Projecção de um biodigestor para a granja da Faculdade de Veterinária da Universidade Eduardo Mondlane

Abstract

Biodigesters are hermetically sealed chambers used to treat organic waste through the process of anaerobic decomposition. It is an excellent choice for the treatment and reuse of organic waste because, as well as being environmentally wholesome, it is also economically viable, due to the fact that its products, biogas and biofertilizer, are used as an alternative source of energy (thermal and electrical) and nutritional enrichment of the soil (organic fertilizer) respectively. Biogas is a gaseous mixture composed mainly of methane (60 - 70 per cent by volume) and carbon dioxide (30 - 40 per cent by volume) and traces of other gases. The aim of this study was to size a bio-digester using the organic waste produced on the farm of the Faculty of Veterinary Science at Eduardo Mondlane University, located in Maputo City, Mozambique. It consisted of 4 phases: the first phase was the preparation of the substrate, the second phase was the assembly of the prototypes using 6-litre plastic bottles, the third phase consisted of evaluating the production of biogas in the prototypes and assembling a mini biodigester for teaching purposes, and the last phase consisted of sizing a biodigester, based on the total production of waste on the farm. The study was carried out experimentally over 4 months (September - December 2022). The aim of the experiment was to assess the potential of the organic waste from the farm at the Faculty of Veterinary Science at Eduardo Mondlane University, specifically the droppings of layers, goats and chicken litter, to produce biogas. The amount of waste produced by the animals on the farm made it possible to size a 28 m3 biodigester, with a daily production of 0.3224 m3 ~ 322.4 liters of biogas. This production is equivalent to a daily estimate of 0.7093 kilowatt-hours of electricity, making it feasible to set up a biodigester that will be fed with the waste from the animals on the farm. In general, the use of biodigesters is recommended as a means of reusing the waste resulting from animal production, which can become a source of proliferation of disease agents and vectors, as well as a potential disseminator of compounds that intensify atmospheric pollution, by emitting gases involved in environmental damage, particularly in the "Greenhouse Effect", It is a favorable and promising proposal for combating global climate change and reducing electricity costs, since biogas, in addition to the advantage of being used as a source of heat (thermal energy), is also used as an alternative source of electricity, functioning as fuel in generators for electricity production