Performance of activated sludge diffusion for biological treatment of hydrogen sulphide gas emissions

摘要

Odours from wastewater treatment plants are comprised of a mixture of various gases with hydrogen sulphide (H_2S) often being the dominant constituent. Activated sludge diffusion (ASD) as a biotreatment system for odour abatement has been conducted for over 30 years but has limited broad application due to disagreement in the literature regarding the effect that ASD may have on wastewater treatment performance. The effects of continuous H 2S diffusion at 25 ppmv, with weekly peaks of approximately 100 ppmv, on H_2S removal efficiency and wastewater treatment performance was evaluated over a 2-month period using an activated sludge pilot plant. H_2S removal averaged 100% during diffusion at 25 ppmv, and 98.9% during the 100 ppmv peak periods. A significant increase in mixed liquor volatile suspended solids concentration (P < 0.01) was observed during H_2S diffusion, which may be due to an increase in H_2S-degrading microorganisms. There was no adverse effect of H_2S on nitrification throughout the ASD trials. Ammonia (NH3) removal was slightly better in the test receiving H_2S diffusion (87.6%) than in the control (85.4%). H_2S diffusion appeared to improve robustness of the AS biomass to operational upsets.