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The packing material selection for a bioreactor is an important factor to consider, since the characteristics of this material can directly affect the performance of the bioprocess, as well as the investment costs. Different types of low cost packing materials were studied in columns to reduce the initial and operational costs of biogas biodesulfurization. The most prominent (PVC pieces from construction pipes) was applied in a bench-scale biotrickling filter to remove the H2S of the biogas from a real sewage treatment plant in Brazil, responsible for 90 thousand inhabitants. At the optimal experimental condition, the reactor presented a Removal Efficiency (RE) of up to 95.72% and Elimination Capacity (EC) of 98 gS·m−3·h−1, similar to open pore polyurethane foam, the traditional material widely used for H2S removal. These results demonstrated the high potential of application of this packing material in a full scale considering the robustness of the system filled with this support, even when submitted to high sulfide concentration, fluctuations in H2S content in biogas, and temperature variations.

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BACKGROUND: This paper evaluates the nitrification and sulfide-driven autotrophic denitrification processes in a structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) applied to the post-treatment of an anaerobic effluent. The SBRRIA reactor was operated during 130 days in which influent sulfide concentrations varied between 220.1 and 231.0 mg TDS L −1 (TDS, total dissolved solids). Temporal tests were performed to elucidate the dynamics and sulfide impacts on combined processes. RESULTS: Sulfide partially inhibited the nitrifying activity, resulting in low NH 4+ -N oxidation. This fact affected the overall nitrogen removal performance as total-N removal efficiencies of 50 and 55% were attained in Conditions III and IV, respectively. On the one hand, under continuous aeration and in the absence of sulfide, the oxidation-reduction potential (ORP) reached 50 mV (versus Ag/AgCl) after 250 min of experiment. On the other, when sulfide was continuously provided in the feeding, the ORP was maintained lower than zero. Under anoxic conditions, the effective use of sulfide as an electron donor by autotrophic denitrification was verified by ORP monitoring. However, a concentration of 260 mg TDS L −1 associated with high pH proved inhibitory for NO 3 − reduction.CONCLUSIONS: Based on the results obtained, new strategies of adding sulfide to the SBRRIA should be tested to minimize its inhibitory effect on nitrification and improve nitrogen removal in this unit.

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