Life cycle environmental impacts of bioethanol production from sugarcane molasses in Iran

Assessing the energy load and environmental footprint of potash fertilizer production in Iran

The goal of this research was to analyze the energy and environmental impact of KCL and K2SO4 production and provide recommendations for enhancing energy efficiency and environmental practices. Data was collected through face-to-face interviews at two potash plants and the CML methodology was employed to assess impact categories. Inventory data for production inputs were sourced from the Ecoinvent, BUWAL 250, and LCA Food DK databases within the Simapro 8.03.14 software. The results showed that the production of one ton of K2O as KCL and K2SO4, required 7080.82 and 15691.5 MJ, respectively. Electricity accounted for 52.96% of energy input in KCL production, whereas fuel oil constituted 38.39% in K2SO4 production. Energy ratios, energy productivity and specific energy for K2SO4 was 0.40, 0.06 kgMJ-1, and 15.6 MJkg-1, while corresponding indices for KCL were 0.90, 0.14 kgMJ-1 and 7.08 MJkg-1, respectively. In KCL production, electricity had eight impact categories, while the use of KCL as a raw material in K2SO4 production had significant effects on seven impact categories. Considering the vast and unoccupied space available in Iran's great desert, where the KCL plant is situated, the installation of a photovoltaic power station near the plant could greatly enhance energy efficiency and reduce emissions.

Digestion of lignocellulosic biomass under an innovative pneu-mechanical system and optimization of process

In this study, an anaerobic pneumatic mechanical digester (PMD) was designed for the first time to investigate the impact of pneumatic agitator on increasing the bioethanol production and compared with a mechanical digester (MD). Fermentation was performed during an optimized pretreatment and hydrolysis process by RSM (Response Surface Method). Ultrasound optimized points (the time values, the acid concentration, and the biomass load) were 30 min, 1.95% v/v, and 6%, and hydrolysis was done within 45 min at the acid concentration of 2.04% v/v and temperature of 148.4 °C. The hydrolysis solutions were poured and the fermentation process took place within 20 days in the PMD and MD. The sampling sequence was every 5 days. According to the results, the PMD could produce bioethanol more than the MD by 27.94%. Besides, CO, H2S and O2 were measured through fermentation. In PMD, the amount of H2S and O2 was lower than the MD, but then the production of CO in the PMD was meaningfully higher. Finally, by the application of the PMD, the amount of harmful mixtures produced throughout the process can be controlled. It can be said that with the new method designed in this study, it is possible to take an important step in the biorefinery and use the biomass produced in nature in an economical and environmentally friendly way.

Critical Analysis for Life Cycle Assessment of Bio-Cementitious Materials Production and Sustainable Solutions

The purpose of this study is to study the life cycle assessment of biocementitious materials production in comparison to traditional cement materials production. The environmental impact of production processes over the life cycle was evaluated on the basis of global warming and ozone depletion, human health, land, freshwater, marine ecotoxicity, and natural water system eutrophication. LCA uses endpoint methods (ECO indicators) and SimaPro 8 software to assess the health and environmental impact of raw materials used in the production process, including cement, Ca(NO3)2·4H2O, urea, molasses, and electricity. The results showed that cement materials made 82.88% of the world’s warming in all raw materials used in production processes, 87.24% of the world’s health, 89.54% of the deforestation of freshwater, and 30.48% to marine eutrophication. Ca(NO3)2·4H2O contributes by 58.88% to ozone depletion, 15.37 to human carcinogenic toxicity, 3.19% to freshwater eutrophication, and 11.76% to marine eutrophication. In contrast, urea contributes 38.15% to marine eutrophication and 5.25% to freshwater eutrophication. Molasses contribute by 13.77% to marine eutrophication. Cement contributes 74.27% to human health damage, 79.36% to ecosystem damage; Ca(NO3)2·4H2O contributes 13.54% to human health damage and 9.99% to ecosystem damage; while urea contributes 6.5% to human health damage and 5.91% to ecosystem damage. Bio-cementitious wastewater should undergo a treatment process to remove urea and molasses residues, as well as nitrates, before final disposal into the environment.

Environmental and economic analysis of bioethanol production from sugarcane molasses and agave juice

In this article, sugarcane molasses and agave juice were compared as potential feedstocks for producing bioethanol in Mexico in terms of their environmental impact and economic factors. Life cycle assessment (LCA) using SimaPro was carried out to calculate environmental impacts by using a cradle-to-gate approach. A preliminary economic analysis was performed to determine the economic feasibility of the studied options. Also, capital goods costs were obtained using the Aspen Plus economy package. Moreover, a sensitivity analysis was involved to compare the environmental and economic viability of producing bioethanol from sugarcane molasses and agave juice. LCA results revealed that cultivation and fermentation were the most harmful stages when producing bioethanol from sugarcane molasses and agave juice, respectively. Furthermore, when it was derived from agave juice rather than sugarcane molasses, it had more environmental benefits. This was ascribed to the lower consumption rate of fertilizers, pesticides, and emissions given off from the former. Regarding financial aspects, the preliminary analysis showed that producing bioethanol was not economically viable when grid energy alone was used. However, if power from the grid is partially replaced with renewable energy, producing bioethanol becomes economically feasible, and sugarcane molasses is the most suitable feedstock.

Development of a molasses wastewater treatment system equipped with a biological desulfurization process

In this study, a laboratory scale experiment for the treatment of synthetic molasses wastewater using a combination of an anaerobic baffled reactor (ABR) and a two-stage down-flow hanging sponge (TSDHS) reactor (ABR-TSDHS system) was conducted. The TSDHS comprised a closed-type first-stage down-flow hanging sponge (first DHS) for desulfurization and an open-type second-stage DHS (second DHS) for post-treatment of effluent from the ABR and first DHS. Effluent from the second DHS was sprinkled on top of the first DHS, whereas biogas produced from the ABR was supplied to its bottom. A chemical oxygen demand (COD) removal efficiency of 88.3% was found for the ABR-TSDHS system during the final treatment phase. The ABR achieved a maximum organic loading rate (OLR) of 3.70 kg COD/(m³ day). Most of the organic matter was degraded in the first compartment of the ABR, with methane-producing archaea as its main consumer. The biogas generated by the ABR contained high concentrations of hydrogen sulfide (up to 4,500 ppm). In the TSDHS, the first DHS achieved 87.3% hydrogen sulfide removal via dissolution into sprinkled effluent water. Dissolved sulfide in the first DHS effluent was oxidized to sulfate in the second DHS in the absence of aeration. In addition, 85.0% of the ammonia and 57.7% of the total nitrogen were removed in the second DHS via biological reactions, including sulfur-based autotrophic denitrification. Therefore, the ABR-TSDHS system can be applied to not only molasses wastewater treatment but also the desulfurization of the produced biogas.

Life cycle assessment of a bioelectrochemical system as a new technological platform for biosuccinic acid production from waste

Waste management is a key environmental and socio-economic issue. Environmental concerns are encouraging the use of alternative resources and lower emissions to air, water and soil. Innovative technologies to deal with waste recovery that produce marketable bioproducts are emerging. Bioelectrochemical synthesis systems (BESs) are based on the primary principle of transforming organic waste into added-value products using microorganisms to catalyse chemical reactions. This technology is at the core of a research project called BIORARE (BIoelectrosynthesis for ORganic wAste bioREfinery), an interdisciplinary project that aims to use anaerobic digestion as a supply chain to feed a BES and produce target biomolecules. This technology needs to be driven by environmental strategies. Life Cycle Assessment (LCA) was used to evaluate the BIORARE concept based on expert opinion and prior experiments for the production of biosuccinic acid and waste management. A multidisciplinary approach based on biochemistry and process engineering expertise was used to collect the inventory data. The BES design and the two-step anaerobic digestion process have many potential impacts on air pollution or ecotoxicity-related categories. The comparison of the BIORARE concept with conventional fermentation processes and a water-fed BES technology demonstrated the environmental benefit resulting from the use of both the BES technology and a waste-based substrate as input thus supporting the BIORARE concept. Some trade-offs among the impact categories were identified but led to options to improve the concept. BES design and synergy management may improve the environmental performance of the BIORARE concept.