• 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.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.47-53
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• 1996

This study was carried out to estimate the amount and the characteristics of sewage sludge disposed of in the Nanjido sludge landfill site. Boring test was conducted to estimated the landfill volume and to get sludge samples to be analyzed. Total analysis and leaching test were performed to find the characteristics of sewage sludge. The Nanjido sludge landfill site had the surface area of $50,000m^2$ and the average depth of 15m. The estimated sludge volume was 600,000ton. Sewage sludge in Nanjido sludge landfill site was very stable. Results of total analysis of heavy metals indicated that the sludge could be classified as a non-hazardous waste according to the California state regulation. The sludge also could be used as compost based on compost quality criteria of foreign countries. Results of Korea Extraction Procedure showed that sewage sludge in Nanjido sludge landfill site was not a hazardous waste.

• KSBB Journal
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• v.16 no.4
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• pp.389-397
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• 2001

The effect of sludge digestion on the leaching efficiency of heavy metals from sludge by bioleaching with Thiobacillus thiooxidans MET was investigated. The used sludges were a non- and anaerobically digested. The leaching efficiency of heavy metals was strongly dependent on the pH of the sludge solution rather than the sludge condition and stolid concentration. The lower the pH the more heavy metal was leached from 3.0 of pH. The sequent orders of leaching heavy metals were Zn, Cu, and Cr. Although the buffering capacity of non-digested sludge was similar to anaerobically digested sludge, the pH decrease rate of the anaerobically digested sludge solution was faster than that of the non-digested sludge solution due to the higher sulfur oxidation rate of T. thiooxidans MET in the anaerobically digested sludge. The amount of leached heavy metals from the anaerobically digested sludge showed higher than that of non-digested sludge at the same pH value. This result might be caused by the difference of the insoluble metal types, which were contained in the sludge. An increase in sludge solids concentration decreased the leaching efficiency of heavy metals in the range of solids concentration 10 g/L to 70 g/L. The optimum ratio of S° to sludge stolid was 0.1 in both the sludge. The bioleaching process of heavy metals with T. thiooxidans MET showed the disinfecting effect over 90% as well as the reduction effect in sludge weight of 20%.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.507-509
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• 2008

유입수 성상이 서로 다른 9개소의 하수처리장에서 발생하는 하수슬러지의 재이용 가능성에 대하여 퇴비 기준 및 부숙토 기준으로 검토하였다. (1) 공장폐수가 유입되는 하수처리장의 탈수케이크에 함유된 Cr, Cu, Pb성분은 퇴비 및 부숙토 기준치를 초과하였다. (2) 중금속의 함량에 관한 기준을 만족하는 탈수케이크는 가연분 함량이 낮으므로 직접적인 재이용은 어려울 것으로 생각된다.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.35-43
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• 2016

COD properties of waste activated sludge (WAS) were investigated for various solubilization rate of mechanical pretreatment method in anaerobic digestion process. Inert COD was 37.0% of total COD in untreated WAS. Particulate biodegradable COD was converted to soluble biodegradables and particulate unbiodegradables as solubilization was processed. Particulate unbiodegradable portion of COD in WAS can be increased as particulate biodegradable portion is decreased in case of relatively long SRT of biological treatment. Thus, COD properties of WAS should be investigated in case of relatively low particulate biodegradable COD, because of possible low effect of solubilization. COD removal rate in anaerobic digester was enhanced as much as 2.1% and 15.1% for solubilization rate 5% and 35% due to pretreatment, respectively. COD removal rate was increased from 25% to 40%, and methane gas generation was increased from $607m^3/d$ to $907m^3/d$ as particulate COD of WAS was solubilized to 35% in pretreatment facilities.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.76-78
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• 2003

• 수도
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• v.23 no.5 s.80
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• pp.46-53
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• 1996

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.93-100
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• 2010

In this study, ways to help anaerobic digestion were studied and waste activated sludge were pretreated by grinding, thawing after freezing and grinding after freezing. The volumes of grinding sludge, thawing after freezing and grinding after freezing were decreased 2.08 times, 3.37 times, 3.54 times compared to the volume of sludge respectively and the larger decline in the sludge has been grinding after freezing, thawing after freezing, and grinding. In addition, when the concentrations of SCOD, SBOD and protein were compared, the concentration of freezing sludge was higher than others and the grinding after freezing method seems to be the highest concentration. When the TS, VS removal rates were compared, thawing after freezing method seems to be higher than others method. From these results, grinding after freezing method is very effective for the pretreatment of sludge and it can be expected grinding after freezing method can be an alternative method for prohibiting ocean dumping of sludge after 2012.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.865-872
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• 2009

Continuous operation of aerobic sludge digestion reactor was attempted for 279 days. Anaerobic digester sludge, the target material of the experiment, was pretreated by sodium hydroxide at $40^{\circ}C$ for 120 minutes, and the pretreated sludge was fed to 5 L CSTR (continuous stirred tank reactor). Reactor performance was affected by properties of input sludge and HRT (hydraulic retention time). 6 days of HRT showed best and stable performance, and under this condition, removal rates of $NH_3$-N, SCOD, TKN, TCOD, SS, and VSS were 97.4%, 81.7%, 68.7%, 61.4%, 50.6%, and 47.0%, respectively. 73.9% of SS in anaerobic digester sludge was reduced by pretreatment and aerobic digestion. Effluent sludge had low soluble COD of 350 mg/L. This implied the sludge was stabilized and suitable for use as liquid fertilizer. Nitrification took place when HRT was higher than 4 days. $NO_3$-N concentration was as high as 658 mg/L while $NH_3$-N was as low as 20 mg/L.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.90-96
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• 2008

In order to meet the stringent requirement of sludge disposal and to find ecological alternative, aerobic digestion coupled with alkaline pretreatment was studied. The treated sludge was tested for the potential of liquid fertilizer. In the aerobic digestion, it was obvious that the performance of digester B(fed with the sludge pretreated by NaOH) was better than that of digester A(fed with raw sludge) in terms of COD and SS removal. SS and VSS removal rates in digester B were 66% and 69%, respectively. At 5 days, TSS removal rate reached 47% in the digester B, which was 71% of final TSS removal rate. It revealed that the pretreatment process can shorten the retention time of aerobic digestion. 94.1% of TCOD in the raw sludge was reduced by alkaline pretreatment and aerobic digestion. Final SCOD was in the range of 220$\sim$230 mg/L implying the sludge was stabilized. Nitrification and pH drop were observed in the aerobic digestion. Final nitrate concentrations in digester A and B were 445.4 and 223.1 mg/L and final pH in digester B was 3.0. Biological assays reported that leaf size of cucumber seedling increased with nitrate concentration and sludge to soil ratio. The sludge treated by alkaline and aerobic digestion promoted the growth of seedling leaf and stem remarkably compared to raw sludge. In contrast, the aerobically digested sludge without pretreatment improved leaf growth and inhibited stem growth.