INTEGRATING INVASIVE MACROPHYTE BIOMASS CONTROL WITH BIOGAS PRODUCTION: A SUSTAINABLE APPROACH IN THE ITAIPU RESERVOIR

Abstract

This study assessed the potential of Hydrilla verticillata, an invasive aquatic plant in the Itaipu Reservoir, as a source of biogas through anaerobic digestion, using swine slaughterhouse sludge as inoculum. The biochemical methane potential (BMP) test was evaluated at three different inoculum/substrate ratios (ISR): 3:1, 2:1, and 1:1. The biogas production in mL g^-1of volatile solids in these ISRs was 638,5 mL g^-1 SV, 842,5 mL g^-1 SV e 820,8 mL g^-1 SV, respectively. Microcrystalline cellulose served as a positive control (ISR 2:1), and blanks (reactors without substrate containing only inoculum) had production (in mL g^-1 VS) of 729,4 and 102,0 ± 10,9, respectively. The systems stabilized within 42 days, maintaining the appropriate pH. There was an 18.3% ± 3.7% reduction in partial alkalinity in the blanks, increases of 34.9% ± 4.0% in cellulose, and 138.5% ± 33.9% in the ISR. Intermediate alkalinity decreased in all tests. Despite the suboptimal C/N ratio, biogas production was satisfactory, with a gradual increase in methane content. On day 30, the ISR reached methane levels of 65.53% ± 3.87%. This study underscores the potential of Hydrilla verticillata as a biogas source, using swine slaughterhouse sludge as inoculum, providing an environmentally sustainable solution for waste utilization.