• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.602-608
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• 2005

A laboratory-scale experiment was conducted to investigate control of soluble microbial products (SMP) by the internal recycle rate in the submerged membrane separation activated sludge process. The internal recycle rate of the reactor RUN 1 and RUN 2 were 100 % and 200 %, respectively. SMP concentration was rapidly accumulated in the reactor (RUN 1). The variation of accumulated SMP concentration was related to the denitrification rate at the beginning experiment however SMP concentration decreased without correlatively to the denitrification rate during long operation time. The microbial kinetic model was rapidly presented in the both microbial growth and extinction in the reactor (RUN 1). In the SMP kinetic model, Internal recycle rate is the lower, value of UAP and BAP which SMP matter were presented low. The study about development of kinetic model is relatively well adjusted to the experiment exception SMP. In the future, SMP formation equation must be thought that continually research is necessary.

• 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.

• Tribology and Lubricants
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• v.22 no.4
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• pp.218-224
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• 2006

The sludge oils were produced necessarily in the ships operation, so that it will be the best way to manage the sludge oils inside ship itself from a viewpoint of the prevention of marine oil pollution. The ultra-sonic breaking system which recycle the sludge oil from ship into usable oil to be brunt is recognized as a most possible recycling device. In this regards, the purpose of this study is to examine erosion damage,on the SS400 specimen by cavitation and the effect of impact pressure generated from the demolition of the cavity of ultrasonic vibration in the marine sludge oil environment.. The erosion damage of specimen was investigated mainly on weight loss, weight loss rate and maximum erosion rate with variation of the oil temperature as well as the change of space between transducer hem and specimen. The experimental results showed that as the space between ultrasonic vibrator horn and specimen disk increased, the weight loss and weight loss rate decreased and the values were larger in SFO than in SLO. The experimental results can be useful to the development of sludge oil disposing systems and to consider a countermeasure for the prevention of erosion damages by cavitation.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E2
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• pp.41-48
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• 2005

A novel hybrid system composed of a biotrickling filter and an activated sludge reactor was investigated under the conditions of four different SRTs (sludge retention times). The performance of the hybrid reactor was found to be directly comparable among the four different sludge ages. Discernible differences in the removal performance were observed among four different SRTs of 2, 4, 6, and 8 days. High removal efficiency was achieved by continuous circulation of activated sludge over the immobilized mixture culture, which allowed on pH control, addition of nutrients, and removal of paint VOCs (volatile organic compounds). The results also showed that the removal efficiency for a given pollutant depends on the activity of microorganisms based on the SRT. As the SRT increased gradually from 2 to 8 days, the average removal performance decreased. The highest removal rate was achieved at the SRT of 2 days at which the highest OUR (oxygen uptake rate), $6.1mg-O_2/liter-min$ was measured. Biological activity in the recycle microbes decreased to a much lower level, $3.6mg-O_2/liter-min$ at a SRT of 8 days. It is thus believed that young microorganisms were more active and more efficient for the VOCs removal of low concentrations and high flow rates. The apparent correlation of $R^2=0.996$ between the average removal efficiency and the average OUR at each SRTs suggests that VOCs degradation by young cells significantly affected the overall removal efficiency for the tested SRTs.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.676-681
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• 2016

For the purpose of reducing the amount of limestone, which is used as a desulfurization agent to absorbing $SO_X$ gas in thermal power plants, and to recycle limestone sludge generated from a steel mill, limestone sludge was utilized as a desulfurization agent. In this study, cement, made of flue gas desulfurization (FGD) gypsum obtained in a desulfurization process using limestone sludge, was manufactured then, experiments were conducted to identify the physical properties of the paste and mortar using the cement. The results of the crystal phase and microstructure analyses showed that the hydration product of the manufactured cement was similar to that of ordinary Portland cement. No significant decline of workability or compressive strength was observed for any of the specimens. From the results of the experiment, it was determined that FGD gypsum manufactured from limestone sludge did not influence the physical properties of the cement also, quality change did not occur with the use of limestone sludge in the flue gas desulfurization process.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.82-91
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• 2004

In order to utilize inorganic components in coal and wastewater sludge as an environmentally stable material, slag-forming is considered as one of the suitable methods better than producing as an ash. Coal slag that was produced by gasification as well as the slag made from wastewater sludge by incineration or melting process have been analyzed with the viewpoint of recyclability. Slags produced by water quenching exhibited a cracked shape that has a size of few millimeters with sharp edges. Slags contain the unburned carbon content below 0.15％ and expose mostly amorphous structural characteristics. Analysis results in the extraction of heavy metal compounds demonstrate that both slags from coal and wastewater sludge could be utilized as a safe recycle material even with a Japanese environmental regulation that is ten times more stringent than the current Korean standard. Slags from coal and wastewater sludge show significant differences in contents of each heavy metal compound. Since the future trend of environmental regulation shifts to the control of total content for each heavy metal compound, proper mixing of slags that contain different heavy metal contents might be an option for manufacturing recycle materials.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.299-310
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• 1993

This study was aimed to evaluate the effects of effluent recycling on the UASB reactor performances at the various organic loading rates and influent substrate concentrations. The organic removal efficiency of the reactors operated with effluent recycle were above 85%. However, the efficiencies of the reactors operated without the recycle were below 40% even though the effort to increase the efficiencies was made by changing the influent substrate concentrations and the organic loading rates, and introducing the effluent recycle at the final stage of the experiment. It was realized that the certain amount of effluent recycling from the start-up stage in UASB reactors seemed to be necessary to provide the effective contact chances between the substrate and granular sludge for better performances of the UASB process.

• Resources Recycling
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• v.8 no.4
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• pp.39-44
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• 1999

Nightsoil and brewery sludges usually contain a high concentration of organic matters. A composting study using reactors was carried out for the recycle of brewery wastewater sludge and nightsoil treatment sludge, which have been landfilled. A good composting process was obtained with a sludge mixing ratio of 1:1 and injual pH had no effect on temperature increase related to microbial activity. The injtial C/N ratio at approximarely 15 decreased to 13 without the increase in pH.. It was found that agitation of one time a week provided the most effective composting process.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.875-883
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• 2006

The carbon and nitrogen removal process using PVA-gel (Polyvinyl Alcohol) immobilized microorganisms was studied. The process has been operated under diverse process conditions for 12 months. The process consists of denitrification with internal recycle of 300%, nitrification, aerobic digestion reactors and settling tank. Nitrificatoin and nitrogen removal efficiency according to gel packing ratio and temperature were studied. Yield for Heterotrophs ($Y_H$), decay coefficient for Heterotrophs($b_H$) in aerobic digestion reactor were determined to seize sludge reduction mechanism and compared with typical data of activated sludge process. Then SRT in aerobic digestion reactor was determined on an experimental basis and sludge reduction efficiency was calculated. The process was implemented successfully with sludge reduction efficiency of 92.0~98.5% on a basis of biomass.

• 수도
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• s.29
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• pp.18-29
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• 1983