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Objective & Scope
1. Development of industrial-wastewater treatment process 2. Modeling of biological nitrogen removal process 3. Process optimization Main Contents Cokes wastewater from POSCO contains high concentration of ammonia and other toxic compounds such as phenol and cyanide. The presence of nitrogen compounds in an effluent causes environmental pollution like the nutrient enrichment in the receiving waterway, therefore provision is required for the removal of these compounds in wastewater treatment. In most cases biological treatments have been used to remove nitrogen compounds because of economy and reliability. These biological treatments are carried out by the successive applications of nitrification and denitrification releasing final harmless product, nitrogen gas. The problems in biological treatment of cokes wastewater are that phenol is the only carbon source in wastewater and cyanide inhibits nitrification. Therefore, the possibility of using phenol as a carbon sourde for denitrification should be investigated and the process configuration to minimize inhibition of cyanide determined. In this study the effects of phenol and other external carbon sources on denitrification were investigated and a modified activated sludge process for the simultaneous removal of ammonia, phenol, and cyanide was developed. It was founded that phenol was not the suitable carbon source for denitrification but sodium acetate was the best one among the tested carbon sources. In the modified activated sludge process, more than 95% of the major pollutants in cokes wastewater were removed. Mathematical model was developed to simulate the response to the change of various operating conditions in the previously developed process. Simulationg results showed that the efficiency of biological reaction in each stage was decreased by increasing HRT, especially, in nitrification. To find the key operating conditions that prevent efficiency from decreasing, simulation was performed with increased recycle rate, sludge residence time, and oxygen transfer rate. Process stability was also examined during the sinusoidal variation of cyanide input. References 1) Development and modeling of biological nitrogen removal process from coke plant wastewater Min Woo Lee, Thesis of Master (1995), POSTECH, KOREA 2) Development of biological nitrogen and phosphorus removal process for the treatment of industrial and domestic wastewater Min Woo Lee, Thesis of Doctor (1998), POSTECH, KOREA 3) Nitrogen removal in activated sludge processes by using chemical pretreatments M.W. Lee and J.M. Park, Biotechnol. News, 1(3), 12 (1994) 4) Biological nitrogen removal from coke plant wastewater M.W. Lee and J.M. Park, Wat. Env. Res., 70, 1090 (1998) 5) Control of external carbon addition in biological nitrogen removal process for the treatment of coke-plant wastewater M.W. Lee, Y.J. Park, J.M. Park, and H.D. Chun, Water Env. Res., 73(4), 415 (2001) Related Patents 1) Isolation of cyanide- and thiocyanide-degrading bacteria and development of wastewater treatment methods by using these bacteria J.M. Park and E.D. Park, Korea Patent (1998) |
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