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Yangsan, South Korea

Lee J.-H.,SU Engineering Co. | Park J.-J.,SU Engineering Co. | Seo K.-S.,Small and Medium Business Administration | Choi G.-C.,SU Engineering Co. | Lee T.-H.,Pusan National University
Korean Journal of Chemical Engineering | Year: 2013

Spent sulfidic caustic (SSC), produced from petroleum plants, contains high levels of H2S and alkalinity. It can be used to denitrify nitrate-nitrogen via a biological nitrogen removal process, as both the electron donor and buffering agent for sulfur-based autotrophic denitrification. However, SSC also contains some recalcitrant organic compounds such as BTEX, so it has to be refined. To remove BTEX, air stripping was conducted in a laboratory scale, and as a result, over 93% of the BTEX were removed within 30min. For the reformation of the refined SSC, Na2S2O3 · 5H2O, methanol and organic material, produced from a biodiesel production plant, were supplemented, and referred to as new sulfidic caustic I (NSCI), II (NSCII), III (NSCIII), respectively. Thereafter, these products were applied to a modified Ludzack-Ettinger (MLE) process to evaluate their effects on the effluent COD and TN concentrations. As a result, there was no increase in the COD level on the injection of NSC due to the removal of BTEX via air stripping. In addition, compared to no NSC injection, 44. 0% more TN was removed with an injection of NSC III, which were the most effective conditions. Thus, the application of NSC to the biological nitrogen removal process was successfully performed. These results may contribute to the development of resource recovery technology. © 2012 Korean Institute of Chemical Engineers, Seoul, Korea. Source

Lee J.-H.,SU Engineering Co. | Lee S.-M.,Pusan National University | Choi G.-C.,SU Engineering Co. | Park H.-S.,Busan Environmental Corporation | And 2 more authors.
Water Science and Technology | Year: 2011

Spent sulfidic caustic (SSC) produced from petrochemical plants contains a high concentration of hydrogen sulfide and alkalinity, and some almost non-biodegradable organic compounds such as benzene, toluene, ethylbenzene and xylenes (BTEX). SSC is mainly incinerated with auxiliary fuel, leading to secondary pollution problems. The reuse of this waste is becoming increasingly important from economic and environmental viewpoints. To denitrify wastewater with low COD/N ratio, additional carbon sources are required. Thus, autotrophic denitrification has attracted increasing attention. In this study, SSC was injected as an electron donor for sulfur-based autotrophic denitrification in the modified Ludzack-Ettinger (MLE) process. The efficiencies of nitrification, COD, and total nitrogen (TN) removal were evaluated with varying SSC dosage. Adequate SSC injection exhibited stable autotrophic denitrification. No BTEX were detected in the monitored BTEX concentrations of the effluent. To analyse the microbial community of the MLE process, PCR-DGGE based on 16 S rDNA with EUB primers, TD primers and nirK gene with nirK primers was performed in order to elucidate the application of the MLE process to SSC. © IWA Publishing 2011. Source

Park S.,Pusan National University | Lee J.,SU Engineering Co. | Park J.,SU Engineering Co. | Byun I.,Pusan National University | And 3 more authors.
Water Science and Technology | Year: 2010

Since spent sulfidic caustic (SSC) produced from petrochemical industry contains a high concentration of alkalinity and sulfide, it was expected that SSC could be used as an electron donor for autotrophic denitrification. To investigate the nitrogen removal performance, a pilot scale Bardenpho process was operated. The total nitrogen removal efficiency increased as SSC dosage increased, and the highest efficiency was observed as 77.5% when SSC was injected into both anoxic tank (1) and (2). FISH analysis was also performed to shed light on the effect of SSC dosage on the distribution ratio of nitrifying bacteria and Thiobacillus denitrificans. FISH results indicated that the relative distribution ratio of ammonia-oxidizing bacteria, Nitrobacter spp., Nitrospira genus and Thiobacillus denitrificans to eubacteria varied little with the pH of the tanks, and SSC injection did not give harmful effect on nitrification efficiency. These results show that SSC can be applied as an electron donor of autotrophic denitrification to biological nitrogen removal process effectively, without any inhibitory effects to nitrifying bacteria and sulfur-utilizing denitrifying bacteria. © IWA Publishing 2010. Source

Choi G.-C.,SU Engineering Co. | Lee J.-H.,SU Engineering Co. | Yu J.-C.,Pusan National University | Ju D.-J.,Pusan National University | Park J.-J.,SU Engineering Co.
Korean Journal of Chemical Engineering | Year: 2011

A biofilm process with the attached bacterial growth onto ceramic media was applied to remove carbonaceous and nitrogenous pollutants from nonpoint water source. The packing ratios of ceramic media were 0.05 and 0.15 (v/v). Thereafter, the reactors were operated intermittently in sequencing batch mode with different cycle periods: 0, 5, 10 and 15 d. The COD and NH4 +-N removal efficiencies were investigated under different operating conditions, such as media packing ratio, temperature and interevent period. Additionally, polymerase chain reaction (PCR)-denaturing gel gradient electrophoresis (DGGE) and INT-dehydrogenase activity (DHA) tests were conducted to observe the microbial community and activity in the biofilm. Consequently, the removal efficiency of the organic matter after 8 h remained stable, even with longer interevent periods, regardless of the packing ratio. The interevent period and packing ratio seemed to have no significant influence on the COD removal efficiency. However, stable nitrification efficiency, with longer interevent period, was only achieved with a packing ratio of 0.15. Therefore, a packing ratio above 0.15 was required to simultaneously achieve stable COD removal and nitrification efficiency. The DGGE profiles revealed that the prevalent microorganism species were changed from that of the seeded activated sludge into those detected in the sediments. Due to the prevalence of microorganisms related to the sediment, their activities did not decrease, even after a 15 d interevent period. © 2011 Korean Institute of Chemical Engineers, Seoul, Korea. Source

Lee J.-H.,SU Engineering Co. | Park J.-J.,SU Engineering Co. | Choi G.-C.,SU Engineering Co. | Byun I.-G.,Pusan National University | And 2 more authors.
Water Science and Technology | Year: 2013

Spent sulfidic caustic (SSC) produced from petroleum industry can be reused to denitrify nitratenitrogen via a biological nitrogen removal process as an electron donor for sulfur-based autotrophic denitrification, because it has a large amount of dissolved sulfur. However, SSC has to be refined because it also contains some aromatic hydrocarbons, typically benzene, toluene, ethylbenzene, xylene (BTEX) and phenol that are recalcitrant organic compounds. In this study, laboratory-scale ultrasound irradiation and air stripping treatment were applied in order to remove these aromatic hydrocarbons. In the ultrasound system, both BTEX and phenol were exponentially removed by ultrasound irradiation during 60 min of reaction time to give the greatest removal efficiency of about 80%. Whereas, about 95% removal efficiency of BTEX was achieved, but not any significant phenol removal, within 30 min in the air stripping system, indicating that air stripping was a more efficient method than ultrasound irradiation. However, since air stripping did not remove any significant phenol, an additional process for degrading phenol was required. Accordingly, we applied a combined ultrasound and air stripping process. In these experiments, the removal efficiencies of BTEX and phenol were improved compared to the application of ultrasound and air stripping alone. Thus, the combined ultrasound and air stripping treatment is appropriate for refining SSC. © IWA Publishing 2013. Source

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