrogen. The anode bacterial community was dominated by exoelectrogenic Geobacter in all MECs, with its abundance being significantly higher when utilizing pre-fermentation effluents (69.0–78.0%) compared to raw FWW (20.6–39.2%). Overall, pre-fermentation proved an effective conditioning approach for enhancing the exoelectrogenic utilization of FWW in MECs.

Removal of silica in rice husk derived Ni/biochar modifies reaction intermediates formed and minimizes coking in steam reforming of glycerol

Metal/biochar catalyst features with the advantages for easy recovery of chemical energy of biochar carrier and metal species via simply combustion. Another unique feature of biochar carrier is intrinsic inorganic species, which might also interact with metal species in resulting catalyst. This was investigated herein by synthesis of the Ni/biochar with rice husk-derived biochar carrier pretreated with NaOH for removal of SiO2 and evaluation of the resulting catalysts in steam reforming of glycerol. The solid phase reactions between NaOH and biochar (mass ratio: 2) plus subsequent washing removed 94.6% of ash (mainly SiO2). This formed Ni/biochar of fragmented surface with specific surface area increasing from 207.8 to 457.4 m2g-1 and simultaneously increasing mesopore percentage from 15.5% to 24.0%. NaOH treatment also effectively removed significant portion of both Lewis and Brønsted acidic sites but created abundant alkaline sites. These drastically enhanced nickel dispersion and activity for steam reforming. In-situ IR characterization suggested enhanced adsorption/activation of CO2 and H2O over Ni/biochar treated with NaOH (Ni/biochar-NaOH), which mitigated accumulation of coke precursors bearing CO or CC via accelerated gasification reactions. This led to the reduced amount of coke (mass ratio to catalyst) from 193.4% to 94.7% over Ni/biochar treated with 2-fold of NaOH or to 111.3% over Ni/biochar treated with 1-fold of NaOH. The coke formed was mainly catalytic type in form of carbon nanotube over Ni/biochar-NaOH. The superior resistivity to coking originated from developed pores, enhanced Ni dispersion and abundant alkaline sites from the NaOH treatment.

The recovery potential and utilization pathway of chemical energy from wastewater pollutants during wastewater treatment in China

Research on the potential for chemical energy recovery and the optimization of recovery pathways in different regions of China is still lacking. This study aimed to address this gap by evaluating the potential and optimize the utilization pathways for chemical energy recovery in various regions of China for achieving sustainable wastewater treatment. The results showed that the eastern and northeastern regions of China exhibited higher chemical energy levels under the existing operating conditions. Key factors affecting chemical energy recovery included chemical oxygen demand removal (ΔCOD), treatment scale, and specific energy consumption (μ) of wastewater treatment plants (WWTPs). Furthermore, the average improvement in the chemical energy recovery rate with an optimized utilization pathway was approximately 40% in the WWTPs. The use of the net-zero energy consumption (NZE) model proved effective in improving the chemical energy recovery potential, with an average reduction of greenhouse gas (GHG) emissions reaching next to 95% in the investigated WWTPs.

Pore-Matched Sponge for Microorganisms Pushes Electron Extraction Limit in Microbial Fuel Cells.

Microbial fuel cells (MFCs) are of great potential for wastewater remediation and chemical energy recovery. Nevertheless, limited by inefficient electron transfer between microorganisms and electrode, the remediation capacity and output power density of MFCs are still far away from the demand of practical application. Herein, a pore-matching strategy is reported to develop uniform electroactive biofilms by inoculating microorganisms inside a pore-matched sponge, which is assembled of core-shell polyaniline@carbon nanotube (PANI@CNT). The maximum power density achieved by the PANI@CNT bioanode is 7549.4±27.6mWm-2 , which is higher than the excellent MFCs with proton exchange membrane reported to date, while the coulombic efficiency also attains a considerable 91.7±1.2%. The PANI@CNT sponge enriches the exoelectrogen Geobacter significantly, and is proved to play the role of conductive pili in direct electron transfer as it down-regulates the gene encoding pilA. This work exemplifies a practicable strategy to develop excellent bioanode to boost electron extraction in MFCs and provides in-depth insights into the enhancement mechanism.

Recovery of chemical energy from retentates from cascade membrane filtration of hydrothermal carbonisation effluent

Organic fraction of municipal solid waste is a type of biomass that is attractive due to its marginal cost and suitability for biogas production. The residual product of organic waste digestion is digestate, the high moisture content of which is a problem, even after mechanical dewatering, due to the significant heat requirement for drying. Hydrothermal carbonisation is a process that can potentially offer great benefits by improved mechanical dewatering and valorisation of the digestate into a better-quality solid fuel. However, such valorisation produces liquid by-product effluent rich in organic compounds. Membrane separation could be used to treat such effluent and increase the concentration of the organic compounds while at the same time facilitating the recovery of clean water in the permeate. This work presents the results of the investigation performed using polymeric membranes. The study showed that membrane separation keeps a significant fraction of organics in the retentate. Such concentration significantly increases the biomethane potential of such effluent as well as the energy that could be theoretically used for the generation of process heat using the concentrated retentate in the wet oxidation process.

Hydrothermal Carbonisation as Treatment for Effective Moisture Removal from Digestate—Mechanical Dewatering, Flashing-Off, and Condensates’ Processing

One of the processes that can serve to valorise low-quality biomass and organic waste is hydrothermal carbonization (HTC). It is a thermochemical process that transpires in the presence of water and uses heat to convert wet feedstocks into hydrochar (the solid product of hydrothermal carbonization). In the present experimental study, an improvement consisting of an increased hydrophobic character of HTC-treated biomass is demonstrated through the presentation of enhanced mechanical dewatering at different pressures due to HTC valorisation. As part of this work’s scope, flashing-off of low-quality steam is additionally explored, allowing for the recovery of the physical enthalpy of hot hydrochar slurry. The flashing-off vapours, apart from steam, contain condensable hydrocarbons. Accordingly, a membrane system that purifies such effluent and the subsequent recovery of chemical energy from the retentate are taken into account. Moreover, the biomethane potential is calculated for the condensates, presenting the possibility for the chemical energy recovery of the condensates.

Greenhouse gas emissions from wastewater treatment plants in China: Historical emissions and future mitigation potentials

Accurate estimation of greenhouse gas (GHG) emissions characteristics and future mitigation potentials of China's wastewater treatment plants (WWTPs) is essential to propose suitable mitigation strategies. Here we employ the population-equivalent method recommended by the IPCC to analyze GHG emission characteristics and hotspots of China's WWTPs from 2005 to 2020 and assess the mitigation potentials by 2035. Results show that GHG emissions from China's WWTPs more than tripled from 13.34 Mt CO2-eq in 2005 to 30.95 Mt CO2-eq in 2020. Due to the differences in electricity consumption intensity, emission factors, and economic development level, there is significant spatial heterogeneity in the amount, structure, and intensity of emissions by province. Scenario analysis reveals that energy-saving improvement generates the largest mitigation potential (15%), followed by operational optimization (10%) and thermal energy recovery (10%), while chemical energy recovery (4%) and solar energy utilization (3%) contribute the least. Taking all mitigation measures, emissions can reduce by about 41% to 21.14 Mt CO2-eq in 2035. What's more, the mitigation effect of different decarbonization measures varies among provinces. Our results highlight the need for targeted policy in priority areas and region-specific strategies.

Coupling photocatalytic fuel cell based on S-scheme g-C3N4/TNAs photoanode with H2O2 activation for p-chloronitrobenzene degradation and simultaneous electricity generation under visible light

Environmental pollution and energy scarcity have become two major challenges with the vigorous development of industry, especially wastewater containing refractory organic pollutants with sufficient chemical energy. Photocatalytic fuel cells (PFCs) have been considered as effective techniques for refractory organic pollutants degradation and simultaneous chemical energy recovery. The poor visible light utilization of photoanode and limited mass transfer efficiency are unfavorable to organic pollution degradation and electricity generation of PFC system. In view of this, the hydrogen peroxide assisted photocatalytic fuel cell (H2O2-PFC) system with S-scheme g-C3N4/TNAs photoanode was constructed for refractory p-Chloronitrobenzene (p-CNB) degradation and electricity generation under visible light. The formed internal electric field between g-C3N4 and TiO2 enhanced visible-light absorption ability and photoelectrochemical properties through the inhibition of photogenerated carrier recombination. The activation of H2O2 in H2O2-PFC system promoted electron transfer and active radical production, which caused more superior p-CNB degradation and electricity generation performances of H2O2-PFC system than those of PFC system. The H2O2-PFC system possessed good stability for p-CNB degradation and electricity generation. The •OH was predominant active radical for p-CNB degradation, and photogenerated holes, •O2– and 1O2 were also involved in p-CNB degradation in H2O2-PFC system. The p-CNB degradation pathways were proposed through density functional theory calculation and gas chromatography mass spectrometry. The toxicity prediction demonstrated that the comprehensive toxicity of p-CNB was alleviated after degradation in H2O2-PFC system.

Novel Denitrification Fuel Cell for Energy Recovery of Nitrate-N and TN Removal Based on NH4+ Generation on a CNW@CF Cathode.

NO3- is an undesirable environmental pollutant that causes eutrophication in aquatic ecosystems, and its pollution is difficult to eliminate because it is easily converted into NH4+ instead of N2. Additionally, it is a high-energy substance. Herein, we propose a novel denitrification fuel cell to realize the chemical energy recovery of NO3- and simultaneous conversion of total nitrogen (TN) into N2 based on the outstanding ability of NH4+ generation on a three-dimensional copper nanowire (CNW)-modified copper foam (CF) cathode (CNW@CF). The basic steps are as follows: direct and highly selective reduction of NO3- to NH4+ rather than to N2 on the CNW@CF cathode, on which negative NO3- ions can be easily adsorbed due to their double-electron layer structure and active hydrogen ([H]) can be generated due to a large number of catalytic active sites exposed on CNWs. Then, NH4+ is selectively oxidized to N2 by the strong oxidation of chlorine free radicals (Cl•), which originate from the reaction of chlorine ions (Cl-) by photogenerated holes (h+) and hydroxyl radicals (OH•) under irradiation. Then, the electrons from the oxidation on the photoanode is transferred to the cathode to form a closed loop for external power generation. Owing to the continuous redox loop, NO3- completely reduces to N2, and the released chemical energy is converted into electrical energy. The results indicate that 99.9% of NO3- can be removed in 90 min, and the highest yield of electrical power density reaches 0.973 mW cm-2, of which the nitrate reduction rates on the CNW@CF cathode is 79 and 71 times higher than those on the Pt and CF cathodes, respectively. This study presents a novel and robust energy recycling concept for treating nitrate-rich wastewater.

Combined Hydrothermal Liquefaction of Polyurethane and Lignocellulosic Biomass for Improved Carbon Recovery

Due to the high versatility of Polyurethane (PUR), its share amongst synthetic polymers to manufacture consumer goods is increasing. This study proposes, tests and validates through pilot processing a highly efficient method for carbon recovery of PUR and in the form of an oil phase concentrated in carbon using hydrothermal liquefaction (HTL). Hot liquid water mixed with PUR residues and a lignocellulosic material (two species of Miscanthus) were treated at subcritical water temperatures, generating an oil-phase rich in hydrocarbons. A high synergistic effect in the co-liquefaction was observed, leading to a carbon and chemical energy recovery to the oil of 71 and 75% respectively. Pilot plant processing, using optimized process parameters, yielded a total process efficiency, accounting heating utilities, of 61%, resulting in a 3.2 ratio of energy return over investment. Using spectroscopic and high-resolution mass spectrometry analysis the oil revealed a high content of nitrogen hetero aromatic and polyol compounds. The high synergy observed for the co-liquefaction of PUR and miscanthus is attributed to recombination of synthetic and biological materials, specifically due to aromatics present in the media and nitrogen-containing compounds recombination. The results show that HTL can be an efficient method for carbon recovery of PUR aided by biomass.

Optimization of recovery and utilization pathway of chemical energy from wastewater pollutants by a net-zero energy wastewater treatment model

Recovering chemical energy from wastewater is an important route to reduce the electricity input in wastewater treatment plants (WWTPs), which can significantly decrease the carbon footprint of wastewater treatment. Existing evaluation models of energy self-sufficiency focused on macroscopic substance-energy flow and considered the overall energy balance of WWTPs but ignored the substance and energy conversion process via microbial metabolism. In this study, a net-zero energy (NZE) model was established based on microbial metabolism and energy balance to estimate the potential for chemical-energy recovery from wastewater pollutants and the optimization of metabolic substrate allocation, which was implemented in a large WWTP with anaerobic digestion. The results indicate that temperature and ΔCOD were key influence factors for specific energy consumption μ. The average energy self-sufficiency rate was 43.9% under the existing operations in the WWTP. The energy self-sufficiency rates with optimized substrate allocation ranged from 58.3% to 110.6%, with an average value of 78.8%. The energy self-sufficiency rates obtained in July and August were higher than 100%, indicating that the WWTP could achieve NZE status and output electric energy in July and August, but not in other months. Seasonal variation significantly affected the potential of chemical energy recovery from wastewater pollutants in the WWTP. The average reduction in greenhouse gas emissions with energy recovery under optimal operation conditions reached 76.4% in the WWTP studied herein. The enhanced anaerobic digestion efficiency and optimization of substrate allocation between catabolism and anabolism could increase the possibility of achieving NZE status based on the model.

A novel technology for liquefied synthetic natural gas production powered by renewable electricity: Process development and impact analysis on vehicular transportation

Overgeneration of wind energy conversion systems represents a grid issue, limiting the growth of renewable energy utilization. Alternative fuels utilization such as liquefied natural gas is emerging as a new market with a big potential in freight transport. In order to mitigate wind energy production curtailment, a power to liquefied synthetic natural gas process is proposed. Solid oxide electrolyser and catalytic methanation integrated system is applied to produce hydromethane. After a dehydration step in a temperature swing adsorption unit, low temperature gas upgrading techniques are applied for the first time to hydromethane mixture. Liquified synthetic natural gas is produced, meeting grid injection and endothermic engines requirements after regasification. A higher energy efficiency with respect to the application of traditional technologies is achieved. Plant configuration was optimized for internal thermal and chemical energy recovery and exploitation, achieving an overall electrical to chemical efficiency of about 50%. A case study was analyzed for the Irpinia (Italy) territory, strongly affected by wind energy overgeneration. Impact on local transport infrastructure was assessed through well-to-wheel analysis, considering the use of produced liquified synthetic natural gas in heavy duty vehicles. Greenhouse gas avoided emissions are expected to correspond to 7.1% of the vehicular emissions related to local traffic statistics for 2016.

Enhanced O2−[rad] and HO[rad] via in situ generating H2O2 at activated graphite felt cathode for efficient photocatalytic fuel cell

The use of a photocatalytic fuel cell (PFC) in wastewater treatment is an intensively researched topic because the device integrates organic pollutant degradation and chemical energy recovery. Herein, we proposed a strategy to enhance PFC performance by increasing the concentrations of hydroxyl radical (HO) and superoxide radical (O2−) produced from H2O2 generated in situ using an activated graphite felt (GF) cathode. This cathode was prepared by H2SO4 treatment to introduce oxygen-containing functional groups on its surface that would serve as surface-active sites and facilitate the two-electron pathway of H2O2 production. Remarkably, the peak current density of the activated GF cathode (−1.25 mA/cm2) was more than thrice that of the original GF cathode (−0.40 mA/cm2), and its Faradaic efficiency significantly improved from 20.01% to 74.09%. The PFC equipped with the activated GF cathode harvested 2.69 times the maximum power density (JVmax) and 5.15 times the degradation rate of the traditional Pt black-PFC system. This was because the O2− and HO concentrations, respectively, were 2.87 (23.98 × 10−5 M) and 2.48 times (13.00 × 10−4 M) as high as those in the Pt black-PFC system. These results were attributed to the high concentration of H2O2 generated in situ at the activated GF cathode, which was 25.13 times (0.402 mM) as high as that generated at the Pt black cathode. Thus, the proposed PFC system demonstrates the feasibility of improving organic pollutant degradation and energy recovery by enhancing H2O2 production.

NiFe layered double hydroxide/BiVO4 photoanode based dual-photoelectrode photocatalytic fuel cell for enhancing degradation of azo dye and electricity generation

Photocatalytic fuel cell (PFC) has recently emerged as a promising technology for simultaneous solar photocatalytic degradation of organic compounds and recovery of chemical energy stored in the organic compounds. Enhanced PFC using NiFe layered double hydroxide (LDH)/BiVO4 photoanode and Cu2O/Cu photocathode is first reported in this paper. The experimental results obtained show that the heterojunction photoanode can extend the spectrum of visible light absorption and effectively increase the photocurrent density. The superior characteristics are attributed to the heterojunction which decreases the interface recombination at the NiFe-LDH/BiVO4 junction and allows favorable Helmholtz layer potential drop. The short-circuit current, open-circuit voltage and maximum power density of the NiFe-LDH/BiVO4-Cu2O/Cu PFC are 0.196 mA cm-2, 0.647 V and 74 µW cm-2, respectively, in photocatalytic degradation of methylene blue dye.

Efficient purification and chemical energy recovery from urine by using a denitrifying fuel cell

Urine is a major biomass resource, and its excessive discharge would lead to severe aquatic nitrogen pollution and even eutrophication. In this study, we designed an innovative denitrifying fuel cell (DFC) under illumination to purify urine and convert its chemical energy into electricity. The central ideas include the following: 1) on the anode, chlorine radicals (Cl) and hydroxyl (HO) radicals were induced to react with amine or ammonia in urine into N2, and to mineralize organics into CO2, respectively; 2) on the cathode, NO2− or NO3− generated in the cell was selectively reduced to N2 and tiny NH4+ by Pd/Au/NF; 3) NH4+ was further oxidized to N2 by Cl according to process 1), then the total nitrogen (TN) was ultimately removed by a continuous redox loop between anode and cathode; 4) the separation and migration of charges were strengthened by a self-bias poly-Si/WO3 photoanode. Result indicated that the DFC showed an efficient yield of electricity and almost completely N-removing properties: power density of 2.24 mW cm−2, total nitrogen and total organic carbon (TOC) removal efficiency, respectively 99.02% and 50.76% for artificial urine; and power density of 2.51 mW cm−2, TN and TOC removal efficiency, respectively 98.60% and 54.55% for actual urine. The study proposes a potential and environment-friendly approach by using novel DFC to purify urine and generate electricity.

Primary sewage sludge filtration using biomass filter aids and subsequent hydrothermal co-liquefaction

Hydrothermal liquefaction (HTL) is a promising technology for biofuel production and treatment of wastewater sludge. The current study investigates a novel utilization of biomass-assisted filtration of primary sludge to obtain high dry matter (DM) content sludge. Drastic improvements in filtration speed are achieved using different types of lignocellulosic biomass filter aids prepared via mechanical pre-treatment. The combined sludge-biomass filter cake is subsequently used as a feedstock for HTL and shows superior bio-crude yields and properties compared to their individual counterparts. The chemical energy recovery to bio-crude is increased to 75% compared to 46% for biomass and 67% for sludge on its own. The increased DM content of filter cakes (∼25%) compared to primary sludge (5%) increases the energy efficiency of HTL of primary sludge by a factor of 4.5. Introducing a biomass filteraid-HTL combination to a wastewater treatment plant would reduce the organic carbon load to treat by 62%. By combining sludge with lignocellulosic biomass the use of alkali catalyst can be avoided entirely which represents a major cost factor in HTL of lignocellulosics.

Microbial Photoelectrosynthesis for Self-Sustaining Hydrogen Generation.

Current artificial photosynthesis (APS) systems are promising for the storage of solar energy via transportable and storable fuels, but the anodic half-reaction of water oxidation is an energy intensive process which in many cases poorly couples with the cathodic half-reaction. Here we demonstrate a self-sustaining microbial photoelectrosynthesis (MPES) system that pairs microbial electrochemical oxidation with photoelectrochemical water reduction for energy efficient H2 generation. MPES reduces the overall energy requirements thereby greatly expanding the range of semiconductors that can be utilized in APS. Due to the recovery of chemical energy from waste organics by the mild microbial process and utilization of cost-effective and stable catalyst/electrode materials, our MPES system produced a stable current of 0.4 mA/cm2 for 24 h without any external bias and ∼10 mA/cm2 with a modest bias under one sun illumination. This system also showed other merits, such as creating benefits of wastewater treatment and facile preparation and scalability.

Contact Stabilization with Enhanced Accumulation Process for Energy Recovery from Sewage

Abstract Conventional activated sludge (CAS) system is currently the predominant technology in wastewater treatment, but its painfully energy-intensive aerobic pathway has led researchers to investigate alternative technologies. These technologies are often focused on recovery of chemical energy from sewage. In this article, we introduce the CoSEA (Contact Stabilization with Enhanced Accumulation) process, a novel upconcentration method that separates the most valuable sewage content through a modified bioflocculation-adsorption-sedimentation-stabilization process for further anaerobic treatment. Raw sewage was treated in a 1 L psychrophilic (15°C) sequencing batch reactor (SBR). By using an SBR, a time–concentration gradient was applied to enhance accumulation abilities of the sludge. The reactor was operated at very low sludge age (<1 day) and with a short (1.5 h) aeration phase. We tested two initial conditions: (1) operation with inoculation by activated sludge and (2) without any inoculation. Average...

Recovery of D‐limonene through moderate temperature extraction and pyrolytic products from orange peels

ABSTRACTBACKGROUNDD‐limonene, a high‐value added molecule found in the flavedo of orange peels (about 0.7% w/w), is used in the nutritional, pharmaceutical and cosmetic fields. An accelerated moderate temperature extraction was investigated in order to recover D‐limonene. Furthermore, the residue from the extraction was used for energy recovery through the pyrolysis process.RESULTSThe proposed extractive process was able to recover D‐limonene up to 0.48 ± 0.002% w/w (on a wet basis) from orange peels at the highest investigated temperature (130 °C for 60 min). The residual matrix was then subjected to a dehydration step, which was carried out at room temperature for 10 days, in order to decrease the moisture from the porous surface, and then to a pyrolysis process. The average chemical energy recovery efficiency (91% ± 0.04) suggested that the thermochemical process is suitable for biofuel production.CONCLUSIONOrange peels can be exploited for the recovery of an important bio‐product and the residue can be used as feedstock for biofuels. This work has confirmed that accelerated extraction is more efficient than Soxhlet extraction (more than 68% w/w against 37% w/w of total D‐limonene, respectively), and that a pyrolysis process can be successfully performed on the residue. © 2016 Society of Chemical Industry