The Low Methanol Diet - A Utility's Recipe for Process Optimization through Advanced Controls and Operational Excellence

摘要

The AlexRenew WRRF (204 ML/d AADF) has recently been upgraded to meet an annual average TN concentration of 3 mgN/L. Recent upgrades have been targeted to increase efficiency including an attempt to "activate" the anammox granules for mainstream nitrogen removal. Customized strategies were developed using Bio Win for aeration and supplemental carbon dosing. The control algorithms include ammonia-based aeration control (ABAC), intermittent aeration, automated methanol dosing and automated ORP control to prevent anaerobic conditions in the post-anoxic zone. Since the systems were placed in service in 2016, the facility has reduced aeration requirements by 30% and methanol consumption by 50% compared to previous years, all the while meeting the more stringent final effluent total nitrogen limits. The facility has saved almost $300,000 per year in chemical expenditures. The increased reliance on instrumentation and controls has created additional demands on AlexRenew's staff and required implementation of a probe maintenance program.