Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×102 mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.

Liquid scintillation cocktail is liquid waste, which consists of an organic solvent, scintillator, surfactant, and radionuclide. Large volumes of liquid scintillation waste are generated each year, and both the organic compound and radionuclide content can negatively affect on the health and the environment. Therefore, the liquid scintillation waste should be treated in an appropriate way. In this study, to facilitate the treatment of liquid scintillation waste, the sulfate-radical advanced oxidation process (SR-AOP) was performed for the mineralization of liquid scintillator waste. In SR-AOP, highly reactive sulfate radicals, which react more selectively and efficiently with organic compounds, are produced in situ by cleaving the peroxide bond in the persulfate molecule. For the experiment, 100 times diluted ULTIMA GOLD-LLT (initial TOC=699,800 ppm) was used as a liquid scintillation waste. The TOC removal efficiency of liquid scintillation waste by the OXONE (potassium peroxymonosulfate, PMS, 2KHSO5+KHSO4+K2SO4) and sodium persulfate (PS) with varying dosages (4–12 mM) was tested, and the effects of Co2+ and Cu2+ catalysts were compared at a range of pHs (3, 7, and 9). The experimental results demonstrated that 91% TOC removal of ULTIMA GOLD-LLT could be achieved for SR-AOP at initial pH=9, Co2+=1.2 mM (catalyst), PMS=4.8 mM (oxidant) for 60 min reaction. Compared to traditional Fenton AOP which is effective only at low pH, PMS based SR-AOP with Co2+ catalyst is effective at wide range of pHs and less dependent on the treatment efficiency of the operational pH. Therefore, it can be useful for the mineralization of liquid scintillation waste which is difficult to treat with a general treatment method due to the mixture of various organic compounds.

Tributyl phosphate (TBP) is a well-known and important compound in the nuclear industry for the nuclear fuel reprocessing, and it is also used in a various field such as plastic industry as antifoaming agent. Untreated organic pollutants in TBP can remain in the soil water and cause serious environmental pollution, thus it should be degraded through environmentally friendly methods. The non-thermal plasma-based advanced oxidation process (AOP) is one of the most widely studied and best developed processes owing to its simple structure and ease of operation. In this study, a plasma-based AOP was stably generated using submerged multi-hole dielectric barrier discharge (DBD) and applied to relatively high concentration of TBP solution. A submerged DBD plasma system was designed to directly interact with water, thereby producing reactive oxygen species (ROS) and functioning as a powerful oxidizer. Additionally, UV, O3, and H2O2 are generated by the developed plasma system without using any other additives to produce OH radicals for degrading organic pollutants; therefore, this system circumvents the use of complex and advanced oxidation processes. The electrical properties and concentrations of the active species were analyzed to establish optimal plasma operating conditions for degrading TBP solution. The results were analyzed by measuring the total organic carbon (TOC) and changes in solution properties. Based on these results, a degradation mechanism of TBP solution is proposed. After 50 min of plasma treatment, the concentration of TOC was gradually decreased. Consequently, we found that plasma-based AOP using submerged multi-hole DBD has advantages as an alternative technology for degrading organic pollutants such as TBP solution.

This study was conducted to evaluate the degradation and mineralization of PPCPs (Pharmaceuticals and Personal Care Products) using a CBD(Collimated Beam Device) of UV/H2O2 advanced oxidation process. The decomposition rate of each substance was regarded as the first reaction rate to the ultraviolet irradiation dose. The decomposition rate constants for PPCPs were determined by the concentration of hydrogen peroxide and ultraviolet irradiation intensity. If the decomposition rate constant is large, the PPCPs concentration decreases rapidly. According to the decomposition rate constant, chlortetracycline and sulfamethoxazole are expected to be sufficiently removed by UV irradiation only without the addition of hydrogen peroxide. In the case of carbamazepine, however, very high UV dose was required in the absence of hydrogen peroxide. Other PPCPs required an appropriate concentration of hydrogen peroxide and ultraviolet irradiation intensity. The UV dose required to remove 90% of each PPCPs using the degradation rate constant can be calculated according to the concentration of hydrogen peroxide in each sample. Using this reaction rate, the optimum UV dose and hydrogen peroxide concentration for achieving the target removal rate can be obtained by the target PPCPs and water properties. It can be a necessary data to establish design and operating conditions such as UV lamp type, quantity and hydrogen peroxide concentration depending on the residence time for the most economical operation.

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.

Climate change is believed to increase the amount of dissolved organic matter in surface water, as a result of the release of bulk organic matter, which make difficult to achieve a high quality of drinking water via conventional water treatment techniques. Therefore, the natural water treatment techniques, such as managed aquifer recharge (MAR), can be proposed as a alternative method to improve water quality greatly. Removal of bulk organic matter using managed aquifer recharge system is mainly achieved by biodegradation. Biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) can be used as water quality indicators for biological stability of drinking water. In this study, we compared the change of BDOC and AOC with respect to pretreatment methods (i.e., ozone or peroxone). The oxidative pretreatment can transform the recalcitrant organic matter into readily biodegradable one (i.e., BDOC and AOC). We also investigated the differences of organic matter characteristics between BDOC and AOC. We observed the decreases in dissolved organic carbon (DOC) and the tryptophan-like fluorescence intensities. Liquid chromatographic - organic carbon detection (LC-OCD) analysis also showed the reduction of the low molecular weight (LMW) fraction (15% removed, less than 500 Da), which is known to be easily biodegradable, and the biopolymers, high molecular weight fractions (66%). Therefore, BDOC consists of a broad range of organic matter characteristics with respect to molecular weight. In AOC, low molecular weight organic matter and biopolymers fraction was reduced by 11 and 6%, respectively. It confirmed that biodegradation by microorganisms as the main removal mechanism in AOC, while BDOC has biodegradation by microorganism as well as the sorption effects from the sand. O3 and O3 + H2O2 were compared with respect to biological stability and dissolved organic matter characteristics. BDOC and AOC were determined to be about 1.9 times for O3 and about 1.4 times for O3 + H2O2. It was confirmed that O3 enhanced the biodegradability by increasing LMW dissolved organic matter.

본 연구에서는 정수처리용 세라믹 한외여과 빛 광촉매의 혼성공정에서 휴믹산 농도 및 광산화, 흡착의 영향을 알아보았다. 휴믹산 농도 각각 2mg/L와 4 mg/L 일 때 UF 단독 공정 및 광촉매를 투입한 공정, UV를 조사한 공정을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피 (VΤ) 측면에서 고찰하였다. 휴믹산 농도가 낮아질수록 Rf는 급격히 감소하고 J는 증가하여, 휴믹산 농도 2 mg/L에서 VΤ는 가장 높았다. 탁도의 평균 처리효율은 휴믹산 농도가 증가할수록 감소하였으나, 4 mg/L에서 휴믹산의 처리효율이 가장 높았다. 이러한 결과는 낮은 휴믹산 농도에서 휴믹산 대부분이 분리막에 의해 제거되고 막을 통과한 일부 휴믹산은 광촉매에 흡착 산화되어, 처리수의 수질이 휴믹산 2 mg/L 와 4 mg/L 에서 거의 같고 원수의 수질은 4 mg/L에서 더 높기 때문이다. 광산화와 흡착의 영향 실험에서 UF + TiO2 + UV 공정의 J가 가장 높게 유지되어, 180분 운전 후 VΤ가 가장 높았다. 휴믹산 및 탁도의 처리효율을 비교한 결과, 휴믹산 농도가 2 mg/L 에서 4mg/L로 증가하였을 때 광산화 보다 광촉매 흡착이 더 주요한 역할을 하였다.

1,4-Dioxane is an EPA priority pollutant often found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to decompose this compound effectively. Therefore, an advanced oxidation process system (AOP) was used for the degradation of 1,4-dioxane. This research investigates the effect of adding oxidants, such as ozone, air, and H2O2 during the UV irradiation of 1,4-dioxane solution. In order to analyze 1,4-dioxane, a modified 8270 method, which is an improved method of U.S EPA 8720, was used. Degradation efficiencies of 1,4-dioxane by only UV irradiation at various temperatures were not significant. However, The addition of oxidants and air bubbling in the UV irradiation system for 1,4-dioxane decomposition showed the higher 1,4-dioxane degradation rate. And, during AOP treatment the tendency of TOC changes was similar to that of 1,4-dioxane decomposition rate.

This study investigated the treatment of acetaminophen in municipal wastewater by conventional ozonation, ozone-based advanced oxidation, ozone/UV, and the electro-peroxone process. The ozone/UV process and electro-peroxone process of electric power consumption increased 1.25 and 2.04 times, respectively, compared to the ozone process. The pseudo-steady OH radical concentration was the greatest in the　electro-peroxone process and lowest in the ozone process. The specific energy consumption for TOC decomposition of the ozone/UV process and electro-peroxone process were 22.8% and 15.5% of the ozone process, respectively. Results suggest that it is advantageous in terms of degradation performance and energy consumption to use a combination of processes in municipal wastewater treatment, rather than an ozone process alone. In combination with the ozone process, the electrolysis process was found to be more advantageous than the UV process.

Advanced oxidation processes involving O3/H2O2 and O3/catalyst were used to compare the degradability and the effect of pH on the oxidation of 1,4-dioxane. Oxidation processes were carried out in a bubble column reactor under different pH. Initial hydrogen peroxide concentration was 3.52 mM in O3/H2O2 process and 115 g/L (0.65 wt.%) of activated carbon impregnated with palladium was packed in O3/catalyst column. 1,4-dioxane concentration was reduced steadily with reaction time in O3/H2O2 oxidation process, however, in case of O3/catalyst process, about 50～75% of 1,4-dioxane was degraded only in 5 minutes after reaction. Overall reaction efficiency of O3/catalyst was also higher than that of O3/H2O2 process. TOC and CODCr were analyzed in order to examine the oxidation characteristics with O3/H2O2 and O3/catalyst process. The results of CODCr removal efficiency and ΔTOC/ΔThOC ratio in O3/catalyst process gave that this process could more proceed the oxidation reaction than O3/H2O2 oxidation process. Therefore, it was considered that O3/catalyst advanced oxidation process could be used as a effective oxidation process for removing non-degradable toxic organic materials.

The degradation of Rhodamine B (RhB) in water was investigated in laboratory-scale experiments, using five advanced oxidation processes (AOPs): UV/H2O2, fenton, photo-fenton, UV/TiO2, UV/TiO2/H2O2. The photodegradation experiments were carried out in a fluidized bed photoreactor equipped with an immersed 32 W UV-C lamp as light source. Initial decolorization rate and COD removal efficiency were evaluated and compared. The results obtained showed that the initial decolorization rate constant was quite different for each oxidation process. The relative order of decolorization was: photo-fenton > UV/TiO2/H2O2 > fenton > UV/H2O2 > UV/TiO2 > UV > H2O2. The relative order of COD removal was different from decolorization: photo-fenton ≒ UV/TiO2/H2O2 > UV/TiO2 > fenton > UV/H2O2. The photo-fenton and UV/TiO2/H2O2 processes seem to be appropriate for decolorization and COD removal of dye wastewater.

The advanced oxidation process (AOP) using ozone combined with hydrogen peroxide and ultraviolet treatment were evaluated for biodegradable dissolved organic carbon (BDOC) formation and dissolved organic carbon (DOC) removal. Oxidation treatment were conducted alone or combination with ozone, hydrogen peroxide and ultraviolet processes. Ozone dosage of ozone process was varied from 0.5㎎/ℓ·min to 5㎎/ℓ·min. Ozone/hydrogen peroxide process was done using 20㎎/ℓ of hydrogen peroxide concentration. Ozone/ultraviolet process was irradiated with 12mW/㎠ of density and 254nm. Ozone dosage was varied from 0.5㎎/ℓ·min to 5㎎/ℓ·min at the ozone/hydrogen peroxide and ozone/ultraviolet processes too. Contact time of all the process was 20 minutes. Oxidation treatment were performed on microfiltration effluent samples. BDOC formation was reached to an optimum at ozone dosage of 1.5㎎/ℓ·min in the ozone/hydrogen peroxide process and 1㎎/ℓ·min in ozone/ultraviolet process, after which BDOC formation was decreased at higher ozone dosages. But BDOC formation was increased with ozone dosages increasing in ozone process. The efficiency of DOC removal was higher AOPs than ozone process. Ozone/ultraviolet proces was the highest for DOC removal efficiency in each process. THMFP removal efficiency by ozone/ultraviolet process was higher than that by each of ozone process and ozone/hydrogen peroxide process.