HYDROGEN SULFIDE REMOVAL IN BIOGAS USING A FULL-SCALE BIOTRICKLING FILTER: EVALUATING SPRAYING TIME AND NITRATE SOURCE

The hydrogen sulfide (H2S) present in biogas needs to be removed due to concerns about corrosion during transportation, storage, health and safety. One of the existing removal processes is biological, using a biotrickling filter (BTF). In this study, the performance of full-scale BTF for H2S removal under different operating conditions was evaluated. The BTF system was operated for 300 days, during which two spraying regimes (constant and intermittent) and two sources of nitrate (NO3-) as nutrient solution were evaluated (residual effluent from pig farming and synthetic solution prepared with commercial NaNO3). The performance was monitored by the following parameters: removal efficiency (RE), elimination capacity (EC), pH, dissolved oxygen (DO), empty bed residence time (EBRT) and nitrate concentration (NO3-). The results showed an REH2S = 36.3% with an EC= 1.95 g(H2S) m(-3) d(-1) for constant spraying, RE= 99.59% and EC= 4.2 g(H2S) m(-3) d(-1) for intermittent spraying with residual effluent from pig farming and RE=99.26% and EC= 4.13 g(H2S) m(-3) d(-1) with synthetic solution prepared with commercial NaNO3 solution. The results indicate that intermittent spraying provides better efficiency in the removal of H2S from biogas regardless of the nitrate source (effluent or synthetic medium).