AVALIAÇÃO COMPARATIVA DO DESEMPENHO DE BIODIGESTORES MISTURA COMPLETA (CSTR) VERSUS LAGOA COBERTA NO SUDOESTE GOIANO

Abstract

Pig farming emerges as an important activity related to protein production, as well as the development of municipalities in the interior of the country. Like any agro-industrial activity, the use of water and the disposal of waste are intrinsic to the process, but in this specific case, the waste is highly polluting due to the presence of a high organic load and pathogens. As an aggravating factor, Rio Verde is located on the Guarani Aquifer System – SAG, which requires extra care in terms of its use in the soil as fertilizer. A common way of treating these wastes is through stabilization ponds, but with low efficiency. With the use of anaerobic biodigester, in addition to enhancing substrate degradation, it provides biogas as a source of renewable and decentralized energy. Although they are already widely used technologies, biodigesters have a certain complexity in operation. The objective of this work is to compare the performance of two different technologies of anaerobic digestion in the region of the Southwest of Goiás, being a Continuous Stirred Tank Reactor - CSTR and the other with Biodigestor Lagoon Covered-BLC, through the analysis of the concentrations of macro and micronutrients , pH, organic matter (OM) and dry matter (DM) of the digestate and also monitoring the components of the biogas Methane, Sulfidric Acid, Carbonic Gas and Ammonia, to evaluate the best technology of anaerobic digestion for biogas production in the southwest region of Goiás. Such technologies are employed in two finishing farms with an average occupancy of 12,000 pigs, in the city of Rio Verde - GO. The semi-solid samples were collected through 6 visits between 30 and 40 days apart, in a time interval of eight months, at the entry and exit points of each biodigester and at the exit of the stabilization lagoon, totaling 36 samples. Gas samples were collected at the gas outlet of each biodigester, totaling 48 samples. The nutrient parameters were obtained through soil analysis laboratories in the city of Rio Verde and the biogas concentrations through the Alfakit biogas analysis kit. The results showed that both systems are similar in reducing the organic load. The CSTR operating alone did not result in better levels of CH4 and H2S than the BLC. The BLC, already widespread in the region, can be optimized with equipment adopted in the CSTR, such as pre-agitation and internal agitation of the manure, ensuring the best performance during anaerobiosis. The monitoring of waste variables such as MO, MS, pH, collaborate against wasting water in the facilities. The monitoring of biogas variables, on the other hand, is fundamental for the good and constant functioning of energy generation systems. The injection of O2 to reduce H2S is fundamental for the full use of biogas in energy generation, but the daily injected volumes must be calculated for each case and the resulting must be monitored frequently in the plant.