Nutrient (Ammonium and Phosphate) Removal Using Aerobic Granulation at Pilot scale

This research investigated the causes of aerobic granulation inhibition and deterioration in nutrient removal performance of aerobic granular sludge (AGS) reactors at pilot scale. Identifying the underlying phenomena seems necessary to enhance predictability and reliability of this process under diverse circumstances. This can ultimately broaden the practicability of this technology for actual applications. Three pilot-scale (22-L) granular sequencing batch reactors (GBSRs) were operated to cultivate aerobic granules and to subsequently evaluate the treatment performance and AGS characteristics in the long run (up to ~500 days). While one reactor was operated under purely aerobic condition (O_SBR), the other two were run using alternating sequencing batch reactor (SBR) reaction phase arrangements (anaerobic/aerobic/anoxic/aerobic (AN/O/AX/O_SBR) and anaerobic/aerobic (AN/O_SBR) conditions). A series of ecophysiological experiments were conducted using an advanced molecular technique (16S rRNA phylogenetic gene sequencing analysis). Suspended-biomass batch experiments seeded with the inoculum of the GSBRs were chosen as the baseline, to reveal the functional diversity of the dominating bacteria in the AGS. Improper aeration pattern was identified as the main cause of preventing granulation at pilot scale. To maintain the aeration pattern and shearing activity regardless of the reactor scale, a scale-up factor (S) was developed which should be applied to the reactor dimensions, aeration rate, and surface area of the gas distributor simultaneously. Granulation time and size and effluent quality in terms of suspended solid concentrations and microbial washout pattern were regulated by the wastewater strength. Whereas, granule structure as well as AGS morphology and flocculent fraction were dictated by the SBR operation mode. Mineral-rich aerobic granules with hydroxyapatite (HAp) core were cultivated in the AGS reactors in this research regardless of the wastewater strength and SBR operation modes. Heterotrophic nitrification and biologically-induced phosphate precipitation (BIPP) were the dominant nutrient depletion pathways performed by the aerobic granules with lifeless cores. The contributions of these pathways to the overall ammonium nitrogen and phosphorus removal were 61 – 84% and 39 – 96%, respectively. Ecophysiological investigations characterized Thauera and Flavobacterium as the core heterotrophic nitrifiers. The species Flavobacterium, Acinetobacter, Pseudomonas, and Corynebacterium were identified as bio-calcifying species. Different types of denitrifiers and potential polyphosphate accumulating organisms (PAOs) were also identified. The long-term performance showed that the ammonium nitrogen (NH4-N) removal efficiencies established inverse relation with ammonium nitrogen loading rate (NLR). Phosphate (PO4-P) removal efficiency, on the contrary, showed a direct relation with chemical oxygen demand to phosphorus (COD:P) ratio. Heterotrophic nitrification and BIPP were the principal nutrient removal pathways during the long-term operation as well. The recovery of autotrophic ammonium oxidizing bacteria (AOBs) was feasible at low NLR (0.15 kg NH4-N m-3 d-1) and FA concentration (< 5 mg NH3 L-1). However, the recovery of autotrophic nitrite oxidizing bacteria (NOB) happened with delay and the PAO recovery was irreversible.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Engineering – Civil

Grantor dc:publisher.institution

Schulich School of Engineering

Year dc:date.issued

2019

Author dc:creator

• Pishgar, Roya

Advisor dc:contributor.advisor

• Chu, Angus

Committee members dc:contributor.committeemember

• Black, Kerry E.
• Hettiaratchi, Joseph Patrick A.
• Cuenca, Manuel Álvarez
• Lu, Qingye

• Aerobic granulation
• Granulation inhibition
• Nutrient removal
• Ammonium
• Phosphate
• Heterotrophic nitrification
• Biologically-induced phosphate precipitation (BIPP)
• Pilot-scale

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/36760

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/110659