Simultaneous nitrogen and organic carbon removal in aerobic granular sludge reactors operated with high dissolved oxygen concentration

Michele Torregrossa, Gaetano Di Bella, Michele Torregrossa

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Simultaneous nitrification and denitrification (SND) together with organic removal in granules is usuallycarried out without Dissolved Oxygen (DO) concentration control, at ‘‘low DO’’ (with a DO < 30–50% ofthe saturation value, about 3–4 mg/L) to promote anoxic conditions within the aggregates. Theseconditions can sometimes be in detrimental of the stability of the granules itself due to a lack of shearforce. In this work, the authors achieved SND without oxygen control with big sized granules. More spe-cifically, the paper presents a experimentation focused on the analysis of two Sequencing Batch Reactors(SBRs), in bench scale, working with different aerobic sludge granules, in terms of granule size, and highDO concentration, (with concentration varying from anoxic conditions, about DO 0 mg/L, to values closeto those of saturation, >7–8 mg/L, during feast and famine conditions respectively). In particular, differentstrategies of cultivation and several organic and nitrogen loading rate have been applied, in order to eval-uate the efficiencies in SND process without dissolved oxygen control. The results show that, even underconditions of high DO concentration, nitrogen and organic matter can be simultaneously removed, withefficiency >90%. Nevertheless, the biological conditions in the inner layer of the granule may change sig-nificantly between small and big granules, during the feast and famine periods. From point of view ofgranule stability, it is also interesting that with a particle size greater than 1.5 mm, after the cultivationstart-up, the granules are presented stable for a long period (about 100 days) and, despite the variationsof operational conditions, the granules breaking was always negligible.
Original languageEnglish
Pages (from-to)706-713
Number of pages8
JournalBioresource Technology
Volume142
Publication statusPublished - 2013

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal

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