Life Cycle Assesment of a Biofertilizer Production Process From Waste Fats

A biofertilizer production process from waste fats is analyzed through Life Cycle Assessment. The stages included in the assessment were: storage of raw material, anaerobic digestion with biogas combustion, and composting with Eisenia foetida. The objective was to identify the environmental impacts of the different stages and propose alternatives to minimize them. The functional unit was “ the production of 120 kg of biofertilizer”. The inventory data was provided by the enterprise operating the process. Data regarding electricity generation were obtained from official national information. The method to evaluate the environmental impacts was CML (baseline) by using the software openLCA. The results showed that the “Compost” stage contributes the most with the environmental impact. This behavior is due to the use of electricity for pumping water and the fuel used in the aeration of composting. “Anaerobic digestion” presents an environmental load mainly due to the pumping of materials to other stages. The most significant effect is on the category “Marine aquatic ecotoxicity”. The reason for this situation is linked to the life cycle of the obtention of electricity and diesel. After that, some alternatives to minimize the environmental impacts are identified: i) to replace fossil fuels by biodiesel, ii) to incorporate solar energy since it receives high radiation. Replacement of biodiesel improves the environmental performance of the process, and the use of solar energy does not contribute to reducing the environmental load of the process. Keywords: wastes revalorization, cleaner production, renewable energy, environmental impact, industrial bioprocesses.