Bart Kraakman, Jacobs(free)
The general approach to reduce odour emissions is the implementation of odour abatement technologies, which entails important costs and often requires compelling operator efforts. Traditional physical/chemical end-of-the-pipe technologies (i.e. chemical scrubbing and activated carbon filtration) for odour abatement are relatively expensive and can present relatively high environmental impacts. On the other hand, biotechnologies (i.e. biofilters and biotrickling filtration) have emerged as more cost-effective and environmentally friendly alternatives but are still limited by their investment costs and sometimes their footprint.
This end-of-pipe treatment approach addresses odour nuisance management once odorants have been produced and released from the wastewater. In this context, a more desirable approach would be the prevention of odorant formation and/or release from the wastewater. Limited options are available for the prevention of odorant release at wastewater treatment facilities beyond proper design and good operating practices such as maintaining aerobic or anoxic conditions in the wastewater where possible, frequent cleaning of process units, minimization of the sludge retention time in thickeners and dewatering systems or the use of buildings and covers to confine the emission in key operation units
This paper assesses two widely-applicable, emerging odour control technologies known as Activated Sludge Recycling (ASR) and Oxidized Ammonium Recycling (OAR), which possess a significant odour prevention potential for wastewater treatment facilities at low investment and operating costs. Despite these technologies have been discussed in technical forums and applied at full scale in WWTPs with promising results over the past decade, their fundamentals and optimal conditions for odour prevention have not been explored using a systematic scientific approach. This review is to present and critically discuss the fundamentals and optimal conditions of ASR and OAR for odour control based on the technical information available to date including data from full-scale applications. The aim is to understand these technologies better and have these technologies available as a tool to be considered when developing plant wide odour and corrosion management strategies. Examples of full-scale applications in North-America will be provided and discussed.
Keywords: activated sludge recycling, centrate recycling, hydrogen sulfide, nitrate, odour control, full-scale.
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