• The Journal of the Korea Contents Association
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• v.9 no.10
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• pp.444-450
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• 2009

We have investigated biosorption kinetics and equilibrium of $Pb^2+$ and $Cr^2+$ using waste sludge, and separation efficiency of waste sludge by dissolved air flotation was evaluated in the various A/S ratio. The biosorption capacity and contact time were shown as a simulation of biosorption equilibrium and kinetics models. Biosorption equilibrium of the $Pb^2+$ and $Cr^2+$ onto the waste sludge could be fitted by the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan equation. The kinetics could be fitted by a pseudo-second-order rate equation more than a pseudo-first-order rate equation. The separation efficiency of waste sludge using DAF was kept above 90%.

• Clean Technology
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• v.15 no.1
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• pp.31-37
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• 2009

This study deals with the production process of activated carbons from the sewage sludge char by chemical activation reaction. KOH and NaOH were used as activating agents, which react well with carbon. From the experiments, it was found that activated carbons made with KOH treatment had better physicochemical properties in terms of iodine number and BET value than those made with NaOH treatment. It was also found that the optimal deposition ratio of an activating agent to the sewage sludge char was 75 wt% of KOH and 50 wt% of NaOH. Activated carbons were washed out by distilled water after neutralization with 5 M hydrochloric acid solution. The activated carbons that were produced from a sewage sludge char at this optimal conditions have BET surface areas of approximately $600m^2/g$.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.775-780
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• 2009

The efficacy of nitrifying sludge existed in biological nutrient removal process was examined for possible removal of endocrine disrupting chemical(EDC) in the effluent of wastewater treatment plant. Some of ammonia oxidizing bacteria causes ammonia oxidation mediated by ammonia monooxygenase(AMO) activity, which has low substrate specificity resulting in cometablic degradation of several chemicals. In this study, the removal of three model EDCs such as bisphenol A(BPA), nonylphenol(NP) and dibutyl phthalate(DBP) was studied in batch cultures using nitrifying sludge, BOD-oxidizing sludge with low nitrifying activity, and sterilized sludge. Nitrifying sludge showed higher initial removal rates in all batches of three EDCs when it was fed with ammonium as an energy source. The acclimation time was required for the removal of EDCs in batches using BOD-oxidizing sludge or nitritefed nitrifying sludge. That retardation seemed to attribute to the slow growth of cells using the EDCs while ammonium-fed nitrifying sludge could degrade EDCs through simultaneous cooxidation with ammonia oxidation. Sterilized sludge was also tested under the same conditions in order to find the contribution of physical adsorption to the removal of EDCs. About 10~20% of initial EDCs dose was removed when using sterilized sludge. Thus the biological activity is likely to play major role for the degradation of BPA, NP, and DBP rather than the physical adsorption from wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.323-329
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• 2000

The coupling of an activated sludge reactor with a membrane unit, i.e., Membrane Coupled Activated Sludge (MCAS) system offers several advantages over conventional process. But the major hurdle in the extensive use of this process is the continuous reduction of permeation flux caused by membrane fouling. The aim of this study is to investigate membrane fouling characteristics in the MCAS process. During crossflow ultrafiltration(CFUF) of activated sludge, floc size decreased abruptly at the beginning of operation and thereafter decreased continuously and gradually. The floc size changed from 100~200 to $6{\sim}8{\mu}m$ depending on recirculation velocity. This floc breakage played a key role in rapid increase of $R_c$(cake layer resistance), which led to flux decline. The floc breakage stimulated biomass to release EPS(Extracellular Polymeric Substance) which has been known to be one of the major membrane foul-ants. The amounts of EPS before and after CFUF were 266 and 405(VS mg/MLSS g), respectively. The rise up of EPS concentration was another factor affecting flux decline in MCAS system.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.362-367
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• 2006

Waste activated sludge(WAS) collected from domestic wastewater treatment plant is biomass that contains large quantities of organic matter. However, relevant literature show that the bio-hydrogen yield using WAS was too low. In this study, the effect of pretreatment of WAS on hydrogen yield was investigated. Pretreatment includes acid and alkali treatments, grinding, heating, ozone and ultrasound methods. After pretreatment organic matters of WAS were solubilized and soluble chemical oxygen demand(SCOD) was increased by 14.6 times. Batch experiments were conducted to investigate the effects of pre-treatment methods and buffer solution, hydrogen partial pressure, and sodium ion on hydrogen production from WAS by using heated anaerobic mixed cultures. Experimental results showed that addition of buffer solution, efficient pre-treatment method with alkali solution, and gas sparging condition markedly increased the hydrogen yield to 0.52 mmol $H_2/g$-DS.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.153-160
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• 1992

To investigate the potential of paper mill sludge and briquet ash as cultural media in turfgrass, zoysiagrass was grown in the mixtures prepared with paper mill sludge and briquet ash. The mixtures were consisted of sludge and briquet ash in the ratio by volume 3:1, 2:1, 1:1, 1:2, and 1:3 in the order. To compare the growth responses, some plants were grown in the medium containing sand(3), field soil(1) and peatmoss (1) by volume anti regarded as control. 1. Activated sludge mixed with sand increased plant height, fresh weight, and dry weight more than 1.5-2.0 times compared to those of the control. The highest plant growth was shown in mixtures containing 67% activated sludge. 2. Plant density per $100cm^2$ and chlorophyll content were higher in all mixtures containing activated sludge than control. 3. The growth of zoysiagrass was reduced along with the increase of non-activated sludge ratio, but no difference was found in chlorophyll content. 4. Plant height, fresh weight and dry weight were greater in activated sludge combined with sand compared to the briquet ash mixtures, but the difference of shoot density between two mixtures was not shown. 5. Even though non-activated sludge appeared not to be appropriate to the growth of seedlings, the number of tillers of plant propagated with rhizome was more increased compared to control when briquet ash content was less than 75%.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.96-102
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• 2009

The effect of ultrasonic and alkaline pre-treatments on waste activated sludge (WAS) disintegration was investigated for improved anaerobic digestion. As WAS was treated by either methods, longer capillary suction time (CST) was required due to the break-up of cell walls, and its supernatant demonstrated increase in soluble chemical oxygen demand (SCOD), protein content and turbidity. Ultrasonic process combined with alkaline pre-treatment demonstrated higher SCOD and protein content in the supernatant as compared with ultrasonic pre-treatment only. However, the degree of disintegration (DDCOD) of WAS decreased with increasing solid concentration as both WAS disintegration methods employed simultaneously.

• Clean Technology
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• v.15 no.4
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• pp.265-272
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• 2009

In this study the experiments on the static adsorption of benzene were carried out using activated carbon made from sewage sludge. The experiment was performed at 303.15 K, 318.15 K and 333.15 K under the pressure up to 7.999kPa. Isothermal adsorption curves were obtained using Langmuir isotherm, Freundlich isotherm and Toth isotherm for comparison. Based on fitting the adsorption quantity of Benzene (q), the isothermal adsorption curves obtained from Langmuir isotherm and Toth isotherm showed the higher accuracy. Although there was little difference in accuracy between result from Langmuir isotherm and that from Toth isotherm, the adsorption quantity of Benzene (q) was expressed in terms of Langmuir isotherm because less parameters were required for Langmuir isotherm than for Toth isotherm. Moreover SEM images of the activated carbon from sewage sludge and the commercial activated carbon were taken to observe the pore size development. The results showed that the perforation development of the commercial activated carbon (DARCO A.C., SPG-100 A.C.) was better than that of activated carbon from sewage sludge. Adsorption quantity of benzene on commercial activated carbon was confirmed to be higher than that on activated carbon from sewage sludge. However the maximum adsorption quantity of benzene on activated carbon from sewage sludge was close to that on SGP-100 A.C. at 303.15K. Therefore, we may conclude that it is feasible to commercialize the process to manufacturing activated carbon from sewage sludge.

• Environmental engineer
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• v.21 s.210
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• pp.68-71
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• 2004

[ $\circ$ ] 본 기술은 기존의 A2O공법과 Sludge Blanket Filtration(SBF)을 단위공법으로 조합한 공정으로서 각 생물반응조의 미생물 농도를 6,000mg/ 이상의 고농도로 운전하여 생물학적 유기물,질소 및 인 제거효율을 극대화하고자 하는 기술 $\circ$ 또한 활성슬러지 반응조로부터 유입된 슬러지를 SBF에서 미세기포를 이용하여 부상시킴으로써 수면에 농축 슬러지층을 형성시키고 이 부

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.304-310
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• 2007

The purpose of this research was to investigate the effects of the co-treatment of municipal wastewater with microwave-irradiated excess sludge on the treatment efficiency and excess sludge production of the activated sludge process. When 250 mL of excess sludge with a MLSS concentration of approximately 2,000 mg/L was microwave-irradiated at $20^{\circ}C$ for $40\sim300$ sec by a microwave oven (2,450 MHz, 700 W), the temperature of the sludge increased at a rate of approximately $20^{\circ}C/min$ and the SCOD, TKN and T-P concentrations of the sludge showed the highest increase in the irradiation time of $40\sim130$ sec. And, the oxygen uptake rate measurement of the sludge microorganism suggested most of the microorganisms in the sludge were destroyed at an irradiation time above 130 sec(above $65^{\circ}C$). When the municipal wastewater and microwave-irradiated excess sludge was co-treated by the activated sludge process, almost no effect was observed in the pH and alkalinity of both the influent and effluent, but the influent concentrations of SS, COD, T-N and T-P increased. Even though the effluent SS, BOD and T-P concentrations showed almost no effect, the COD and TKN concentrations increased. The microbial yield coefficient decreased at a rate of 0.91 g SS/g COD removed as the irradiation ratio increased at a rate of 1 g SS/g SS-day.