IMPROVED RELIABILITY OF A NITRIFICATION/DENITRIFICATION ACTIVATED SLUDGE TREATMENT PLANT THROUGH A SYSTEMATIC APPROACH

Solutia Inc. (formerly Monsanto Chemical Company) owns and operates a major organic chemicals and acrylic fibers production complex in Decatur, Alabama. The process wastewaters are treated in an on-site wastewater treatment plant prior to discharge into the Tennessee River. In 1995, as a result of a program initiated to reduce nitrogen discharges, the wastewater treatment plant was upgraded from a conventional activated sludge treatment system to a 3.2 mgd nitrification/denitrification system. The upgraded system can treat 700 to 1,800 mg/L TC and 300 to 500 mg/L TKN.Although the upgraded treatment plant performed well, it was subject to several upsets and needed optimization to provide consistent and reliable treatment. In early 2000, Solutia initiated an intense proactive technical/operational program designed to prevent operation upsets, to detect potential upsets earlier and to aggressively respond more rapidly and more effectively. One of the first steps of this program was to conduct a critical review and functional analyses for the treatment plant. These results were used as a basis to formulate an action plan to bring about stability to the treatment system.The results of this program have maximized the use of all wastewater treatment resources, while maintaining compliance and avoiding impacts to production. Implementation has produced a more stable, robust nitrification/denitrification treatment system. Effluent ammonia concentrations are now consistently less than 1.0 mg/L, typically being non detect.