• Membrane and Water Treatment
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• 제14권1호
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• pp.1-10
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• 2023

This study explored the feasibility of calcium-rich food waste, Mactra veneriformis shells (MVS), as an adsorbent for phosphate removal, and its removal efficiency was enhanced by the thermal activation process. The CaCO3 in MVS was converted to CaO by thermal activation (>800 ℃), which is more favorable for adsorbing phosphate. Thermal activation did not noticeably influence the specific surface area of MVS. The MVS thermally activated at 800 ℃ (MVS-800), showed the highest phosphate adsorption capacity, was used for further adsorption experiments, including kinetics, equilibrium isotherms, and thermodynamic adsorption. The effects of environmental factors, including pH, competing anions, and adsorbent dosage, were also studied. Phosphate adsorption by MVS-800 reached equilibrium within 48h, and the kinetic adsorption data were well explained by the pseudo-first-order model. The Langmuir model was a better fit for phosphate adsorption by MVS-800 than the Freundlich model, and the maximum adsorption capacity of MVS-800 obtained via the Langmuir model was 188.86 mg/g. Phosphate adsorption is an endothermic and involuntary process. As the pH increased, the phosphate adsorption decreased, and a sharp decrease was observed between pH 7 and 9. The presence of anions had a negative impact on phosphate removal, and their impact followed the decreasing order CO₃^2- > SO₄²- > NO₃^- > Cl^-. The increase in adsorbent dosage increased phosphate removal percentage, and 6.67 g/L of MVS-800 dose achieved 99.9% of phosphate removal. It can be concluded that the thermally treated MVS-800 can be used as an effective adsorbent for removing phosphate.

• 상하수도학회지
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• 제24권4호
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• pp.453-462
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• 2010

Nowadays, the challenges of ensuring good water quality and quantity of river are becoming more important for human society, but there has been troublesome for purifying river water. In this study, we performed the fundamental study of a river water treatment system using riverside soil and eco-friendly optimal media for improving river water quality and can also treat a large amount of river water. As the results of the physical and chemical characterization of the two different soils (Kyungan and Chungrang, The Republic of Korea), which were collected from real stream sides in the Han River basin, and five kinds of media (zeolite, perlite, steel slag, woodchip and mulch), both soils were all classified as a sand, and effective size ($D_{10}$) and uniformity coefficient (U) of the soil were about 0.2 mm and 4 or so, respectively. Through the batch and column experiments with the soil and eco-friendly media, zeolite and mulch were found to be efficient for decreasing nitrogen. In addition, steel slag was especially superior to the other media for phosphorus removal. From soil reforming tests volume ratios were 2.8, 1, and 1 of Kyungan soil, zeolite, and steel slag hydraulic conductivity of mixed soil was increased $1.30{\times}10^{-2}$ from $2.85{\times}10^{-3}$ of Kyungan soil, and the removal efficiencies of nitrogen and phosphorus were also improved. These results show that reforming of the soil enhanced the purification of a large amount of water, and zeolite, mulch, and steel slag might be facilitated as proper functional media.

• 대한환경공학회지
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• 제22권5호
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• pp.939-947
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• 2000

연속 회분식 반응기를 이용하여 생물학적 인 제거에 관한 미생물 분포 연구를 수행하였다. 탄소원으로 초산을 넣은 합성 폐수를 사용하였고 미생물 체류 시간과 수리학적 체류 시간은 각각 10일과 16시간으로 유지하였다. 인 방출과 흡수가 운전 시간이 경과됨에 따라 점점 빠르게 일어났으며 약 200일 경과 후 안정적인 인 제거가 유지되었다. 안정적인 생물학적 인 제거가 유지될 때의 미생물 분포를 조사하기 위하여 17개의 ribosomal RNA (rRNA) signature probe를 합성하여 슬러지로부터 분리한 전체 rRNA에 대하여 slot hybridization을 실시하였다. 분리한 전체 RNA에는 proteobacteria의 베타군 (beta subclass)에 속하는 rRNA가 가장 많이 함유되어 있음을 확인하였고 CTE probe와 관계된 rRNA가 다음으로 많이 분포하였다. 전통적으로 생물학적 인 제거를 담당하는 미생물로 여겨져 왔던 Acinetobacter, Aeromonas, Pseudomonas의 rRNA는 10% 미만으로 존재하고 있음이 확인되었다. 이러한 결과로부터 Rhodocyclus 그룹같은 proteobacteria의 베타군과 CTE에 속하는 미생물이 인 제거에 중요한 역할을 수행할 것으로 생각되었고 Acinetobacter, Aeromonas, Pseudomonas 등은 생물학적 인 제거에 있어서 과평가된 것으로 판단되었다.

• 대한환경공학회지
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• 제30권10호
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• pp.992-998
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• 2008

SND 공정은 최근에 하수내 질소제거를 위한 새로운 공법으로 많은 연구가 이루어지고 있다. 이에 본 연구는 무산소조, 혐기조 및 담체를 충진한 포기조로 구성된 DMR(Daiho Microbic Revolution)공정을 이용하여 포기량을 2.0, 1.0, 0.5, 0.4 및 0.2 L/min으로 변화시키면서 영양염류 제거효율과 동시 질산화/탈질 효율을 검토하였다. 유기물제거율은 포기량에 차이를 보이지 않았으며 모든 조건에서 93%의 제거율을 얻을 수 있었다. T-N 제거효율은 포기량이 적어짐에 따라 높아져 0.2 L/min의 조건에서 80%의 효율을 얻었으며, SND효율 또한 각 조건에서 62, 65, 72 및 78%를 나타내어 포기량 조절만으로 높은 질소제거율을 얻을 수 있었다. T-P는 포기량에 따라 75$\sim$96%의 제거율을 보였지만, 0.2 L/min의 조건에서는 2차 인방출이 발생하였다. 0.5 L/min의 조건에서 슬러지의 poly-P함량은 5.08%였으며 소모된 유기물 양과 방출된 인 농도의 비는 0.72 mg P/mg HAc였다.

• 한국환경농학회지
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• 제17권4호
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• pp.352-357
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• 1998

양액조성의 차이에 따른 토마토의 오존 감수성을 구명하고자 1/2농도의 Hoagland 용액을 표준으로 하여 양액을 조성하였다. N-P-K의 수준을 $N_{100}$ $P_{100}$ $K_{100}$(대조구), $N_{47}$ $P_{100}$ $K_{100}$(질소 감량구), $N_{93}$ $P_0$ $K_{100}$(인산 제거구), $N_{100}$ $P_{100}$ $K_0$(칼륨 제거구), $N_{153}$ $P_{100}$ $K_{100}$(질소 중량구), $N_{107}$ $P_{200}$ $K_{100}$(인산 2배구), $N_{140}$ $P_{100}$ $K_{200}$(칼륨 2배구) 등으로 나누어 수경재배한 후 $0.25{\mu}l/L$의 오존에 접촉시킨 결과 다음과 같은 결론을 얻었다. 1. 지상부 생육은 질소 감량구와 인산 제거구에서 가장 저조하였고, 인산 및 갈륨 제거구에서 인산가 칼륨의 엽중함량이 극히 낮았다. 시비수준의 차이에 따른 가시피해율은 칼륨 제거구에서 가장 심하게 나타났다. 인산 제거구, 질소 감량구 및 중량구 또는 인산과 칼륨 2배구의 피해율은 표준구와 비슷한 경향을 보였다. 2. 오존접촉 후 칼륨 제거구에서 다른 처리구에 비하여 ethylene발생량, 전해질 유출량과 MDA함량이 증가하였으며 엽록소의 함량은 크게 감소였다. 3. 가시피해가 가장 심했던 칼륨 제거구에서 SOD의 활성이 가장 낮았으며 오존접촉 후에도 활성 증가율이 가장 낮게 유지되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.105-108
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• 2000

Enhanced biological phosphorus removal (EBPR) is not always successfully achieved by anaerobic/aerobic operation. It has been reported that the EBPR deterioration was caused by the outgrowth of glycogen-accumulating organisms (GAO) over polyphosphate-accumulating organisms (PAO). It was found that pHcould be a tool which might induce the success of EBPR in a sequencing batch reactor (SBR) supplied with acetate. When the pH of anaerobic phase was controlled at 7.0, the operation resulted in failure of EBPR. However, when the pH of anaerobic phase increased up to 8.4, complete EBPR was achieved. We explained the mechanism of pH effect on the competition between GAO and PAO with experimental results and previously proposed biochemical models.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2007년도 춘계 학술발표회 발표논문집
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• pp.383-389
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• 2007

호기시간 변경에 따른 SBR에서의 영양염류제거특성과 MLVSS의 변화를 본 이번 연구에서는 다음과 같은 결론을 얻었다. 1) 충분하지 못한 산소의 공급은 미생물의 wash-out으로 인한 영양염류 제거 효율의 저조를 나타냈다. 2) 산소 공급량이 $0.045m^3$였던 R2에서 저조산 질산화가 나타났으나, 인을 과다 축적하는 EBPR(Enhanced Biological Phosphorus Removal)을 나타냈다. 3) 산소 공급량이 $0.06m^3$이상이었던 R3, R4에서는 60%이상의 질산화 및 탈질화와 약 100%에 달하는 인 제거 효율을 나타내었다. 4) 단위 미생물당 $1.5{\sim}1.8ml/mg$의 공급 산소량이 인 흡수에 유리한 것으로 나타났다. 5) 공급되는 산소에 있어 유기물 분해>인흡수>질산화에 우선적으로 소모되는 것으로 나타났다.

• 한국물환경학회지
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• 제21권4호
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• pp.398-402
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• 2005

The enzyme Xeronine was investigated as a microbial activating substance in biological wastewater treatment processes. Xeronine as bio-stimulant was injected in the anaerobic sludge and the activated sludge treating wastewater in order to examine the effect of hidden benefits. Bio-stimulant did not show significant improvement of anaerobic treatablity. In the aerobic system, higher bio-stimulant dose condition resulted in slightly more removal of nitrogen and phosphorus. Floc aggregation and zone settling velocity as solid-liquid separation factors in activated sludge systems was enhanced by bio-stimulant. Effects of bio-stimulants injection on improvement of water quality and microbial activity did not clear in terms of normal operation conditions.

• 분석과학
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• 제35권2호
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• pp.41-52
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• 2022

The leaching of nitrate from soil increases the concentration of elements, such as nitrogen, phosphorus, and potassium, in water, causing eutrophication. In this study, the feasibility of using clinoptilolite as an ion-exchange material to reduce nitrate leaching in soil was investigated. Soil samples were collected from three soil depths (0 - 30, 30 - 90, and 90 - 120 cm), and their sorption capacity was determined using batch experiments. The effects of contact time, initial concentration, adsorbent dosage, pH, and temperature on the removal of NO₃^- were investigated. The results showed that an initial concentration of 25 mg L^-1, a contact time of 120 min, an adsorbent dosage of 5.0 g/100 mL, a pH of 3, and a temperature of 30 ℃ are favorable conditions. The kinetic results corresponded well with a pseudo-second-order rate equation. Intra-particle diffusion also played a significant role in the initial stage of the adsorption process. Thermodynamic studies revealed that the adsorption process is spontaneous, random, and endothermic. The results suggest that a modification of clinoptilolite effectively reduces the leaching of nitrate in soil.

• 한국환경농학회지
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• 제25권1호
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• pp.40-46
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• 2006

This study was initiated to evaluate the inhibitory effect of selected heavy metals on the growth of Acinetobacter sp. Down as one of the phosphorus accumulating microorganisms (PAO) involved in the enhanced biological phosphorus removal (EBPR) process of the wastewater treatment plant. Acinetobacter sp. was initially selected as a starting model microorganism and was grown under aerobic condition for this experiment. The heavy metals selected and investigated in this study were cadmium (Cd), copper (Cu), mercury (Hg), nickel (Ni), and zinc (Zn). Median $(IC_{50})$ and threshold $(IC_{10})$ inhibitory concentrations for Cd, Cu, Hg, Ni, and Zn were 2.95 and 1.45, 4.92 and 2.53, 0.03 and 0.02, 1.12 and 0.43, 14.84 and 5.46 mg $L^{-1}$, respectively. We demonstrated that most of heavy metals tested in the experiment inhibited the growth of Acinetobacter sp. in the range of predetermined concentrations. Based on the data obtained from the experiment, Hg was the most sensitive to Acinetobacter sp., then Ni, Cd, Cu, and Zn in order.