Toxicity and Degradation of the Wastewater of the Urea Fertilizer Plants, Oxidation of Fenton and Pseudomonas fluorescens Bacteria

_Treating the wastewater with high level of urea and ammonia-nitrogen is one of the problems faced by urea fertilizer plants in Indonesia. The alternative treatment being studied is the one which uses Fenton oxidation process which is continued with the use of Pseudomonas fluorescens bacteria. This study is conducted with the concentration of ammonia-nitrogen of 2500 ppm, 2000 ppm, and 1500 ppm. The response being observed is the level of ammonia-nitrogen (NH3-N) and nitrate-and nitrite in the influent and the level of ammonia-nitrogen (NH3-N) and nitratenitrite in the effluent. This study also aims to estimate the IC50 (Inhibition Concentration), NOEC (No Observed Effect Concentration) and LOEC (Lowest Observed Effect Concentration) for 96 hours after being given toxicant in the form of the wastewater of the urea fertilizer plants against the development of the number of cells of P. fluorescens. The value of IC50 after 96 hours of being given the toxicant of the wastewater of urea fertilizer plants against P.fluorescens is 723,219 ppm, while the value of LOEC is 393, 992 ppm and that of NOEC is 2533,658 ppm. The result of the study shows that the biggest average percentage of decline of ammonium is that of the level of ammonium-nitrogen of 2500 ppm in a ratio of 1:10 which is 94.50%. Further study using P. fluorescens results in a decrease of nitrate-nitrite in the ratio of 1 : 4 and 1 : 6 which satisfies the quality standards specified in the Environment Minister's Decision No.122 of the year 2004 and the Decree of the Governor of South Sumatra No. 18 of the year 2005. The result of this study provides a fairly high efficiency, hence it is expected that it can be applied in the industrial world.