Yong-Jun Jung

Rejection properties of pesticides with a hollow fiber NF membrane (HNF-1)

NF membranes are potentially useful to remove residual hazardous organic pollutants such as pesticides and alkyl phthalates in drinking water treatment processes. In this study, the rejection properties of a hollow fiber NF membrane (HNF-1) for 8 kinds of pesticides were investigated using a bench scale cell: the membrane consisted of polyamide skin layer and polysulfone support membrane with a nominal desalting degree fo 35% at 0.3 MPa. In addition, hydrophilic organic compounds (molecular weight: 74.1–504.5), i.e. alcohols and saccharides, were also used as reference solutes. The hydrophilic compounds were rejected at rates of 9.0–97.8%, revealing that the molecular sieving effect was significant since the logarithm of solute permeability, log B, correlated linearly with the molecular width parameter, MWd, of the solute. Phenylic pesticides, such as alachlor, metolachlor, methoxychlor, and thiobencarb, were rejected at 88.7–99.3%. However, non-phenylic pesticides, such as aldicarb, simazine, atrazine, and pirimicarb, were rejected at lower degrees: 42.2–89.9%. The batch type sorption experiments indicated that all of the pesticides were adsorbed on the membrane, and the adsorption properties were controlled mainly by the hydrophobic property of the pesticides. Sorption properties based on solute recovery rates in the separation experiments, however, were different from those in the batch type experiments.

Acidogenic Fermentation: Utilization of Wasted Sludge as a Carbon Source in the Denitrification Process

Laboratory scale batch experiments were conducted at 20°C to investigate the acidogenic fermentation for the conversion of wasted sludge into short chain fatty acids (SCFA) to be utilized as a carbon source in the denitrification process. Hydraulic retention time (HRT), volatile solid (VS) loading rate and pH were studied as these are the important parameters governing the production of volatile fatty acids (VFA). Four different phases were investigated by varying these parameters. HRT was varied from 2.7 to 8.2 days whereas VS loading rate was varied from 1.2 to 3.6 g d−1. VFA production decreased with the increase in HRT above 2.7 days. 538.37±19.39 mg VFAproduced l−1. d−1 (0.176±0.010 mg VFAproduced mg−1 VSfeed) was found as the maximum value of VFA at 2.7 days. The present results based on wasted sludge showed that almost 0.0483±0.0016 mg VFA (as COD mg−1 initial COD) and about 5 % of soluble COD production were achieved, which are slightly less than the results reported for primary sludges. The rates of VFA production increased with the increase in VS, however, opposite results were obtained when pH was increased in the reactor. SCFA/FA ratios during fermentation were found in the range of 67-73 %. The specific denitrification rates (SDNR) of methanol (2.20±0.44mg NO3-N g−1 MLVSS · h−1) and the fermenter supernatant (2.00±0.45 mg NO3-N g−1 MLVSS · h−1) were found to be comparable. Fermenter supernatant, therefore, has the potential to be utilized as a carbon source. However, the results need to be investigated further on a larger scale to ascertain their validity.

Biological removal characteristics of phenol with filtration bio-reactor

AbstractA laboratory scale bio-reactor equipped with a filter module was examined for the separation of activated sludge, where the effluent was withdrawn by mesh filtration. The synthetic wastewater containing phenol was fed into the reactors, and the removal performance was evaluated under the following conditions: 7 or 14 d of HRT, room temperature (ca. 20°C), synthetic wastewater containing 5,000–20,000 mg/L of phenol, 262 mg/L of NH4-N, 43.7 mg/L of PO4-P, maximum phenol loading rate: 1.43 kg/m3/d, feeding the synthetic wastewater for 5 or 10 h (Run-1) or feeding at once (Run-2), and filtration once a day. The reactors maintained high concentrations of MLSS (10,000–15,000 mg/L), and the filtration was carried out stably in a short time. When the synthetic wastewater containing 5,000 mg/L of phenol was fed into the reactor at 7 d of HRT (0.7 kg/m3/d of phenol loading rate), in the operation of Run-1, the removal rates for phenol, NH4-N, and D-TN were above 99.9, 98, and 96%, respectively. Similar resu...

Removal of phosphite and sulfate from electroless nickel–phosphorus plating bath with hydrotalcite for the management of watershed

Abstract This study was focused to remove both and for the improvement of efficiency in electroless nickel–phosphorus plating process with hydrotalcite-like compound (HT). The adsorbed amount, q e, of which was main component was low and had little influence on the adsorption of and . and were similar in the adsorption behaviors of the adsorption isotherm and the influence of solution pH. The q e was increased with the increase of water temperature, because the was decreased with the increase of water temperature. On the coexisting adsorption, the q e of was decreased with . The ion selectivity of HT was in the order of  >   >   ≫  at pH 10. The results indicated that the HT-Cl is a useful adsorbent for and removal in the exhausted electroless nickel-phosphorous plating bath.

Investigations on the growth ofRhodococcus rubra in relation to the formation of stable biological foams

The growth characteristics of a foam-forming species,Rhodococcus rubra were studied on different substrates. The basic medium contained Czapek (3.34%), yeast extract (0.2%), potassium dihydrogen phosphate (0.12%), dipotassium hydrogen phosphate (0.25%) and ammonium chloride (0.1%). This was supplemented with varying concentrations of glucose (0–2%). The same basic medium was also used to examine the growth ofR. rubra in combination with varying concentration of n-hexadecane (0.0–0.5%) as a source of energy while varying the concentration of ammonium chloride in the range 1–3 gl−1. Studies based on determining the biomass concentration, the surface activity related to the cell suspensions and measuring the variations in broth pH revealed that glucose encouraged the growth ofR. rubra, compared to the control. However, increasing the glucose concentration from 0.1 to 2.0% had no further effect on growth. The surface activity of the cell suspensions increased with increasing glucose concentration. Results similar to glucose were exhibited by the addition of n-hexadecane, suggesting same degree of growth among different concentrations with higher surface activity increasing with increase in substrate concentration. Results have also shown that the pH of all the culture broths decreased as the ammonium chloride concentration increased, suggesting that there was a production of hydrogen ions during the course of its metabolism.

Contaminant loads of CSOs at the urban area in Korea

AbstractCombined sewer overflows (CSOs) were examined in an urban catchment with three areas of 11.9, 19.9, and 57.7 ha located in northern Daegu city in Korea. A total of two non-rainfall run-off events were monitored and a variety of water quality parameters were analyzed. During the non-rainfall run-off, most water quality parameters, particularly organic pollutants, were fluctuated accordingly to the discharge of sewage flow. Event mean concentrations (EMCs) during the storm water run-off were shown higher than EMCs of non-rainfall events. The loading rates of overflows against total flow particularly, SS load was 14 times higher. Total CSOs emissions were expected to be around 1.38 to 5.18 kg/ha per event. Few obvious first flush phenomenons were observed due to the inflow of unknown sources and dilution with incessant duration of rainfall.

Fundamental Study of the Regeneration of Layered Double Hydroxide Saturated with Phosphate

Abstract LDHs(layered double hydroxides) are of use adsorbent to remove heavy metals, micro-organic pollutants as well as high concentration of phosphorus from wastewater to low concentration of surface water without pH adjustments. This study examined the generation condition of LDHs saturated with phosphorus. Less than 20% regeneration rate was obtained in the absence of alkali and regeneration solution. After the desorption of LDHs with several conditions of acid and alkali solution, more than 60% of regeneration rate could be expected in the case of using MgCl2 as regeneration solution. Key words : Alkali desorption, Desorption, LDH, Regeneration 1. 서 론 1) 호소나 댐과 같은 폐쇄성 수역에 질소와 인으로 대표되는 영양물질이 유입될 경우 조류가 과다 번식하게 되어 수계는 부영양화를 유발할 수 있다. 예방 대책으로는 질소계 화합물보다는 제어가 비교적 용이하고, 유입량이 상대적으로 적은 인 화합물을 제어하는 것이 효과적이라고 보고되고 있다(Kim 등, 1995).인을 제거하기 위한 가장 일반적인 방법으로는 생물학적 처리공법(Bashan 등, 2004)과 화학적 응집침전법(Cho 등, 2012)을 들 수 있다. 생물학적 처리공법은 처리장으로부터 이차 오염물질의 발생 가능성이 낮고, 대량 처리가 가능하여 경제성 측면에서는 유리한 반면, 인 제거가 상대적으로 어렵고, 처리 공법의 종류에 따라 제거 효율이 다양하게 나타날 뿐만 아니라 고도의 운전기술을 필요로 한다(Kim 등, 2006). 석회나 응집제를 이용한 화학적 처리공법은 인 제거 효율이 높고, 처리 효율을 안정적으로 확보할 수 있는 반면, 약품 비용이 많이 소요되고, 슬러지를 다량으로 배출할 뿐만 아니라 추가적인 기계 장치를 설치해야 하는 단점이 있다(Lee 등, 1997; Park 등, 2012). 또한 다양한 재질의 흡착제를 사용하여 인과의 침전물 형성을 통한 흡착 제거를 보고하였는데, 대부분의 연구가 인 화합물의 흡착 제거 기작에만 치중하였고, 경제성 향상을 위한 회수 및 재활용에 대한 연구는 미미한 실정이다(Lee 등, 2002). 따라서 흡착공정 적용 시, 흡착제 사용에 따른 인 제거와 회수 및 재생공정의 검토

Waste sludge reduction with a pilot-scale membrane bioreactor for point source pollution management

Abstract It is an important subject to reduce the amount of waste sludge from small-/middle-scale wastewater facilities for the establishment of point source pollution management. In this work, we focused on the development of sludge decomposition system which did not increase organic loading ratio into wastewater treatment units. The excess sludge produced from wastewater treatment plant of a food factory was decomposed by an aerobic digestion technology with a membrane bioreactor (MBR) system. It was composed of digestion tank (500 L) and a membrane filtration unit (350 L). Sludge was decomposed under the following conditions: 25 g L−1 of MLSS, 36.9 d of HRT, average temperature 32.3°C, and 0.565 kg-SS m−3 d−1 of sludge loading rate. The system decomposed 77.2% of the fed sludge to inorganic carbon, and all of average TOC, CODMn and CODCr in the effluent were less than 50 mg L−1. However, the effluent contained T–N and T–P at 200 mg N L−1 and 150 mg-P L−1, respectively. The quinone profile analysis indi...

Treatment Characteristics of Trichloroethylene(TCE) by Oxidation and Reduction with Nanoscale Zero-valent Iron

This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study tried to find out the degradation characteristics of TCE by Fenton-like process, in which H2O2 is dosed additionally. In this study, different ratios of nZVI and H2O2, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were used. When 1.0 mM of nZVI was dosed with 1.0 mM of H2O2, the removal efficiency of TOC was the highest and the first order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of H2O2, the first order rate constant and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI 1.0 mM : H2O2 1.0 mM > nZVI 1.0 mM : H2O2 2.0 mM > nZVI 1.0 mM : H2O2 0.5 mM > H2O2 1.0 mM > nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of H2O2, Fe ion generated by nZVI and H2O2 react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM of nZVI is dosed with 2.0 mM of H2O2, excessive H2O2 work as a scavenger of OH radicals and excessive H2O2 reduce Fe into Fe. As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and H2O2, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale Fe is oxidized to Fe and TCE is pre-reduced and becomes easier to degrade. When H2O2 is dosed at this time, OH radicals are generated and degrade TCE actively.