By Patrick Higgins
The introduction of simple, reliable, and affordable in situ sensors based on ion selective electrode (ISE) technology provides the opportunity for more advanced activated sludge control strategies. For example, aeration control using ammonium as a response variable in addition to or in place of dissolved oxygen (DO) using continuous monitoring and control instruments. Ammonium-based aeration control has already been implemented at many water resource recovery facilities (WRRF). Many more are wondering if it is right for them. The simple answer is that automation of aeration based on ammonium measurement would be beneficial for many facilities. However, the applicable control strategy for a particular facility depends on specific factors including system configuration, performance requirements (discharge limitations), and wastewater characteristics. The following article identifies several control strategies. The approaches described offer the potential to enhance treatment performance, reduce operating costs and, in some cases, even generate revenue from nutrient credits.