Alejandro Estrada-Baltazar

The waste, by-products, and rejects generated in the processing, distribution, and sale of bananas are not optimally utilized. If not properly managed, this organic waste can cause serious environmental problems. Between 24% and 40% of bananas are not marketed and end up in landfills until they decompose, mainly because they do not comply with export regulations. Although it is feasible to use this waste to produce flour and bioethanol, it is necessary to evaluate the potential environmental consequences of these processes. This study assessed the environmental viability of flour and bioethanol production from immature plantain within the plantain production chain in Mexico, using life cycle analysis (LCA). The functional unit for the agronomic stage was 1 kg of plantain produced for direct sale. In contrast, for the industrial processes, 1 kg of flour produced was used as the functional unit, with bioethanol as a co-product. A sensitivity analysis was performed by varying the allocation between mass and economic value, while holding the total product flow constant across scenarios. E-LCA was performed using SimaPro 9.6.0.1 with ReCiPe Midpoint (H) v1.13 and Ecoinvent v3.3 data. Monte Carlo simulations modeled input uncertainty using probability distributions, enabling variability/sensitivity analysis to support robust environmental results. The results showed that the transport of inputs, together with the use of machinery, fertilizers, herbicides, and insecticides, has the most significant environmental impact during cultivation. In addition, the production of flour and bioethanol has substantial implications due to the complexity of the underlying technological processes. In conclusion, this work provides reliable environmental inventories and criteria to support decisions aimed at reducing environmental impacts in the banana marketing chain, thereby contributing to its sustainability and the circular economy.

Mexico generated 8.9 million tons of food loss and waste (FLW) in the year 2022, which was primarily managed through linear economy schemes where final disposal sites are predominant, leading to significant contributions to climate change and economic losses. This study, as a continuation of a prior work (Part 1), aims to evaluate the economic and environmental feasibility of implementing waste-to-energy anaerobic digestion (WtE-AD) plants for FLW management across Mexico, identifying the key factors that influence the competitiveness of these systems compared to conventional waste management practices. Using the outcomes of an energy feasibility analysis (Part 1), alongside life cycle assessment (LCA), geographic information systems, and cost engineering, this research analyzes the eco-efficiency and viability of WtE-AD for FLW valorization throughout the Mexican territory. The results indicate that, with a conventional waste management fee of USD 35.4 t⁻¹, only the largest WtE-AD plant in the State of Mexico (treatment capacity of 2536.8 t FLW d⁻¹) achieved a positive net present value (NPV) of USD 70.1 million, while all the other plants remained economically unviable. Conversely, under an optimistic scenario with a fee of USD 139 t⁻¹, plants processing over 50 t FLW d⁻¹ achieved profitability, with the largest plant reaching an NPV of USD 1.15 billion. The environmental assessment showed that larger plants effectively act as carbon sinks, with the largest plant reducing emissions by up to −89.8 kg CO₂ eq t⁻¹ of FLW. These findings emphasize the need for appropriate waste management fees and governmental incentives to ensure the economic viability of WtE-AD plants. This study provides valuable insights for policymakers, highlighting the potential of WtE-AD technologies to contribute to Mexico’s energy transition and the shift toward a circular economy.

Waste to energy processes from anaerobic digestion (WtE-AD) from cattle manure (CM) have low CH₄ yields due to CM’s structural composition. The search for alternatives to increase the energy yields of these processes must consider the optimization of operating parameters within a framework of mitigating the environmental footprint. The goal of this paper is to provide a statistical optimization strategy based on experimental designs to improve CH₄ yields and reduce the environmental profile of CM valorization through a WtE-AD process. Biochemical methane potential tests were conducted to determine the energetic and environmental effects that alkaline pretreatments, different AD temperatures, and co-digestion formulations with fruit and vegetable waste (FVW) have on the WtE-AD process from CM. The evaluation was conducted following a life cycle assessment approach through energy balances. The results indicate that the highest CH₄ yield (384.3 mL CH₄ g VS⁻¹) and the lowest environmental impact (−0.06 kg CO₂ eq kWh⁻¹ of electricity production) were achieved with the co-digestion of CM with FVW 1:1, pretreatment with 10 g NaOH 100 g⁻¹ of VS of CM, and a temperature of 45 °C. It was found that the CM pretreatment with NaOH substantially increases the energy profile of the WtE-AD process without compromising the environmental impact since greenhouse gas emissions in chemical production are negligible.

The environmental profile of milk production in Mexico was analysed for three manure management scenarios: fertilization (F), anaerobic digestion (AD) and enhanced anaerobic digestion (EAD). The study used the life cycle assessment (LCA) technique, considering a ‘cradle-to-gate’ approach. The assessment model was constructed using SimaPro LCA software, and the life cycle impact assessment was performed according to the ReCiPe method. Dairy farms with AD and EAD scenarios were found to exhibit, respectively, 12% and 27% less greenhouse gas emissions, 58% and 31% less terrestrial acidification, and 3% and 18% less freshwater eutrophication than the F scenario. A different trend was observed in the damage to resource availability indicator, as the F scenario presented 6% and 22% less damage than the EAD and AD scenarios, respectively. The magnitude of environmental damage from milk production in the three dairy manure management scenarios, using a general single score indicator, was 0.118, 0.107 and 0.081 Pt/L of milk for the F, AD and EAD scenarios, respectively. These results indicate that manure management systems with anaerobic digestion can improve the environmental profile of each litre of milk produced.