• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.438-446
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• 2006

A lab-scale batch test was conducted to develop capping materials to reduce the sediment phosphorus in the stagnant water zone of Gyeongancheon in Paldang Lake. The mean grain size(Mz) of sediment in the investigated area was 7.7 ${\phi}$, which is very fine, and the contents of organic carbon($C_{org}$) was 2.4%, which is very high. For the phosphorous release experiment to select the optimal capping material, sand layer, powder-gypsum($CaSO_4{\cdot}2H_2O$), granule-gypsum, complex layer(gypsum+sand) and the control were compared and evaluated in the 150 L reactor for 45 days. In case of the capping with the sand, it was found that the phosphorous from the sediment could be reduced by around 50%. However, it was found that this caused the reduction of the dissolved oxygen in the water column(by less than 3 mg/L) due to the resuspension of sediment and the organic matter decomposition that comes from the generation of $CH_4$ gas in the 1 cm of the sand layer. Therefore, it is likely that the sand layer has to be thickener in case of the sand capping. Powder-gypsum and granule-Gypsum reduced phosphorous release by more than 80%. However, the concentration of ${SO_4}^{2-}$ in the water column increased, making it difficult to apply it to the drinking water protection zone. We developed Fe-Gypsum and $SiO_2$-gypsum materials to reduce the solubility of ${SO_4}^{2-}$. Powder-Gypsum creates the interception film that does not have any aperture on the sediment layer when it is combined with the water. However phosphorous release caused by the generation of $CH_4$ gas may happen at a time when the gypsum layer has the crack. Capping through the complex layer(granule-Gypsum+sand(1 cm)) found to be suitable for the drinking water protection zone because it was effective to prevent phosphorus release. Moreover, this leads to the lower solubility from the concentration of ${SO_4}^{2-}$ into the water column than the powder-Gypsum and granule-Gypsum. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment can reduce the progress of methanogensis because fast early diagenesis and sufficient supply of ${SO_4}^{2-}$ to the sediment, stimulate the SRB(sulfate reducing bacteria) highly.

• Advances in environmental research
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• v.5 no.4
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• pp.251-262
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• 2016

The biodegradability and decomposition efficiencies increase with the pre-treatment of sludge in a digestion process. In this study, the feasibility of ultrasound coupled with potassium permanganate oxidation as a disintegration method and digestibility of aerobic reactor fed with disintegrated sludge with ultrasound coupled potassium permanganate were investigated. The first stage of the study focused on determining the optimum condition for ultrasonic pre-treatment for achieving better destruction efficiency of sludge. The second part of the study, the aerobic digestibility of sludge disintegrated with ultrasound and potassium permanganate oxidation alone and combined were examined comparatively. The results showed that when 20 min of ultrasonic pre-treatment applied, the specific energy output was 49384 kJ/kgTS with disintegration degree of 58.84%. During the operation of aerobic digester, VS/TS ratios of digesters fed with disintegrated sludge decreased indicating that disintegration methods could obviously enhance aerobic digestion performance. The highest reduction in volatile solids was 75% in the digester fed with ultrasound+potassium permanganate disintegrated sludge at the end of the operation compared to digester fed with raw sludge. Total Nitrogen (TN) and Total Phosphorus (TP) levels in sludge supernatant increased with this combined method significantly. Besides, it promoted the production of ${\bullet}OH$, thus enhancing the release of Carbon (C), Nitrogen (N) and Phosphorus (P) from the sludge. Disintegration with all methods used in this study could not improve Capillary Suction Time (CST) reduction in disintegrated digesters during the operation. The results demonstrated that the combined ultrasound treatment and potassium permanganate oxidation method improves the biodegradability compared to control reactor or their single application.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.165-170
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• 2009

The increase in P availability to rice under flooded soil conditions involves the reductive dissolution of iron phosphate and iron (hydr)oxide phosphate. However, since $NO_3^-$ is a more favourable electron acceptor in anaerobic soils than Fe, high$NO_3^-$ loads function as a redox buffer limiting the reduction of Fe. The effect of adding $NO_3^-$ on Fe reduction and P release in paddy soil was investigated. Pot experiment was conducted where $NO_3^-$ was added to flooded soil and changes of redox potential and $Fe_2^+$, $NO_3^-$ and $PO_4^{3-}$ concentrations in soil solution at 10 cm depth were monitored as a function of time. Redox potential decreased with time to -96 mV, but it was temporarily poised at about 330${\sim}$360 mV when $NO_3^-$ was present. Nitrate addition to soil led to reduced release of $Fe_2^+$ and prevented the solubilization of P. Phosphate in pore water began to rise soon after incubation and reached final concentrations about 0.82 mg P/L in the soil without $NO_3^-$ addition. But, in the soil with $NO_3^-$ addition, $PO_4^{3-}$ in pore water was maintained in the range of 0.2${\sim}$0.3 mg P/L. The duration of inhibition in $Fe_2^+$ release was closely related to the presence of $NO_3^-$, and the timing of $PO_4^{3-}$ release was inversely related to the $NO_3^-$ concentration in soil solution. The results suggest that preferential use of $NO_3^-$ as an electron acceptor in anaerobic soil condition can strongly limit Fe reduction and P solubilization.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1180-1185
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• 2006

Lab-scale batch experiments using several 25-L transparent acrylic reactors were conducted to develop optimum capping materials that can reduce phosphorus released from polluted sediments. The sediment used in the experiment was very fine clay(8.8 $\Phi$ in mean grain size), and organic carbon($C_{org}$) content was as high as 2%. Four kinds of batches with different capping materials Brucite($Mg(OH)_2$), Sea sand($SiO_2$), Granular-gypsum($CaSO_4{\cdot}2H_2O$), Double layer(brucite+sand), and one control batch were operated for 30 days. Phosphorus fluxes released from bottom sediments in the control batch were estimated to be 14.6 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, while 9.5 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, 5.2 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, 4.2 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, and 3.1 $mg{\cdot}m^{-2}{\cdot}d^{-1}$ in the batch capped with Sea sand, Granular-gypsum, Double layer, and Brucite, respectively. The results obtained from lab-scale batch experiments show that there were 70% reduction of phosphorus for some materials such as Brucite, Double layer(brucite+sand), and whereas sea sand only about 35%. The pH range of surface sediment to which Brucite was applied showed about $8.0{\sim}9.5$ in the weak alkaline state. This effect can prevent liberation of $H_2O$. The addition of gypsum into the sediment can reduce the progress of methanogenesis because of fast early diagenesis and sufficient supply of $SO_4^{2-}$ to the sediments, stimulate the SRB highly. Therefore, the application of Brucite and Gypsum can reduce phosphorus release from the sediment as a result of formation of $Mg_5(OH)(PO_4)_3$, pyrite($FeS_x$), and apatite-mineral.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.563-572
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• 2006

In order to propose optimum in-situ treatment for reducing phosphorous release from sediment of stationary lakes, a series of column tests were performed. The sediment used in experiment was very fine clay with a mean grain site $7.7{\phi}$ and high $C_{org}$ contents(2.4%). Phosphorous releases were evaluated in two ways : in lake water(with microbial effect) and in distilled water(without microbial effect). As in-situ capping material, sand and loess were used while Fe-Gypsum and $SiO_2$-Gypsum were used for in-situ chemical treatment. In case of lake water considering the effect of microorganism, phosphorous concentration rapidly decreased in the early stage of experiment but it was gradually increased after 10 days. Flux of phosphorous release for control was $3.0mg/m^2{\cdot}d$. Whereas, those for sand layer capping(5 cm) and loess layer capping(5 cm) were $2.5mg/m^2{\cdot}d\;and\;1.8mg/m^2{\cdot}d$, respectively because the latter two were not consolidated sufficiently. For Fe-gypsum and $SiO_2$-gypsum the fluxes were $1.4mg/m^2{\cdot}d$ which meant that reduction efficiency of phosphorous release was more than 40% higher than that of control. The case capping with complex layer was $1.0mg/m^2{\cdot}d$, which showed high reduction efficiency over 60%. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment reduced release of Phosphorus from the sediments. Gypsum acted as a slow-releasing source of sulphate in sediment, which enhanced the activity of SRB(sulfate reducing bacteria) and improved the overall mineralization rate of organic matter.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.305-327
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• 1999

In the paper insight is given in the legislation policy to restrain environmental pollution by pig husbandry, focused on The Netherlands (Mineral Accounting System). Besides, nutritional measures are presented to reduce environmental pollution by lowering excretion of N and P, emphasizing (multi) phase feeding, the use of low protein, synthetic amino acids supplemented diets, phytase and its effect on phosphorus and calcium digestibility, its interaction with phytic acid and proteins, and the environmental impact of the use of phytase in pig diets. Also, nutritional means are indicated to reduce ammonia volatilization from pig operations. It is concluded that nutrition management can substantially contribute to reduction of N and P excretion by pigs, mainly by lowering dietary protein levels, (multi) phase feeding and the use of microbial phytase, and that the use of phytase on a large scale in The Netherlands has a tremendous environmental impact. In 20 years the excretion of P in growing-finishing pigs has more than halved. Ammonia emission from manure of pigs can be reduced substantially by lowering dietary protein content, but also by including additional non-starch polysaccharides in the diet. A very promising method to reduce ammonia emission is to manipulate dietary cation-anion difference, e.g. by adding acidifying salts to the diet, which will lower pH of urine substantially. Further research is desirable. This also applies to determining dietary factors influencing the odour release from manure. Finally, some speculation on the future of pig farming from an environmental viewpoint is presented.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.145-147
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• 2009

Nutrients in wastewater should be removed prior to release in the receiving waters to prevent the occurrence of eutrophication. In this study, seawater is used to remove ammonia and phosphate by the formation of struvite ($MgNH_{4}PO_{4}{\cdot}6H_{2}O$). It aims to know the optimum conditions for the removal of nutrients using seawater as source of magnesium ions. Experiments were performed using jar tester and pH of ammonium-phosphate solutions were adjusted Samples were drawn at different mixing times. It was shown that simultaneous removal of ammonia and phosphate is rapid, with no significant reduction beyond 10 min of mixing Another important parameter is pH, where range 10-11 showed the optimum nutrient removal. Increase in the volume of seawater, which meant an increase in magnesium ions also lead to better removal.

• Korean Journal of Microbiology
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• v.36 no.1
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• pp.52-57
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• 2000

A method for quantitative and qualitative analysis of geosmin, odorant produced by several actinomycetes and cyanobacteria, was established and optimized. The effects of environmental conditions on the growth of Phormidium sp. NIVA-CYA7 were examined and the production and release of geosmin by the species was analyzed by using the purge and trap-gas chromatographic technique. One of the major advantages of the technique established in the present study is that the preparation of sample is simpler and purge time is shorter. Under the culture conditions (pH 7.9, $20^{\circ}C$, 120-140 $\mu$E/$m^2$/s and Z8 medium), Phormidium showed growth characteristics with a lag phase for 8 days and an exponential phase for 14 days followed by a stationary phase. Reduction of inorganic nitrogen concentrations in the culture medium from 250 to 100 or 25 $\mu$M brought no significant effect on the cell growth. However, the cell growth was significantly inhibited with decreasing concentrations of inorganic phosphorus from 25 to 10 or 2.5 $\mu$M. When the inorganic phosphorus concentration in the medium was lowered from 25 to 10 $\mu$M, the levels of geosmin in the organism expressed as percentages per unit TOC and chlorophyII-$\alpha$ increased by 35% and 68%, respectively. When the initial pH of the medium was 9.4, geosmin content was 0.0824 $\mu$g/mg C, which was 2-fold higher than that at pH 7.9 Consequently, the level of geosmin in Phormidium was found to vary with growth phases of the culture, external inorganic phosphorus concentration and external pH, while the release of geosmin was not significantly affected by the factors.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.101-107
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• 1984

The suitable paddy soil for application of rice straw under well to moderately well drained soil, the yield and yield components were pronounced more than poorly drained soil. Based on laboratory experiment, application of rice straw promoted the decrease of oxidation-reduction potential in well to moderately well drained soil. This results seems to be enhanced the release of some mineral nutrients such as calcium, potassium, silicon, and increases of availability of soil phosphorus. This explains reason why soil condition became more favorable for the increases of mineral nutrient in rice plant. On the contrary, poorly drained soils, became readily reduced even without application or rice straw, when soil wat submerged. Application of rice straw did not promoted the decrease of oxidation-reduction potential as much as in well drained soil. It was suggested that in this type of soil series, the release of mineral nutrients and the additional increase of available soil phosphorus did not proceed well. It was also suggested that the retardation of root development owing to accumulation of toxic substances such as organic acid, hydrogen sulfide or some other reducing substances formed by the application of rice straw in poorly drained soil series might be considered. In fact, the effect of rice straw on the yield of brown rice became lower.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3285-3294
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• 2012

A field test on mud flat remediation was carried out in order to observe the effects of the treatments such as microbial dose and an oxygen releasing compound like $CaO_2$. The size of each treatment site was $100m^2$ and the dosage was 3.6 kg per site. The 6 week monitoring showed that pH on two sites was below 7 and ORP increased from .178~-188 mV to .121~-142 mV. In Ignition loss and COD there were no significant changes. Meanwhile nitrogen and phosphorus concentrations changed: ammonia concentration decreased both on control and treatment sites. Nitrate nitrogen decreased more on combined treatment site than on single microbial treatment (11.3% vs. 7.3%) probably because the extra oxygen supplied by $CaO_2$ formed more oxic environment so that the facilitated nitrification might produce more nitrate but the nitrate would be much rapidly released into the water layer out of the sediment. That also explains the total nitrogen reduction(6.1%). Similarly, T-P and $PO_4-P$ reduced by 29% and 31.8%, respectively on combined treatment sites, resulting from the phosphorus release effect though the initial concentrations of the two factors were considerably high.