• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.437-442
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• 2001

In an integrated steel mill, zinc (Zn) inputs from raw materials and steel scrap are enriched in the dusts and sludges collected from gas and water cleaning systems. The reuse of these dusts and sludges must be controlled within certain limit to avoid Zn accumulation and related operational problems in blast furnace. An integrated system has been established at China Steel Corporation (CSC) to enhance the internal reuse of Zn-containing dust/sludge while keeping Zn input within control lim it. However. the performance of this system has not been very satisfactory until one and half years ago when a rationalization process was initiated. The essence of this rationalization process, the recent improvements in Zn control and dust and sludge reuse are reported and discussed.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.513-521
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• 2000

Intermittently aerated activated sludge process was applied as a water reuse process of $70m^3/day$ for the upgrade of organic, nitrogen and phosphorus removal efficiency and clarifier performance. After application of the intermittently aeration, removal efficiency of BOD, SS, T-N and T-P were achieved 95%, 90%, 80% and 60%, respectively. Removal efficiencies in intermittently aerated process were considerably increased. comparing to those of continuously aerated activated sludge process. Also sludge rising problem in clarifier was improved. Average concentration of supplied reusing water were BOD 5 mg/L, turbidity 4 NTU and after chlorination, residual chlorine 0.4 mg/L, coliform 0 MPN/100mL. Intermittently aerated activated sludge process could be one of the best alternative process for the retrofit of conventional activated sludge process for the removal of nutrient in water reuse system.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.86-96
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• 1995

Alum recovery has recently gained more attention because many water utilities need to improve their sludge handling and disposal practices. As part of an overall sludge management program recovery can reduce the amount of solids and allow for reuse of the recovered Alum as a coagulant. This study was examined the effectiveness of Alum recovery from the Sludge at the D water treatment plant in Kwangju city. The results were summarized as follows 1. Alum recovery was obtained sufficiently acidification(An optimum condition was pH2-3) With $H_{2}SO_{4}$ to settled sludge. In this case recovered liquid Alum from sludge of 2.1% solids concentration at pH 2.1 was contains Aluminum $1,602mg/{\ell}$(as $Al_{2}O_{3}$ 0.3% ) and other metal of low level. 2. It was an optimum condition to all reuse of recovered Alum as a coagulant that rate of Commercial Alum:Recovered Alum=$14{\mu}{\ell}/{\ell}{\;}:{\;}200{\mu}{\ell}/{\ell}$ In a result of Jar Tests. 3. It was a result of Alum recovery from sludge, the reduction effect of amount of solids was about 57.4%. 4. If all recovered Alum were reused the reduction effect of solid wastes disposal cost and chemical drug's cost was about 22%.

• 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.

• Resources Recycling
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• v.9 no.1
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• pp.36-43
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• 2000

This study was carried out for treatment and reuse of inorganic sludge from Fenton process at B dyeing wastewater treatment plant. The parameters for pilot-scale treatment system were derived from the results of this study. It was found that $COD_{cl}$ of the treated effluent became lower than 100 mg/l approximately on the optimal reaction condition. 2nd sludge which was generated after redissolving sludge was analyzed, and it showed that reduction ratio of ash in 2nd sludge and total dry sludge weight in comparison with current sludge were 85% and 65%. Also Fe salt in sludge was redissolved about 90~95% of initial Fe by weight. It was estimated almost ￦350,000,000 for sludge reuse process. It was estimated saving of about ￦1,300,000 per day (￦420,000,000 per year) in operating cost based on 30,000 $m^3$/d treatment, which these were about ￦430,000 per day in chemical, ￦1,100,000 per day in sludge transportation and ￦200,000 per day in equipment maintenance. Payback period with interest charge for investment cost was estimated about 10.5 months. Also, net present value (NPV) was ￦792,000,000 and internal rat of return (IRR) was about 110%.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.80-85
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• 2022

In wastewater treatment processes huge quantities of sludge are produced continuously each year. This work investigated the reuse of two types of sludge as biosorbents of a toxic dye. The potential of granular and filamentous fungus dried sludge for the elimination of eosin from aqueous solution was studied in batch system. The effect of initial concentration and temperature was examined. Maximum uptake was observed at 100 mg l^-1 and 30 ℃. The maximum removal rate was 92% for the granular sludge and 90% for the filamentous one. Equilibrium was attained after 30 min for the studied dye concentrations. The equilibrium uptake increased with the initial eosin concentration. The Freundlich and Langmuir adsorption models were also investigated. The reuse of disposed sludge as adsorbent could be a solution for the valorization of such dangerous waste to resolve two environmental problems at the same time.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.413-424
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• 2014

The potential of using the biogas as energy source has long been widely recognised and current techniques are being developed to upgrade the technical quality and to enhance energy efficiency. The objective of this paper is to present efficient and effective pre-treatment methods of increasing the amount of produced biogas in anaerobic digestion of activated sludge treatment process. The paper also presents a review of the effect on biogas production between pre-treated and raw sludge, and also put forward the advantages and disadvantages of each pre-treatment method.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1083-1091
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• 2000

The objective of this study is to develop effective and economical treatment processes for the removal of non-biodegradable organics by reusing the sludge generated from Fenton's Oxidation Process. It was found that about 50% of coagulants and 50% of catalyst can be reduced by reusing the sludge generated from Fenton's Oxidation Process. It was also found that the amount of sludge generation can be reduced in coagulation process and Fenton's Oxidation Process. From the results of bench-scale test, it was found that the average removal efficiency increased to 8.5% and the amount of sludge generation was reduced up to 35% by reusing the sludge as coagulant. The average organic removal efficiency increased to 5.3% and the amount of sludge generation was reduced up to 14% by reusing the sludge as catalyst in Fenton's Oxidation. It can be concluded that the reuse of sludge generated from Fenton's Oxidation Process would be reduced cost of chemical consumption and Fenton's sludge treatment.

• Journal of the Korean Applied Science and Technology
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• v.22 no.4
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• pp.379-384
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• 2005

In general, water treatment sludge (WTS) had high concentration of heavy metal, thus it made the reuse or recycling of WTS difficult. The optimal solidification conditions for maximum suppression of heavy metal elution from WTS were decided in this study. Under the optimal solidification conditions (i.e., temperature, $320^{\circ}C;$ ratio of WTS and MgO, 9:1; solidification time, 1hr), all of heavy metal including aluminum were not detected. Therefore there are no problems for reuse or recycling of WTS which was solidified under the optimal solidification conditions found in the study.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.493-496
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• 2005

The Re-mi-con sludge water has been investigated because of environmental pollution and disposal cost. So, sludge water is partially reused as mixing water. However, if sludge water is reused too much that would influence the quality of concrete. KS specification limits the amount of sludge content up to 3$\%$ of cement weight. In this study, the effect of re-mi-con sludge on the characteristics of concrete is compared to raise the reuse ratio of re-mi-con sludge. From the test results, as blending ratio of re-mi-con sludge increases, workability is decreases. However, the re-mi-con sludge water have a minor effect on the strength development, the drying shrinkage and the resistance of freeze and thawing. Also, the existing model codes of drying shrinkage do not coincide with the test results of this study.