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Pretreatments have been identified as the core of lignocellulosic biorefinery design due to biomass fractionation and the influence on subsequent reaction and downstream processes. However, most pretreatments are described as single-step, maximizing the valorization of a side stream. Therefore, sequential pretreatments could better describe the integral valorization of lignocellulosic biomass to obtain platform products that can be further used for value-added products. This work experimentally analyzed the sequential pretreatments for the fractionation of rice husks to obtain individual lignocellulosic fractions. It was demonstrated that the dilute acid-wet air oxidation (DA-WAO) sequence is suitable for biorefinery designs since it is possible to solubilize up to 80% of hemicellulose during the first stage and subsequently fractionate almost 90% of lignin after the second stage, obtaining a pretreated solid with high cellulose content. The isolated lignocellulosic fractions were used as platform products to obtain furfural, levulinic acid, and phenolic compounds. As a main result, yields and conversions were improved when valorizing the cellulose platform based on sequential pretreatment. In contrast, valorizing the black liquor after a combination scheme decreased aldehyde yields such as vanillin and syringaldehyde by 4.8–11.9%. The findings indicate that from the biorefinery approach, sequential pretreatments improve the yield of platform products. Despite the decrease of phenolic compounds, levulinic acid and furfural production is significantly enhanced.

The industrial applicability of exotic and wild fruits has been investigated as stand-alone processes framed to obtain a single main product. However, their combination and the valorization of the processing residues in a biorefinery scheme have not been explored. Therefore, this work aims to assess the technical and economic feasibility of small-scale biorefineries based on annatto and açai as raw materials. Therefore, the actual processing of both fruits was carried out experimentally. For annatto, the abrasion extraction of dye paste was performed, obtaining mass yields of up to 58.4% by working with ground seed. Regarding the açai, the pulp was obtained with a polyphenol content of 23.56 mg of gallic acid equivalent per gram of sample. The residues generated in both processes were used as substrates for biogas production, achieving biomethane yields between 186 and 533 mL gTVS−1. These results were the basis for designing and simulating process scale-up in biorefinery contexts. Five scenarios were evaluated, involving the production of annatto dye paste, açai pulp, biogas from exhausted annatto seeds, slurry and seeds of açai, and feedstock integration. As the main energy result, it was found that the scenarios contemplating biogas production can supply thermal energy to more than 1400 households. From the economic perspective, it was found that economic feasibility is reached at flows below the national production in Colombia for all scenarios. This work demonstrated that small-scale biorefineries based on the processing of tropical forest fruits are an opportunity to improve the life quality of communities through the coupling of techno-economic results with social and governmental needs to strengthen the value chains of low-technified fruits in agribusiness.

Panela is the second most important rural agro-industry after coffee in Colombia. This agro-industry produces a large amount of bagasse from non-centrifugal sugar (B-NCSP) without valorization. B-NCSP is used in combustion boilers in panela production, causing greenhouse gas emissions and health problems. This research aims to compare the sustainability of two B-NCSP biorefineries considering the current residue use. The sustainability of the biorefinery scenarios was analyzed to promote rural economic development in Colombia. In both biorefinery scenarios, biogas was evaluated as an energy vector to meet the energy demand of panela production. Two biorefinery scenarios were considered: (i) saccharification, bioethanol, and biogas production and (ii) acid pretreatment, saccharification, xylitol, bioethanol, and biogas production. Experimental data of the pretreatment, saccharification, and anaerobic digestion stages were used as input information in simulations. Technical, economic, environmental, and social metrics were used to estimate a sustainability index. The experimental glucose yield in scenario 2 was 0.42 ± 0.03 (31.52 ± 2.36 g/L) g/g B-NCSP, 1.8 times greater than scenario 1. The biogas yield in scenario 2 was 504.23 ± 21.68 (71.16% CH4) L/kg B-NCSP, 3.3 times greater than scenario 1. Scenario 1 was unfeasible at different scales. Xylitol production helps to improve the economic feasibility in scenario 2 since the payback period was 15 years. This scenario can create 36 job positions with a wage 18% higher than the minimum wage in Colombia (highest sustainability index of 72.44%). Finally, biogas produced in scenario 2 supplies 62.76% of the energy demand needed in the panela production process, reducing the environmental impact.

Graphical abstract:

The use of lignocellulosic biomass to produce commercial high-value products has taken force in recent years. Aromatic plants are key raw materials to obtain bioactive compounds with high added value, such as phenolic compounds, but its extraction produces a high amount of wastes. In this sense, the present work aimed to evaluate experimentally the extraction of phenolic compounds from thyme and subsequently, the production of biogas from the remaining of the extraction. To evaluate the prefeasibility of the processes, the simulations of the stand-alone (conventional extraction), as well as the biorefinery (phenolic compounds extraction, biogas production, and a cogeneration system), were carried out and evaluated according to technical, economic, and environmental approaches. The bioactive compound extraction yield was 11.95% (w/w) and the methane yield was 114 ml/g volatile solids. In the present work, it was suggested that the stand-alone process becomes to be profitable from a small scale (23 T/day) in comparison with the biorefinery approach, which needs to be worked on a major scale (61 T/day) to be economically feasible. The comparison of the environmental impact generated by each scheme shows the major impact for the biorefinery case.

Catheter ablation is an effective therapy for atrial fibrillation (AF). However, risks remain, and improved efficacy is desired. Stereotactic body radiotherapy (SBRT) is a well‐established therapy used to noninvasively treat malignancies and functional disorders with precision. We evaluated the feasibility of stereotactic radioablation for treating paroxysmal AF. Two patients with drug‐refractory paroxysmal AF underwent pulmonary vein isolation with SBRT. After placement of a percutaneous active fixation temporary pacing lead tracking fiducial, computed tomography (CT) angiography was performed to define left atrial anatomy. A tailored planning treatment volume was created to deliver contiguous linear ablations to isolate the pulmonary veins and posterior wall. Patients were treated on an outpatient basis in the radioablation suite. Clinical follow‐up was performed through at least 24 months after therapy. Both patients successfully underwent SBRT planning and treatment without significant early or long‐term side effects up to 48 months of follow‐up. One patient had AF recurrence after 6 months free of arrhythmia, while the second patient remains free of AF after 24 months with fibrosis detected on MRI scan consistent with the ablation lesion set. An incidentally noted small pericardial effusion occurred in one patient. Stereotactic radioablation may be feasible for the treatment of drug‐refractory AF. Further evaluation is warranted. We evaluated the feasibility of stereotactic radioablation for treating paroxysmal atrial fibrillation. Two patients with drug‐refractory paroxysmal atrial fibrillation underwent pulmonary vein isolation with SBRT and followed for more than 24 months; one patient remained free of AF, with MRI findings consistent with left atrial fibrosis at ablation sites. We conclude that it is feasible to apply radioablation to the treatment of AF and further evaluation is warranted.

Introduction:Catheter ablation for atrial fibrillation (AF) is effective but requires an invasive and often prolonged procedure with attendant risks. Stereotactic body radiotherapy (SBRT), often used for targeted tumor ablation, is a noninvasive alternative to achieve pulmonary vein isolation with proof of concept provided by animal studies.Hypothesis:We hypothesized that it feasible to deliver a treatment volume using SBRT for isolation of the pulmonary veins and posterior wall to treat AF.Methods:5 symptomatic AF pts (age 68?11, 3 male, 3 with metastatic malignancy, 3 persistent/permanent AF, time since AF diagnosis 6.6?2.1 yrs, LA diameter 41.6?7.6mm) with structurally normal hearts underwent SBRT after failing antiarrhythmic therapy for symptomatic AF. Prescribed dose of 25.2?3.6Gy over 96?13.4min was delivered aiming to isolate the pulmonary veins and posterior wall.Results:SBRT was well tolerated and without clinically significant adverse events over a median follow-up of 6 (IQR 5-24) months. A small asymptomatic incidentally detected pericardial effusion occurred in 1 patient. 1 pt was deceased at 4 days post treatment due to malignancy; at autopsy, an inflammatory infiltrate and fibroblasts were seen at left atrial ablation sites. Median AF free survival in the remaining 4 pts was 4.5 (IQR3-10.5) months, with 1 pt remaining free of AF at 24 months where cardiac MRI demonstrated fibrosis in the atrium consistent with ablation. In 1 pt where oesophageal electrograms were recorded, SBRT diminished amplitude following treatment and repeat assessment at 3months demonstrated posterior wall isolation.Conclusions:SBRT is feasible, and potentially safe and effective for non-invasive pulmonary vein and posterior wall isolation to treat AF. Methods to determine effective electrical isolation with this technique are required given its non-invasive nature and delayed time course for conduction block due to the mechanism of tissue injury.