This study investigated the degradation characteristics and biodegradability of phenol, refractory organic matters, by injecting MgO and CaO-known to be catalyst materials for the ozonation process-into a Dielectric Barrier Discharge (DBD) plasma. MgO and CaO were injected at 0, 0.5, 1.0, and 2 g/L, and the pH was not adjusted separately to examine the optimal injection amounts of MgO and CaO. When MgO and CaO were injected, the phenol decomposition rate was increased, and the reaction time was found to decrease by 2.1 to 2.6 times. In addition, during CaO injection, intermediate products combined with Ca2+ to cause precipitation, which increased the COD (chemical oxygen demand) removal rate by approximately 2.4 times. The biodegradability of plasma treated water increased with increase in the phenol decomposition rate and increased as the amount of the generated intermediate products increased. The biodegradability was the highest in the plasma reaction with MgO injection as compared to when the DBD plasma pH was adjusted. Thus, it was found that a DBD plasma can degrade non-biodegradable phenols and increase biodegradability.

This objective of this study was to investigate the degradation characteristics of phenol, a refractory substance, by using a submerged dielectric barrier discharge (DBD) plasma reactor. To indirectly determine the concentration of active species produced in the DBD plasma, the dissolved ozone was measured. To investigate the phenol degradation characteristics, the phenol and chemical oxygen demand (COD) concentrations were evaluated based on pH and the discharge power. The dissolved ozone was measured based on the air flow rate and power discharged. The highest dissolved ozone concentration was recorded when the injected air flow rate was 5 L/min. At a discharge power of 40W as compared to 70W, the dissolved ozone was approximately 2.7 – 6.5 times higher. In regards to phenol degradation, the final degradation rate was highest at about 74.06%, when the initial pH was 10. At a discharged power of 40W, the rate of phenol decomposition was observed to be approximately 1.25 times higher compared to when the discharged power was 70W. It was established that the phenol degradation reaction was a primary reaction, and when the discharge power was 40W as opposed to 70W, the reaction rate constant(k) was approximately 1.72 times higher.

The Electron/Hole Pair is generated when the activation energy produced by ultraviolet ray illuminates to the semiconductor and OH- ion produced by water photocleavage reacts with positive Hole. As a results, OH radical acting as strong oxidant is generated and then Photocatalytic oxidation reaction occurs. The photocatalytic oxidation can oxidate the non-degradable and hazardous organic substances such as pesticides and aromatic materials easier, safer and shorter than conventional water treatment process. So in this study, many factors influencing the oxidation of chlorophenols, such as inorganic electrolytes addition, change of oxygen and nitrogen atmosphere, temperature, pH, oxygen concentration, chlorophenol concentration, were throughly examined. According to the experiments observations, it is founded that the rate of chlorophenol oxidation follows a first-order reaction and the modified Langmuir-Hinshelwood relationship. And the photocatalytic oxidation occurs only when activation energy acting as Electron/Hole generation, oxygen acting as electron acceptor to prevent Electron/Hole recombination, $TiO_2$ powder acting as photocatalyst are present. The effects of variation of dissolved oxygen concentration, temperature and inorganic electrolytes concentration on 2-chlorophenol oxidation are negligible. And the lower the organic concentration, the higher the oxidation efficiency becomes. Therefore, the photocatalytic oxidation is much effective to oxidation of hazardous substances at very low concentration. The oxidation is effective in the range of 0.1 g/L-10 g/L of $TiO_2$. Finally when the ultra-violet ray is illuminated to $TiO_2$, the surface characteristics of $TiO_2$ change and Adsorption/Desorption reaction on $TiO_2$ surface occurs.

With the rapid industrialization, an ever-increasing quantity and kind of new organic compounds pose environmental problems due to their toxicity and physiological effect. However, research on the biodegradation of these compounds under anaerobic condition is very limited inspite of its efficiency and economical advantage. In this research, the pH effect on the ring cleavage of phenol under anaerobic condition was investigated, and the theory of phase separation was applied to the degradation of phenol for investigating the role of acidogenic bacteria. Results, obtained from biochemical methane potential(BMP) assay for 15.5 days of incubation, showed that acidic condition was more desirable for phenol degradation than alkaline condition. By both unacclimated methanogenic granular sludge and two mixed cultures, phenol was completely removed within six weeks of incubation with a gas conversion rate of over 86% of theoretical one. However, phenol was not degraded by unacclimated acidogenic culture, and thus it is considered as a syntrophic substrate. In case of phase separated biochemical methane potential(PSBMP) assay, in which acidogenic and methanogenic culture were seeded separately and consecutively, those that had been subjected to normal acidogens for 3 to 4 weeks showed higher gas production than those seeded with sterile or frozen culture.

Oxidative degradation of phenol, three monochlorophenols (2-chlorophenol, 2-CP; 3-chlorophenol, 3-CP; 4-chlorophenol, 4-CP), four dichlorophenols (2,3-dichlorophenol, 2,3-DCP; 2,4-dichlorophenol, 2,4-DCP; 2,5-dichlorophenol, 2,5-DCP; 2,6-dichlorophenol, 2,6-DCP), and two trichlorophenols (2,4,5-trichlorophenol, 2,4,5-TCP; 2,4,6-trichlorophenol, 2,4,6-TCP) was conducted with heat activated persulfate. As the number of chlorinations increased, the reaction rate also increased. The reaction rate was relatively well fitted to the zero-order kinetic model, rather than the pseudo-first order kinetic model for the reactions at 60℃, which can be explained by insufficient activation of the persulfate at 60℃, and the oxidation reaction of 2,4,6-TCP at 70℃ was relatively well fitted to the pseudo-first order kinetic model. The oxidation reaction rate generally increased with increase of persulfate concentration in the solution. 2,6-dichloro-2,5-cyclohexadiene-1,4-dione was found as a degradation product in a GC/MS analysis. This compound is a non-aromatic compound, and one chlorine was removed. This result is similar to the result of previous studies. The current study proved that heat activated persulfate activation could be an alternative remediation technology for phenol and chlorophenols in soil and groundwater.

인쇄회로기판 폐기물의 발생량은 꾸준히 증가하고 있으며, 구리 등 고가 금속을 함유하고 있어 적절한 재활용 방법의 적용이 시급한 상황이며, 그 대안으로서 열분해가 주목을 받고 있다. 본 연구에서는 페놀 인쇄회로기판(Phenol Printed Circuit Board, p-PCB) 폐기물의 열분해 특성을 규명하여 p-PCB 폐기물 열분해 공정 설계에 기초 자료를 제공하는데 그 목적을 두고 있다. 이를 위해 열중량분석기(Thermogravimetric analyzer; TGA)를 통한 동역학 분석과 더불어 부산물 특성 파악을 위해 Py-GC/MS(Pyrolyzer-Gas Chromatography/Mass Spectrometry, Py-GC/MS)를 적용하였다. 동역학분석과 휘발가스분석(Evolved Gas Analysis, EGA)을 통하여 p-PCB 열분해 반응은 크게 3 단계로 구분할 수 있다. 첫 번째 단계는, 280℃ 이하에서 반응이 일어나며, 초기질량의 10%로 감소하는 구간으로 미경화된 페놀 성분의 휘발과 열적으로 불안정한 물질들이 분해 배출된다고 여겨진다. 두 번째 단계는 280℃~380℃ 구간으로 초기 질량의 60%가 분해되는 구간으로서 주로 p-PCB를 구성하고 있는 종이와 경화된 브롬화(Brominated) 페놀수지의 분해로 판단된다. 마지막 분해구간인 380℃ 이상에서는 비브롬화(Non-Brominated) 페놀수지의 분해 및 촤(Char) 형성 단계로 판단된다. p-PCB의 열분해는 브롬화 페놀수지의 생성으로 특성지울 수 있으며, 열분해를 통해 페놀수지의 추출 재활용 가능성을 시사하고 있다.

The degradation of 3-chlorophenol(3-CP) by various AOPs(Advanced Oxidation Processes) including the ultraviolet / hydrogen peroxide, the Fenton and the ultraviolet(UV)-Fenton process has been conducted. The highest removal efficiency for 3-CP in the aqueous phase was obtained by the UV-Fenton process among the AOPs. In the UV-Fenton process, The removal efficiency of 3-CP decreased with increasing pH in the range of 3 to 6, and it decreased with increasing initial concentration. As the intermediates of 3-CP by UV-Fenton reaction, 3-chlorocatechol, 4-chlorocatechol, and chlorohydroquinone were detected thus the degradation pathways were proposed.

Electrochemical degradation of phenol was evaluated at DSA (dimensionally stable anode), JP202 (Ru, 25%; Ir, 25%; other, 50%) electrode for being a treatment method in non-biodegradable organic compounds such as phenol. Experiments were conducted to examine the effects of applied current (1.0~4.0 A), electrolyte type (NaCl, KCl, Na2SO4, H2SO4) and concentration (0.5~3.0 g/L), initial phenol concentration (12.5~100.0 mg/L) on phenol degradation and UV254 absorbance as indirect indicator of by-product degraded phenol. It was found that phenol concentration decreased from around 50 mg/L to zero after 10 min of electrolysis with 2.5 g/L NaCl as supporting electrolyte at the current of 3.5 A. Although phenol could be completely electrochemical degraded by JP202 anode, the degradation of phenol COD was required oxidation time over 60 min due to the generation of by-products. UV254 absorbance can see the impact of as an indirect indicator of the creation and destruction of by-product. The initial removal rate of phenol is 5.63 times faster than the initial COD removal rate.

The isolated strain, Rhodococcus sp. EL-GT was able to degrade high phenol concentrations up to 10 mM within 24 hours in the medium consisting of 5.3 mM KH2PO4, 95 mM Na2HPO4, 18mM NH4NO3, 1mM MgSO4·7H2O, 50μM CaCl2, 0.5μM FeCl3, initial pH8.0, temperature 30℃ in rotary shaker at 200rpm. This strain was good cell growth and phenol degradation in the alkaline pH range range, and the highest in the pH range of 7 to 9. The microorganism was able to grow at the various chlorinated phenols, benzene, toluene, and bunker-C oil. As Rhodococcus sp. EL-GT was good capable of attachment on the acryl media, it would be used as microorganism to consist of biofilm in wastewater treatment.

This study was investigated to evaluate the effect of the sodium ion and pH on toxicity of dinitrophenol at high concentrations (0.41 to 0.54 mM), over a sodium concentration range of 0.1 mM to 107 mM and over a pH range of 5 to 9. The concentration of sodium ions in the activated sludge mixed liquor seemed to have very little effect on dinitrophenol toxicity. However, lack of sodium in the growth media resulted in a reduction of the dinitrophenol degradation rate by bacterial isolate from the activated sludge culture, which has been identified as Nocardia asteroides. Dinitrophenol inhibition was found to be strongly dependent on mixed liquor pH. The dinitrophenol degradation rate was highest in the pH range of 6.95 to 7.84; at pH 5.94 degradation of 75 mg/L dinitrophenol was significantly inhibited; at pH < 5.77, dinitrophenol degradation was completely inhibited after approximately 30% of the dinitrophenol was degraded.

Pseudomonas sp. EL-04J was previously isolated from phenol-acclimated activated sludge. This bacterium was capable of degrading phenol and cometabolizing trichloroethylene (TCE). After precultivation in the mineral salts medium containing phenol as a sole carbon source, Pseudomonas EL-04J degraded 90% of TCE 25μM within 20 hours. Thus, phenol-induced Pseudomonas sp. EL-04J cells can degrade TCE. Following a transient lag period, Pseudomonas sp. EL-04J cells degraded TCE at concentrations of at least 250μM with no apparent retardation in rate, but the transformation capacity of such cells was limited and depended on the cell concentration. The degradation rate of TCE followed the Michaelis-Menten kinetic model. The maximum degradation rate (Vmax) and saturation constant (Km) were 7nmo ℓ/min·㎎ cell protein and 11μM, respectively. Cometabolism of TCE by phenol fed experiment was evaluated in 50·mℓ serum, vial that contained 10 ㎖ of meneral sals medium supplemented with 10μM TCE. TCE degradation was inhibited in the initial period of 1 mM phenol addition, but after that time Pseudomonas sp. EL-04J cells degraded TCE and showed cell growth.