1. Granules abrasion cause deterioration of nitritation in a mainstream granular sludge reactor with high loading rate.
- Author
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Liu, Wenru, Yin, Fangfang, and Yang, Dianhai
- Subjects
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MECHANICAL abrasion , *SEQUENCING batch reactor process , *SHEARING force , *UPFLOW anaerobic sludge blanket reactors , *AIRDROP , *BIOMASS - Abstract
Biomass detachment generally occurred in granular sludge systems. However, little is known about the influence of biomass detachment on the granules performing nitritation. Here, a granular sludge reactor with high loading rates (6.8 ± 0.4 kg N·m−3·d−1) was achieved at mainstream conditions. Though the low ratio control strategy was maintained, the deterioration of nitritation performance was observed after the further increase of air supply rates to 3.4 ± 0.2 L min−1. In parallel with that, the loss of AOB and the proliferation of NOB was observed. Additionally, with the decrease of granules size and biomass concentration, the incomplete stratification of nitrifiers in the granules was confirmed by batch tests. All these results suggested that granules abrasion under the high shear stress conditions caused the detachment of external AOB and hence resulted in the deteriorated stratified structure of nitrifiers, which subsequently contributed to the proliferation of the internal NOB and the deterioration of nitritation. These findings highlight that the granules abrasion should be well controlled in the development of high-rate nitritation process with granular sludge. • High-rate nitritation with granular sludge was achieved at mainstream conditions. • Granules abrasion-based deterioration of nitritation was firstly observed. • Detachment of AOB resulted in incomplete stratification of nitrifiers in granules. • Granules abrasion must be well controlled in high-rate granular nitritation system. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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