Real-time optimisation of Intermittently Aerated Sequencing Batch Reactor (IASBR) technology: A novel approach for efficient wastewater treatment

Sequencing batch reactors (SBRs) are one of the most globally recognised configurations of activated sludge treatment processes. These systems are effective and efficient in the removal of organic carbon and nitrogen from wastewater. The intermittently aerated sequencing batch reactor (IASBR) technology is a modification of the conventional SBR process, which has potential benefits, including a reduced oxygen requirement of 25%, a reduced carbon requirement of 40% and the capacity to remove phosphorus biologically. IASBR technology was well-characterised in laboratory investigations but had not yet been tested at a significant scale under real-world conditions, and efficiency gains that might be gleaned via real-time control have not been studied at scale. This research investigated IASBR technology and its efficacy for two treatment applications: dairy processing wastewater and high-strength municipal wastewater treatment. In addition to scaling up the technology, one of the key aims of this research was to investigate real-time control (RTC) measures and how they impact the technology's effectiveness, reliability, and efficiency. The study focuses on how these systems apply to biological nutrient removal (BNR) specifically and how they can be optimised to remove these nutrients efficiently. The research started at a laboratory scale of 8 litres. It incrementally increased in size, first to a 3 m3 IASBR system at a dairy processing facility, followed by a 20 m3 reactor at a full-scale municipal treatment plant. There were varying levels of control implemented. First, rudimentary time-based control was employed at the pilot facility, basic RTC at the full-scale facility, and more sophisticated RTC measures at the same site to provide the IASBR system (as far as the author is aware) with the most advanced control system deployed with this technology at scale to date. The laboratory scale systems verified the performance of the IASBR technology when applied to the treatment of dairy processing wastewater, achieving average removal rates of 91.5% and 97.7% for ammonium nitrogen (NH4-N) and orthophosphate phosphorus (PO4-P), respectively. The technology was then scaled for deployment at a pilot-scale facility to test dairy processing wastewater at a factory. The pilot IASBR exhibited high removal efficiencies of 89.5% and 93.0% for NH4-N and PO4-P, respectively. The research validated that the technology worked well under real-world conditions and at scale. An optimisation regime was conducted at the site, showing that 36-86% reductions were achievable in carbon emissions. The IASBR technology was deployed at a full-scale wastewater treatment testing facility in Tuam, Galway, Ireland. A completely mixed activated sludge reactor was operated to test a new aeration technology. The performance of this process was then compared to the IASBR operation at the facility to evaluate energy efficiency. During the investigation, the IASBR was tested with three stages of control. In the third stage, a novel control methodology for intermittently aerated systems was developed in this work. For the first time, dissolved oxygen (DO) aerator power and derivatives of (oxidation-reduction potential) ORP were utilised to assess and optimise the cycle times in real-time. Leveraging these parameters together allowed for a control approach that terminated cycles as loading to the reactor was reduced while also providing resilience to process changes influenced by mechanical elements in the treatment system. Throughout the investigation, the IASBR reactor achieved average removal rates of >90% for NH4-N and PO4-P. Results showed that energy efficiency savings of over 50% were achievable by implementing advanced RTC. The results show that the IASBR technology offers a practical, energy-efficient alternative for removing nitrogen and phosphorus from wastewater. The solution has advanced RTC capabilities that can improve resilience and reliability and reduce the energy intensity of treatment processes. The benefits highlighted in this work contribute directly to UN SDG 6 (Clean Water and Sanitation), ensuring resources are used efficiently, and SDG 13 (Climate Action), which has a direct link to reducing energy consumption and emissions, demonstrating the importance of sustainable water management practices.

Publisher

University of Galway

Rights

CC BY-NC-ND

cbn

Collections

University of Galway Theses (PhD Theses)