PDU Scale Nitrification and Denitrification of Great Plains Gasification Plant's Stripped Gas Liquor

摘要

Gasification wastewater treatment at UNDERC has focused on treating wastewater to suitable quality for reuse. Reuse criteria have centered on reduction of organic compounds; the major reuse option for these wastewaters has been for cooling water. Pilot studies at UNDERC have demonstrated that significant quantities of ammonia will be stripped in a cooling tower using stripped gas liquor as makeup, requiring further reductions in ammonia concentrations prior to reuse. Moreover, reuse can be very expensive due to the cost of chemical additives, high corrosion of construction materials and other expenses. Therefore, interest has developed in treatment of these wastewaters for discharge. Nitrogen removal to low concentrations will be required for discharge of these wastewaters and may be required for most reuse options. Biological removal of nitrogen from Great Plains Gasification Plant's stripped gas liquor (SGL), through the processes of nitrification and denitrification, are the subject of this report. Over 43,000 liters (11,360 gallons) of pretreated SGL were nitrified in 3 PDU scale reactors, and 14,500 liters (3800 gallons) of this wastewater were denitrified. The kinetics of nitrification were determined by obtaining removal data simultaneously in three activated sludge reactors operating at different solids retention times. Suspended growth (activated sludge) complete-mix, stirred-tank reactors were used for this research. Process performance data for nitrification and denitrification are reported. Essentially complete removal of ammonia, at influent concentrations of greater than 500 mg/l NH sub 3 -N, was observed, and influent nitrate-N concentrations of greater than 750 mg/l were completely denitrified. 16 refs., 25 figs., 7 tabs. (ERA citation 11:025297)