One of the byproducts of sugarcane bagasse combustion in sugarcane mills is sugarcane bagasse ash (SCBA), which contains up to ~40 mass% of organic matter. Currently, SCBA is partially used as a soil fertilizer. However, SCBA’s poor content of minerals, which are required by soils, restricts its use in soils, resulting in the disposal of large amounts of SCBA in landfills. Alternatively, SCBA has shown promise for some environmental applications such as wastewater treatment, but its use in gas cleaning deserves further study. The objective of this work was to assess the use of as-received SCBA to remove hydrogen sulfide (H₂S) from biogas, thus, to add value to the ash. The experimental procedure consisted of passing biogas containing H₂S through a column with SCBA and monitoring the H₂S content inline by employing a gas chromatograph until the concentration of H₂S, measured after the column, was ~10% of the original concentration. The breakthrough time of the SCBA adsorption curve was ~75% the breakthrough time observed with activated carbon, showing that SCBA could be a cheap alternative to commercial materials that are currently used for biogas scrubbing. This result could positively impact ethanol sugarcane mills that need to clean biogas produced from vinasses, as part of a strategy to integrate biogas production and cleaning operations using low-value residues (i.e., vinasses and ash). SCBA’s capacity for removing H₂S from biogas results from the presence of K-compounds (e.g., K₂SiO₃ and K₂Si₂O₅) on the ash’s surface and its relatively high porosity. Additionally, S-enriched SCBA (due to H₂S retention) can expectedly be more beneficial to soils than directly adding the ash since S is an essential nutrient for the growth of plants.

Although a number of works present biochar as a promising material for improving the quality of degraded soils, only a few show the effect of this material in soils from the Andean highlands. The objective of this work was twofold: (a) to study the effect of two types of biochars on two agricultural soils commonly found in the Andean highlands (Andisol and Inceptisol) and the corresponding soil–biochar–fertilizer interactions, and, (b) to assess the response to biochar of two vegetable crops (lettuce and radish) grown in succession in a simulated double-cropping system. Biochar was produced at 400 °C and 500 °C, for 1 h (B400 and B500, respectively), using hardwood residues. Properties of biochar that could potentially affect its interaction with soil and water (e.g., functional groups, surface area, elemental composition) were assessed. Experiments were conducted to test for main and interaction effects of biochar type, soil type, and the addition of NPK fertilizer on the soils’ characteristics. Bulk density and water content at field capacity and permanent wilting point were affected by two-way interactions between biochar and soil type. Biochar impacted bulk density and water retention capacity of soils. Higher available water content was found in soils amended with B400 than with B500, which is a consequence of the higher hydrophilicity of B400 compared to B500. After the lettuce crop was planted and harvested, the soil pH was unaffected by the biochar addition. However, after the second crop, the pH in the Inceptisol slightly decreased, whereas the opposite was detected in the Andisol. The CEC of the Inceptisol decreased (e.g., from 36.62 to 34.04 and from 41.16 to 39.11 in the control and in the Inceptisol amended with B400 only) and the CEC of the Andisol increased (e.g., from 74.25 to 90.41 in the control and from 79.61 to 90.80 in the Andisol amended with B400 only). Inceptisol amended only with biochar showed decrease of radish weight, while a large increase was found in B400 + fertilizer Inceptisol (i.e., from 22.9 g to 40.4 g). In Andisol, the weight of radish after the second crop increased in less proportion (i.e., from 43 g in the control to 59.7 g in the B400 + fertilizer Andisol), showing a visible positive impact of B400. The results suggest that biochar produced at 400 °C performs better than biochar produced at 500 °C because B400 apparently promotes a better environment for bacteria growth in the soils, as a consequence of more OH available groups in B400 and its better interaction with water and the fertilizer.

High dependency on fossil fuels, low energy efficiency, poor diversification of energy sources, and a low rate of access to electricity are challenges that need to be solved in many developing countries to make their energy systems more sustainable. Cogeneration has been identified as a key strategy for increasing energy generation capacity, reducing greenhouse gas (GHG) emissions, and improving energy efficiency in industry, one of the most energy-demanding sectors worldwide. However, more studies are necessary to define approaches for implementing cogeneration, particularly in countries with tropical climates (such as Ecuador). In Ecuador, the National Plan of Energy Efficiency includes cogeneration as one of the four routes for making energy use more sustainable in the industrial sector. The objective of this paper is two-fold: (1) to identify the potential of cogeneration in the Ecuadorian industry, and (2) to show the positive impacts of cogeneration on power generation capacity, GHG emissions reduction, energy efficiency, and the economy of the country. The study uses methodologies from works in specific types of industrial processes and puts them together to evaluate the potential and analyze the impacts of cogeneration at national level. The potential of cogeneration in Ecuador is ~600 MW_el, which is 12% of Ecuador’s electricity generation capacity. This potential could save ~18.6 × 10⁶ L/month of oil-derived fuels, avoiding up to 576,800 tCO₂/year, and creating around 2600 direct jobs. Cogeneration could increase energy efficiency in the Ecuadorian industry by up to 40%.