Monitoramento e diagnóstico de plantas de biogás no sudoeste do Paraná

Abstract

The agricultural sector emerges as one of the main economic activities in Brazil. Its rise is linked to the gradual implementation of confined animal production systems, the SPACs. However, there is a worrying environmental problem around these systems, due to the high volume of waste generated, which is rich in organic matter and nutrients, and requires adequate management systems. The implementation of biological systems is one of the most effective alternatives for the treatment of animal waste, with anaerobic digestion being the most promising option for rural areas. Anaerobic digestion is the process by which complex organic matter is converted to biogas, a mixture of gases composed mainly of methane (CH4), and used as an energy source. The use of these systems has been growing year after year, however, there are few biogas plants where the quality of the gas and the identification of irregularities in the process are properly monitored. Thus, this work aimed to monitor biogas plants installed in the southwest mesoregion of Paraná, analyzing and evaluating the biogas composition, and relating it to process parameters. For this, five properties with anaerobic digestion systems were selected, encompassing three different animal production systems: dairy cattle, B1 and B2, swine, S1 and S2, and poultry, AV1. The evaluation of the biogas composition was carried out in loco, with an interval of 15 days between each collection. Subsequently, the input and output effluents of each anaerobic digestion system were collected in the third and sixth month of follow-up, and submitted to physical-chemical characterization, pH, Intermediate and Partial Alkalinity, Chemical Oxygen Demand (COD), Solids Total, Fixed, and Volatile and Total Ammonia Nitrogen (NAT). The results showed that AD systems are efficient and stable for removing high concentrations of organic matter found in manure. S1 and S2 had the highest COD removals for both collections, with means of 66.6 ± 0.9% and 79.4 ± 0.4%, respectively, followed by B1 with 57.4 ± 0.35%, AV1 49.5 ± 1.35% and B2 42.2 ± 1.3%. The same happened to SV, but AV1 obtained averages below 25%, possibly due to the low TRH. The results showed that swine manure has a better biodegradability compared to cattle and poultry, also promoting higher methane contents, with averages of 68.6 ± 2.4% for S1 and 67.9 ± 2.8% for S2. Not far apart, the AD of bovine and poultry manure showed means of 51.5 ± 2.0% for B1, 56.3 ± 3.4% for B2 and 62.1 ± 3.4% for AV1. Although the AD systems are efficient and stable, the monitoring and assistance of the process parameters by trained professionals is necessary, given the identification of some problems. In this way, existing Technologies can be improved and the environment preserved.