Impacts of Post Aerobic Digestion on the Design of Nutrient Removal Facilities

Author: Johnson Bruce R.   Menniti Adrienne   Murthy Sudhir  

Publisher: Water Environment Federation

ISSN: 1938-6478

Source: Proceedings of the Water Environment Federation, Vol.2011, Iss.1, 2011-01, pp. : 503-509

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Abstract

Advanced digestion processes have gained recent interest because they provide improved volatile solids reduction and reduced biosolids for disposal. Furthermore, increasingly stringent effluent nutrient limits have focused industry attention on the management of phosphorus and ammonia-rich recycle streams typically associated with anaerobic digesters. Post-aerobic digestion is a recently developed advanced digestion process where aerobic digestion is done after an anaerobic digestion step, thus improving overall VSS removal (Menniti, et al., 2010, Novak et. al. 2009). Operation of the post aerobic digester can also provide total nitrogen removal without the need for external carbon source addition or alkalinity addition. Additionally, post aerobic digestion biomass may also serve as an external source of nitrifiers (bioaugmentation) if a fraction of the digested sludge is returned to the aeration basin.It has been found that post aerobic digestion has a wide range of impacts upon the design of nutrient removal facilities, some of which are unique to this sidestream nutrient removal technology.10% to 30% additional VSS destruction of the biosolidsStruvite formation stabilization prior to dewateringHigh levels of sidestream nitrogen removal without needing alkalinity or carbon additionPotential nitrifier bioaugmentation to mainstream liquids treatmentPost aerobic digestion has been investigated for use in facilities up above 300 mgd in size and has been found to be a viable option for sidestream nutrient removal, while providing other benefits not possible with other sidestream treatment technologies.

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