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.
|Numero di pagine||8|
|Stato di pubblicazione||Published - 2013|
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Renewable Energy, Sustainability and the Environment
- Waste Management and Disposal