Hyun-Goo Lee

Nitrate removal by electro-bioremediation technology in Korean soil.

The nitrate concentration of surface has become a serious concern in agricultural industry through out the world. In the present study, nitrate was removed in the soil by employing electro-bioremediation, a hybrid technology of bioremediation and electrokinetics. The abundance of Bacillus spp. as nitrate reducing bacteria were isolated and identified from the soil sample collected from a greenhouse at Jinju City of Gyengsangnamdo, South Korea. The nitrate reducing bacterial species were identified by 16s RNA sequencing technique. The efficiency of bacterial isolates on nitrate removal in broth was tested. The experiment was conducted in an electrokinetic (EK) cell by applying 20V across the electrodes. The nitrate reducing bacteria (Bacillus spp.) were inoculated in the soil for nitrate removal process by the addition of necessary nutrient. The influence of nitrate reducers on electrokinetic process was also studied. The concentration of nitrate at anodic area of soil was higher when compared to cathode in electrokinetic system, while adding bacteria in EK (EK+bio) system, the nitrate concentration was almost nil in all the area of soil. The bacteria supplies electron from organic degradation (humic substances) and enhances NO(3)(-) reduction (denitrification). Experimental results showed that the electro-bio kinetic process viz. electroosmosis and physiological activity of bacteria reduced nitrate in soil environment effectively. Involvement of Bacillus spp. on nitrification was controlled by electrokinetics at cathode area by reduction of ammonium ions to nitrogen gas. The excellence of the combined electro-bio kinetics technology on nitrate removal is discussed.

Evaluation of EK System by DC and AC on Removal of Nitrate Complex

Abstract DC (Direct current) is used in electrokinetic (EK) technology to extract hazardous materials from soils. Besides, AC (alternating current) electric field is also used to induce particle and fluid motion in electrokinetics. The influence of AC and DC on electrokinetic phenomena was studied for the removal of nitrate complex in soil environment. The experiments were performed by employing three systems – DC, AC, and AC overlapped DC. The removal of cations was higher at the anodic spot while applying DC. Involvement of AC on cation removal was very poor and nitrate removal was about 50%. AC and DC can be used for the removal of nitrate complex in agricultural soils.

Effect of Electrode Materials on Electrokinetic Reduction of Soil Salinity

Laboratory electrokinetic (EK) tests were conducted for the restoration of saline soil which contained mainly Na+, Cl− and ions. The effect of anode materials on salt removal was investigated by comparing various anodes such as dimensionally-stable anode, Pt, Si/BDD (boron-doped diamond), and Fe electrode. In all tests Na+ and Cl− were easily removed from the soil (>97%). Fe tests showed higher reduction of concentration and resulted in higher electrical conductivity reduction (∼90%) than the other anode tests. The results demonstrated that the EK process can reduce soil salinity effectively and the Fe anode is more suitable for restoration of sulfate-rich saline soil than other insoluble anodes.

In Situ Electrokinetic Removal of Salts from Greenhouse Soil Using Iron Electrode

An electrokinetic (EK) field study was performed on a pilot scale (2.2 × 3.3 × 0.3 m3, W × L × D) in a greenhouse by using Fe electrodes and bentonite backfill. When a constant voltage gradient was applied, the current intensity was affected by electrode position, and the soil temperature increased with the current intensity. After the EK treatment, the soil pH was little changed and the cations were hardly removed because of the ion exchange in the bentonite. However, the anions were mostly removed by electromigration, resulting in the reduction of the soil electrical conductivity. The field study demonstrated that in situ EK process is feasible for the remediation of greenhouse soils. In addition, the improvement of EK system and the role of bentonite backfill were discussed.

Analysis of voltages induced by distribution lines on gas pipelines

Because of the continuous growth of energy consumption and the tendency to site power lines and pipelines along the same route, the close proximity of power lines and buried metallic pipelines has become more and more frequent. Therefore, there has been and still is a growing concern about possible hazards resulting from the influence of power lines on metallic pipelines. Underground pipelines that run parallel to or in close proximity to power lines are subjected to induced voltages caused by the time-varying magnetic fields produced by the power line currents. The induced electro-motive force causes currents circulation in the pipeline and voltages between the pipeline and surrounding earth. This paper analyses the induced voltage on the gas pipelines buried in parallel with overhead power distribution lines.

Data logger apparatus for stray current measurement of subway and power line

In present, most of metallic structures (gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in Korea. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential, amplitude of stray current, point of source of stray current and so. In this paper, results of development about data logger apparatus for measurement stray current of subway and power line are presented.

Restoration of saline greenhouse soil and its effect on crop’s growth through in situ field-scale electrokinetic technology

ABSTRACT An in situ electrokinetic (EK) system was designed and applied to highly saline greenhouse soil with a view to investigating the effects of the EK process on growing crops. In situ EK tests in field scale were conducted on the salt accumulated lands in the greenhouse where cabbages and lettuces were being cultivated. A voltage gradient of 0.25–0.6 V cm−1 was applied for 50 days in the cultivated lands. The changes in the process, viz. current, voltage, and soil temperatures, were monitored. After the EK process, the initial electrical conductivity (EC, 6.0 dS m−1) of the soil was reduced to about 1.7 dS m−1 homogeneously below the recommended value (2.5 dS m−1). The growth rate of cabbages and lettuces under EK treatment was about twice higher than those in the untreated area. The present study revealed that the EK process encourages the growth of the crops considerably and also removes the salts in the soil efficiently during the growth of the crops.

Implementation of the integrated management system for electric vehicle charging stations

We proposed an integrated management system for Electric Vehicle Charging Stations, which were controlled by a remote monitoring server. All the information transferred by the charging stations was stored in the database, and was used for the analysis. Using the accumulated data, the proposed system was able to predict the amount of electricity. The system users could read various reports using a Web browser. In addition, the proposed system could be used in V2G due to its bidirectional communication and remote control abilities.

Rapid potential-controlled rectifier for securing the underground pipeline under electrolytic interference

In electrolytic interference circumstances such as underground pipelines in the vicinity of DC rail transportation power systems, either drainage methods or ICCP method has been widely used in order to secure the integrity of the pipelines. The drainage method is applied either by forced drainage system in which the driving voltage for draining the stray current from the pipelines is controlled by thyristors or by polarized drainage system which connects the pipeline with the railroads by diodes. In ICCP method, the phase-controlled rectifier with thyristors is in common use. Both methods, however, cannot respond to the dynamic fluctuation of the stray current. As a result, the pipe-to-soil potentials of the pipelines near railroads vary rapidly and therefore a new counter measure with dynamic response is necessary. In this paper, we introduce a new rapid potential-controlled rectifier consisting of full bridge circuits for bidirectional power output and IGBT switching device. Field test comparison with the existing forced drainage method showed the effectiveness of the developed rectifier for securing the pipelines under electrolytic interference.

Development of Remote Corrosion Monitoring and Control System for Oil Tanks by Using a High Efficiency CP Rectifier

Abstract Recently, advanced countries have used the corrosion monitoring system in chemical plants and oil tanks in order to protect them from corrosion because corrosion causes large accidents, soil pollution, and money loss. Generally, the owners of such facilities adopt Cathodic Protection (CP) systems for corrosion protection. However, Korea has adopted neither the CP system nor the corrosion monitoring system for oil tanks yet. This study presents a system we developed. It is a system that can not only automatically and remotely monitor corrosion but also remotely control corrosion by using a high efficiency CP rectifier. We hope that the results of this study will be used for the effective and economic operation of CP system. It can also extend the life of an oil tank.