Cyanide is a by-product of incomplete combustion in the multiple hearth furnace at Seneca Water Resource Recovery Facility (WRRF). The cyanide is removed from incinerator exhaust, along with other air pollutants, in the venturi and after-cooler wet scrubbers. Spent venturi and after-cooler water containing cyanide is sent to the head of the plant, mixing with plant influent before entering the primary clarifiers. Cyanide is a known inhibitor of nitrification and is thought to have contributed to the 2025 Seneca plant upset where incomplete nitrification during secondary treatment lead to high nitrite concentrations in plant effluent and subsequent failure of chlorine disinfection (See the Report titled Seneca Nitrifier Washout and Disinfection Upset for reference). Starting in August of 2025, weekly monitoring of cyanide concentrations in venturi and after-cooler waste streams was implemented. A thorough attempt was made, using multiple regression and principle component analyses, to relate cyanide production in Seneca’s incineration system with various operating parameters including incinerator, afterburner, venturi scrubber, and after-cooler setpoints and process values. However, no variables were found to strongly correlate with cyanide concentration in scrubber water streams. Multiple sources, including a publication by Daigger et al. (1998) and a 2000 WEFTEC Report by the Central Conta Costa Sanitary District (Martinez, CA) have reported that increasing the afterburner temperature to > 1300°F in a multiple hearth furnace system can serve to destroy cyanide before it is collected into aqueous streams by the wet scrubbers. Seneca WRRF currently operates their afterburners at 1250°F with process values controlling tightly to this setpoint. The following study was performed on April 30, 2026 at Seneca WRRF to determine the efficacy of increased afterburner temperatures for destroying cyanide at the plant.