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Decreasing sulfide generation in sewage by dosing formaldehyde and its derivatives under anaerobic conditions

Abstract:

Hydrogen sulfide emission in sewers is associated with toxicity, corrosion, odour nuisance and high costs. In this study, a new method to inhibit sulfide generation by means of formaldehyde and its derivatives has been evaluated under anaerobic conditions. The possible impact of formaldehyde on an activated sludge system and an appraisal of the economic aspects are presented as well. A dosage of 19 mg LT1 formaldehyde resulted in a decrease of the sulfide production of 90%. Dosing of 32 mg paraformaldehyde and addition of 100 mg L∼1 urea- formaldehyde were not sufficient to inhibit the sulfide generation in sewage to the same extent. The impacts of I9mg L 1 formaldehyde on activated sludge, in terms of COD removal, nitrification rate and oxygen uptake rates, were negligible. This suggests that formaldehyde dosage is a feasible technique to abate the sulfide problem in sewers.