• 상하수도학회지
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• 제21권2호
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• pp.195-201
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• 2007

A submerged flat-sheet membrane separation system integrated with PAC (powdered activated carbon) was used in this research in order to investigate the effects of PAC on the efficiencies of operation and treatment and to evaluate the performance of the system. The experiments were carried out under operating conditions of a filtration rate of 0.38 m/d, water temperature of $20-28^{\circ}C$, and PAC dose of 0 g/L (Run-A) and 20 g/L (Run-B). The influent concentrations of TOC (total organic carbon), $NH_4{^+}-N$ (ammonia nitrogen) and $UV_{254}$ (UV absorbance at 254 nm) were 2.48 mg/L, 1.4 mg/L and 2.53 1/m, respectively. TOC removal of 43.2 and 73.6%, ammonia nitrogen removal of 4.9 and 15.9%, and $UV_{254}$ removal of 20.6 and 31.6% were obtained for Run-A and Run-B, respectively. During an experimental period of 33 days, no change was found in TMP (Run-B), but the TMP in Run-A increased by 5 kPa after 29 days. This research showed that the filtrate quality and the performance efficiency were enhanced when PAC was introduced into the filtration system.

• 상하수도학회지
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• 제27권3호
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• pp.339-349
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• 2013

Biological treatment of RO concentrate from wastewater reuse process is known to be very difficult due to its high concentration of non-degradable organics and salt ions such as chloride, nitrate and phosphate. In this research, the treatment performance of MBR was examined using RO concentrate mixed with raw wastewater as the influent of MBR. Addition of PAC (powdered activated carbon) to MBR was also evaluated in order to enhance the treatment performance and stability. The performance of MBR for treating only RO concentrate decreased gradually although external carbon source was added. The average removal performance of MBR with and without PAC decreased from 99.1 %(98.8 %) to 94.9 %(91.4 %) for COD, 81.3 %(80.3 %) to 42.0 %(41.9 %) for T-N and 57.3(55.0 %) to 30.0 %(21.0 %) for T-P with the increase of RO concentrate mixing rate of 0 % to 20 % in the feed water. Addition of PAC showed positive effect on the performance of MBR for the removal of COD and phosphorus in case that the ratio of RO concentrate to feed water increased.

• 상하수도학회지
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• 제22권1호
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• pp.141-148
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• 2008

This study was conducted to evaluate the effect of PAC(Powder Activated Carbon) retention time on stable operation of high concentration powered activated carbon(HCPAC-MBR) in the treatment of secondary domestic wastewater. The pilot scale HCPAC-MBR system was operated at two different SRTs, 25 days and 100 days. The main drawback of HCPAC-MBR system was the rapid increase of trans-membrane pressure. The increase rate of trans-membrane pressure was proportional to SRT value at constant flux. This result seemed to be caused by reduced amount of EPS adsorbed on the PAC in the reactor by decreasing the SRT of the PAC. The particle size of the PAC was also influenced by SRT. The PAC size was decreased as SRT was increased. The change of particle size could be one reason for the change of trans-membrane pressure. The pore volume in the cake-layer formed on the membrane surface became to be increased by reducing SRT, because the cake-layer was highly composed of the PAC. Therefore, increased pore volume might play a role to reduce the trans-membrane pressure. The removal rate of E260 and TOC was also inversely proportional to SRT value.

• 한국농공학회지
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• 제32권3호
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• pp.102-115
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• 1990

Importance of anaerobic digestion as an energy generating device has been increased as fuel shortage becomes serieous. Several modification methods on the conventional digesters including Powdered Activated Carbon (PAC) addition and two-phase digestion were studied to enhance the gas production. This study investigated the effects of PAC on anaerobic digestion of chicken manure in terms of gas production and sludge stabilization. As a first experiment, an optimum PAC dose for efficient gas production was determined in a batch test. In semi-continuous experiments, an optimum Sludge Retention Time (SRT) at that PAC concentration and an overall substate utilization rate coefficient were investigated. A portion of gas increased by PAC addition was estimated using a substrate utilization rate coefficient of microorganisms attached on PAC. This test was performed in batch experiments using acetic acid as a substrate. The digesters for all experiments were kept 35${\pm}$ 1˚C in a heated water bath. Mixing was performed manually once a day and the produced gas was collected for daily reading. The following conclusions were made for this study. 1. Cptimum PAC concentration was 5% total solids, where gas production rate was increased by 20 percents. 2. Optimum SRT was 7.5 days. 3. Substrate utilization rate coefficient of microorganisms attached on PAC was about twice as much as that of suspended ones.

• Membrane and Water Treatment
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• 제9권4호
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• pp.285-292
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• 2018

In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high $R^2$ value). Finally, the results present that ANN provide best results ($R^2$ value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

• 대한환경공학회지
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• 제22권7호
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• pp.1319-1330
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• 2000

유기성폐슬러지를 염화아연과 황화칼륨으로 약품활성화하여 제조한 활성탄의 세공발달과 흡착특성을 연구하였다. 유기성폐슬러지로 제조한 탄소의 세공발달은 77K에서 질소흡착법을 이용하여 특성화하였다. 염화아연으로 약품활성화하여 제조한 $ZnCl_2$-활성탄은 활성화공정에 의해 미세공이 형성되었음을 지적해주는 BDDT 분류의 type I의 흡착특성을 보여주었다. 상용 분말활성탄과 $K_2S$-활성탄은 BDDT 분류의 type IV와 유사한 이력현상을 나타냈는데, 이것은 이들 활성탄에 중세공이 형성되었음을 말해준다. 이것은 $K_2S$-활성탄은 주로 중세공과 미세공으로 이루어졌으며, 거대세공의 발달은 미비하다는 것을 의미한다. 유기성폐슬러지로 제조한 $K_2S$-활성탄의 중금속 흡착능은 상용입상활성탄보다 우수한 것으로 나타났다. $K_2S$-활성탄에 대한 중금속의 흡착은 단분자층 흡착을 나타내는 Langmuir와 Freundlich 등온식에 잘 부합되었다. $PO_4$-P에 대한 흡착능은 $K_2S$-활성탄이 $ZnCl_2$-활성탄보다 우수한 것으로 나타난 반면, $NO_3$-N의 흡착은 $ZnCl_2$-활성탄이 우수한 것으로 나타났다. 본 연구결과, 활성화제로 염화아연과 황화칼륨을 사용하여 유기성폐슬러지를 약품처리할 경우, 탄화와 활성화공정을 거치는 2단계 공정을 통하여 상용입상활성탄보다 흡착능이 뛰어난 활성탄을 제조할 수 있었다.

• Carbon letters
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• 제13권3호
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• pp.167-172
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• 2012

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb (II) removal. This procedure is based on using powdered activated carbon, which was prepared from walnut shells that were generated as plant wastes and modified with potassium carbonate and phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb (II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich adsorption models. The kinetic study of Pb (II) on activated carbon from walnut shells was performed based on pseudo- first order and pseudo- second order equations. The data indicate that the adsorption kinetics follow the pseudo- second order rate. The procedure was successfully applied for Pb (II) removal from aqueous solutions.

• Carbon letters
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• 제13권2호
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• pp.115-120
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• 2012

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb(II) removal. The study was based on using powdered activated carbon, which was prepared from walnut shells generated as plant wastes and modified with potassium carbonate or phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb(II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich adsorption models. The kinetic study of Pb(II) on activated carbon from walnut shells was performed based on pseudo-first order and pseudo-second order equations. The data indicate that the adsorption kinetics follow the pseudo-second order rate. The procedure was successfully applied for Pb(II) removal from aqueous solutions.

• 상하수도학회지
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• 제22권5호
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• pp.511-516
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• 2008

Since 1989, Advanced drinking water treatment processes began to build in Korea, especially the water treatment plants around the Nak-dong river stream due to sequential pollutant accidents. Moreover, Advanced drinking water treatment processes, ozone and GAC, are again to be built in water treatment plants around Han-river stream to control taste and odor, micro pollutants. However, there are still a lot of discussion to decide the processes to apply for advanced treatment. Thus there are still need to understand clearly on the cost evaluation of each advanced treatment processes. The cost evaluation was accomplished based on the data of six water treatment plants which are currently being either operating or constructing. Exceptionally, PAC(Powdered Activated Carbon) process was evaluated with cost estimation from construction company. The capital cost per unit volume of ozone process was significantly decreased as the treatment capacity increased. The capital cost was in the order of GAC, ozone and GAC. The operation cost decreased in the order of PAC, GAC and ozone. The total cost considering present value shows that ozone process covers 84% of ozone and GAC process for $30,000m^3/d$ capacity while it covers less than 35% for over 140 thousands $m^3/d$ capacity. Comparing GAC only, and ozone/GAC process, ozone/GAC process is more cost effective for high capacity water treatment plant.

• Environmental Engineering Research
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• 제23권3호
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• pp.301-308
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• 2018

We investigated simultaneous removal of heavy metals such as Cr, Ni, and Zn by adsorption onto powdered activated carbon (PAC) and PAC modified with sodium diethyldithiocarbamate (PAC-SDDC). Modification of PAC was confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy and energy dispersive X-ray spectroscopy. Both PAC and PAC-SDDC reached adsorption equilibrium within 48 h, and the adsorption kinetics followed a pseudo-second order reaction kinetics. The removal of metals was enhanced with increasing both adsorbent dosage and followed the descending order of Cr > Ni > Zn for PAC and Cr > Zn > Ni for PAC-SDDC, respectively. Adsorption kinetics followed pseudo-second order kinetics. Adsorption kinetic results were well fitted by the Freundlich isotherm except for Cr adsorption onto PAC. The optimum pH for heavy metal adsorption onto PAC was 5, whereas that for PAC-SDDC ranged from 7 to 9, indicating that modification of PAC with SDDC significantly enhanced heavy metal adsorption, especially under neutral and alkaline pH conditions. Our results imply that SDDC modified PAC can be applied to effectively remove heavy metals especially Cr in plating wastewaters without adjusting pH from alkaline to neutral.