• Environmental Engineering Research
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• v.19 no.2
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• pp.175-184
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• 2014

Weirs are conventional structures that control water level and velocity in streams to facilitate water resource management. Despite many weirs built in streams, there is little information how weirs change hydrology regime and how that translates to sediment and phosphorus (P) responses. This study evaluated the influence of weirs on P retention and mobilization in an urban tributary of the Han River in Korea. Total P concentrations in sediments upstream of weirs were higher than the downstream site, mainly due to the increase of potentially available fractions (labile P and aluminum- and iron-bound P) (p < 0.05). Equilibrium phosphorus concentrations ($EPC_o$) were lower than soluble reactive phosphorus (SRP) concentrations of stream waters, but there was an increasing trend of sediment $EPC_o$ upstream of weirs compared to the downstream site (p < 0.001) indicating a greater potential for P release upstream of weirs. Sediment core incubation showed that SRP release rates upstream of weirs were higher than the downstream site under anoxic conditions of the water column (p < 0.01), but not under oxic conditions. SRP release rates under anoxic conditions were greater than that measured under oxic conditions. Un-neutral pH and increased temperature could also enhance SRP release rates upstream of weirs. We conclude that weirs can increase P retention within stream sediments and potentially promote significant P releases into waters, which in turn cause eutrophication.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.213-220
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• 2002

In this study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from sediment in Lake Sihwa were investigated. No phosphorus release occurred at $10^{\circ}C$ for all pH values. DO concentrations were decreased and equilibrium was obtained 4-8 days after phosphorus release started. The DO concentrations were less than 1 mg/L. Sediment depth had little effect on phosphorus release rate. In order to control the released phosphorus, raw sludge and chalk were used. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. About 90 % phosphorus removal was observed using sludge and calcinated chalk from the water sample in Lake Sihwa.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.97-104
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• 2000

The purpose of this is made an examination of phosphorus loading model for eutrophication response in the Yongsan lake. For the model, we measured the total amount of nutrients derived from the Yongsan river watershed, inflow rate to the Yongsan lake, water quality, and water budget from January to December in 1999. The total amount of precipitation in the Yongsan river watershed was 4,951.7$\times$10$^{6}$ ㎥/y and inflow amount was 2,569.7$\times$10$^{6}$ ㎥/y, therefore the outflow rate of the Yongsan river watershed was 51.9%. The develop loading of total nitrogen was 86,928.1kg/d and that of total phosphorus was 22,007.6kg/d at the Yongsan river watershed, But, as the inflow loading of total nitrogen was 33,962kg/d and the inflow loading of total phosphorus was 2,218kg/d to the Yongsan lake. so each infolw rate was 39.0% and 10.1%. The hydraulic residence time was 34days, total phosphorus loading [L(P)] on the surface area was 23.398g/㎥/y, the hydraulic load( $Q_{s}$) of inflow water was 74.269m/y, the reserve rate of phosphorus in the lake was 0.359, and the settinh velocity of phosphorus was 0.114m/d at the Yongsan lake. Mathematical model of phosphorus loading to estimate the responses of eutrophication at the Yongsan lake is [ $P_{j}$] = 0.838 [L(P)/Q.(1+√ $T_{w}$)$^{-1}$ ] . ] . .

• Journal of Environmental Science International
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• v.9 no.1
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• pp.95-99
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• 2000

Laboratory experiments were performed to investigate the effects of various factors on the phosphorus removal by electrolysis with aluminium electrodes. The efficiency of phosphorus removal increases with increasing of voltage applied, surface area of electrodes and electrolyte concentration, and decreasing of electrode distance. The phosphorus removal was not affected by the connection number of an electric circuit. The amount of aluminium ion eluted from electrodes according to Faraday's law was 4.47 mg and the A/P mole ratio was 2.14 at the electric current value of 20 mA.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.192-197
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• 1990

The study of characteristics of phosphorus release in Nakdong Estuary Barrage was conducted in June and July, 1989. Batch type reactor was designed for evaluating of release flux. The fractional composition of organic phosphorus and inorganic phosphorus in sediment were $34.7\%,\;66.7\%$, respectively. Inorganic phosphorus was fractionated into three types; Adsorbed-P, Non Apatite Inorganic-P, Apatite-P. The major forms of inorganic phosphorus were Non Apatite Inorganic-P($61.1\%$) and apatite-P($30.0\%$). Release rates of phosphorus from sediment were $-4.4mg/m^2/d$ in aerobic condition, and $39.4mg/m^2/d$ in anaerobic condition. According to the result of this study, sediment plays an important role in Nakdong Estuary Barrage as an internal load source of phosphorus.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.664-668
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• 2005

An experimental study for the comparison of nitrogen and phosphorus removal efficiencies between $A^2/O$ and modified Phostrip (M-Phostrip process) were carried out with bench-scale reactors. In case of nitrogen removal efficiencies both of processes showed similar ones when influent organic loadings were high. However, M-phostrip process was more effective than $A^2/O$ at low organic loadings. This is why M-phostrip process consumes the whole mass of influent organics as a carbon sources for denitrification in anoxic reactor but the anoxic reactor of $A^2/O$ process utilizes the residual carbon followed by consumming a part of influent carbon for phosphorus release in anaerobic reactor. $A^2/O$ process required the influent COD/T-P and COD/TKN ratios were more than 56 and 10, respectively, to take place the phosphorus release in anaerobic process and phosphorus uptake in oxic process. However, the luxury uptake of phosphorus in M-phostrip process was not affected by influent COD/T-P and COD/TKN ratios and the adverse effect of nitrate in return sludge introduced to the p-stripper from the 2nd clarifier was not significant due to the configurational advantage of the p-stripper.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.1
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• pp.33-39
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• 2022

Batch experiments were conducted to find out the effects of various types of magnesium compounds on phosphorus recovery by magnesium ammonium phosphate (MAP) crystallization. The phosphorus recovery from the centrate of anaerobic digested sludge was performed using magnesium chloride, magnesium hydroxide and magnesium oxide under different pH (7.5, 8.0 and 8.5) and Mg/P molar ratio (1.0, 1.5, 2.0, 2.5) conditions. The phosphorus recovery rate increased with increasing pH and Mg/P molar ratio in all magnesium compounds. At pH 7.5, magnesium oxide showed the highest phosphorus recovery rate, followed by magnesium hydroxide and magnesium chloride. However, at pH 8.5, more than 90% of phosphorus recovery rate was obtained in all Mg/p molar ratios. Thus, it is expected that magnesium hydroxide and magnesium oxide are able to replace magnesium chloride as a magnesium source in terms of phosphorus recovery efficiency and cost.

• Carbon letters
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• v.15 no.4
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• pp.277-281
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• 2014

A series of high capacity soft carbons with different phosphorus contents were successfully prepared by carbonizing petroleum cokes treated with hypophosphorous acid at $900^{\circ}C$. The effect of phosphorus content on the electrochemical performance of the soft carbons was extensively investigated. The P-doped soft carbons exhibited greatly enhanced discharge capacities and outstanding rate capabilities with increasing phosphorus content. In addition, the influence of temperature on the electrochemical behaviors of the soft carbons was investigated in a wide temperature range of $25^{\circ}C$ to $50^{\circ}C$. Surprisingly, the electrochemical properties of the pristine and P-doped soft carbons were highly sensitive to the operating temperature, unlike conventional graphite. The pristine and P-doped soft carbons exhibited significantly high discharge capacities of 470 and 522 mAh/g, respectively, at a high temperature of $50^{\circ}C$.

• Analytical Science and Technology
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• v.24 no.4
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• pp.304-309
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• 2011

In this research, behaviour of turbidity and phosphorus in water and soil dependent upon pH and a change of water was studied. Phosphorus dissolve rate from turbidity was increased for water if potential of hydrogen was less than pH 4 or more than pH 7. Turbidity release rate from soil was increased with pH. Turbidity release rate from soil was drastically increased for water if potential of hydrogen was more than pH 4. turbidity release rate from soil was stabilized more than pH 6. Dissolved phosphorus was increased from 2 hours to 24 hours and stabilized in 24 hours. Turbidity was reached the peak of 24 hours and decreased from 24 hours to 96 hours. Turbidity and dissolved phosphorus was decreased for water if these samples were changed a overlying water. Behaviour of turbidity was analogous to dissolved phosphorus when potential of hydrogen was increased from pH 6 to pH 10 and a change of overlying water was increased from 1 time to 4 times. These results suggest that phosphorus dissolve rate and turbidity were directiy correlated with pH. These results are of great importance in lakes because most lakes have a pH in the range of pH 7-10.

• Korean Journal of Poultry Science
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• v.27 no.1
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• pp.19-23
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• 2000

The effects of microbial phutase on laying performance and phosphorus utilization were examined at different levels of dietary nonphosphorus(NPP) in 320 23-week-old Hy-line brown hens for 12weeks. Diets were formulated 0.275%(T1), 0.220%(T2), 0.165%(T3) of NPP levels, and supplemental microbial phytase was 300DPU/kg diet constantly. Conventional diet(C) was formulated 0.275% NPP level without microbial phytase. Egg production and egg mass were higher in T2 than the others (p<0.05), and average egg weight was higher in T1 than the other (p<0.05). Egg productivity was tended to increase with supplemental phytase compared to conventional diet. Daily feed intake a hen also increased in T2 (p<0.05). Feed conversion ratio was improved slightly without significant difference. Eggshell breaking strength and thickness were not different significantly among the treatments. Haugh unit and yolk color were also not different. Calcium and phosphorus retention in body increased in T2 (p<0.05), but dry matter and nitrogen retention were not different significantly. Differences in nitrogen and calcium excretions were not found among the treatments. But phosphorus excretion decreased in order of dietary phosphorus levels with supplement phytase compared to C (p<0.05). Tibial ash, calcium and phosphorus were similar among the treatments. In conclusion, supplemental microbial phytase in laying diet may help to utilize phytase phosphorus, and could decrease NPP intake.