Resilience of hollow fibre membrane bioreactors for treating H2S under steady state and transient conditions

Abstract

H2S removal performance by hollow fibre membrane bioreactors (HFMBs) was investigated for 271 days at ambient (20 ± 2 °C) temperature employing an inlet H2S concentrations up to 3600 ppmv and empty bed residence time (EBRT) of 187, 92 and 62 s. Different operating conditions including pH control (with or without), famine period, shock loads (4–72 h) and different biomass types (presence or absence of suspended biomass) were investigated. The H2S flux and mass-transfer coefficient were significantly higher for the biotic HFMBs (R1 and R2) compared to the abiotic control (R3) at all employed EBRTs. Significant differences in H2S removal efficiency (RE) and elimination capacity (EC) were noted for different inlet H2S concentrations, EBRTs, pH and biomass type. The HFMB achieved >99% RE at steady-state for biotic operation with an EC of 33.8, 30.0 and 30.9 g m−3 h−1 at an EBRT of 187, 92 and 62 s, respectively. Sulfate (92–93%) was the main sulfur species in the H2S bioconversion process. The HFMB showed a good resilience to shock loads and showed quick recovery (<24 h) after withdrawal of the shock loads. The HFMB had a critical loading rate of H2S about 135 g m−3 h−1 under transient-state.