• 환경위생공학
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• 제24권3호
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• pp.28-36
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• 2009

We have closely examined the concentration change characteristics, emission amounts, and the material balance of hazardous air pollutants at both early and later stages of the prevention facilities. These results will be uses as the basic data when preparing for the regulatory and management plans for hazardous air pollutants. The results of the study on heavy metals illustrated that the content of heavy metals in sludge across five facilities were as follows: copper> zinc> chrome> nickel> cadmium> mercury. In terms of heavy metal content in swage sludge, the sludge in incinerating facilities other than the sludge in the D incinerating facility containing industrial water waste, was examined in order to satisfy the ocean contamination standard and fertilizer specifications. Most of the items were shown to have satisfied the emission tolerance standards in the latter part of the prevention facilities(The average elimination rate was over 90%). Therefore, it is concluded that swage sludge containing high-concentrate heavy metals needs to be incinerated rather than recycled as fertilizer.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.73-77
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• 2003

Red mud is a waste material formed during the production of alumina when the bauxite ore is subjected to caustic leaching. It is a brick-red colored highly alkaline (pH 10-12) sludge containing mostly oxides of iron, aluminum, titanium, and silica. Red mud, due to its high aluminum, iron, and calcium contents, has been suggested as a cheap adsorbent for removal of toxic metals (e.g., As, Cr, Pb, Cd) as well as for water or wastewater treatment. The basic advantage of red mud is its versatility in application. This study was conducted to evaluate the effect of red mud on stabilization and fixation of heavy metals (such as Pb, Cu, C $r^{6+}$, Cd, Zn) contained in the Al-coating sludge and soil. The results showed that the concentration of heavy metals leached from the treated sludge and soil was low, meeting the regulatory permit level.

• 대한환경공학회지
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• 제29권3호
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• pp.283-288
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• 2007

연속회분식반응조(SBR) 공정에서 슬러지 체류시간(SRT)에 따른 중금속의 독성도 변화를 측정하였다. 중금속은 구리(Cu), 카드뮴(Cd) 및 아연(Zn)을 사용하였고, SRT는 $2\sim30$일로 변화시켰으며, 독성도는 INT-dehydrogenase 활성도의 변화로 측정하였다. 중금속의 농도가 증가함에 따라 독성도가 증가하였으며, Cu가 Zn 및 Cd 보다 독성도가 높았다. SRT를 변화시켰을 때 $IC_{50}$ 값이 Cu의 경우 $0.37\sim1.96$ mg/L의 범위를 나타내었으며, Cd의 경우는 $15.4\sim16.9$ mg/L를 나타내었다. 또한 Zn의 경우는 $9.70\sim23.4$ mg/L의 범위를 나타내었다. Cu와 Zn의 경우, SRT가 증가함에 따라 독성이 감소하였으며, 이는 긴 SRT에서 세포외 중합체의 농도가 증가하기 때문인 것으로 판단된다. 따라서 중금속을 포함한 산업폐수를 처리하는 SBR 공정에서 SRT를 길게 운영하는 것이 바람직할 것으로 판단된다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1998년도 가을 학술발표회 프로그램
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• pp.2-4
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• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• 자원리싸이클링
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• 제13권5호
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• pp.3-16
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• 2004

2002년도 지정폐기물 중 오니의 발생량은 190천통으로 이 중에 중금속 함유 오니(주로 도금폐수처리오니)가 포함되어 있고, 대부분 매립 처리하고 있다. 즉 매년 190천톤의 중금속 오니가 토양과 지하수를 오염시키지 않을까 우려스럽다. 본고에서는 먼저 폐수 및 오니처리에 관련되는 법규를 정리하고, 다음에는 1차적으로 중금속 함유오니의 발생과 처리현황을 조사 검토하였다. 또한 필자 주위의 연구자 중에서, 이와 관련되어서 행한 대형 연구를 간략하게 소개하였다. 이러한 조사내용이 우리나라 중금속 함유 폐수 및 오니의 발생과 처리실태를 파악하고, 리싸이클링과 같이 더욱 앞선 처리대핵을 강구하는데 도움이 되었으면 한다.

• 한국환경보건학회지
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• 제19권2호
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• pp.46-54
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• 1993

This study was carried out on the stabilized/solidified treatment for the reducing leachability of hazardous heavy metals copper, lead, chromium and cadmium in the hazardous sludge which treated to be unleached heavy metals by sodium diethyl dithiocarbamate. Cement matrix was analyzed for the leachability of 24 hrs and dynamic leaching test, structure and the optimum condition for the stabilization and solidification of the hazardous sludge. In 28 days of curing time the unconfined compressive strength was 21.5 kg/cm$^2$ at the ratio of portland cement (0.5)+fly ash (0.25) and 23.5 kg/cmz at the ratio of portland cement (0.5)+fly ash (0.25) + cake (0.25). High concentration of Pb, Cr and Cd in the sea water and Cu in the distilled water were leached at the dynamic leaching test. The concentration of leaching heavy metals for specimens which were tested 24 hrs were found low leachability with decreasing pH of leachant. According to dynamic leaching test, the low level of copper, lead, cadmium and chromium were leached in the cement matrix with sodium diethyl dithiocarbamate. But the effective diffusion coefficient of unleached cement matrix which was treated sodium diethyl dithiocarbamate was decreased above 2 times than that of cement matrix. The relation of leachant renewal period (Y) and cumulative fraction ion leached (X) was the following regression equations. Solidification with unleached agent. Y$_{Cu}$ = 1413752X + 247, Y$_{Pb}$ = 223501IX + 214, Y$_{Cr}$ = 8310601X - 472, Y$_{Cd}$ = 168787X + 1061 The structure of' solidified matrix with X-ray diffraction analysis was composed more Ca(OH)$_2$, Si, Mg(OH)$_2$ and Al in the unleached cement matrix than those in cement matrix.

• 산업기술연구
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• 제16권
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• pp.169-174
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• 1996

Microstructural analyses of synthetic arsenic-containing heavy metal sludges solidified with Portland cement were performed. Heavy metal sludges containing 0.04M of cadmium, chromium, copper, lead, and arsenic were prepared by sodium hydroxide precipitation and successive vacuum filtration. The sludges mixed with cement were cured for 14 days. The solidified sample was characterized by 1) leaching test, 2) scanning electron microscopy and 3) X-ray diffractometry. Of the metals tested, only Pb concentration in the leachate exceeded the Korean regulatory limit. The level of lead in the leachate was as high as 10 times the regulatory limit. X-ray analysis suggested that the metal hydroxides might be present in complex or impure crystalline phases.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.448-452
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• 2001

An Experimental study was carried out to develop a simple method of processing copper waste sludge which is produced by PBC manufacturing. The procedure is based on leaching of wet sludge in 2N H$_2$SO$_4$, and the solid / liquid ratio is controlled approximately at 1/10. The recovery of copper is 85.4%, and pH of the leachate is 3.20. Adding ammonia solution into leachate forms ammine, and hydroxide compounds derived from other impurities in leachate at pH 10. The hydroxide compound can be treated by ferrite process, and the product is a stable oxide compound. Then the ammine solution is heated to evaporate ammonia, and the copper hydroxide is formed. Heating at 8$0^{\circ}C$by aeration, copper hydroxide is transformed into copper oxide with a purity of 98.4%. This process can recover most copper from sludge and the residue can be stabilized by the formation of a stable oxide compound which is not hazardous to environment.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.186-198
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• 2022

Heavy metals recovery from Printed Circuit Boards industrial wastewater is crucial because of its cost effectiveness and environmental friendliness. In this study, a copper recovery route combining the sequential processes of acid leaching and LIX 984N extracting with an electrowinning technique from Printed Circuit Boards production's sludge was performed. The used residual sludge was originated from Hanoi Urban Environment One Member Limited Company (URENCO). The extracted solution from the printed circuit boards waste sludge containing a high copper concentration of 19.2 g/L and a small amount of iron (0.575 ppm) was used as electrolyte for the subsequent electrolysis process. By using a simulation model for multi-step current electrolysis, the reasonable current densities for an electrolysis time interval of 30 minutes were determined, to optimize the specific consumption energy for the copper recovery. The mathematical simulation model was built to calculate the important parameters of this process.

• 아시안잔디학회지
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• 제6권1호
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• pp.11-22
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• 1992

To determine the use of waste materials as root zone soil mixtures for turfgrass culture, the effects of paper mill sludge and briquet ash on physical and chemical properties of soil and growth of turfgrasses were examined. Three turfgrass species of zoysiagrass(Zoysia japonicaSteud.). kentycky bluegrass(Poa pratensis L. 'Ram I') and creeping bentgrass(Agrostis panistris Huds 'Persucross') were cultured in 32cm diameter plastic pots containing various soil mixtures. The basic ingredients used for mixtures included sand(SD), field soil(SL), paper mill sludge(PS), sphagnum peat moss(PM) and briquet ash(BA). Seven combinations using these ingreients were mixed in different percentage by volume as follows: SD+SL+PM(80:10.10), SH+SL+PS(80:10:10), SD-PM(80:20), SD+PS (80:20), SD+BA(80:20), SD+BA+PM(60:20:20) and SD+BA+PS(60:20:20). 1. Paper mill sludge showed pH of 6.6, more than 30% of organic matter content, and higher concentrations of total N, P, k, Ca, Mg and CEC. Bulk density, fild moisture capacity and electrical conductivity of soil mixtures were increased by the comimation of 10~20% PS by volume. 2. Briquet ash showed pH of 8.0, and higher levels of P, k, Ca and Mg than those of field soiks. Bulk density, field moisture capacity and hardenss of soil mixtures were increased but vertical water flow rate and electrical conductivity were decreased by the combination of 20% BA by volume. 3. Phytotoxic effects of PS and BA on growth of turfgrasses were not found. Shoot growth of all three species was higher in soil combination of SD+BA+PS than that of SD+SL+PM added with fertilizer. However, root growth was better in soil mixtures combined with PM. Soil mixtureomposed of 60% SD, 20% BA and 20% PS by volume was most effective on growth of all three species. 4. Paper mill sludge resulted in higher N level in the leaf tissue. The contents of heavy metals such as Cd and Ph did not vary significantly among soil mixtures and species. However, the Mn level was 2~3 times higher in plants growh in mixtures containing PM compared with others, and especially it was higher in creeping bentgrass than other species.