Avanços e desafios para a recuperação energética de Biogás em Estações de Tratamento de Esgoto brasileiras

Abstract

Brazil has the largest park of UASB anaerobic reactors in the world, with high potential for biogas recovery in large-scale Wastewater Treatment Plants (WWTPs), although most of the biogas is still flared without energy use. The topic has gained relevance due to its potential to mitigate greenhouse gas emissions and reduce operational costs through self-consumption. This thesis aimed to analyze, from historical, technological, and comparative perspectives, the advances and challenges in biogas energy recovery in Brazilian WWTPs, structured around three articles. The first article, based on a bibliometric review of 217 studies, mapped the global evolution of the field, highlighting trends such as co-digestion, recovery of dissolved methane, and the use of emerging technologies such as MBR. Brazil stands out through reference centers such as the University of São Paulo (USP) and the Federal University of Minas Gerais (UFMG). The main funding source is Chinese, while Brazil occupies prominent positions in the global ranking—second, third, and tenth—through CNPq, MCTI, and CAPES. The second article examined the Brazilian sociotechnical transition using the Multi-Level Perspective (MLP), revealing a fragmented scenario and regime, with São Paulo leading with 32.4% of biofuel patent deposits, followed by Paraná (15%) and Rio de Janeiro (13.2%), while the North and Northeast have marginal participation. In sanitation, the North received just over 10% of the Southeast’s investment, with an infrastructure gap 4.4 times larger; in the Northeast, the gap is 2.2 times. Three key transition phases were identified: (i) initial experimentation (1970–1990), (ii) pilot projects driven by regulations (2000– 2010), and (iii) the current expansion phase (after 2013), characterized by policies such as RenovaBio and net metering. Currently, Brazil is in the take-off phase, with projected advancement to the breakthrough stage by 2033 in an optimistic scenario or 2043 in a realistic one. The third article compared Brazil and Spain: Spain follows a “top-down” model, with 70% of plants focused on sanitation, while Brazil adopts a “bottom-up” model, with 73% in the agricultural sector and only 13% in sanitation. Cases such as El Prat (Spain) and Franca (Brazil) demonstrate that the integration of technology, public policies, and territorial governance is crucial for success. The thesis concludes that consolidating biogas use in WWTPs is feasible and strategic, requiring integrated policies, economic incentives, and innovation.