• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.23-28
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• 1999

Phosphate removal through adsorbent, such as activated alumina, powdered aluminum oxide, flyash, blasted furnace slag and other materials, is commonly and widely practiced. The purpose of this study was to improve the removal efficiency of phosphorus in waste sludge earned at seafood processing factories. To investigate the utility and the feasibility of this sludge disposal process, experiment was carried out with a batch process. As a result, phosphate removal appears to increase with increasing adsorbent does, but shows no changes at an adsorbent does over 5g/l. With increasing ratios of initial phosphate concentration to adsorbent does, the amount of removed phosphate is increased while phosphate removal(%) is decreased. Wasted sludge, treated with zinc chloride chemically, represented a better efficiency than the untreated activated sludge and zinc chloride itself, when they reacted with phosphate solution.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.701-708
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• 2018

Chemical batch tests were conducted to investigate the amount of nutrients that were released from the wasted activated sludge during microwave heating. For this study, three types of activated sludge were obtained from $A_2/O$, MLE and oxidation ditch (OD) processes. Polyphosphate-accumulating organisms in the activated sludge have a unique trait: they releases phosphate from the cell when they are exposed to high temperatures. The sludge obtained from the $A_2/O$ process released the largest amount of phosphate, followed by those from the MLE and OD processes. The release of phosphate increased with increasing polyphosphate content in the sludge under strongly alkaline or acidic conditions. Furthermore, ammonia and heavy metals were released with phosphorous. The largest amount of ammonia was observed from the sludge obtained from the MLE process. The release of heavy metals strongly depends on the pH conditions. Therefore, the chemical analysis results strongly suggest that both phosphorus and ammonia react with $Mg^{2+}$ or $Ca^{2+}$ to form metal complexes such as magnesium ammonium phosphate or hydroxyapatite under alkaline conditions.

• Journal of Environmental Science International
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• v.24 no.2
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• pp.237-244
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• 2015

This objectives of research are to figure out combustion characteristics with increasing temperature with petrochemical sludge by adding wasted organic matters which are waste electric wire, anthracite coal and sawdust, and to exam heating value and ignition temperature for using refused derived fuels(RDFs). After analyzing TGA/DTG, petrochemical sludge shows a rapid weight reduction by vaporing of inner moisture after $170^{\circ}C$. Gross weight reduction rate, ignition temperature and combustion rates represent 68.6%, $221.9^{\circ}C$ and 54.1%, respectively. In order to assess the validity of the RDFs, the petrochemical sludge by adding wasted organic matters which are waste electric wire, anthracite coal and waste sawdust. The materials are mixed with 7:3(petrochemical sludge : organic matters)(wt%), and it analyzes after below 10% of moisture content. The ignition temperatures and combustion rates of the waste electric wire, anthracite coal and waste sawdust are $410.6^{\circ}C$, $596.1^{\circ}C$ and $284.1^{\circ}C$, and 85.6%, 30.7% and 88.8% respectively. In heating values, petrochemical sludge is 3,600 kcal/kg. And the heating values of mixed sludge (adding 30% of the waste electric wire, anthracite coal and waste sawdust) each increase up to 4,600 kcal/kg, 4,100 kcal/kg and 4,300 kcal/kg. It improves the ignition temperatures and combustion rates by mixing petrochemical sludge and organic matters. It is considered that the production of RDFs is sufficiently possible by using of petrochemical sludge by mixing wasted organic matters.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.1-3
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• 2002

This study was to evaluate on the removal efficiencies of total nitrogen and phosphorus in municipal wastewater at MUNR process using sludge carbon source for environmental micro-organism. The removal efficiencies of total suspended solid were 85.9~91％, total nitrogen were 38.6~87.2％ and total phosphorus were 30.8~39.0％, respectively. It was shown that removal efficiency of nitrogen was effectively influenced by sludge carbon source treated with ultrasonication. The removal efficiency of total phosphorus was low because the sludge was not wasted during this treatment.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.264-270
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• 2006

In this research, volume reduction of activated sludge using electrolysis was studied to find an optimum condition using lab scale experiments. Wasted sludge was treated by electrolysis with controlling current density, chloride concentration, electrode distance, and reaction time. Volume of return sludge was reduced by 9.79% in average while maximum was 16.7%. Sludge volume reduction efficiency was affected by current density and reaction time. It was reversely proportional to the electrode distance. Especially current density was effective on the system performance significantly. Electric conductivity, salinity and COD were increased by electrolysis implying sludge disintegrated and converted to COD in part. An empirical equation for total solid removal efficiency by electrolysis was proposed by multiple linear regression analysis as: $TS_{rem}$(%) = 5.534 ${\times}$ current density (A/l) + 0.178 ${\times}$ reaction time (m) + 2.758.

• Journal of Adhesion and Interface
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• v.2 no.1
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• pp.1-8
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• 2001

In this study, wasted stone powders (WSP) obtained from sludge and Wasted Tire Chips (WTC) as fillers have been used to formulate polymer hybrid composites based on Unsaturated Polyester (UPE) resin. To further enhance not only the interfacial bond between the inorganic filler and the polymer matrix, but also the filler dispersion by wetting the particulate surfaces to uniformly spread the resin during the mixing, silane coupling agent[${\gamma}$-methacryloxy propyl trimethoxy silane (${\gamma}$-MPS)] was used. The influences of organic recycled fillers contents and the concentrations of coupling agent in polymer hybrid composite formulations have been investigated from a mechanical and microstructural point o view through Mercury Porosimeter and SEM.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.3
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• pp.257-262
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• 2017

Several disposal processes for waste sludge from wastewater treatment plants such as landfill, ocean dump, incineration, reuse as fuels or fertilizers are practiced. However, ocean dumping is prohibited by international treat. New constructions of landfill sites or incineration facilities are limited by NIMBY and reuse processes are still suffering from low energy yield. Therefore, development of alternative processes for sludge disposal are currently needed. In this study, alternative technique for sludge solubilization using HVI (high voltage impulse) was suggested and verified experimentally. Sludge solubilization was carried out for 90 minutes using HVI discharge with peak voltage of 16 kV and pulse duration for 40 microsecond. About 3~9 % of MLSS and MLVSS concentration were reduced, but the soluble COD, TN, TP of the sludge increased to 372 %, 56 % and 102 % respectively. It indicates that the flocs and/or cells of the sludge were damaged by HVI. These resulted in flocs-disintegration and cells-lysis, which means the internal matters were bursted out of the flocs as well as the cells. Thus, electrical conductivity in bulk solution was increased. All of the results verified that the HVI could be used as an alternative technique for sludge solubilization processes.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.344-352
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• 2010

Magnetite and inorganic sludge were mainly composed of $Fe_2O_4$ and $Fe_2O_3$, respectively. Initial specific surface areas of magnetite and inorganic sludge were 130 $m^2$/g and 31.7 $m^2$/g. $CO_2$ decomposition rate for inorganic sludge was increased with temperature. Maximum $CO_2$ decomposition rates were shown 89% for magnetite at $350^{\circ}C$ and 84% for inorganic sludge at $500^{\circ}C$. Specific surface area for magnetite was not varied significantly after $CO_2$ decomposition. However, specific surface area for inorganic sludge was greatly decreased from initial 130 $m^2$/g to approximately 50~60 $m^2$/g after reaction. Therefore, it was estimated that magnetite could be used for $CO_2$decomposition for a long time and inorganic sludge should be wasted after $CO_2$ decomposition reaction.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.130-137
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• 2005

This research programme include investigation of the adsorption behavior of heavy metals and VOCs by Pyrolysis char for using landfill cover material. The volatile potions in the sludge gasified during the pyrolysis period and gave birth to porosity throughout the matrix. The result of the ad/desorption experiment of nitrogen to find out the formation of some pore by the gasification of the volatile matter, we can certify that the pyrolysis char($14.56\;m^2/g$) has increased twice more than the organic wasted sludge($6.68\;m^2/g$) in specific surface area. The pyrolysis char has the adsorption characteristic of medium type of Type II and V in BDDT classification, and showed a little micro pore. In the adsorption experiment of ethylbenzene and toluene, as a result of applying the Freundlich adsorption isotherms, the pyrolysis char was higher in the adsorptivity of ethylbenzene and toluene than the granite and the organic wasted sludge. The results of the heavy metal adsorption test for the char indicated that it had some ability of adsorption. It is suggest that pyrolysis char has some advantages for utilizing as landfill covers because the pyrolysis char can adsorb/absorb hazardous substances from the landfill sites and inhibit the ground water and soil contamination.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.561-567
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• 2001

It is reported that a lot of sludge powder is produced during the process of manufacturing crushed fine aggregate in mines. However, there is a limitation on the its use that most of them are disposed and wasted, which cause environmental pollution. Therefore, in this paper, tests are carried out in order to recycle sludge powder as filler for cement mortar products. Kinds of aggregates and mix proportion of mortar are varied under various contents of sludge powder. According to test results, it is found that cement mortar products using sludge powder as substitution of fine aggregate about 10% have better qualities than those without sludge powder.