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Membrane‐aerated biofilm reactors (MABRs) are being increasingly being implemented at full‐scale for domestic wastewater treatment and effective biofilm control is critical to their performance. This study investigated the impact of three biofilm scouring strategies on nitrogen removal performance of a pilot‐scale MABR operated in Houston, TX: (1) regular air scouring, (2) high intensity air scouring, and (3) high liquid flow scouring. Normal and high intensity air scouring regimes and a high liquid flow scour (10× baseline flow) were each tested sequentially. High NH4+‐N removal efficiency of 52% in flow‐through mode was observed post‐high liquid flow scouring, which was comparable to the performance during the intense scouring regime. The absolute abundance ofamoAgene for ammonia oxidizing bacteria (AOB) increased significantly by over 200%, between pre‐ and post‐high liquid flow scouring. The energy consumption was 43% lower for the combination of high liquid flow scouring with regular air scouring as compared to the intense air scouring. This study showed that high liquid flows may be utilized as an energy‐efficient biofilm control strategy in nitrifying MABR systems. Practitioner PointsPilot‐scale MABR reactors were operated with different scouring settings: regular aeration, intense aeration, and high liquid flow.High liquid flow scouring improved nitrification efficiency, comparable to intense scouring.High liquid flow scouring selected for nitrifiers as seen by an increase in AOB quantified asamoAgene abundance.Using high liquid flow with regular aeration scouring reduces electrical energy consumption by 43% as compared to intense aeration scouring.High liquid flows may be used as an energy‐efficient biofilm control strategy to improve nitrification performance in MABR systems.
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Pilot-scale comparison of biological nutrient removal (BNR) using intermittent and continuous ammonia-based low dissolved oxygen aeration control systems
Abstract Sensor driven aeration control strategies have recently been developed as a means to efficiently carry out biological nutrient removal (BNR) and reduce aeration costs in wastewater treatment plants. Under load-based aeration control, often implemented as ammonia-based aeration control (ABAC), airflow is regulated to meet desired effluent standards without specifically setting dissolved oxygen (DO) targets. Another approach to reduce aeration requirements is to constantly maintain low DO conditions and allow the microbial community to adapt to the low-DO environment. In this study, we compared the performance of two pilot-scale BNR treatment trains that simultaneously used ABAC and low-DO operation to evaluate the combination of these two strategies. One pilot plant was operated with continuous ABAC while the other one used intermittent ABAC. Both processes achieved greater than 90% total Kjehldal nitrogen (TKN) removal, 60% total nitrogen removal, and nearly 90% total phosphorus removal. Increasing the solids retention time (SRT) during the period of cold (∼12 °C) water temperatures helped maintain ammonia removal performance under low-DO conditions. However, both processes experienced poor solids settling characteristics during winter. While settling was recovered under warmer temperatures, improving settling quality remains a challenge under low-DO operation.
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- Award ID(s):
- 1803055
- PAR ID:
- 10362290
- Publisher / Repository:
- DOI PREFIX: 10.2166
- Date Published:
- Journal Name:
- Water Science and Technology
- Volume:
- 85
- Issue:
- 2
- ISSN:
- 0273-1223
- Page Range / eLocation ID:
- p. 578-590
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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