• 한국물환경학회지
• /
• 제18권3호
• /
• pp.291-301
• /
• 2002

In this study, nutrients treatment by sequencing batch reactors(SBR) was performed. Nitrogen and phosphorus removal efficiencies were evaluated by changing SRT and mixing/aeration ratio. Not only nitrogen but also phosphorus removal patterns were investigated through track studies on 1 cycle. As SRT was fixed and mixing/aeration ratio was changed, maximum nitrogen removal efficiency was 87.6% at mixing/aeration ratio 0.67. Phosphorus removal efficiencies were more than 85.5% except no mixing condition. As mixing/aeration ratio was fixed and SRT was changed, nitrogen removal efficiencies were 70.5~79.8%, which represented slight changes, while phosphorus removal efficiencies were 49.0~97.3%, which represented sharply decreasing tendency at less than 20 day. Both phosphorus release rate k and maximum phosphorus release rate $P_{max}/M$ were are decreased as SRT was decreased, but they were not affected by mixing/aeration ratio. It was found that there is a linear relationship between ortho-phosphate uptake and maximum ortho-phosphate release.

• Macromolecular Research
• /
• 제14권5호
• /
• pp.504-509
• /
• 2006

Poly(vinyl phosphate-b-styrene) (PVPP-b-PS) block copolymers were synthesized successfully from poly(vinyl alcohol-b-styrene) (PVA-b-PS) by reaction with phosphorus oxychloride and subsequent hydrolysis. The obtained block copolymers were slightly crosslinked, and were characterized by various analytical techniques. The total phosphorus content and the ratio of the differently bound phosphorus were obtained by both solid-state $^{31}P$ NMR and pH titration, but the results differed slightly. Characterization by energy dispersion X-ray analysis (EDS) or Rutherford back scattering (RBS), on the other hand, determined the total phosphorus contents, but the results were quite different from those by solid-state $^{31}P$ NMR.

• Elastomers and Composites
• /
• 제49권4호
• /
• pp.313-322
• /
• 2014

난연제 가운데 가장 많이 사용되는 할로겐 함유 난연제는 사용상 환경적인 제한을 받고 있어서 비할로겐타입인 인계에 기초한 난연제가 각광을 받고 있다. 난연제는 수지에 가해지는 경우에 흔히 열분해와 기계적 특성저하를 일으킨다. 물성의 열화를 최소화하고 충분한 난연성을 얻기 위한 시도로 새로운 난연제에 대한 연구를 수행하였다. 본 연구에 있어서는 diaryl alkyl phosphate esters, aromatic phosphate esters 및 phosphonium nitron 난연제 등 세가지 형태의 비할로겐 인계에 기초한 난연제를 합성하여 GC, IR 및 TGA 등으로 합성 및 열적 특성을 확인하였다.

• Membrane and Water Treatment
• /
• 제8권2호
• /
• pp.161-169
• /
• 2017

The adsorption of phosphate onto mesoporous $TiO_2$ was investigated in order to reduce phosphorus concentrations in wastewater and provide a potential mode of phosphorus recovery. Three equilibrium isotherms were used to optimize and properly describe phosphate adsorption ($R^2$>0.95). The maximum capacity of phosphate on the adsorbent was found to be 50.4 mg/g, which indicated that mesoporous $TiO_2$ could be an alternative to mesoporous $ZrO_2$ as an adsorbent. A pseudo-second order model was appropriately fitted with experimental data ($R^2$>0.93). Furthermore, the suitable pH for phosphate removal by $TiO_2$ was observed to be in the range of pH 3-7 in accordance with ion dissociation. In contrast, increasing the pH to produce more basic conditions noticeably disturbed the adsorption process. Moreover, the kinetics of the conducted temperature study revealed that phosphate adsorption onto the $TiO_2$ adsorbent is an exothermic process that could have spontaneously occurred and resulted in a higher randomness of the system. In this study, the maximum adsorption using real wastewater was observed at $30^{\circ}C$.

• Fisheries and Aquatic Sciences
• /
• 제19권9호
• /
• pp.39.1-39.9
• /
• 2016

Magnesium hydrogen phosphate (MHP, $MgHPO_4$) recovered from swine manure was prepared as an alternative phosphorus (P) source. Conventional P additives, monocalcium phosphate (MCP), dicalcium phosphate (DCP), and tricalcium phosphate (TCP) were compared with the MHP in terms of growth and P availability by juvenile carp Cyprinus carpio. A basal diet as a negative control was prepared using practical feed ingredients without P supplementation to which four supplemental P sources were added at the level of 2%. Five groups of 450 fish having mean body weight of 6.5 g following 24 h fasting after 2 weeks of adaptation period were randomly distributed into each of 15 tanks (30 fish/tank). Fish were hand-fed to apparent satiety twice a day for 9 weeks. Fish fed the MHP had weight gain (WG), feed conversion ratio (FCR), protein efficiency ratio (PER), and specific growth rate (SGR) comparable to those fed the MCP. Those values of both the MHP and MCP groups were significantly different (p < 0.05) from the other groups. Fish groups fed control and the TCP showed the lowest WG, PER, and SGR and the highest FCR among treatments. No fish were died among treatments during the experimental period. Fish fed control and the TCP showed hematocrit and hemoglobin significantly lower (p < 0.05) than fish fed the MHP. The lowest inorganic P (Pi) in plasma was found in the control group. Even though Pi was not significantly different (p > 0.05) from other phosphate groups, fish fed the MCP and MHP retained higher P in whole body than the other groups. P availability was determined to be 93.2, 62.4, 6.1, and 98.0% for MCP, DCP, TCP, and MHP, respectively. The present results suggested that the MHP recovered from wastewater stream could be used as an alternative P source in carp diet.

• 한국수산과학회지
• /
• 제41권4호
• /
• pp.301-304
• /
• 2008

For bioremediation of the benthic layer uptake kinetics of phosphate by microphytobenthos Nitzschia sp.(JFH200406) were investigated. A short-term phosphate uptake revealed that the maximum uptake rate(${\rho}_{max}$) and half-saturation constant($K_s$) were 0.132 pmol/cell/hr and 502.6 ${\mu}M$, respectively. The maximum specific uptake rate calculated between ${\rho}_{max}$ and the phosphorus cell quota($Q_p$), calculated from Strathmann equation, was 14.4/day. The values of these parameters indicate that Nitzschia sp. accommodates well to surroundings of high phosphate, and can uptake over 14-times more than the phosphorus cell quota. Thus, microphytobenthos Nitzschia sp. may be a useful species for bioremediation of the benthic layer.

• 한국물환경학회지
• /
• 제28권1호
• /
• pp.50-56
• /
• 2012

In this study, loess composites, loess with lanthanum and with aluminum, were made and evaluated for treatment of phosphorus removal in natural water system. Desiccation method for production of loess composite was superior to centrifugation method in obtaining high concentrated composites of lanthanum and aluminum. Washing of loess lanthanum composite by water did not deteriorat the lanthanum concentration in the composite, but this lowered the aluminum concentration of loess aluminum composite. Total of 15 and 37.5% of aluminum contents were removed after first washing treatment in aluminum loess of 0.05% and 0.1% respectively. However, no more aluminum loss was monitored with increase of washing times. Phosphorus removal efficiencies were not decreased with washed loess aluminum composite. Phosphorus removal was successfully achieved by adsorption of phosphate to loess composite at pH range of 5.0 ~ 8.0. Freundlich and Langmuir adsorption isotherm was observed in the adsorption of phosphate for loess composite. Dosages of 0.05% and 0.1% lanthanum composite for 95% of phosphorus removal could reduce its usage amount to 25% and 50%, respectively, comparing with dosage of loess alone. Dosages of 0.05% and 0.1% aluminum composite could reduce its usage amount to 48% and 63%, respectively.

• 한국잠사곤충학회지
• /
• 제35권1호
• /
• pp.11-16
• /
• 1993

인산이 축적된 뽕밭에서 인산 시비량을 조절하기 위하여, 유효인산 300ppm 정도 포장 2개소, 450 ppm정도 포장 1개소에서 인산 표준시비량구(13kg/10a), 반량구, 무인산구, 무시비구 등을 설정하여 4년동안의 포장시험과 엽질검정을 위한 누에 사육시험을 3년동안 수행한 결과 다음과 같았다. 1. 토양유효인산 함량이 450ppm포장에서는 4년간 계속된 인산 무시비구에서도 뽕잎 수량감소가 없었으나, 300ppm포장에서의 무인산구에서는 3년차 봄부터, 인산 반량구에서는 4년차 가을부터 감수가 시작되었다. 2. 연차별로 토양 인산의 감소에 따른 수량감소와의 관계에 의하여 인산시비 개시 시기를 조사한 결과, 토심 10~20cm 부위에서 유효인산의 함량이 150ppm 이하로 떨어졌을 때 인산시비를 개시하는 것이 적당한 것으로 나타났다. 3. 인산 감량시비에 따른 뽕잎 중의 인산함량은 표준량 시비구 대비 0.18%까지 감소하였다. 4. 인산의 감량시비가 뽕잎의 질에 미치는 영향을 알기 위하여 3년간 토양인산 300ppm 포장의 뽕잎으로 누에를 사육하여 검정한 결과, 인산 무시비에 의해 수량이 감소하고, 엽중의 인산 함량이 최저 1.13%까지 감소하였어도, 수견량 및 견질에는 영향을 주지 않았다.

• 유기물자원화
• /
• 제30권1호
• /
• pp.33-39
• /
• 2022

혐기성 소화 슬러지 탈리여액을 대상으로 마그네슘 공급원이 인산암모늄마그네슘(MAP) 결정화에 의한 인산염 회수에 어떠한 영향을 미치는지 알아보기 위해 회분식 실험을 실시하였다. 마그네슘 공급원으로 염화마그네슘, 수산화마그네슘 그리고 산화마그네슘을 사용하여 다양한 pH (7.5, 8.0 및 8.5) 조건 및 Mg/P 몰 비율(1.0, 1.5, 2.0 및 2.5)에서 인산염 회수를 실시하였다. 그 결과, 마그네슘 공급원과 관계없이 pH 조건과 Mg/P 몰 비율이 높을수록 인산염 회수율이 증가하였다. pH가 가장 낮은 7.5의 조건에서는 Mg/P 몰 비율이 증가할수록 인산염 회수율이 증가하였는데 산화마그네슘, 수산화마그네슘, 염화마그네슘의 순으로 높았다. 그러나 pH가 가장 높은 8.5의 조건에서는 Mg/P 몰 비율과 관계없이 모든 마그네슘 공급원에서 90% 이상의 높은 인 회수율을 얻을 수 있었다. 따라서 낮은 pH 조건에서도 높은 인산염 회수율을 얻을 수 있었던 수산화마그네슘과 산화마그네슘이 경제적인 측면뿐만 아니라 효율적인 측면에서도 염화마그네슘을 대체할 수 있을 것으로 기대된다.

• 한국산림과학회지
• /
• 제98권2호
• /
• pp.170-177
• /
• 2009

There are remarkable differences in growth and morphological characters of roots between mountain and field cultivated Panax ginseng. Growth of root in mountain cultivated ginseng was much slower than that of field cultivated ginseng. However, the factor affecting the retarded growth in mountain ginseng was not known. Soil analysis revealed that phosphorus (P) content of mountain soil was exceptionally low at least ten-fold lower compared to that of field soil. Thus, we suggest that low availability of P in mountain soil may be one of the limiting factors for growth of ginseng in mountain soil environment. We had monitored the growth of ginseng plants after one and three years of phosphate fertilizer application. Three kinds of phosphate fertilizers: fused magnesium phosphate, fused superphosphate, and single superphosphate were applied to mountain soil. Application of phosphate fertilizers increased the fresh-, dry weight, and diameter of ginseng roots and resulted in increased P accumulation in roots. These results demonstrate that slow growth of ginseng in mountain soil environment might be attributed to the low P content in mountain soil. Thus, analysis of P amount in mountain soil will be a good indicator for the selection of suitable site the ginseng cultivation in forest.