Use of Activated Sludge to Reduce Hydrogen Sulfide Emission from Anaerobic Digestion Pond

Hydrogen sulfide (H₂S) is a highly toxic gas that can be found in nature, sewage, biogas production, as well as wastewater under strictly anaerobic condition. It causes a wide range of effects to human health, environment and equipment corrosion. Emissions of H₂S from anaerobic digestion pond is a serious problem, therefore treatment of these emissions is essential. In this work, the use of activated sludge (AS) to remove H₂S from the wastewater of anaerobic digestion pond (ADP) of a slaughterhouse was investigated in lab scale. It was carried out by filling AS at various concentration into the ADP wastewater containing in plastic bottles and left the bottles stand outdoor for 6 h. The sulfide ions were monitored by the iodometric titration method and H₂S quantity was evaluated by gas analyzer. It was found that the addition of 20-25% (v/v) AS was the best amount to reduce H₂S emission. The highest reduction was 77% within 6 h. The AS can reduce H₂S in both light and dark condition. The amount of H₂S in AS-added wastewater was reduced from 1623.00 ± 291.98 ppm to 810.67 ± 117.18 ppm and 921.33 ± 262.08 ppm, while that of AS-free wastewater continually increased from 1160.67 ± 76.49 ppm to 2026.67 ± 474.22 and 1800 ± 114.97 ppm after 9 h in light and dark condition, respectively. These results can be the way of using AS to reduce H₂S emitted from ADP for the suitability of the factory-wastewater-treatment system.