Optimizing upflow velocity and calcium precipitation in denitrifying granular systems

•Study of the granulation of denitrifying biomass in USB reactors.•Upflow velocity and calcium concentration optimization to speed up granulation.•Minimum values for stable granules formation: vup=0.19mh−1 and [Ca+2]=60mgL−1.•Low required values of vup and calcium concentrations diminished operation...

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Bibliographic Details
Published in:Process biochemistry (1991) 2015-10, Vol.50 (10), p.1656-1661
Main Authors: Val del Río, A., Buys, B., Campos, J.L., Méndez, R., Mosquera-Corral, A.
Format: Article
Language:English
Subjects:
Biochemistry
Biomass
Calcium
Concentration (composition)
Denitrification
Granular materials
Granule
Optimization
Precipitation
Texts
Upflow velocity
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Summary:•Study of the granulation of denitrifying biomass in USB reactors.•Upflow velocity and calcium concentration optimization to speed up granulation.•Minimum values for stable granules formation: vup=0.19mh−1 and [Ca+2]=60mgL−1.•Low required values of vup and calcium concentrations diminished operational costs.•High treated nitrogen loads (2.0–3.5gNL−1d−1) at high removal efficiency (>98%). The denitrification process was studied in two granular biomass denitrifying reactors (USB1 and USB2). In USB1 large quantities of biomass were accumulated (9.5gVSSL−1) allowing for the treatment of high nitrogen loads (3.5   g   NO3−N   L−1   d−1). As the biomass granulation process is not immediate the effects of different upflow velocities (0.12–5.5mh−1) and calcium contents (5–200mgCa2+L−1) were studied in order to speed up the process. Obtained results indicate that the optimum values for these parameters, which allow for the stable operation of USB1, are of 0.19mh−1 and 60mgCa2+L−1. Then these optimum conditions were applied to USB2 where the effects of concentrations from 335 to 1000   mg   NO3−N   L−1 were tested. In these conditions nitrate concentrations of 1000   mg   NO3−N   L−1 are required for denitrifying granular biomass formation. Summarizing denitrifying granules can be formed at low upflow velocities and in hard or extremely hard water composition conditions if sufficient high nitrogen loads are treated.
ISSN:1359-5113
1873-3298
DOI:10.1016/j.procbio.2015.05.028