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

Abstract

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.

Potential and limitations of modern equipment for real time control of urban wastewater systems

“…Chemical dosing concerns, for example, the supply of biodegradable COD to improve the denitrification processes, the addition of acid or base for maintaining pH within adequate range, or the addition of ballasting particles to increase the generation of biological flocs or settling of specific pollutants. Recently some new applications have been reported that use controlled dosing of chemicals for sewer corrosion control (Oriol et al 2010, Zhang et al 2011.…”

Odour Prevention Strategies in Wastewater Treatment Plants: A Pilot Scale Study of Activated Sludge Recycling and Oxidized Nitrogen Recycling

“…The implementation of ASR and ONR as odour control processes in WWTPs is considered a relatively new technology, and there is limited research available on this specific topic. Zhang [15] conducted a study on the potential of dosing aerated iron-rich waste activated sludge (WAS) to control the soluble sulphide concentration in sewers. The study demonstrated an average reduction in soluble sulphide concentration of up to 99 % when using an iron-rich WAS to sewage ratio (v/v) of 12-16 %.…”

Mechanistic Understanding of Beneficial Aspects of Iron Salts and Waterworks Sludge Uses in Urban Wastewater System

“…As a result, the Fe dosed into the sewer networks will be transported into the downstream WWTP although in different forms, potentially assisting in P removal (Gutierrez et al, 2010), desulfurization of digester biogas (Ge et al, 2013), and control of struvite/vivianite scale formation in AD systems (Frossard et al, 1997;Mamais et al, 1994b). Few studies have demonstrated the feasibility of such multiple re-uses of Fe-salt (Zhang et al, 2011) and waterworks Fe-sludge (Edwards et al, 1997) within the UWWS and derivation of above-stated benefits. Consequently, new…”