Simultaneous autotrophic biodegradation of H2S and NH3 in a biotrickling filter

An efficient co-treatment of H2S and NH3 was achieved in a horizontal biotrickling filter (HBTF) inoculated by autotrophic nitrifying and sulfide-oxidizing microbial consortia and packed with exhausted carbon. NH3 and H2S were removed completely at the beginning of operation, in terms of nitrate and sulfate mainly by autotrophic biodegradation, respectively. Under the steady state, removal efficiency (RE) of H2S and NH3 was investigated with different gas retention times (GRT = 4–20 s), inlet concentrations (20–100 ppmv) and inlet loadings. At GRT > 4 s, above 98% of NH3 was removed while 95% RE of H2S was reached at GRT > 8 s. The critical elimination capacity (at 99% RE) was attained at 44 g NH3 m−3 h−1 and 36 g H2S m−3 h−1, and no interaction between NH3 and H2S treatment was found at low loadings. Furthermore, the experiment at high loadings of NH3 and H2S was purposely designed to evaluate the potential inhibition of each other. The metabolic products of N and S bearing species in recycling liquid were analyzed to explore the removal mechanisms. Compared with previous studies, the present filter showed a better removal capacity of NH3 and H2S. Overall, the results indicated that the HBTF was highly efficient and cost-effective for simultaneous autotrophic biodegradation of NH3 and H2S.