STARTUP OF A BIOLOGICAL SCRUBBER FOR HYDROGEN SULFIDE REMOVAL FROM ANAEROBIC DIGESTER BIOGAS

Hydrogen sulfide is a contaminant, which is found in anaerobic digester biogas and may damage furnaces and other gas handling equipment. The biological scrubber process removes hydrogen sulfide from biogas generated in anaerobic digestion systems utilizing bacteria.A full-scale biological scrubber installation was built at a paper mill's wastewater treatment facility. Two packed towers 3.4 m (11 ft) in diameter and 11.6 m (38 ft) in sidewall height were operated in parallel. A suspension of sulfur-oxidizing bacteria was delivered to each reactor sump at the beginning of operation. Biogas from an anaerobic digester was delivered in an upward direction through each biological scrubber. The average inlet biogas flow rate was increased incrementally from 4820 m3/d to 7823 m3/d.The startup proceeded rapidly and a stable biofilm capable of removing hydrogen sulfide from biogas developed on the packing surface of the biological scrubber. Steady-state operation was reached in 14 days when the hydrogen sulfide removal consistently exceeded 99%. This result is excellent for biological gas scrubbing. Following startup, the biological scrubbers operate above the performance warranty standard of 97% removal.