Produção de biogás e metano em biodigestores anaeróbicos com controle de temperatura

Abstract

The use of anaerobic digestion process with a focus on water treatment and waste is a common practice in many countries, but with population growth came a new demand to improve the process, also to convert the biogas generated by anaerobic digestion, by burning it and converting thermal energy, transforming it into electricity. Studies show that the temperature control is essential to increase biogas production and to reduce the time required for the manure, sludge or waste to stay inside the reactor to complete their treatment. In this context, the present study is aimed to analyze which technologies and which temperature control levels are used and their consequent effects in the biogas production. New technologies have been identified with greater potential for plants that already use anaerobic reactors as well as for new projects, particularly for colder regions, which are subject to sudden variations in temperature which have a negative effect in the process. The best installation setting identified, with a higher potential for faster obtaining biogas with an acceptable methane composition, averaging sixty percent of methane in the biogas is the two phased anaerobic digestion (TPAD), which uses an upflow anaerobic sludge blanket (UASB), adopting a thermophilic temperature range of 55 °C with two to three days of hydraulic retention period, followed by another UASB reactor in the temperature range mesophilic 35°C with twelve to fifteen days of hydraulic retention period. Another technology was studied with potential to increase the biogas production in the system was the pre-treatment of the manure, such as the techniques of microwave heating and mechanical treatment systems, like ultrasound, which may be incorporated in future studies together with TPAD systems, but more experiments are needed to get the best parameter and operation system settings for optimal condition of waste, manure and sludge treatment for an increased biogas production.