• Journal of Environmental Science International
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• v.16 no.10
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• pp.1169-1177
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• 2007

The main objective of this research was to evaluate the effects of process variables which were forming ability, flow displacement, effective stress, effective strain, fluid vector and products defects on manufactured artificial lightweight aggregate made of both incinerated sewage sludge ash and clay by means of the numerical analysis of a rigid-plastic finite element method. CATIA (3D CAD program) was used for an extrusion metal mold design that was widely used in designing aircraft, automobile and metallic molds. A metal forming analysis program (ATES Co.) had a function of a rigid-plastic finite element method was used to analyze the program. The result of extrusion forming analysis indicated clearly that a shape retention of the manufactured artificial light-weight aggregate could be maintained by increasing the extrusion ratio (increasing compressive strength inside of extrusion die) and decreasing the die angle. The stress concentration of metal mold was increased by increasing an extrusion ratio, and it was higher in a junction of punch and materials, friction parts between a bottom of the punch and inside of a container, a place of die angle and a place of die of metal mold. Therefore, a heat treatment as well as a rounding treatment for stress distribution in the higher stress concentration regions were necessary to extend a lifetime of the metallic mold. A deformity of the products could have made from several factors which were a surface crack, a lack of the shape retention and a crack of inside of the products. Specially, the surface crack in the products was the most notably affected by the extrusion ratio.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.187-194
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• 2011

In compliance with an international law about the ocean dumping of the sludge, the proper sewage treatment process which occurs from the wastewater treatment process has been becoming problem. Generally the sewage and the sludge are controlled from anaerobic condition when the sewage is treated and land filled, where the methane$(CH_{4})$ and the nitrous oxide $(N_{2}O)$ from this process are discharged. Because these gases have been known as one of the responsible gases for global warming, the wastewater treatment process is become known as emission sources of green house gases(GHG). This study is to suggest a new approach of estimate and environmental assessment of greenhouse gas emissions and sludge emissions from wastewater treatment processes. It was carried out by calculating the total amounts of GHG emitted from biological wastewater treatment process and the amount of the sludgegenerated from the processes. Four major biological wastewater treatment processes which are Anaerobic/Anoxic/Oxidation$(A_{2}O)$, Bardenpho, Virginia Initiative Plant(VIP), University of Cape Town(UCT)are used and GPS-X software is used to model four processes. Based on the modeling result of four processes, the amounts of GHG emissions and the sludge produced from each process are calculated by Intergovernmental Panel on Climate Change(IPCC) 2006 guideline report. GHG emissions for water as well as sludge treatment processes are calculated for environmental assessment has been done on the scenario of various sludge treatments, such as composting, incineration and reclamation and each scenario is compared by using a unified index of the economic and environmental assessment. It was found that Bardenpho process among these processes shows a best process that can emit minimum amount of GHG with lowest impact on environment and composting emits the minimum amount of GHG for sludge treatment.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.523-532
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• 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to $27^{\circ}C$, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to $3.84kg\;BOD/m^3{\cdot}day$ in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration. biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14~0.26 kg VSS/kg BODrem, 0.43~0.48 kg VSS/kg BODrem, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.260-265
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• 2004

Acid mine drainage(AMD) is one of the most serious environmental concerns associated with the mining industry around the world. The objective of this study is to assess the potential of sewage sludge as a carbon source for sulfate reducing bacteria and waste lime and steel slag as a neutralize agent for acid mine drainage bioremediation for use in permeable reactive materials. The study was performed using synthetic AMD in six column experiments. The effluent solution was systematically analysed throughout the experiments. The results of the study indicated that sewage sludge, waste lime and steel slag were the most effective for the AMD treatment as a permeable reactive materials.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.42-45
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• 2006

A new and reusable energy source is water-treatment sludges. There is a significant need for understanding the characteristics of sludge combustion related to improving efficiency and ensuring the safety of this new energy source. Because sludges are composed of solids and gas mixture, the combustion of the mixture may become quite complex. Not only decomposition of conventional organic elements but also dust explosion may be important during the process of converting sludges into a new and safe form of energy. Sludge combustion mainly involves hydrogen, methane, hydro carbons, carbon, and organic particles. Dust explosion during the gasification stage may depend on the surrounding temperature and the composition of gases. The uncertainty in the explosive behavior of energetic source is noted in this work. We study the explosion characteristics of sludge combustion while the reusability of sewage sludges as a new form of energy is also investigated.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.109-115
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• 2009

The purposes of this study are to treat sewage sludge that has increasingly become an issue and to recycle it as the adsorbent. The adsorbent was produced by carbonization and simultaneous steam activation, and its characteristics were studied. Parametric screening studies were carried out for the preparation of good adsorbent. Optimum operating conditions were confirmed as input carbonization-activated temperature of $840^{\circ}C$, feed steam flow rate of 70 g/min, carbonization-activated time of 30 min and feed dried sludge of 10.8 kg/day, respectively. At this time, the iodine adsorptivity was maximized as 328.1 mg/g. Pore development, structure, element compound and content were confirmed by using nanoPOROSITY, SEM (Scanning electron microscope), and EDS (Energy dispersive spectroscopy). Through this result, it was known that the adsorbent derived from sewage sludge could be used for the treatment of leachate in a landfill, VOCs (Volatile organic compounds), and so on.

• Resources Recycling
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• v.8 no.4
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• pp.3-10
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• 1999

An experimental study for manufacturing lightweight aggregates from sewage sludge ash of sewage treatment facilities was carned out in senses of sludge disposal and utilization. In case of SA alone, aggregates with S.G. 1.67 was obtained at sintering temperature of $1250^{\circ}C$, and heating rate affects little to volume expansion rate and volume expansion rate was decreased more or less by heating time. In case of adding 10 wt% of RFCC to SA, lightweight aggregates with S.G. 1.07 was obtained and volume expansion rate was increased by heating time. The optimum adding amounts of RFCC to manufacture lightweight aggregates was 10wt% and the condition that shows maximum volume expansion rate was $20^{\circ}C/min$ of heating rate, $1250^{\circ}C$ of sintering temperature and 50 mmutes of heating time. According to adding amounts of RFCC, Compressive strength of sample results in 30 wt% RFCC>SA>20 wt% RFCC>10 wt% RFCC.

• Journal of Animal Environmental Science
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• v.12 no.1
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• pp.29-34
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• 2006

The effects of turning frequency were examined on the efficiency of composting lime treated excess sludge amended with sawdust from the activated sludge process after a liquid/solids separation process. The raw and excess sludge from the activated sludge process associated with the hog wastewater treatment system is a significant problem and composting is an effective method far reducing the pollution potential of hog wastewater sludge. The coagulant used sludge composting and ammonia emissions from composting are not well established. The effect of compost properties such as high total carbon, C/N ratio and pH value on performance of composting sludge and biofiltration of ammonia from composting process were investigated. The ammonia emission was not significantly increased during composting. The ammonia concentrations of the exhaust air of composter were ranged from 0.5 and 7 ppm about 12 days after composting. The performance of the hog wastewater sludge composting was the most sensitive to chemical treated sludge properties such as high total carbon and high C/N ratio of the initial compost mixes. Temperature in compost and ammonia emission were not greatly affected by the turning frequency.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.129-137
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• 2000

In this study, biological treatment process of MWWT(Municipal wet-waste Treatment) has been developed through a moduling of the containerized closed ATAD(Auto thermal aerobic digestion) system & closed vertical dynamic acerator, which were used for food waste and cattle manure, respectively. Though biological process has several advantages such as low concentrations of heavy metals and salts, proper and stable C/N ratio and constant reaction rate against the process treating two wastes separately, it has a obstacles of salt concentration and much usage of bulking agent such as wood chip. After rapid oxidation in the boxed tower reactor for 5 days, the content of sewage sludge would be reduced 65% on around, might be mixed with the food waste that had been treated in the static closed reactor during 6 days and put in the secondary static reactor for curing. During composting process, the odor contained in the gas generated from the reactor was removed by passing it through a biofilter as well as the leachate was treated in the wastewater treatment facility. Consequently, it seemed to be possible to compost sewage sludge at mild and stable operating condition and at low cost through the biological ATAD process resulting in the production of organic compost satisfying the specifications regulated by itself.

• Clean Technology
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• v.13 no.2
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• pp.87-98
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• 2007

As the interest in environmental problems increased, the guideline of effluent qualities becomes strict and the amount of sludge produced from the wastewater treatment facilities steeply increased. The revised Korean acts prohibit the direct reclamation of the sludge exhausted in sewage treatment works from 2003, and the ocean dump of sludge will be also prohibited from 2012. Therefore, the sludge must be recycled, incinerated or composted. To properly perform the utilization and disposal operations, the establishment of well-defined procedures for the characterization of sludge by physical, chemical and biological method and setting up of guidelines for different treatment and disposal routes has become necessary. However, there have not been such standardized methods for sludge characterization in Korea. This review analyzes the present status of establishment and problems of sludge characterization method of Korea. Finally, it was proposed total 15 items of standardized characterization methods suitable to our country for proper sludge recycling and disposal, which was based on the more systematic standard methods of Germany (DIN 38414) and those of advanced nations.