• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1347-1351
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• 2006

It was tried to utilize organic waste sludge from wastewater treatment plant as a starting material to produce a solid fuel by vacuum flying. The effects of decompression levels, frying time and temperature on the calorific value and moisture of vacuum fried sludge were systematically investigated. Dewatered raw sludge used in this study had a moisture of 81.1% and calorific value of 2,930 kcal/kg. Based on the experimental observation, it was identified that the decompression level and frying time have the greatest influence on the calorific value of vacuum fried sludge. Moistures of the fried sludge at $180^{\circ}C$ for 25 min in 760 mmHg, 684 mmHg and 630 mmHg were 32.4%, 14.2% and 11.6%, respectively. Calorific values of the vacuum fried sludge at $140^{\circ}C$ for 15 min and 25 min were 5,400 kcal/kg and 5,540 kcal/kg in 684 mmHg and 5,520 kcal/kg and 5,660 kcal/kg in 630 mmHg, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.694-702
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• 2013

The purpose of this study is to evaluate a de-watering filtrate treatment and the possibility of securing biological treatment capacity by changing the structure of the secondary clarifier. Accordingly, the column test was conducted to determine the effect of polymer in the de-watering filtrate on sludge sedimentation. Also, the characteristics of de-watering filtrate processing was evaluated through batch test and continuous processing operation. The results showed that sludge settling velocity increased with higher polymer concentration, and that effluent SS concentration was found to decrease. Regarding processing characteristics of de-watering filtrate, the removal efficiency of TSS and TBOD5 increased as the length of secondary clarifier was longer. Also, comparing injections into anoxic tank and secondary clarifier, de-watering filtrate by continuous infusion treatment process showed stability in both conditions. Therefore, by modifying the structure of secondary clarifier, efficient processing of de-watering filtrate is expected to be possible and processing capacity of small sewage treatment plants is considered to be improved.

• 수도
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• v.24 no.1 s.82
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• pp.36-40
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• 1997

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.53-59
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• 2014

In this study, the sewage sludge dryer is installed before and after dehydration of the sludge and aqueous phase composition, the heavy metal content, and measurement and analysis were investigated. The removal efficiency of water content of sewage sludge was about 95.7% in the sewage sludge dryer. The removal efficiency of water content for primary dryer was designed for 35% of primary drying, secondary drying to remove the water content to 10%, but as the measurement revealed that 20.8% of primary drying, the second dryer 3.3% a better effect to the actual operation respectively. Before the installation of the sewage sludge dryer, the content of heavy metal was as follows, Cu:352~614 ppm, Hg: 1.3~1.44ppm, Cd : 1.1~1.86ppm, Pb : 17.25~ 28.93 ppm, As : 1ppm. And after the installation of the sewage sludge dryer, the content of heavy metal changed to as follows, Cu : 340~350 ppm, Hg : 0 ppm, Cd : 0~0.021 ppm, Pb : 0 ppm, As : 0~0.043 ppm which is Also below the legal limits. Also, the sewage sludge dryer produce 1/4 of the sewage sludge into dried sludge.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.89-96
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• 2018

This study aimed to investigate the feasibility of improving dewaterability and settleability of sewage sludge using coagulation sludge. When mixed with sewage sludge and coagulation sludge at 1:1 ratio, capillary suction time(CST) and specific resistance to filtration(SRF) decreased by about 56% and 68%, respectively. It is found that total solids(TS) and volatile solids(VS) of mixing sludge are increased by about 59% and 53%, respectively. Also, the turbidity of the mixing sludge supernatant was reduced from 99 to 16 NTU. It is observed that the mixing of sewage sludge and coagulation sludge at 1:1 showed better effect than using poly-aluminum chloride(PAC) coagulant at 25 mg/L.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.251-253
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• 2002

• 수도
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• v.24 no.2 s.83
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• pp.28-38
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• 1997

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.407-414
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• 2013

Full scale livestock wastewater treatment plant (100 t/d) was constructed and operated to develop compact and cost effective treatment process for public plant as well as individual farm. Liquid form of livestock wastewater after belt press filter was treated through MBR/NF/RO. NF/RO brine water was mixed with livestock wastewater sludge and treated using denitrification, coagulation and air flotation process. Mixed effluent of NF/RO and air flotation meet public livestock wastewater treatment standard, BOD, T-N and T-P, 30 mg/L, 60 mg/L, 8 mg/L below, respectively. Condensed sludge of air flotation returned belt press filter. Dewatered cake contained 90% water and could be used fertilizer after mixing sawdust.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.84-89
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• 2003

The purpose of this study was to evaluate and improve the pre-treatment facility for foodwaste and sewage sludge mixture treatment. The process of foodwaste pre-treatment consists of storage, classification with crushing, and thickening. The effluent of sewage treatment facility was used as the diluting and washing water. The panicle size of foodwaste after pre-treatment was almost under 2mm, the mixture of foodwastes and sewage sludge showed an advantage to the anaerobic digestion. The amount of gas production increased from 0.8ton/day ($CH_4$ : 0.5ton/day) to 3.5ton/day ($CH_4$ : 2.3ton/day) after the anaerobic digestion of the foodwastes and sewage sludge mixture. The amount of sludge cake increased from 11.2ton/day to 21.2ton/day. Therefore, the proper operation of the foodwaste pre-treatment facility was contributed to the efficient anaerobic digestion of foodwaste and sewage sludge mixture treatment.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.179-186
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• 2006

Chemical wastes are generated from nuclear facilities and R&D laboratories, but the uranium concentration in the final dried cake is evaluated into 11.2 Bq/g, which exceeds the exemption level of 10 Bq/g for each U isotopes, so the cake is categorized into a radioactive waste. Acid dissolution was applied to extract uranium from the waste sludge, and uranium adsorption on the dissolved solution was experimented by using IRN-77 and Diphosil bead. A large amount of resin was required to get above 80% of uranium removal, which was found to be due to a large amount of metal ions simultaneously dissolved from the precipitates with uranium. As an alternative method, acid dissolution is applied to the dewatered wet cake of the sludge, and the natural evaporation method is adopted for the dissolved solution. The uranium concentration of the dissolved solution was estimated to be 6.97E-01 Bq/ml, and the specific activity of the final waste sheets is evaluated to be 4.3 Bq/g. These results lead to the suggestion that the application of acid dissolution to the wet cake and the natural evaporation for the dissolved solution is an effective treatment method for chemical wastes containing uranium.