This study was conducted to identify intermediate products and a possible pathway of propylene glycol degradation under anaerobic conditions. In a 60-day continuous run of two chemostat in series, suspended growth was inoculated with a detached biofilm from the anaerobic fluidized bed bioreactor(AFBR) carriers. The influent was made up of 9.0g COD/L of propylene glycol with an essential nutrient supplement for anaerobes. The fermentative bacteria were dominant in the reactor. Propionaldehyde, propionate, propanol and acetate were detected and identified in the anaerobic propylene glycol degradation. Propionate and propanol were produced at equal concentrations in the intermediate products. No significant growth of microorganisms was observed in the reactor under the imposed experimental conditions. A considerable amount hydrogen was observed at about 1.08~1.10×10-3atm, indicating that hydrogen plays a key role in the anaerobic propylene glycol degradation. This suggests a possible pathway, where propionaldehyde is an intermediate via a dehydration reaction in the initial diol cleavage. This result leads to a hypothesis of a possible pathway that has propionaldehyde as a transient intermediate product in the very initial degradation stages of propylene glycol. Propionaldehyde would then be disproportionated into an equal molar amount of propionate and n-propanol, which would be further converted to acetate and hydrogen. Propionate would be subsequently degraded to acetate, carbon dioxide and hydrogen. Lastly, methane would be produced both from acetate by acetoclastic methanogens and from hydrogen and carbon dioxide by hydrogenotrophic methanogens.

This study was performed to identify the influencing factors and operating conditions on the treatment of acid mine drainage(AMD) from the Il-kwang mine by porous Zeolite-Slag(ZS) ceramics packed in a column reactor. The hydraulic retention time(HRT) of the column reactor was a pivotal operating condition. Additionally, the mixing ratio of zeolite to slag (Z:S) significantly affected the column's alkali supply capacity and heavy metal removal efficiency. An HRT of 1.0 day was more effective than 0.5 day HRT in terms of alkali supply capacity and heavy metal removal efficiency. The heavy metal removal efficiency of the 1:3 (Z:S) porous ZS ceramics was higher than that of the 1:1 (Z:S). The average heavy metal removal efficiencies of the 1:3 (Z:S) in a continuous column reactor (1.0 day HRT, 31 operating days) were 92.4%, 86.3%, 96.5%, 99.2%, 96.1%, 89.3%, 98.9% and 93.7%, for Al, As, Cd, Cu, Fe, Mn, Pb, and Zn, respectively. These results suggest that a porous 1:3 (Z:S) ceramic column reactor at an HRT of 1.0 day might be an effective long-term treatment strategy for AMD from the Il-kwang mine.

In many industrial plants, foaming at liquid surfaces can reduce process efficiency and cause environmental problems with waste discharge. In most industrial sites, such as wastewater treatment plants, it is necessary to remove foam to improve water quality and process efficiency. The formation of persistent foams can be a critical problem in wastewater treatment since it can lead to operational issues and reduce the overall system performance. For basic research for the development of new defoamers, we tested defoamers for wastewater treatment. A 50% (v/v) water-dispersible foaming liquid was prepared using a foaming agent-A. Two types of defoaming agents were tested: silicone emulsion anti-foaming agents, B and C, and non-silicone oil anti-foaming agents, corn oil and mineral oil. The defoaming properties of these substances were tested as a function of pH, defoamer concentration, viscosity of defoamer dispersion, and defoamer storage period. At a pH of 3, 5, and 7, the defoaming by the silicone oil emulsion and non-silicone oil was greater than 80% effective. The foam quantity (L/min) of the silicone-based defoamer was lower even at lower concentrations than the non-silicone corn oil and mineral oil. At lower pH, the viscosity of the defoamer dispersions was slightly higher. We observed little difference in defoaming capacity after 30 days of storage.

A previously-developed complex of K3[Fe(CN)6] and FeCl3 is a blue-coloured dye known for its effectiveness in removing cesium from the water. However, despite its superior cesium adsorption capacity and high disposal effectiveness, the powdered complex of K3[Fe(CN)6] and FeCl3 also dissolves under water, which makes it difficult to isolate and recover, and as such it accumulates in the hydrosphere, possibly leading to secondary environmental problems. Therefore, in this study, we produce and apply a new adsorbent to the cesium disposal in order to overcome the problems of the powdered complex of K3[Fe(CN)6] and FeCl3. Carbonyl iron, a ferromagnetic substance produced in the manufacturing of pentacarbonyl iron, was selected as the main ingredient of the new compound. The compound is produced through a process of oxidation of its surface with a particle of CI, and a process of silane treatment with the complex of K3[Fe(CN)6] and FeCl3. An X-Ray Diffractometer (XRD) analysis of the surface of the produced compound confirmed its surface being uniformly coated with the complex of K3[Fe(CN)6] and FeCl3. A batch experiment conducted in order to evaluate cesium disposal capability of the compound granted it a high cesium removal efficiency of 99.5%. With a distribution coefficient value of 113,136 mL/g, the compound can be classified as a high quality absorbent. We believe that the new adsorbent developed in this study can be applied as an economical and environment-friendly viable alternative that can be used to dispose of cesium from the water safely and completely.

A novel multi-fiber media filtration process was developed to treat pollutants in combined sewer overflow (CSO) effluents under a natural flow rate (12 m/hr). Most conventional CSO filtration processes operate in an upward flow, resulting in low filtration efficiency and high operating cost. In this multi-fiber filtration process, we used a horizontal filtration method with radial flow from the center of the multi-fiber medium. The fibers and filtration efficiencies were characterized using various techniques. The fibers exhibited a surface charge of -29.5 mV. The fibers' filtration performance was evaluated under pilot-scale conditions (Q=22.5 ㎥/day) with mixed raw water amd final discharged water in an existing sewer treatment plant. In the pilot experiment, the average particle sizes for influent and effluent were 21.4 ㎛ and 4.45 ㎛, respectively, while the removal efficiency of BOD, COD, TOC, and SS was 82.9%, 77.9%, 50.1%, and 86.1%, respectively. These results are consistent with the sieving effects and electrostatic effects between fibers and pollutants. From these results, we can infer that this novel multi-fiber filtration process has the potential to treat CSO.

With the mitigation of membrane fouling by aeration in the membrane bioreactor (MBR), advanced treatments such as activated carbon, synthetic resin adsorption, and coagulation for reducing a foulants have been studied. Activated carbon adsorption is a common and generally effective treatment method for removing organic compounds with small molecular weight in wastewater treatment plants. Biofiltration of a submerged MBR using a dead-end stirrer cell was conducted to investigate the effects of granular activated carbon (GAC) addition to the MBR on substrate removal and the membrane fouling mitigation. Real wastewater (32±4 NTU, 34±0.7 mgTOC/L, 23±0.2 mgT-N/L, 5±0.08 mgT-P/L, and 4600±30 mgMLSS/L), used as raw water, was collected from a real aeration tank. Compared with the MBR in the absence of GAC, the membrane filtration of MBR with the addition of GAC achieved a higher efficiency (exceeding 92%) for particles and organic matter, except T-N for which it exhibited lower efficiency (<45%) regardless of the permeate flux. An increase in permeate flux resulted in a rise in transmembrane pressure (TMP) and total membrane resistance regardless of the addition of GAC to MBR, indicating that both low permeate flux and high solid retention time for MBRs with and without the addition of GAC are needed to improve membrane resistance and enhance the efficiency of nitrogen removal by providing an oxic and anoxic zone in the GAC in MBR.