This study evaluates the potential of various coagulants to enhance the efficiency of total phosphorus removal facilities in a sewage treatment plant. After analyzing the existing water quality conditions of the sewage treatment plant, the coagulant of poly aluminium chloride was experimentally applied to measure its effectiveness. In this process, the use of poly aluminium chloride and polymers in various ratios was explored to identify the optimal combination of coagulants. The experimental results showed that the a coagulants combination demonstrated higher treatment efficiency compared to exclusive use of large amounts of poly aluminium chloride methods. Particularly, the appropriate combination of poly aluminium chloride and polymers played a significant role. The optimal coagulant combination derived from the experiments was applied in a micro flotation method of real sewage treatment plant to evaluate its effectiveness. This study presents a new methodology that can contribute to enhancing the efficiency of sewage treatment processes and reducing environmental pollution. This research is expected to make an important contribution to improving to phosphorus remove efficiency of similar wastewater treatment plant and reducing the ecological impact from using coagulants in the future.

Complaints about foul odors are emerging as an issue, and the number of complaints is steadily increasing every year. Biofiltration is known to remove harmful or odorous substances from the atmosphere by using microorganisms, and full-scale biofilters are being installed and operated in various environmental and industrial facilities. In this study, the current status and actual odor removal efficiency of full-scale biofilters installed in publicly owned treatment facilities such as sewage, manure, and livestock manure treatment plants were investigated. In addition, the effects of design and operating factors on their efficiency were also examined. As a result, it was found that odor prevention facilities with less than 30% odor removal efficiency based on complex odors accounted for 40%-50% of the biofilters investigated. In investigating the appropriate level of operating factors on odor removal efficiency, it was found that compliance with the recommended values p lays a significant role in improving odor removal efficiency. In the canonical correlation analysis for the on-site biofilter operation and design data, residence time and humidity were found to be the most critical factors. The on-site biofilter operation and design data were analyzed through canonical correlation analysis, and the residence time and humidity maintenance were found to be the most important factors in the design and operations of the biofilter. Based on these results, it is necessary to improve the odor removal efficiency of on-site biofilters by reviewing the effectiveness of the operation factors, improving devices, and adjusting operating methods.

Eutrophication and algal blooms can lead to increase of taste and odor compounds and health problems by cyanobacterial toxins. To cope with these eco-social issues, Ministry of Environment in Korea has been reinforcing the effluent standards of wastewater treatment facilities. As a result, various advanced phosphorus removal processes have been adopted in each wastewater treatment plant nation-widely. However, a lot of existing advanced wastewater treatment processes have been facing the problems of expensive cost in operation and excessive sludge production caused by high dosage of coagulant. In this study, the sedimentation and dissolved air flotation (SeDAF) process integrated with sedimentation and flotation has been developed for enhanced phosphorus removal in wastewater treatment facilities. Design and operating parameters of the SeDAF process with the capacity of 100 m3/d were determined, and a demonstration plant has been installed and operated at I wastewater treatment facility (located in Gyeonggi-do) for the verification of field applicability. Several empirical evaluations for the SeDAF process were performed at demonstration-plant scale, and the results showed clearly that T-P and turbidity values of treated water were to satisfy the highest effluent standards below 0.2 mg/L and 2.0 NTU stably for all of operation cases.

Due to lack of established operating conditions, the swine manure management process circulates bio-liquor between the slurry pit and the bioreactor process cannot be effectively used yet. Therefore, a lab scale study comprising a single bio-reactor and slurry pit was conducted to investigate the optimal operating conditions. The main experiment was performed after conducting a preliminary study on the operating conditions. In the preliminary study, the volume ratio of the bioreactor to the slurry pit was fixed at 1 and hydraulic retention time (HRT) of the bioreactor was set as 5, 10 and 15 d. In the main experiment, the HRT of the bioreactor was fixed at 5 d based on preliminary results and the ratio of bioreactor to slurry pit was set at 1:3, 1:5, 1:7 and 1:10. Since, a decrease in bioreactor performance occurred when NH4-N loading rate reached 60 g/m3/d, the loading rate of NH4-N was required to be maintained below 55 g/m3/d to achieve stable operation. Although manure excretion can definitely increase the loading rate into the bioreactor as well as NH4-N concentration in the slurry pit, the NH4-N in slurry pit can be kept consistent with the circulation rate above 9.5Q (ratio to manure excretion). The optimal volume ratio of the bioreactor to the slurry pit and HRT of the bioreactor to fulfill these operating conditions was 1:3 and 5d, respectively. Notably, studying of the individual farm situation is very important to establish an ideal method to apply the optimal operation conditions suggested in this study.

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical · chemical · biological functions (① flotation and oxidization using microbubbles, ② vegetation purification and ③ bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than 3.5 kgf/cm2. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.

In this study, the effectiveness of electrodialysis in removing inorganic arsenic from groundwater was investigated. To evaluate the feasibility of the electrodialysis, operating parameters such as treatment time, feed concentration, applied voltage and superficial velocity were experimentally investigated on arsenic removal. The higher conductivity removal and arsenic removal efficiency were obtained by increasing applied voltages and operation time. An increase of salinity concentrations in arsenic polluted groundwater exerted no effects on the arsenic separation ratios. Arsenic polluted waters were successfully treated with stack voltages of 1.8 ~ 2.4 V/cell-pair to approximately 93.4% of arsenic removal. Increase flow rate in diluate cell gave positive effect to removal rate. However, increase of superficial velocity in the concentrated cell exerted no effects on either the conductivity reduction or on the separation efficiency. Hopefully, this paper will provide direction in selecting appropriate operating conditions of electrodialysis for arsenic removal.

폐기물로부터 에너지를 회수하고자 하는 노력은 전세계적인 추세이며, 국내에서도 가연성 폐자원의 효율적인 친환경적 처리, 에너지 회수를 위한 다양한 정책과 법규가 만들어져 진행되고 있다. 가연성 폐기물로부터 에너지를 회수하는 전통적인 방법인 소각과 비교하여 가스화 기술은 생산된 합성가스를 다양한 방법으로 활용할 수 있으며, 100톤 미만의 폐기물 처리시 소각보다 월등히 높은 효율을 보이고 있다. 따라서 사용연한이 다 되어가는 국내 중소규모 소각시설의 대체 및 플랜트의 해외 수출 등을 위해 폐기물 고형연료의 가스화 기술의 개발이 진행중이다. 본 연구에서는 이러한 폐기물 고형연료 가스화 플랜트 기술의 개발을 위해 국내 한 지자체의 생활폐기물을 대상으로 비성형 고형연료를 제조하고, 제조된 고형연료를 공기사용 고정층 가스화를 통해 합성가스를 생산하여 이를 직접 가스엔진 발전기에 도입함으로써 일정량의 전력을 생산할 수 있는 반응 특성에 대해 연구하였다. 실험 설비와는 다르게 파일럿 플랜트 이상의 실증시설은 강제로 온도를 유지할 수 없으므로, 공급하는 산화제에 의해 로내 온도가 변화되며, 최적 가스화 효율을 얻기위해 다양한 운전인자의 변화에 따른 가스화 특성에 대해 평가하였다.

전 세계적으로 에너지 수요증가와 유가 불안정 현상이 지속됨에 따라 이를 대체할 방안으로 신재생에너지 사용에 대한 관심이 높아지고 있으며 신재생 에너지의 수요가 늘어날 것으로 예측된다. 우리나라는 신재생에너지 공급의무화 제도(Renewable & Portfolio Standards; RPS)를 2012년부터 도입하여 50만kW 이상의 발전소는 총 발전량에 대한 신재생에너지를 사용한 전력공급율을 2012년 2%를 시작으로 2024년까지 10%로 실시할 계획이다. 최근 RPS 의무이행자인 발전사들의 신재생에너지발전원 중 바이오 비율이 70%에 이르며 이는 바이오매스 발전이 투자비 및 연료구매 비용이 낮고 운영효율성이 높아 RPS 이행이 쉽기 때문이다. 하지만 바이오매스로의 쏠림현상은 국내 목재시장의 유통구조에 악영향을 미치고 있으며 바이오매스발전 급증으로 폐목재 수요도 동반 증가하면서 재활용 가능한 목재까지 연료로 사용되고 있는 실정이다. 최근 팜오일 바이오매스는 인도네시아 산업을 이끌 잠재력 있는 자산으로 대두되어 왔으며, 2013년 기준 1억 4,200만 톤의 팜오일과 이에 따른 6,654만톤의 팜 부산물이 생산되고 있어 이를 연료화시 국내에서 거론되고 있는 바이오매스 문제를 해결할 수 있는 신재생에너지원으로써 확보가 가능할 것으로 판단된다. 본 연구에서 대상으로 하는 EFB는 팜오일 생산과정에서 발생되어 일부분만 비료로 사용되고 처리되지 못해 야적되어 있는 것을 사용하였다. 3ton/day급 Pilot급 일체형 다단건조 탄화기를 사용하여 고열량인 EFB(저위발열량 : 4,320 kcal/kg)를 반탄화 고형연료로 생산하기 위해 반탄화 온도(200~300℃)와 시간(30~60분)을 고려하여 고형연료 생산량 및 발열량에 미치는 영향에 대하여 검토하였다. 반탄화 온도 변화에 따라 EFB의 저열량휘발성분의 감소와 탄소함량의 증가로 발열량(5,150 kcal/kg)이 증가하는 경향을 나타나는 것으로 분석되었다. 본 연구로 최적 EFB 반탄화 고형연료 생산인자를 도출함에 따라 경쟁력 있는 바이오매스 신재생에너지로 확보 될 것으로 전망된다.

미세조류는 광합성 반응을 통해 대기 중의 이산화탄소를 흡수하고, 산소를 배출하며, 체내에 카로티노이드, 피코시아닌 같은 유용물질을 생성할 수 있다. 또한, 미세조류의 대사특성은 하폐수처리, 바이오연료 생산, 이산화탄소 고정 및 유용물질 생산 등 다양한 분야로 적용이 가능하고, 전 세계적으로 연구가 활발히 진행되고 있다. 이러한 미세조류의 배양방법은 open system과 closed system이 존재하는데, 이 중 closed system은 미세조류 배양을 위한 다양한 조건들을 쉽게 조절할 수 있는 반면 운영 및 유지관리 비용이 든다. 따라서 본 연구에서는 저비용/고효율의 PBR(photo-bioreactor) 운전을 위한 최적운전 조건을 도출하기 위해, aeration rate와 pH가 미세조류 대량배양에 미치는 영향을 살펴보았다. 실험에 사용한 미세조류는 Scenedesmus dimorphus를 이용했고, NO3--N 100 mg/L, PO43--P 10 mg/L로 modified BBM 배지를 사용하였으며, 광도 40 ~ 100 ㎛ol/m²/s, 광주기 24(light) : 0(dark)로 설정하고 working volume 2 L인 photo bioreactor를 batch로 운전하였다. Aeration rate는 0.1 ~ 1 vvm, pH 7 ~ 10로 설정하여 실험을 진행하였다. Aeration rate이 Scenedesmus dimorphus 의 성장에 미치는 영향을 평가한 결과, 0.3 vvm과 0.5 vvm 에서 높은 성장량을 나타냈다. 무기탄소의 공급량이 많은 1 vvm 조건에서는 성장량이 다소 낮게 나타났는데, 이는 과도한 폭기로 인해 미세조류에 미치는 전단응력이 증가하여 성장에 저해를 유발한 것으로 사료된다. 폭기조건의 경제성을 고려하여 0.3 vvm을 유지하는 것이 적정조건으로 도출되었다. pH가 Scenedesmus dimorphus의 성장에 미치는 영향을 평가한 결과, pH 9에서 가장 높은 성장량을 나타냈다

This paper examined reasonable operating factor for treatment of carcass burial leachate in High Temperature Thermal Desorption (HTTD) and calculated the amount of fuel used in each device using heat and mass balance under condition of 4 scenarios. As a result, we concluded that rotary kiln for dryness and thermal desorption shoud be separated dual type and mixing ratio of sawdust and soil should be restricted no more than 1 : 14. Also, operating temperature should be kept 260, 550, 850 or higher in dryer kiln, thermal desorption kiln and secondary chamber respectively and residence time should be kept 30min in each kiln. The total amount of fuel used in each device was compared under 4 scenarios on the mixing ratio. According to a study, it showed the highest value under the scenario of 1 : 1, which showed 2.5 times higher than the scenario of 1 : 14 in terms of treatment of leachate per unit of LNG.

The purpose of this study is to degradation of Rhodamine B (RhB, dye) and N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the electro-generation of OH radical) in solution using boron doped diamond (BDD) electrode. The effects of applied current (0.2~1.0 A), electrolyte type (NaCl, KCl, and Na2SO4) and electrolyte concentration (0.5~3.0 g/L), solution pH (3~11) and air flow rate (0~4 L/min) were evaluated. Experimental results showed that RhB and RNO removal tendencies appeared with the almost similar thing, except of current. Optimum current for RhB degradation was 0.6 A, however, RNO degradations was increased with increase of applied current. The RhB and RNO degradation of Cl type electrolyte were higher than that of the sulfate type. The RhB and RNO degradation were increased with increase of NaCl concentration and optimum NaCl dosage was 2.5 g/L. The RhB and RNO concentrations were not influenced by pH under pH 7. Optimum air flow rate for the oxidants generation and RhB and RNO degradation were 2 L/min. Initial removal rate of electrolysis process was expressed Langmuir - Hinshelwood equation, which is used to express the initial removal rate of UV/TiO2 process.

The purpose of this study is to investigate electro-generation of free Cl, ClO2, H2O2 and O3 and degradation of Rhodamine B in solution using Ru-Sn-Sb electrode. Electrolysis was performed in one-compartment reactor using a dimensionally stable anode(DSA) of Ru-Sn-Sb/Ti as the working electrode. The effect of applied current (0.5-3 A), electrolyte type (NaCl, KCl, HCl, Na2SO4 and H2SO4) and concentration (0.5-2.5 g/L), air flow rate (0-3 L/min) and solution pH (3-11) was evaluated. Experimental results showed that concentration of 4 oxidants was increased with increase of applied current, however optimum current for RhB degradation was 2 A. The generated oxidant concentration and RhB degradation of the of Cl type-electrolyte was higher than that of the sulfate type. The oxidant concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.75 g/L. Optimum air flow rate for the oxidants generation and RhB degradation was 2 L/min. ClO2 and H2O2 generation was decreased with the increase of pH, whereas free Cl and O3 was not affected by pH. RhB degradation was increase with the pH decrease.