• Resources Recycling
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• v.28 no.2
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• pp.31-39
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• 2019

The pelletizing of printed circuit board (PCB) sludge was researched for copper recovery in pyrometallurgical process. This pelletizing was carried out by using self-manufactured compression-type apparatus after pre-treatments (drying, water scrubbing, size classification) were proceeded. The physical properties (compression strength and drop-breakage test) were tested with a change of sludge sizing and the number of compression. In the case of using the undersized sludge of #140, its properties were improved to 0.6 MPa and 9.3 times. Moreover, they increased to 0.82 MPa and 19.0 times by using the #140 ~ 325 sludge. These imply that the packing density increases due to the elimination of large-sized sludge (#140), and also the weight of required binder decreases by the removal of fine-sized sludge (#325).

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.236-245
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• 2000

A laboratory scale fluidized bed reactor was developed to treat the combustion characteristics of some fuels (wood, paper sludge, refuse derived fuel). The aims were to introduce the means of experiment and interpretation of the results and finally determine the particle characteristics on the pyrolysis and combustion process of the fuel. A single particle combustion process in the fluidized bed was closely observed. Understanding experimental facility characteristics and determining parameters were also carried out. The fuel combustion processes were observed by carbon conversion rate, recovery and mean carbon conversion time. They were estimated with the CO, $CO_2$ gas concentration monitored at the exit of the combustor. Fuel drying and pyrolysis process were governed by temperature distribution in the fuel particle. There was a significant overlap of the drying and devolatilization. However, transition process from devolatilization to char combustion seemed to be determined by mechanical solidity of the fuel particle after devolatilization process.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.5-13
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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. For the economical feasibility the 30 plants with anaerobic digestion treatment and the 17 plants without anaerobic digestion treatment were investigated. In regarding to the environmental assessment, the air emission pollutants (SOx, NOx, etc) from incineration and carbonization plants were assessed and 1~34 % of emission limits was emitted. Drying and solidification plants emitted about 30 % of odour limits. And the rest of the pollutants were emitted either at not-detectable level or at below the limits. When the by-products from the solidification treatment was used as landfill cover materials, the unconfined compression strength could be below the limit and it could cause an unsafe condition for those passing vehicles and the possibility of the ground subsidence. There has been a maintenance difficulty due to frequent blockage and operational failure. 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.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.703-709
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• 2018

Dielectric heating materials were prepared through the thermal treatment for composites of Li and Zn type precursors that are major materials being responded to microwave under diversified conditions. The prepared heating material samples were analyzed by SEM and it was confirmed that $Li_5Fe_5O_8$ materials being formed on the surface was a major influencing factor for the heating performance. Heating materials improved the moisture removal in a sludge drying facility, for example, the moisture content of 25 v/v% sludge decreased to 15.22 v/v%. Accordingly, heating materials were confirmed to directly affect the performance and efficiency of the microwave drying process.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.77-84
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• 2006

The objective of this research is to evaluate various reclamation methods of sewage sludge cake after treating with microwave under optimum conditions. In this study the sewage sludge cakes used from S and N wastewater treatment plants in the P city. Microwave with an induced electricity heating way was employed for dehydration of sewage sludge cake. Microwave operation conditions is 2,450 MHz of frequency and the power with 1 to 4 kW. This sewage sludge cake had a moisture content of 70%. The moisture content of the sludge decreased notable up to 2%(wt) resulted in breaking of cell wall. When the treated sewage sludge cake mixed with soils could be applied to use midterm and last cover material soils. Moreover, the adsorption ability of heavy metals such as copper, lead, chromium and cadmium was greatly enhanced by treated sewage sludge cake. Within 30 minutes, 1ppm of copper, chromium and cadmium and 10ppm of lead with 1g of the treated sewage sludge cake in $100m{\ell}$ were below detection. It was possible to use the treated sewage sludge cake as an absorbent for absorption of toxic heavy metals. Results from this research indicated that using of microwave radiation was an effective method for treating sewage sludge cake economically and environmental. A point of view of reclamation, the treated sewage sludge cake appeared to be feasible with an adsorption of heavy metals in steady of using expensive yellow earth.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.223-231
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• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.1
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• pp.87-98
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• 1994

Sludge minimization in an water treatment plant can be achieved by optimizing a main water treatment process as well as by enhancing a thickening and a dewatering facilities. In this study, dewatering and drying techniques for reducing the quantity of the water sludge generated from the conventional water treatment plant in the local states were investigated by reducing its water content. Not only the types and dosages of polymers but also the mixing intensity of the mixtures of a concentrated sludge and polymers on the different pH were evaluated for the optimum dewatering conditions of the water sludge. Weight reduction of the water sludge was also tested at a given temperature range. The dewatering efficiency of the water sludge was not affected by the types of polymer but by mixing intensity(GT value) in this study. pH effect on dewaterbility of the water sludge took a major role at the neutral pH range. The optimal polymer dose was 1.5 mg-polymer/g-TSS(about 40mg/L as polymer). Dewaterability was enhanced at a lower mixing intensity(GTbelow 10,000 sec-1). Free water in the void of sludge cake was dried around $100^{\circ}C$, chemical bound water was evaporated around $320^{\circ}C$, and organic material was burned out at the range of 300 to $600^{\circ}C$. Ignition losses of the water sludge were varied 15 to 40 % as the raw water quality. The ignition loss due to the chemical bound water was 10-20% and the loss due to the organic material was 4-20% of the total ignition loss.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.54-61
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• 2006

In order to prevent the environmental pollution, the dryers are commonly used to treat sludge that one of sewages is polluting the quality of water. Generally, the drying method is various as to the property of material and use. Rotary dryer is a good apparatus to treat them. The rotary dryer is the way that is to make substance transmission and heating using hot air between sludge particles and heated gas. In this paper, we performed a numerical analysis of the inner air flow of the ANDRICH type dryer through the changing rotational speed from 3rpm to 10rpm. A PIV can be applied to research a inner flow of ANDRICH type dryer.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.72-78
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• 2002

Among the disposal techniques of inorganic wastewater sludges from industries most of sludges were dealed with buring underground inefficiently. But we have tried to recycle the resources that exhausted inorganic sludges were properly blended to certain ratioes to make lightweight aggregate, that means manufacturing of it can be possible through blending of various components, drying, sintering, cooling and crushing to certain sizes that are needed by consumers. As disposal method of inorganic wastewater sludge is changed to environmentally fraternative method, this method could be very useful to make lightweight aggregates for decoration of building and the other so many purposes of those usages. That could be economically useful due to expected income for buring costs of ordinary disposal method form industries and sales income after manufacturing it. The second important profit is saving foreign currency from purchasing self-developed lightweight aggregate insteas of importing expensive foreign product. This product will be also very impressive to user because of the fraternative lightweight to be composed of apatite structure that is important part of human body.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.34-42
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• 2015

The paper investigates environmental hazards and characteristics of the artificial lightweight aggregate manufactured by using dyestuff sludge from dyeing industrial complex. The dyestuff sludge used in this study is chemically treated with Ti and Fe salt for the purpose of recycling. The artificial lightweight aggregate is manufactured through 3 step; 1) Selecting the optimum moisture content by evaluating plasticity from the mixing ratio of the clay and sludge, 2) shaping round type based on the optimum mixing ratio, 3) drying and Sintering process. Based on KS F 2534 "Lightweight Aggregate for Structural concrete", the particle size, fineness modulus, the density, absorption, unit volume weight, stability and environmental hazards of the manufactured lightweight aggregate are evaluated. Experimental results show that the particle size and fineness modulus is out of the range. However, it is observed that other physical properties are within criteria. In addition, it is confirmed that the problem of the particle size and fineness modulus could be solved in the manufacturing process.