Treatment of refractory wastewater from MIC process using chemical hydrolysis and biological degradation화학적 가수분해와 생물학적 방법에 의한 난 분해성 MIC 공정 폐액 처리

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Methyl isocyanate(MIC) is an important chemical as a raw material to produce polymer, drugs, and carbamate pesticides. The phosgen-free MIC process is a safe process, but generates a large quantity of concentrated wastewater which contains various recalcitrant compounds. Only half the COD in the wastewater was removed in the activated sludge plant which has been acclimated for more than 15 years. Any additional conventional processes were not effective to improve the COD removal efficiency. To solve these problems, some fundamental studies, such as identification of the wastewater components and evaluation of their toxicities and biodegradabilities, were performed. Then a chemical hydrolysis, which was not common in the wastewater treatment field, was applied to enhance the COD removal efficiency. The mass and IR spectra of the extract from the wastewater demonstrated that trimethylisocyanurate(TMIC), trimethylbiuret(TMBU), tetramethylurea (TMU), and 1,3-dimethylurea(DMU) were the important components of the wastewater. TMIC, TMBU and TMU were the major recalcitrant compounds in the wastewater, while other unidentified but small amount of recalcitrant compounds were detected by HPLC analysis. On the other hand, DMU was readily degraded biologically releasing ammonia as a metabolite. The EC50 by Microtox test were 7393, 6728, 141272 , and 103 mg/l for TMIC, TMBU, DMU, and TMU, respectively. Their toxicity indices indicated that the relative acute toxicities of the wastewater components on the aquatic environment were not significant. The base catalyzed process was much more effective to hydrolyze the wastewater components than the acid catalyzed one. The reaction temperature and NaOH concentration affected largely the rate of hydrolysis. TMIC was easily hydrolyzed even at ambient temperature and the second order rate constants were estimated as $10^{-2}$ order at 28℃. Higher temperature was required to hydrolyze TMBU into the biodegradable DMU, and the secon...
Advisors
Shin, Hang-Sikresearcher신항식researcher
Description
한국과학기술원 : 토목공학과,
Publisher
한국과학기술원
Issue Date
1997
Identifier
128574/325007 / 000845182
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 토목공학과, 1997.8, [ xiii, 97 p. ]

URI
http://hdl.handle.net/10203/30490
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=128574&flag=dissertation
Appears in Collection
CE-Theses_Ph.D.(박사논문)
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