• Environmental Engineering Research
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• 제17권3호
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• pp.133-138
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• 2012

Polyvinyl alcohol/alginate hydrogel beads containing Mg-Al layered double hydroxide (LDH-PVA/alginate beads) were synthesized for phosphate removal. Results showed that blending PVA with the LDH-alginate beads significantly improved their stability in a phosphate solution. The kinetic reaction in LDH-PVA/alginate beads reached equilibrium at 12 hr-post reaction with 99.2% removal. The amount of phosphate removed at equilibrium ($q_e$) was determined to be 0.389 mgP/g. The equilibrium data were described well by the Freundlich isotherm with the distribution coefficient ($K_F$, 0.638) and the constant (n, 0.396). Phosphate removal in LDH-PVA/alginate beads was not sensitive to solution pH. Also, the removal capacity of LDH-PVA/alginate beads ($q_e$, 1.543 mgP/g) was two orders of magnitude greater than that of PVA/alginate beads ($q_e$, 0.016 mgP/g) in column experiments. This study demonstrates that LDH-PVA/alginate beads with a higher chemical stability against phosphate compared to LDH-alginate beads have the potential for phosphate removal as adsorptive media.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.414-422
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• 2006

Before applying PVA bio-beads to practical biological treatment of nitrate-containing wastewater, their characteristics were examined. PVA bio-beads could steadily produce nitrogen gas from nitrate for 28 batches with 0.04 ml/l/h of the maximum gas production rate; however, the maximum gas production rate dropped remarkably thereafter with apparent deformation of beads. Addition of 2.2% solution containing 1% casamino acid, 1% yeast extract, 0.1% mineral solution, and 0.1% vitamin solution to the culture medium resulted in not only recovery of activity of deactivated beads, but also a higher rate of gas production. Calculation of economic benefit for the use of bio-beads in a long-run operation indicated that reactivation of bio-beads by chemicals had economical advantages over packing new bio-beads in the system. The continuously stirred bioreactor exhibited a satisfactory performance at HRT of 20.0 h. With a 9.5 mg $NO_{3}^{-}N/l/h$ nitrate removal rate, nitrate could completely be removed without nitrite accumulation. The use of PVA bio-beads in nitrate removal appears very promising.

• 한국환경보건학회지
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• 제27권1호
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• pp.83-87
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• 2001

In this study, the characteristics of lead removal by PVA and alginate bead which used widely as immobilizing agents were investigated, and the difference of removal amounts between pure PVA/alginate bead and Sargassum thunbergii immobilized bead was studied. All PVA beads, pure and S. thunbergii immobilized, reached an equilibrium state in about 1 hour, and S. thunbergii immobilized bead adsorbed more lead than pure one. But in the case of alginate beads, they needed much time, about 5 hours, to reach an equilibrium state, and adsorbed lead four times higher than PVA beads. Therefore, it was considered that alginate beads had more mass transfer resistance and function groups which adsorb lead such as hydroxyl, carboxyl and etc. than PVA bead. To examine the continuous usage of alginate beads, the process of adsorption/desorption of lead was conducted repeatedly. As the process proceeded, the amounts of lead adsorption decrease, so it was indicated that the non-desorbed lead from alginate bead at first adsorption/desorption process remained constantly.

• 청정기술
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• 제20권3호
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• pp.251-255
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• 2014

테노일트리플루오로아세톤(thenoyltrifluoroacetone, HTTA)과 트리옥틸포스핀옥사이드(trioctylphoshineoxide, TOPO)를 폴리비닐알콜(poly vinyl alcohol, PVA)로 고정화한 PVA 겔 비드를 제조하고, 이를 사용하여 수중의 $Cu^{2+}$를 제거하였다. 제조한 PVA 겔 비드의 $Cu^{2+}$ 제거특성은 유사 2차 속도식에 잘 적용되었으며, 랑미어 등온식에서 구한 $Cu^{2+}$의 최대 제거량은 9.59 mg/g이었다. $Cu^{2+}$ 제거의 최적 pH 범위는 pH 3.5~6이었다. PVA겔 비드를 5차례 재사용한 경우에도 추출제의 손실이나 PVA겔 비드의 손상은 관찰되지 않았다.

• 한국습지학회지
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• 제9권1호
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• pp.115-121
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• 2007

A novel hydrogen fermentation technique by using polyvinyl alcohol (PVA) gel beads as a biomass carrier was investigated. The hydrogen gas was stably produced throughout the experimental period in a continuous reactor. Even though the hydrogen productivity was suddenly decrease by experimental troubles, the bacteria attached to the PVA gel beads played as an inoculum, it was promptly recovered. The hydrogen yield per glucose was not very high ($1.0-1.2mol-H_2/mol-glucose$), thus the optimization of the experimental conditions such as ORP and HRT should be considered to improve the hydrogen productivity. Bacterial community was stable during experimental period after the PVA gel beads applying, which indicated that applying of biomass carrier was specific to keep not only the biomass but also the bacteria commonly. Clostridium species were phylogenetically detected, which suggested that these bacteria contributed to the hydrogen production in the biofilm attached to the PVA gel beads.

• 한국환경과학회지
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• 제23권9호
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• pp.1583-1591
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• 2014

PVA-D2EHPA/TOPO beads containing two extractants, di-(2-ethylhexyl) phosphoric acid (D2EHPA) and trioctylphoshine oxide (TOPO) were prepared for the removal of copper ions from aqueous solution. The prepared PVA-D2EHPA/TOPO beads were characterized by SEM and FT-IR. The removal characteristics of copper ions by PVA-D2EHPA/TOPO beads was investigated using batch and continuous systems. In batch experiments, the maximum removal capacity calculated from Langmuir isotherm model was 18.6 mg/g and the optimal pH was in the range of 4.5~6. The continuous experiments showed that the removal capacity of copper ions increased with increasing inlet copper ion concentrations and bed heights, but decreased with increasing inlet flow rates.

• 대한환경공학회지
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• 제37권8호
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• pp.450-457
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• 2015

본 연구에서는 제올라이트를 PVA에 고정화시켜 새로운 흡착제인 PVA-Zeolite 비드를 제조하고, XRD 및 SEM 분석을 통해 제조한 PVA-Zeolite 비드는 내부에 제올라이트가 잘 고정화된 다공성 구조를 가지고 있는 것을 확인할 수 있었다. 제조한 흡착제에 의한 Cs 이온과 Sr 이온에 대한 흡착특성을 살펴보기 위하여 pH의 영향, 흡착속도, 흡착등온을 검토하였다. Sr 및 Cs 이온에 대한 평형흡착시간은 약 540 min으로 나타났으며, 흡착속도는 유사 1차 속도식 보다는 유사 2차 속도식에 더 잘 부합하였다. 흡착평형 실험결과는 Langmuir 등온식에 잘 적용되었으며, Langmuir 등온식으로부터 구한 Sr 이온과 Cs 이온의 최대 흡착량은 각각 52.08 mg/g와 58.14 mg/g이었다. PVA-Zeolite 비드에 의한 Sr 이온과 Cs 이온의 흡착공정은 외부물질전달단계는 매우 빠르게 이루어지며, 내부입자확산에 의한 흡착반응은 느리게 진행되어 내부입자확산 단계가 흡착속도 결정단계인 것으로 판단된다.

• KSBB Journal
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• 제14권1호
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• pp.51-57
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• 1999

양어장 순환수 속의 암모니아성 질소를 제거하기 위하여 PVA를 boric acid. 처리법과 ethanol 처리법 및 freezing-thawing 처리법으로 제조된 구형 bead와 칼럼형 bead에 이들을 이용한 질화균군을 고정화 시켰다. 유가식 배양에서는 boric acid 처리법으로 제조된 구형 bead가 유동층 반응조에서 사용하기에 성상면에서나 암모니아 제거율에서 가장 이상적이었으며, 90일 동안의 유동층 반응기에서 운전하였으나 bead의 성상이나 효율은 변화없이 일정하였다. Boric acid 처리법으로 제조된 bead를 충전한 연속 빈용기에서의 암모니아성 질소 제거에 대한 실험에서 수리학적 체류시간이 0.6시간에서 암모니아 제거 속도는 31.9g $NH__3-N/m^3$/day였으며 제거효울은 36% 였다. 연속 반응기내에 2mg/L의 암모니아가 주입되고 공기량을 0.1vvin으로 공급하더라도 용존산소 농도를 4,64~5.40mg/L로 유지할수 있었으므로 질산화에 필요한 용존산소를 충분히 유지할 수가 있는 것으로 나타났으며 pH는 7.7~7.9의 범위를 유지할 수가 있어 pH에 따른 위해 요소는 없는 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.756-762
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• 2001

As a component for a recirculating aquaculture system, a new strain of denitrifying bacterium was isolated from municipal sewage. The isolate was motile by means of one polar flagellum, catalase-positive, and a Gram-negative rod-shaped cell measuring $0.5-0.6{\mu}m$ in width and $1.3-1.9{\mu}m$ in length. The isolate was identified as Pseudomonas fluorescens and produced dinitrogen gas via the reduction of nitrate. The optimal growth conditions (pH, temperature, carbon source, and C/N ratio) of the isolate were found to be 6.8, $30^{\circ}C$, malate, and 3, respectively. Under optimal growth conditions of P. fluorescens, dinitrogen gas was first detected in the exponential growth phase, then a small amount of nitrite was developed and converted to dinitrogen gas in the stationary phase. Pseudomonas fluorescens cells were immobilized in modified polyvinyl alcohol (PVA) gel beads, and the maximum denitrification rate was measured as $36.6 {\mu}lN_2h^-1$ per bead with an optimum cell loading of $20mg {\mu}l^-1$ and $2\%$ sodium alginate added to the PVA gel. The operating stability of the modified PVA gel beads remained unchanged for up to 43 repeated batches.

• 한국물환경학회지
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• 제38권4호
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• pp.171-176
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• 2022

Recently, an autotrophic single-stage nitrogen removal (ASSNR) process based on the anaerobic ammonium oxidation (ANAMMOX) reaction has been proven as an economical ammonia treatment. It is highly evident that double-layered gel beads are a promising alternative to the natural biofilm for ASSNR because of the high mechanical strength of poly(vinyl alcohol) (PVA)/alginate structure and efficient protection of ANAMMOX bacteria from dissolved oxygen (DO) due to the thick outer layer. However, the thick outer layer results in severe mass transport limitation and consequent lowered bacterial activity. Therefore, the effects of the thickness of the outer layer on the overall reaction rate were tested in the biofilm model using AQUASIM for ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and ANAMMOX bacteria. A thickness of 0.5~1.0 mm is preferred for the maximum total nitrogen (TN) removal. In addition, a DO of 0.5 mg/L resulted in the best total nitrogen removal. A higher DO induces NOB activity and consequent lower TN removal efficiency. The optimal density of AO B and NO B density was 1~10% for a 10% ANAMMOX bacterial in the double-layered PVA/alginate gel beads. The real effects of operating parameters of the thickness of the outer layer, DO and concentrations of biomass balance should be intensively investigated in the controlled experiments in batch and continuous modes.