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Addition of an aerated iron-rich waste-activated sludge to control the soluble sulphide concentration in sewage


Willy Verstraete, Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium. Email:


Hydrogen sulphide emission in sewers is associated with toxicity, corrosion and odour and also yields considerable costs. The purpose of this study was to evaluate whether the soluble sulphide concentration in raw sewage can be controlled by dosing an iron-rich waste-activated sludge (WAS) or an iron-rich aerated waste-activated sludge (AWAS). An average soluble sulphide elimination of 99% was achieved at an iron-rich AWAS to sewage ratio (v/v) of 16%, whereas dosage of iron-poor AWAS at the same ratio decreased the soluble sulphide in the raw sewage by only 53%. Our lab-scale tests suggest that dosing iron-rich AWAS to sewage did not affect the chemical oxygen demand (COD) and total ammonia nitrogen (TAN) removal as well as the nitrification efficiency in the receiving activated sludge system. The results indicate that iron-rich AWAS dosage is a feasible technique to remediate the sulphide problem in sewers.

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