• Analytical Science and Technology
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• v.13 no.3
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• pp.357-367
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• 2000

The polycyclic aromatic hydrocarbon (PAH) content in sewage sludge and in farm soils were determined by gas chromatography linked to mass spectrometry (GC/MS) with use 2-ethylantracene as internal standards. Twelve PAH were identified in both sludges with naphthalene ($0.78{\mu}g/g$) being the most predominant in industrial sludge and pyrene ($0.26{\mu}g/g$) in municipal sludge. The total PAR content in industrial sludge and in municipal sludge were $1.74{\mu}g/g$ and $1.19{\mu}g/g$ respectively. PAH were contained in paddy soils and the concentration were very low in the range of $0.01-0.04{\mu}g/g$. The total PAH content in industrial and in municipal sludge were about 9.2 times and 6.3 times greater than in paddy soils ($0.19{\mu}g/g$).

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.170-173
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• 1998

This study was conducted to investigate the effect of municipal sludge application on the change of physico-chemical properties and contents of heavy metals in soils. The application of the sludge resulted in increasing the content of total nitrogen, available phosphate,exchangeable K, Ca, Mg, and the soil porosity and permeability but soil hardness was reduce. It is clear that application of municipal sewage sludge would not due to increase in the heavy metals content in soil because of the lower concentration of heavy metal in the sludge. Totally it is evident that municipal sewage sludge application should play an important role in improving soil physico-chemical properties.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.271-282
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• 2020

Sewage treatment plants are social infrastructure of cities. The sewage distribution rate in Korea is reaching 94% based on the sewage statistics based in the year of 2017. In Korean sewage treatment plants, use of PAC (Poly Aluminum Chloride) accounts for 58%. It contains a large amount of impurities (heavy metal) according to the quality standards, however, there have been insufficient efforts to reinforce the standards or technically improve the quality, which resulted in secondary pollution problems from injecting excessive coagulant. Also, the increase in the use of chemicals is leading to the increases in the annual amount of sewage sludge generated in 2017 and the need to reuse sludge. As such, this study aims to verify the possibility of reusing sludge by evaluating the stability of heavy metals based on the injection of coagulant mixture during water treatment which uses the torrefield wood powder and natural materials, and evaluating the sedimentation and heating value of sewage sludge. As a result of analyzing heavy metals (Cr, Fe, Zn, Cu, Cd, As, Pb, and Ni) from the coagulant mixture and PAC (10%), Cr, Cd, Pb, Ni, and Hg were not detected. As for Zn, while its concentration notified in the quality standards for drinking water is 3 mg/L, only a small amount of 0.007 mg/L was detected in the coagulant mixture. Maximum amounts of over double amounts of Fe, Cu, and As were found with PAC (10%) compared to the coagulant mixture. Also, an analysis of sludge sedimentation found that the coagulant mixture showed a better performance of up to double the speed of the conventional coagulant, PAC (10%). The dry-basis lower heating value of sewage sludge produced by injecting the coagulant mixture was 3,378 kcal/kg, while that of sewage sludge generated due to PAC (10%) was 3,171 kcal/kg; although both coagulants met the requirements to be used as auxiliary fuel at thermal power plants, the coagulant mixture developed in this study could secure heating values 200 kal/kg higher than the counterpart. Therefore, utilization of the coagulant mixture for water treatment rather than PAC (10%) is expected to be more environmentally stable and effective, as it helps generating sludge with better stability against heavy metals, having a faster sludge sedimentation, and higher heating value.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.768-774
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• 2008

To evaluate the effect of the solidified/stabilized sewage sludge on landfill sites, lysimeter tests were conducted. Lysimeters (LR1, LR2, and LR3) were filled with the material(Compost : Fodder : Sand = 10 : 10 : 80) and covered with different types of the cover soils, the G solidified sludge produced from the neutral solidifying chemical agent(LR1), the A solidified sludge produced from the alkali solidifying chemical agent(LR2), and the weathered granite soil(LR3). Those lysimeters were kept at the temperature controlled room with 30 $\pm$ 2$^{\circ}C$ for about 450 days. As the results, it was appeared LR2 > LR1 > LR3 that total gas production rate(L), gas production rate(L/VS(kg)) and cumulative gas(CO$_2$ + CH$_4$) production. There were not significant differences at decrease of the COD$_{Cr}$ in the leachate from LR1 and LR3. Thus, it had been shown that the use of the G solidified sludge as cover soil did not affect the COD$_{Cr}$ in the leachate. The COD$_{Cr}$ from LR2 had been increased since around 250 days because solidified/stabilized sewage sludge became re-slurry. T-N and T-P from LR3 also were higher than LR1 and LR2. Also were, the use of the solidified/stabilized sewage sludge as a cover soil, therefore, did not affect the T-N and T-Pconcentrations in the leachate.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.2
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• pp.84-96
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• 1995

The dewatering characteristics of the sewage sludge was investigated through the experimental observations and model simulations. The activated sludge and the anaerobically digested sludge were examined for the dewaterability evaluation within the pressure range of $0{\sim}10^6N/m^2$. Modified Buchner funnel test and compression test by the consolidometer were conducted to evaluate average specific resistance, porosity, and moisture percentage of filter cake. Shirato's technique of compression-permeability test was followed for the pressure range lower than about $10^2N/m^2$. The flocculation effects on sludge dewatering was also examined for ferric chloride and polymeric flocculant. The application of hydrated lime which can be used for flue-gas desulfurization showed improved moisture percentage, and was thought to have positive feasibility in combined system of sludge dewatering and incineration. Determined characteristic constants were applied to Tiller's cake filtration model to simulate liquid pressure distribution and porosity distribution in cake. Model simulations showed a sharp drop of the porosity close to the cake-medium interface for the highly compressible material such as the activated sludge and the anaerobically digested sludge.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.59-65
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• 2004

The change of the microbial community structure in excess sludge of different sewage treatment plants by ozone treatment was investigated by quinone profiles. The resulting ozone dosage ranged from 0.1 to $0.4gO_3/gTS$. In terms of overall sludge reduction, more than 50% reduction of the total sludge mass could be achieved by ozone treatment at $0.4gO_3/gTS$. Quinone concentration and type in sludge of different treatment plants were remarkably decreases with increasing ozone dose. Ubiquinones(UQs)-8, -10 and MK-8 were still remained in the ozonized sludge at $0.4gO_3/gTS$. The results of this study showed that the remaining microorganisms belong to UQs-8, -10 and MK-8 were difficult to destruct cell membrane or wall by ozonation. Fecal Streptococci and Salmonella were not detected at ozone dose of $0.2gO_3/gTS$, but Fecal Coliform was not detected at ozone dose of $0.4gO_3/gTS$.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.81-87
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• 2008

We have investigated the efficacy and efficiency of the used briquets for the sewage treatment in this study. The effluent of wastewater treated by Used Briquets Process (UBP) showed very low values of $BOD_5$, CODcr, and SS (1.1 mg/L, 9.5 mg/L, and 3.8mg/L, respectively), which corresponded to 99%, 92.7%, and 96.3% of removal efficiency to the raw wastewater. The number of total bacteria and E. coli in the effluent water treated by UBP was found to be 9 and 1.2 cfu/ml, respectively, showing the remarkable decrease in number, when compared to that of other sewage treatment plants. In the long period of experiment over 1 year, UBP has also shown the high removal efficiency with less sludge production, and low seasonal fluctuation of the values. This UBP is very environmentally-friendly process in the aspects of recycling used briquets and reducing the sludge production. We think that this process will be useful for both the small-scale sewage treatment and reuse of the effluent water.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.509-514
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• 1999

The sewage sludges and livestock manures, respectively, were composted with sawdust used for control moisture in the static piles system composter. The variations of temperature, pH, moisture, C/N ratio, inorganic content, forms of organic materials and nitrogen, and contents of heavy metals were investigated. The results were summarized as follows ; The temperature for composting the sewage sludges reached the highest temperature of 52$^{\circ}C$, after 3 days and lasted for 7 days, and then went down 3$0^{\circ}C$ after 52 days. In the case of composting livestock manures, the temperature reached to 63$^{\circ}C$ after 10 days, that lasted for 10 days, and then went down gradually. After upsetting the sewage sludges and livestock manures for composting were decreased to 30% and 36%, respectively. The contents of inorganic matters and heavy metals were changed by the characteristics of raw materials but increased gradually during composting process. The total contents of organic materials in the sewage sludges and livestock manures for composting were decreased to 7% and 9%, respectively. The contents of ether extracts, resins, hemicellulose and cellulose were decreased but those of water soluble polysaccharides and lignins were not changed. The total contents of nitrogen in sewage sludges and livestock manures were decreased to 43% and 34%, respectively.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.275-280
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• 2004

This study was performed to investigate the disinfection efficiency and the formation characteristics of disinfection by-products(DBPs) by chlorination in the sewage effluent. The effluent was sampled from the sewage treatment plants operated in the activated sludge process and the advanced sewage process. The type of DBPs investigated were Trihalomethanes(THMs), Dichloroacetonitrile(DCAN), Chloral hydrate(CH), Dichloroacetic acid(DCAA), Trichloroacetic acid(TCAA). Major findings are as follows. First, the optimum injection concentration for chlorination in sewage effluent were found to be in the range $0.5{\sim}1.0mg\;cl_2/L$. Also, It was found that the chlorine dosage in the effluent of activated sludge process was higher than in the effluent of advanced sewage process. Second, the maximum formation concentration of THMs were $12.7{\mu}g/L$. The THMs formation reaction was finished in a short time of several seconds and chloroform was mainly formed. Also, it was found that the concentration of ammonium nitrogen is higher, the concentration of THMs is lower. Third, it was found that DCAA and TCAA were mainly formed as DBPs by disinfection.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.3
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• pp.42-50
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• 2003

Pyrolysis of maize is experimentally investigated in bench-scale rotary kiln in semi-continuous operation. The operational parameters varied are the temperature($450{\sim}800^{\circ}C$), the solids residence time(7~20 min). Important parameters studied include the running time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas production components was observed. The gas of $C_1{\sim}C_3$ yield increased and oil of $C4{\sim}C6$ yield decreased along with pyrolysis temperature of $670^{\circ}C$ by the run time of 9 min. The results showed the expected strong influence of pyrolysis temperature and a noticeable influence of running time.