• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.443-446
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• 2000

The feasibility study on paraffin binder as a solidifying agent of digested sewage sludge cake was peformed. The availability of paraffin binder as a solidifying agent was investigated by several tests. Based on the tests, it is ascertained that paraffin binder with a small amount of quicklime and fly ash enhances the solidification of digested sewage sludge cake. Paraffin binder shortened the drying time of digested sewage sludge cake and solidified sludge with paraffin was not dissolved in water again. Also, the unconfined compressive strength of solidified sludge with paraffin increases.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.47-56
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• 2008

The objective of this research is to evaluate the optimum recycling methods for the sewage sludge cakes at different microwave power-settings and for different periods of time. The dehydrated sewage sludge cakes used in this study was obtained from N wastewater treatment plan in the P City. The beginning drying processes were carried out in a microwave oven with 2,450 MHz frequency and power ranges of 1kW to 4 kW. The continuous conveyer drying system was also operated with 2,450 MHz frequency and power setting, ranging from of 1 kW to 6 kW. Initial moisture content of the sewage cake is 78~80%, and the moisture content decreased rapidly up to 0.2~2(wt%) within short periods due to breaking the cell walls. This study is also conducted to evaluate the characteristics of sewage sludge cakes with respect to important physical parameters effect on the thermal kinetics for evaporation water in the sludge which are operation times, moisture contents, drying rates, input amounts, flow rates and calorific values. It takes 60 minutes and 120 minutes to reach the critical moisture contents with power setting of 4 kW for 3kg/min and 6kg/min of the flow rates respectively. It takes 120 minutes and 110 minutes to reach the critical moisture contents with flow rates of 2.5 cm/min and sludge input of 6kg/min for the power settings of 4 kW and 6 kW respectively. The most effective value of the power for drying the sludge is 4 kW. Operation with 6kg/min and 4kW on 2cm of the sludge thickness can be effectively and inexpensively to reach the critical moisture contents, when you compare 2cm of the sludge thickness with 1cm and 3cm of the sludge thickness.

• Environmental Engineering Research
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• v.24 no.4
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• pp.591-599
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• 2019

To convert sewage sludge to energy, drying-gasification characteristics during microwave heating were studied. During the gasification of carbon dioxide, the main products were gas, followed by char, and tar in terms of the amount. The main components of the producer gas were carbon monoxide and hydrogen including a small amount of methane and light hydrocarbons. They showed a sufficient heating value as a fuel. The generated tar is gravimetric tar, which is total tar. As light tars, benzene (light aromatic tar) was a major light tar. Naphthalene, anthracene, and pyrene (light polycyclic aromatic hydrocarbon tars) were also generated, but in relatively small amounts. Ammonia and hydrogen cyanide (precursor for NO_x) were generated from thermal decomposition of tar containing protein and nitrogen in sewage sludge. In the case of sludge char, its average pore diameter was small, but specific area, pore volume, and adsorption amounts were relatively large, resulting in superior adsorption characteristics.

• Journal of the Korean Wood Science and Technology
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• v.22 no.1
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• pp.54-65
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• 1994

This research carried out to investigate the effects of inorganic materials in paper sludge on the thermal degradation and of paper sludge addition on physical and mechanical properties of paper sludge-wood particle mixed boards in comparison with unmodified particleboards. Also these unmodified particleboards and paper sludge-wood particle mixed boards were soaked in aqueous solutions of fire-retardant chemicals(diammonium phosphate and zinc chloride), and their fire retardancy were tested by oxygen index method and ISO ignition test to determine the feasibility of paper sludge, industrial waste, as a recyclable resource in fabrication of fire-resisting panels for building material. Since the redrying of fire-retardant treated particleboards and paper sludge-wood particle mixed boards were made by press drying method, this process was a simple and effective method. On the other hand, flexural bending strength and internal bonding strength were also analysed to evaluate mechanical properties through standard method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.143-144
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• 2020

For modern people who spend 80% of the day indoors, indoor air quality is an important factor in their lives. Radon and fine dust, which are indoor air quality pollutants, cause various diseases and lung diseases, so a method is needed to reduce them. Therefore, this study intends to utilize the air pollutant adsorption properties of the carbonized sludge by using the carbonized sludge generated through drying and carbonization of the sludge. As a result of the experiment, it was shown that the concentration of radon and fine dust gradually decreased as the replacement ratio of carbonized sludge increased. The reason is that the carbonized sludge has the ability to adsorb fine dust and radon, so it is considered that it gradually decreases as the replacement ratio increases. Also, the compressive strength and flexural strength tend to decrease gradually. The reason for this is that the carbonized sludge has a number of internal voids, and as the replacement ratio increases, the internal voids increase and the strength decreases. If the refinement and strength of the carbonized sludge replacement ratio are supplemented, it is believed that it will be able to replace the existing finishing materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.409-412
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• 2005

Because the underwater structures are subjected to the deterioration according to use environment, it is necessary to repair and reinforce when the durable performances are considered in structures. In generally, epoxy mortar is used to repair materials of underwater concrete. It is divided epoxy and filler which is organized cement and sand. Cement can be replaced by stone powder sludge in waste because the grading of stone powder sludge in drying state has similar to that of cement. As result of study, it is possible that stone powder sludge can be applied for replacement materials of cement in epoxy mortar, because the strength is not different when filler in epoxy mortar is alternated stone powder sludge.

• 수도
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• v.24 no.5 s.86
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• pp.29-44
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• 1997

Sewage sludge produced in Korea was 1,275,800 tons (dewatered sludge cake) per year in 1996, which is 3,495 tons per day, 0.303% of 11,526,100 tons per day of sewage treated in 79 sewage treatment plants. Sludge production has been and will be increasing in accordance with construction of new facilities for sewage treatment. Most of the sludge is currently disposed by landfill and ocean dumping, but it is becoming difficult to find suitable sites for landfill, particularly in big cities such as Seoul. In addition, rapid increase of landfill cost is anticipated in a near future. Current trend for sludge disposal in advanced countries is land application. Over the past 10 to 20 years in the United States, sludge management practices have changed significantly, moving from disposal to beneficial use. They use biosolid for utilization instead of sludge for disposal. Under the Clean Water Act of 1972, amended in 1987 by Congress, the U.S. EPA was required to develop regulations for the use and disposal of sewage sludge. The EPA assessed the potential for pollutants in sewage sludge to affect public health and the environment through a number of different routes of exposure. The Agency also assessed the potential risk to human health through contamination of drinking water sources or surface water when sludge is disposed on land. The Final Rules were signed by the EPA Administrator and were published (Federal Register, 1993). These rules state that sewage sludge shall not be applied to land if the concentration of any pollutant in the sludge exceeds the ceiling concentration. In addition, the cumulative loading rate for each pollutant shall not exceed the cumulative pollutant loading rate nor should the concentration of each pollutant in the sludge exceed the monthly average concentration for the pollutant. The annual pollutant loading rate generally applies to applications of sewage sludge on agricultural lands. The most popular beneficial use of sewage sludge is land application. The sludge has to be stabilized for appling to land. One of the stabilization process for sewage sludge is lime stabilization process. The stabilization process is consisted of the stabilizing process and the drying process. Stabilization reactor can be a drum type reactor in which a crossed mixer is equipped. The additive agents are a very reactive mixture of calcium oxide and others. The stabilized sludge is dried in sun drier or rotary kiln.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.2
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• pp.3-13
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• 2016

This study investigated the environmental and economical assessment for sewage sludge treatment options including biogasification, incineration, carbonization, drying, and solidification. Additionally it is also investigated the economical feasibility of the current guidelines (Digestion efficiency for organic waste = 45 %, Moisture content of sludge = 95 and 93 %) and it aimed to suggest the scientific informations for a policy-making. For the economical feasibility the 30 plants with anaerobic digestion treatment and the 17 plants without anaerobic digestion treatment were investigated. The result of the comparison of sewage sludge treatment options showed that anaerobic digestion+incineration was the most economically feasible considering incineration and drying. For smaller treatment capacity, solidification was the most economically feasible considering carbonization and solidification and anaerobic digestion+carbonization was the most economically feasible considering carbonization and solidification.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.53-61
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• 2023

Most of the sewage sludge is organic waste containing a large amount of organic substances decomposable by microorganisms by biological treatment. As for existing sewage sludge treatment methods, reduction and fuel conversion are being carried out using technologies such as drying, incineration, torrefaction, carbonization. However, the disadvantage of high energy consumption has been pointed out as latent heat of 539 kcal/kg is consumed based on drying. Therefore, in this study, we intend to produce solid fuel through hydrothermal carbonization(HTC), which is a thermochemical treatment. To evaluate the value of solid fuel, the characteristics of carbonization and fuel ratio were analyzed. As a result, as the hydrothermal carbonization reaction temperature increased, the lower heating value also increased by about 500 kcal/kg due to the increase in the degree of carbonization. H/C, O/C, ratio showed a decreasing trend from 1.78, 0.46 to 1.57, 0.32. When the ratio of ash to combustible content (fixed carbon + volatile) of dry sludge was 0.25 or more, it was derived that the degree of carbonization and calorific value did not increase even when hydrothermal carbonization was performed.

• Magazine of RCR
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• v.10 no.3
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• pp.33-35
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• 2015